Deutsche Neutronenstreutagung

Lithium-ion batteries are the popular choice for power sources in consumer electronics. As they have achieved a tremendous boost in their performance in the last decades, they are being increasingly employed in electrical vehicles and grid-scale energy storage systems as well.

However, there is still room for improvement in terms of life expectancy, safety, cost, energy storage capabilities and interfacial stabilities. In this regard, understanding fundamental aging mechanisms that lead to capacity fade in Li-ion batteries becomes important to design batteries with improved components for performance enhancement.

With help of several examples, this presentation will reveal how different aging contributors such as loss of electrochemically active Li, active material degradation, and Li metal deposition can be detected using neutrons and conventional lab-based methods. For each of these cases, I will demonstrate how we optimized electrode design with feedback from obtained data and enhanced cell performance by positively affecting key parameters such as lifetime, charging rate, energy density, interfacial stability, and safety.

For example; using anodes containing mesocarbon microbeads instead of needle coke graphite we obtained faster charging capabilities and a longer lifetime [1]; by coating electrodes with polymers we achieved interfacial stability and obtained superior cycling performance [2]; by using Co-free cathodes and extending the operating voltage limits, we achieved both reductions in costs and increase in energy densities compared to conventional cathodes [3]; by incorporating silicon in anodes, we obtained increased energy densities compared to conventional anodes [4,5].

[1] N. Paul, J. Wandt, S. Seidlmayer, S. Schebesta, M. J. Mühlbauer, O. Dolotko, Hubert A. Gasteiger, R. Gilles, Journal of Power Sources, 85, 345 (2017).
[2] Z. Huang, S. Choudhury, N. Paul, J. H. Thienenkamp, P. Lennartz, H. Gong, P. Müller-Buschbaum, G. Brunklaus, R. Gilles, Z. Bao, Advanced Energy Materials, 12, 2103187 (2022).
[3] N. M. Jobst, N. Paul, P. Beran, M. Mancini, R. Gilles, M. Wohlfahrt-Mehrens, P. Axmann, Journal of the American Chemical Society 145, 4450 (2023).
[4] N. Paul, J. Brumbarov, A. Paul, Y. Chen, J.‐F. Moulin, P. Müller-Buschbaum,J. Kunze-Liebhäuser, R. Gilles, Journal of Applied Crystallography, 48, 444 (2015).
[5] E. Moyassari, L. Streck, N. Paul, M. Trunk, R. Neagu, C.-C. Chang, S.-C. Hou, B. Märkisch, R. Gilles, A. Jossen, Journal of the Electrochemical Society, 168, 020519 (2021).

The hydrogen storage in light-weight hydrides for mobile applications is an extensively discussed but a rather controversial topic. Is it safe enough? Is it efficient enough? Does the hydrogen energy have future? The questions are numerous and complicated and hardly any of them has a definite answer yet. A complex hydride system 6Mg(NH2)2:9LiH with LiBH4 as a dopant is one of promising candidates on a role of on-board hydrogen storage, since it it actively decomposes with hydrogen-only emission already at the 180oC. The role of the LiBH4 is expressed in forming of an low-melting liquid-phase with high hydrogen mobility with an intermediate product LiNH2, which highly enhances the rate of the dehydrogenation reaction. There are 2 mixed phases with a high Li-ion conductivity described: a metastable Li2BH4NH2 and a peritectically melting Li4BH4(NH2)3, and both of these phases were registered while performing DSC and XRD measurements. This 2-component system is investigated and a number of ratios was analyzed and thereupon a phase diagram was plotted. Its lowest melting point, i.e. eutectic point is located at 33% LiNH2 and at 90oC. The behavior under heating and the intrinsic structure of this eutectic composition was investigated by neutron total scattering. The composition corresponding to this eutectic mixture would be 6Mg(NH2)2:9LiH:6LiBH4.

We present recent findings from neutron diffraction measurements on hyperbranched polymer (HBP) dispersed nanocomposite gratings, revealing the highest scattering length density (SLD) modulation amplitudes to date. Optimized for light diffraction, these materials exhibit ultrahigh refractive index modulation (∼ 3×10^(-2)). The first test for slow neutron diffraction was conducted at the SANS-I instrument in Paul Scherrer Institute, using a grating with the optimal composition for light diffraction as described in Ref. [1]. Despite the low diffraction efficiency values, due to the very small grating thickness (< 10 µm) and the relatively short neutron wavelength used (≃ 2 nm), a five-coupled-waves analysis revealed SLD modulation amplitudes surpassing our recently reported records with nanodiamond-based gratings in Ref. [2]. Higher diffraction efficiencies at longer neutron wavelengths, such as those available at the ILL's PF2 instrument, are promising. The task of fabricating two- to three-times thicker gratings in the future becomes demanding. Our findings contribute to the development of reliable and efficient optical elements for slow neutron experiments.
[1] A. Narita et al., Opt. Mater. Express, 11(3), 614-628, 2021.
[2] E. Hadden et al., Appl. Phys. Lett., 124(7), 071901, 2024.

Additive manufacturing methods such as laser powder bed fusion offer an enormous flexibility in the efficient design of parts. In this process, a laser locally melts feedstock powder to build up a part layer-by-layer. It is this localized processing manner imposing large temperature gradients, resulting in the formation of internal stress and characteristic microstructures. Produced parts inherently contain high levels of residual stress accompanied by columnar grain growth and crystallographic texture. On a smaller scale, the microstructure is characterized by competitive cell-like solidification with micro segregation and dislocation entanglement. In this context, it is crucial to understand the interplay between microstructure, texture, and residual stress to take full advantage of the freedom in design. In fact, X-ray and neutron diffraction are considered as the benchmark for the non-destructive characterization of surface and bulk residual stress. The latter, characterized by a high penetration power in most engineering alloys, allows the use of diffraction angle close to 90°, enabling the employment of a nearly cubic gauge volume. However, the complex hierarchical microstructures produced by additive manufacturing present significant challenges towards the reliable characterization of residual stress by neutron diffraction. Since residual stress is not the direct quantity being measured, the peak shift imposed by the residual stress present in a material must be converted into a macroscopic stress. First, an appropriate lattice plane must be selected that is easily accessible (i.e., high multiplicity) and insensitive to micro strain accumulation. Second, a stress-free reference must be known to calculate a lattice strain, which can be difficult to define for the heterogeneous microstructures produced by additive manufacturing. Third, an appropriate set of diffraction elastic constants that relate the lattice strain to the macroscopic stress must be known.
In this presentation, advancements in the field of residual stress analysis using neutron diffraction are presented on the example of the Ni-based superalloy Inconel 718. The effect of the complex microstructure on the determination of residual stress by neutron diffraction is presented. It is shown, how to deal with the determination of the stress-free reference. It is also shown that the selection of an appropriate set of diffraction elastic constants depends on the microstructure. Finally, the role of the crystallographic texture in the determination of the residual stress is shown.

Surface functionalization is needed for synthesizing and controlling the properties of iron oxide nanoparticles (IONPs) in various applications for biomedicine, ferrofluids, or heterogeneous catalysis [1,2]. Yet, experimental investigations of interfacial properties such as the dynamics of ligand and water molecules near the nanoparticle surface have been scarce. Previously, quasielastic neutron scattering (QENS) was successfully used to access the dynamics of water molecules on surfaces of TiO2 and SnO2 nanoparticles [3]. QENS studies of ligand dynamics on the surface of nanoparticles have also emerged recently. Dodecanethiol on PbS nanoparticles and oleates on IONPs were shown to exhibit rotational motion [4,5]. However, the dynamics of citrate ligands on the surface of magnetic IONPs are largely unknown. We report on QENS experiments on 6 nm IONPs synthesized according to ref [6] and equilibrated at 8 % relative humidity in H2O (measured at IN16B, ILL) and D2O (measured at Emu, ANSTO). Energy-resolved measurements as well as elastic and inelastic fixed window scans were performed in the temperature range of 2 – 380 K, covering a Q-range of 0.19 – 1.83 Å-1. Given the complex quasielastic scattering signal including the magnetic nature of the IONPs, we demonstrate the power of fixed window scans in separating multiple, dynamic processes, thermal vibrations, magnetic relaxations, and hydrogen dynamics. Employing samples equilibrated in D2O allowed for distinguishing water and citrate motion. To create a complete dynamical model, we implemented a simultaneous fit approach for elastic and inelastic fixed window scans, as well as energy-resolved spectra at different temperatures. We observed that the introduction of additional datasets into a simultaneous fit routine increases the stability of the fit, allowing for the application of more complex models. Further, the Q-dependence of energy-resolved spectra shows, that citrate molecules only exhibit a rotational motion on the IONPs surface, while water diffuses translationally.

[1] Y. Sahoo, et al., J Phys Chem B, 109, 3879–3885 (2005)
[2] E. Amstad, et al., Nanoscale, 3, 2819 (2011)
[3] E. Mamontov, et al., J. Phys. Chem. C, 111, 4328-41 (2007)
[4] M. Jansen, et al., ACS Nano, 12, 20517-20526 (2021)
[5] A. Sharma, et al., Chem. Phys., 156, 164908 (2022)
[6] M. Eckardt, et al., ChemistryOpen, 9, 1214–122 (2020)

The physical properties of complex oxides can be tuned via controlling oxygen vacancies thus enabling potential applications. In La0.7Sr0.3MnO(3-δ) (LSMO), the topotactic phase transition from the Perovskite (PV, ABO3) phase to the layered oxygen-vacancy-ordered Brownmillerite (BM, ABO2.5) phase can be triggered by deoxygenation. Here, we employed polished Aluminum foils as oxygen getter during the thermal vacuum annealing and realized the PV-to-BM phase transition in both a strained LSMO thin film system and bulk-like unstrained LSMO powder system. For LSMO thin films, the structural changes were monitored using X-ray Diffraction. A metal-to-insulator and simultaneously a ferromagnetic-to-antiferromagnetic transition is found. The variation of the manganese oxidation state is characterized using X-ray Absorption Spectroscopy. Rutherford Backscattering Spectroscopy implies a manganese-deficient BM phase after annealing. This BM phase shows in the magnetization vs. temperature curves a peculiar peak above room temperature which cannot be explained within the usual AF ordering at low temperatures. For LSMO powder, the evolution of the crystal structure and spin structure at different oxygen-deficient states from PV to BM is investigated using neutron diffraction. The neutron diffraction study hints at a process including multiple transitions of the crystal structure and spin structure.

The gradual ferromagnetic spin reorientation in the hcp phase of cobalt between 230°C and 330°C reported for a Co single crystal [1] suggests that this phase cannot have a hexagonal symmetry [2,3]. This hypothesis is verified positively by synchrotron radiation diffraction and neutron diffraction on powder of cobalt [4]. The hexagonal close packed phase of cobalt (hcp-Co) is associated with numerous stacking faults while the face centered cubic phase of cobalt (fcc-Co) has considerably less stacking faults, as shown e.g. in [5,6]. The analysis of diffraction data has been done by using a specific set of Bragg peaks, which are not affected by the stacking faults. The crystal structure of the hcp-type ordered areas of cobalt is described by a monoclinic symmetry with the magnetic space group C2'/m', where the former hexagonal [001] axis is no longer perpendicular to the hexagonal layers. The hexagonal [001] and [010] axes make an angle equal α≈90.10(1)°, while the angle between in-plane [100] and [010] axes equals γ≈120.11(1)°. In addition, we report [4] a one order of magnitude smaller lattice mismatch in the hexagonal planes between hcp-Co and fcc-Co than the mismatch of about 0.5% between the hexagonal layers in hcp-Co and fcc-Co layers [5, 6]. Williamson-Hall analysis shows that microstrains are larger inside hexagonal planes than along the stacking faults direction [4]. Moreover, a higher content of the fcc-Co phase reduces microstrains in hcp-Co [4].
[1] E. Bertaut, A. Delapalme and R. Pauthenet, Solid State Commun. 1 (1963) 81
[2] R. Przeniosło, P. Fabrykiewicz and I. Sosnowska, Acta Cryst. A74 (2018) 705
[3] P. Fabrykiewicz, R. Przeniosło and I. Sosnowska, Acta Cryst. A77 (2021) 327
[4] P. Kozłowski, P. Fabrykiewicz, I. Sosnowska, F. Fauth, A. Senyshyn, E. Suard, D. Oleszak and R. Przeniosło, Phys Rev. B107 (2023) 104104
[5] O. S. Edwards and H. Lipson, Proc. R. Soc. Lond. Ser. A-Math. Phys. Sci. 180 (1942) 268
[6] O. Blaschko, G. Krexner, J. Pleschiutschnig, G. Ernst, C. Hitzenberger, H. P. Karnthaler and A. Korner, Phys. Rev. Lett. 60 (1988) 2800

The barocaloric effect (BCE) is characterized as a thermal response (variation of temperature or entropy) in solid-state materials induced by external hydrostatic pressure and cooling technologies based on the BCE have emerged as a promising alternative to conventional vapor-compression cooling. Recently, spin crossover (SCO) transitions, where the low spin (LS) and high spin (HS) states can be switched by hydrostatic pressure, were proposed as a potential mechanism to generate outstanding BCE. The considerable overall entropy change across the SCO transition is primarily attributed to the significant change in lattice vibration, which is directly linked to the dynamic features.
In this study, we correlate the structural changes of a classic SCO complex Fe(PM-BiA)2(NCS)2 (with PM = N-2’- pyridylmethylene and BiA = 4-aminobiphenyl) in the vicinity of a spin transition as functions of temperature and pressure with the dynamic properties and aim at a better understanding of the role of cooperativity on the transition. The two polymorphs of Fe(PM-BiA)2(NCS)2 are ideal in this respect, as the orthorhombic polymorph (Pccn) features a high cooperativity indicated by an abrupt transition, while the gradual transition in the monoclinic polymorph (P21/c) hints towards a low cooperativity. From the structural studies, we determined which intermolecular interactions (hydrogen bridges, π-π interactions, van der Waals interactions) play a key role at the spin transition in both polymorphs.
We investigate the changes in dynamic features at the temperature- and pressure-induced spin transition using different spectroscopic methods on a wide range of energy and time scales in combination with ongoing ab-initio modelling. Raman and IR spectroscopy give access to the energy difference of vibrational energy levels in the molecules. The Fe-related phonon density of states in the monoclinic polymorph is obtained through nuclear inelastic scattering (NIS) to extract the Fe-related vibrational entropy change in the energy range well below 100 meV. The result from quasi-elastic neutron scattering (QENS) confirms the existence of dynamic disorder in the order of picoseconds corresponding to sub-meV energy. Our combined approach allows us to unravel the different entropy contributions (electronic, vibrational, configurational) to the overall entropy change at the spin transition.

Mixed valence lead oxide phases obtained at ambient pressure are reported by Byström [1] belonging to either black [2] or red minium [1, 3]. For red minium the composition of Pb₃O₄ is described without any variance in the number of oxygen atoms [1, 3]. The formula could therefore be written as Pb(II)₂Pb(IV)O₄, expressing the different oxidation states of lead. For the black minium Byström [1] proposed two structures, namely, α-PbO_x and β-PbO_x. Pure α-PbO_x exits for 1.628 (~ Pb₁₂O_19.5) > x ≥ 1.475 (~ Pb₁₂O_17.7). For lower x, β-PbO_x and red minium coexist in the range of x = 1.475 – 1.352 (~ Pb₁₂O_16.2). We synthesized phase pure Pb₁₂O₁₉ by decomposing PbO_1.96(2) at 600 K for 1390 h, showing a dark brown color. Neutron time-of-flight (TOF) total scattering data (nPDF) were collected on the powder diffractometer POWGEN@SNS (Oak Ridge National Lab, USA) within the Proposal IPTS-20531 and respective synchrotron radiation data (xPDF) on the P02.1@Petra III (DESY, Germany) powder diffractometer at E = 59.78(3) keV (λ = 20.74(4) pm). The combined machine-learning (ML) – density function theory (DFT) – pair distribution function (PDF) approach [4] was used to refine the structure of Pb₁₂O₁₉ starting with an unbiased set of structural models using both neutron and X-ray PDF data sets at the same time. Based on the ML-DFT-xPDF-nPDF refinements a structure model with a 2x2x1 bigger unit cell compared to those reported by Byström [1] was found. Instead of the CaF₂-type [1] derived arachno-cube like coordination of the lead atoms, which could hardly be described as strongly distorted octahedra, different coordination numbers were found, giving rise for differently pronounced stereo-chemical activities of the Pb 6s² lone pairs and void channels in the structure which might be described with a triangular shape. The new crystal structure enables to additionally describe the non-explained weak reflections of the earlier findings [1].
1] A. Byström, Arkiv Kemi Mineral. Geol. 20(4) (1945) 1-31.
[2] M. Le Blanc, E. Eberius, Z. für Phys. Chem. 160A(1) (1932) 69-100.
[3] S.T. Gross, J. Am. Chem. Soc. 65(6) (1943) 1107-1110.
[4] M. Klove, S. Sommer, B.B. Iversen, B. Hammer, W. Dononelli, Adv Mater (2023) e2208220.

Figure: PDF-Plots of the refinement of the Pb₁₂O₁₉ structure to the synchrotron (a) and neutron data (b).

The exchange coupling in bimagnetic core-shell nanoparticles is a promising pathway to permanent magnetic materials [1]. For iron oxide core-shell nanoparticles, consisting of a wuestite-like particle core and a spinel-type shell, transition metal doping was recently shown to significantly enhance the magnetic anisotropy and exchange coupling [2]. Native iron oxide core-shell nanoparticles synthesized by thermal decomposition of iron oleate typically form as an intermediate through topotaxial oxidation of an initial wuestite phase towards highly defective maghemite [3]. We have recently reported how the combination of such native core-shell nanoparticles (with their alignment of core and shell phases) and cobalt doping leads to a significant enhancement of the exchange pinning between both phases, which is promising for a rational synthesis of nanoparticles with strong coercivity and exchange field. Using magnetic SANS [4,5], we have unambiguously revealed a significant net magnetization even in the wuestite-type nanoparticle core that is commonly presumed antiferromagnetic or paramagnetic at room temperature [6].

In this contribution, we will present the systematic influence of a subtle variation in particle size on the exchange coupling within such native core-shell, Co-doped iron oxide nanoparticles. For freshly synthesized samples with a particle diameter ranging from 8.5 to 9.6 nm, a clear transition from exchange spring to exchange bias behavior is evident. We employ magnetic SANS to elucidate the intraparticle magnetization individually for the wuestite-like particle core and the spinel-type shell and to follow their coupling mechanism.

References:

[1] A. López-Ortega et. al., Phys. Rep. 553, 1−32 (2015).
[2] B. Muzzi et. al., Small 18, 2107426 (2022).
[3] E. Wetterskog et al., ACS Nano 7, 7132–7144 (2013).
[4] S. Mühlbauer, S. Disch, A. Michels et al., Rev. Mod. Phys. 91, 015004 (2019).
[5] D. Zákutná, S. Disch et al., Phys. Rev. X 10, 031019 (2020).
[6] D. Zákutná, N. Rouzbeh, S. Disch et al., Chem. Mater. 35, 2302–2311 (2023).

In the superconductor niobium the vortex-vortex interaction exhibits in addition to the purely repulsive also an attractive term. This leads to the formation of the intermediate mixed state (IMS) where flux-free Meissner state domains and mixed state domains filled with vortex lattice coexist separated on the micrometer length scale. Besides being a prominent example of exotic vortex matter this two-phase structure can also act as a highly tunable model system for universal domain physics as both the intervortex distance and the domain structure can be tuned via the magnetic field and temperature [1].
Small angle neutron scattering (SANS) is the ideal tool to study the Bragg peaks from the vortex lattice with inter-vortex distances of 100-200 nm. Given the rough upper limit in SANS of 1 micrometer it struggles to capture the diffuse scattering from the domain boundaries with sizes of up to 50 micrometers. However, the power-law tail of the diffuse scattering extends into the SANS regime and contains valuable information about the domain structure. Conventionally, the power-law of diffuse scattering is analyzed using the Porod law connecting the scattering intensity to the specific surface area of randomly distributed scattering particles [2]. We show that in the specific case of the IMS, where the domain boundaries are close to parallel to the direct beam, the specific surface area can be interpreted as an inverse length corresponding to the size of the domain structure [3]. Using this approach, that takes into account the alignment of the domain boundaries along the beam direction to extract the correct specific surface area, we are able to extend the accessible length scales from 1 micrometer to up to 40 micrometers using a standard SANS setup.
Our results fit well with Landau's theory of superconducting domains [4], previous attempts of extracting this length scale using ultra small angle neutron scattering [5] and highlight the power of our approach of extending the accessible length in SANS to the micrometer regime. Our analysis approach should be applicable to other two-phase systems where the domain boundaries are close to parallel to the incoming neutron beam.
[1] A. Backs et al., Phys. Rev. B 100, 064503 (2019).
[2] G. Porod, Small angle X-ray scattering, pp. 15–51. Academic Press (1982).
[3] X. Brems et al., in preparation (2024).
[4] L. Landau, JETP, 7, 371 (1937).
[5] T. Reimann et al. Phys. Rev. B 96, 144506 (2017).

RMn6Sn6 (R=Gd-Lu, and Y) family is a subject of current interest owing to its Mn-Kagome lattice, which can host exotic topological quantum states and frustrated magnetism [1]. Tuning the rare-earth ions in RMn6Sn6, where R is magnetic, can engineer the topological transport properties, including quantum oscillation and the anomalous Hall effect (AHE) [2, 3], thus indicating a close relationship between the localized rare-earth magnetism and topological band structures. In this talk, we will present our recent investigations on three representative systems: for R without spin-orbit coupling L=0 (GdMn6Sn6), for R with spin-orbit coupling J=L+S (DyMn6Sn6), and for R with mixed valances (YbMn6Sn6). We mainly used single-crystal hot-neutron diffraction to solve the magnetic structures to reduce the neutron absorption by the natural Gd and Dy elements. Our refinement of the magnetic structure shows that GdMn6Sn6 exhibits a ferrimagnetic order. Interestingly, the DyMn6Sn6 exhibits ferrimagnetic order with spin reorientation behavior. Distinguishably, neutron diffraction on YbMn6Sn6 (with mixed Yb2+and Yb3+ valances) reveals a ferromagnetic order of the Mn moments, but without the ordering of the Yb ions, indicating that the Yb is non-magnetic. Our studies clearly suggest that the magnetic anisotropy of the rare-earth ion (R) plays a crucial role in controlling the spin orientation of the Mn kagome layers. The solved magnetic structures will help further in gaining more understanding of the underlying physics and its correlation with the topological properties in this family.

The spin-$1/2$ Heisenberg model on the antiferromagnetic kagome lattice is one of the fundamental models in frustrated quantum magnetism with a predicted quantum spin liquid (QSL) ground state, spinon excitations and a complex sequence of magnetization plateaus in applied magnetic fields [1-3]. From an experimental viewpoint, the mineral herbertsmithite with uniform couplings in the kagome layer stands out as candidate material featuring a QSL ground state [4]. Recent advances in quantum magnetism also explicitly cover deformed kagome lattices leading to many different motifs of non-uniform exchange couplings containing novel physics (see, for instance, Refs. [5,6]).

Here, we present a combined experimental and theoretical study on clinoatacamite, Cu$_2$Cl(OH)$_3$ [7], a mineral which is closely related to herbertsmithite. By means of density-functional theory we have derived the dominant magnetic exchange paths in this material forming non-uniform antiferromagnetic kagome layers of Cu sites with weak ferromagnetic coupling to the interlayer Cu site. Experimentally, we have investigated the zero-field magnetic phase diagram of clinoatacamite by means of thermodynamic measurement techniques as well as neutron diffraction using for the first time single-crystalline material. In agreement with earlier studies, we have found a transition of little entropic change at $T_\mathrm{N} = 18.1~\mathrm{K}$ (with an order parameter developing below this temperature) [8]. Further, we have resolved for the first time a sequence of two close-lying transition anomalies at $6.2$ and $6.4~\mathrm{K}$, which leads to a large entropy change in the material. We have refined the magnetic structure at $1.7~\mathrm{K}$ based on single-crystal neutron diffraction data and present inelastic neutron scattering results revealing the low-energy spin excitations in the same temperature region.

[1] C. Broholm et al., Science 367, eaay0668 (2020).
[2] L. Balents, Nature 464, 199 (2010).
[3] S. Nishimoto et al., Nat. Commun. 4, 2287 (2013).
[4] P. Khuntia et al., Nat. Phys. 16, 469 (2020).
[5] O. Janson et al., Phys. Rev. Lett. 117, 037206 (2016).
[6] K. Matan et al., Nat. Phys. 6, 865 (2010).
[7] J. D. Grice et al., Can. Mineral. 34, 73 (1996).
[8] X. G. Zheng et al., Phys. Rev. Lett. 95, 057201 (2005).

Research into magnetic nanoparticles is being propelled by their promising applications across diverse fields such as medicine, biology, and nanotechnology. Numerous studies have highlighted their potential in targeted drug delivery, imaging, and hyperthermia treatment. However, assumptions about the uniformity of the magnetization distribution within nanoparticles, often made in application-oriented studies, can fall short in capturing the true complexity of these systems. This complexity is exemplified in magnetic hyperthermia, where microstructural defects may lead to enhanced specific absorption rates compared to defect-free particles. Understanding the spin structure of nanoparticles thus becomes pivotal not only for fundamental scientific inquiry but also for optimizing technological applications.

To delve into the magnetic microstructure of nanoparticles and its relation to macroscopic properties both observational and computational methods are crucial. Among experimental techniques, magnetic small-angle neutron scattering (SANS) stands out as it can probe spin structures on the mesoscopic length scale and within the volume of magnetic materials. Consequently, numerous experimental SANS investigations, including those on ferrofluids, have been conducted to date, revealing a plethora of nonuniform spin configurations within nanoparticles. These configurations range from canted to vortex-type or core-shell-type arrangements, underscoring the rich complexity of magnetic behavior at the nanoscale.

Complementing experimental efforts, numerical micromagnetic simulations are increasingly valuable in predicting nanoparticle spin structures and their related scattering signatures. These simulations consider various factors influencing the magnetic ground state of nanoparticles, such as particle size, shape, defects, and magnetic interactions. Here, by combining SANS with numerical micromagnetic computations, we discuss the transition from single-domain to multi-domain behavior in nanoparticles and its implications for the ensuing magnetic SANS cross section. Above the critical single-domain size we find that the cross section and the related correlation function cannot be described anymore with the uniform particle model, resulting, e.g., in deviations from the well-known Guinier law. In the simulations we identify a clear signature for the occurrence of a vortexlike dipolar-energy-driven spin structure at remanence---the magnetic correlation function exhibits a damped oscillatory behavior. Recent experimental SANS data on an isotropic Nd-Fe-B magnet seem to support the occurrence of mesoscaled flux-closure patterns in the magnetic microstructure that give rise to the corresponding feature in the correlation function. The resulting field dependence of the correlation length (see figure) exhibits a power-law behavior that varies with a different exponent than the numerically-computed data, which poses a challenge to theory.

Neutron spectroscopy gives unique insight into microscopic dynamics and excitations in matter. Crystal spectrometers such as IN16B at the Institut Laue-Langevin in Grenoble (France) operating in backscattering provide high energy resolution down to sub-micro-eV. While IN16B serves its international user community for about a decade by now, we continuously strive to improve and extend its capabilities with new developments. In this presentation, we will review past and ongoing projects.

A first upgrade phase has been successfully completed and brought into routine user operation with the so-called BATS option (Backscattering And ToF Spectrometer) which offers an energy transfer range increased by more than one order of magnitude. In parallel, the feasibility for a future construction of an ultra-high energy resolution spectrometer based on GaAs 200 could be demonstrated.

The second key enhancement currently ongoing concerns the installation of a 10m long variable focusing/defocusing neutron guide system for the BATS chopper system. This innovative and unique upgrade is already partially commissioned and brings BATS to its full potential in terms of neutron flux.

Last but not least, we are currently implementing an extension of the instrument’s capabilities at low scattering angles, which entails re-designing the low angle analyser section and improvements of the detector arrangement. This will strengthen both the ‘classical’ high-resolution backscattering as well as the BATS mode on IN16B.

POWTEX is a TOF neutron powder diffractometer [1] under construction at MLZ. Funded by the Federal Ministry of Education and Research (BMBF, 05K22PA2), it is built by RWTH Aachen University and Forschungszentrum Jülich. Dedicated texture sample environments are contributed from Geo Science Centre at Göttingen University.
Several new concepts have been developed and components built. The two double-elliptic neutron-guides featuring octagonal cross sections with graded super-mirror coating are focusing on the sample, resulting in Gaussian intensity and divergence distributions [2]. Their common focal point at the pulse-chopper serves as “eye of a needle” in time and space, optimizing time-resolution and reducing the source background. The innovative, solid ¹⁰B jalousie volume detector was tailormade for POWTEX [3] and achieves high efficiency for a remarkably large coverage of nine steradians with almost no blind spots. The current status of components, their tests and implementation at MLZ will be shown.
POWTEX aims for short measurement times and in situ chemical experiments, e.g., phase-transitions as a function of T, p, and B₀. For texture-analysis, in situ deformation, annealing, simultaneous stress, etc., the large angular coverage drastically reduces the need for sample tilting/rotation.
As regards theoretical concepts, multidimensional data-reduction algorithms handling angular- and wavelength-dispersive data-sets have been developed and implemented, e.g. in Mantid [6], plotting intensity as function of the newly introduced orthogonal coordinate-system d, d_⊥ [4,5] as alternative to λ, 2θ coordinates. This very procedure, in addition to analytical instrument parametrizations based on fundamental design values, has allowed for multidimensional Rietveld analysis using a modified version of GSAS-II for various TOF diffractometers (POWGEN@ORNL, POWTEX@POWGEN@ORNL, SNAP@ORNL) and various samples (powdered diamond, BaZn(NCN)₂, PbNCN, Fe(dca)₂(py)₂), hence demonstrating the applicability of the method.

[1] Conrad H., Brückel Th., Schäfer W. and Voigt J., J. Appl. Cryst., 2008, 41, 836.
[2] Houben A., Schweika W., Brückel Th. and Dronskowski R., Nucl. Instr. and Meth. A, 2012, 680, 124.
[3] Modzel G., Henske M., Houben A., Klein M., Köhli M., Lennert P., Meven M., Schmidt C. J., Schmidt U. and Schweika W., Nucl. Instr. Meth. A, 2014, 743, 90.
[4] Jacobs P., Houben A., Schweika W., Tchougréeff A.L. and Dronskowski R., J. Appl. Cryst., 2015, 48, 1627.
[5] Jacobs P., Houben A., Schweika W., Tchougréeff A.L. and Dronskowski R., J. Appl. Cryst., 2017, 50, 866.
[6] PowderReduceP2D, Mantid 6.8, October 2023, dx.doi.org/10.5286/Software/Mantid6.8.
[7] Houben, A.; Jacobs, P.; Meinerzhagen, Y.; Nachtigall, N.; Dronskowski, R., J. Appl. Cryst., 2023, 56, 633–642.

Magnetic systems are fertile ground for the design of novel quantum and topologically non-trivial states characterized by exotic excitations. Recent examples include spin chain and square-lattice low-dimensional antiferromagnets, quantum spin liquid candidates, spin-ice compounds, and unusual spin textures. These systems are not only of fundamental interest but may also pave the way to new technologies. For example, skyrmion spin textures open new possibilities for data storage in race track memories [1] and allow for the design of electronic–skyrmionic devices [2]. Key features of the ground state and finite-temperature behavior of a magnetic system are captured by the spectrum of its excitations. All of the aforementioned systems reveal exotic excitations dissimilar to standard magnons that form narrow bands in conventional ferro- and antiferromagnets. The detection of exotic excitations is by far more challenging, as they show broad distribution in the energy and momentum space.

We present a concept for an indirect geometry crystal time-of-flight spectrometer, which we propose for the FRM-II reactor in Garching. Recently, crystal analyzer spectrometers at modern spallation sources have been proposed and are under construction [3]. The secondary spectrometers of these instruments are evolutions of the flat cone multi-analyzer for three axis spectrometers (TAS). The instruments will provide exceptional reciprocal space coverage and intensity to map out the excitation landscape in novel materials. We will discuss the benefits of such a time-of-flight primary spectrometer with a large crystal analyzer spectrometer at a continuous neutron source. The dynamical range can be very flexibly matched to the requirements of the experiment without sacrificing the neutron intensity. At the same time, the chopper system allows a quasi-continuous variation of the initial energy resolution. The neutron optic of the proposed instrument employs the novel nested mirror optics [4], which images neutrons from a bright virtual source onto the sample. The spot size of less than 1 cm x 1 cm at the virtual source allows the realization of very short neutron pulses by the choppers, while the small and well-defined spot size at the sample position provides an excellent energy resolution of the secondary spectrometer thanks to the prismatic focusing of the analyzer.

[1] Shu Y. and et al., JMMM, 568:170387, 2023.
[2] Zang X. and et al., Science Report, 5:11369, 2015.
[3] R.I. Bewley, Nucl. Instr. Meth. Phys. Res. A, 998:165077, 2021.
[4] C. Herb, O. Zimmer, R. Georgii, P. Böni., Nucl. Instr. Meth. Phys. Res. A, 1040:167154, 2022.

Grazing incidence small angle neutron scattering (GISANS) is a powerful techniqu to investigate surface-near lateral structures on the nanometer scale. It is particulary useful in soft-matter experiments to disentangle surface near structures from bulk effects. But even in hard-matter magnetism the technique can be used to improve the signal when scattering from magnetic particles on or near surfaces.

One chellange of the technique is the need for SANS-like angular resolution while the sample geometry is more similar to reflectometers and wavelength resolution requirements can vary strongly in dependence of the science case. When investigating effects on the surface of liquids, the additional need for changing of reflection angle on a horizontal sample surface arises.
To tackle these challenges we have started to develop a novel instrument concept as part of an investigation into a new guide hall at the PSI SINQ neutron source. The Adjustable Monochromator to Perform Liquid grazing Incidence, Focused or magnetic Yoneda scattering (AMPLIFY) makes use of two parabolic multilayer monochromators to provide a tunable wavelength resolution between 2% and 10% Delta Lambda/Lambda. The neutron optics deflect the beam by 24° and end at 10 m from the sample, leading to low background and flexible collimation. The sample stage can be moved vertically to change the incident angle with the collimation system tilting down to follow. A fixed detector vessel with large entrance window evacuuates the flight path after the sample.
With 10 Å wavelength, 10 m collimation and 20 mm sample width the GISANS resolution would be moderate compared to typical SANS machines. Replacement of the second monochromator mirror with a different shape will allow to focus the beam onto the detector for high resolution experiments on sample width up to 50mm.

We have compared the expectec instrument performance with a SANS-like configuration. For collimations in the range of 5m to 20m AMPLIFY can reach similar or better angular resolution with slightly higher intensity and more homogenous beam profile. When increasing the wavelength resolution, a SANS-like instrument would require an additional chopper which would further decrease the efficiency.

Advances in neutron instrumentation and techniques offer new opportunities for researchers. At the same time there is an increasing demand to make measured data accessible to the wider community through improved research (meta)data- management, and for implementation of FAIR data principles by which data should be made Findable, Accessible, Interoperable and Reusable. The challenge is becoming even greater due to increasing data rates, multi-dimensional data sets and in-situ / operando experiments.

The consortium DAPHNE4NFDI (DAta from PHoton and Neutron Experiments for NFDI) addresses this challenge within the German National Research Data Infrastructure (NFDI), in relation to European/worldwide initiatives [1]. Users and facilities engage to develop data solutions and infrastructure for the wider photon and neutron community. New data management and analysis schemes are established, metadata capture for re-use with searchable catalogues is deployed, and on-the-fly data analysis and reduction are developed in the consortium.

This presentation will give an overview of our activities and elaborate on our progress, showcasing progress in some of our use-cases including:

(1) Data@MLZ: Providing FAIR data combined with user friendliness, the qualified data chain is built on the metadata catalogue SciCat and an electronic laboratory notebook, including persistent sample identifiers, different interfaces and community-specific metadata specifications. For several techniques, “ML-readiness” of (meta)data will be available. The data chain is tested on virtual instruments.

(2) SECoP&DAPHNE: The flexible SECoP protocol facilitates the integration of sample environment devices into experiments and complements the FAIR metadata collection on the facility side by automatically providing metadata regarding the sample environment.

(3) Combination of simulation and experiment: The program Sassena was further developed to compute simultaneously correct small-angle and wide-angle diffractograms, and the incoherent intermediate scattering function. [2]

(4) TOF neutron diffraction: To exploit the large-area detectors on new neutron TOF diffractometers, multidimensional Rietveld refinement needs to be applied [3]. Based on a fundamental instrument description, all instrument parameters are provided as NeXuS files, and metadata are available for the treatment and analysis process as well as for AI aided structure solution methods.

References
[1] A. Barty et al., Zenodo, DAPHNE4NFDI - Consortium Proposal, 2023. https://doi.org/10.5281/zenodo.8040606
[2] A. Majumdar et al.: Int. J. Mol. Sci. 2024, 25(3), 1547.
[3] A. Houben et al.: POWTEX visits POWGEN, J. Appl. Cryst.56, 633–642(2023).

This work was supported by the consortium DAPHNE4NFDI in the context of the work of the NFDI e.V. The consortium is funded by the DFG - project number 460248799.

Neutron scattering in high-pressure environments offers unique opportunities to measure the physical properties of matter but faces challenges due to low signal intensity and high background noise. In this study, Monte Carlo simulations were employed to identify background sources in low-temperature and high-pressure sample environments at the SINQ instrument CAMEA. Simulation results suggest that the piston pressure cell (PC) contributes significantly to the background noise in neutron scattering experiments. To counter this background, a compact radial neutron collimator was developed to reduce background in the sample environment, and its performance was evaluated experimentally. Measurements show that the collimator reduces the background generated by the PC effectively, especially for low q. Noise from the collimator was observed, and strategies to address this issue were discussed.

Diffraction studies during chemical reactions reveal details of reaction
pathways, which are often crucial in the synthesis of functional materials.
Neutron diffraction is particularly valuable as a probe due to its sensitivity to light elements in the presence of heavy elements, especially in gas reactions involving elements such as hydrogen, nitrogen, oxygen, and carbon oxide. Therefore, it is necessary to develop sample environment tailored for in situ neutron diffraction experiments at high temperatures and gas flow, with low background noise and good neutron penetration.
A series of gas-pressure and gas-flow cells based on sapphire single crystals have been developed for real-time, in situ neutron diffraction studies of hydrogenation reactions. These cells can operate at temperatures up to 1110 K and pressures of up to 15 MPa, respectively [1,2]. The aim of presented project  is to extend the capabilities of cells to 1500 K and 100 MPa, respectively. Results on a new metal single-crystal based gas-pressure and gas-flow cell for operando neutron diffraction with low background will be presented.
This work was supported by the BMBF - German Federal Ministry of Education and Research, project 05K22OL2.

An increase in demand and the resulting price increase of Helium-3 has
sparked the development of alternative kinds of neutron detectors for
various applications in neutron science. Our group is developing three
detectors with solid Boron-10 converters. With their scalability,
up-to-date readout electronics, high-rate capabilities and wide range of
active readout areas they are promising candidates as detectors in
imaging and scattering experiments.

The first design features a boronated Microchannel Plate and uses a
Timepix3 ASIC readout with an active readout of 2.8x2.8 cm². This
upgrade improves the resolution of an already successful implementation
for the now discontinued Timepix ASIC and guarantees the the
accessibility in future uses. The mechanical construction is completed
and readout implementation studies are ongoing.

The second detector uses a boron-lined Gas Electron Multiplier, which
acts simultaneously as a conversion and gas amplification stage. With
an active area of 10x10 cm² and the VMM3a ASIC a highly granular readout
with rates above 1e6/s is easily achievable. Currently the construction
of the first layer is ongoing. In further stages of development an
expansion to an active area of 30x30 cm² and implementation of up to ten
layers for enhanced detector efficiency is planned.

Thirdly we develop the BOron DEtector with Light and Ionisation
Reconstruction (BODELAIRE), which combines the concept of a Time
Projection Chamber (TPC) with a highly granular readout with high time
resolution and a boronated glass window for neutron conversion. Boron
absorbs incoming neutrons and decays into an alpha particle and a
Lithium ion. One of the ions enters the drift volume of the TPC and
creates a trace of electron-ion pairs, which the readout detects. The
other ion emitted in opposite direction is used to start the readout
with the help of a scintillator inside the glass vessel. The light
created in the scintillator is coupled to a trigger board via wavelength
shifting fibers to generate a start signal in silicon
photomultiplier-based electronics. The trigger system is
FPGA-controlled, which the user can interface with to set signal
thresholds. The TPC has been successfully build and the trigger system
is in its final stages of development.

In this work I will give an overview of the neutron detector projects in
our group and go into detail over the detector concept of the BODELAIRE
and its current status of development.

D20 at ILL provides highest intensity in constant-wavelength neutron powder diffraction at medium and high resolution. The most critical ingredient to this, besides optical versatility and a high incident neutron flux, is a large position sensitive detector (PSD) that covers the whole range of diffraction angles with sufficient definition. More than a quarter of a century ago, this was very difficult to realise and led to the development of micro-strip gas chamber detectors, a technology that has been used successfully in the current PSD for 25 years. However, the technology suffers from a niche status when it comes to the provision of parts and lacks robustness. At the time-scale of an experiment, the detection stability is very high (which is critical for small signals and high backgrounds, so for small samples, incoherent scattering, small magnetic moments, absorbing samples, high pressure, amorphous and liquid samples). Unfortunately, over longer time-scales, the detection efficiency changes, micro-strips being very sensitive to oxidation by traces of poisoning oxygen in the detector gas. This requires frequent recalibration or acquisition methods like two-theta scans. The earlier is too time-consuming in a tight schedule of an oversubscribed instrument, the latter is not adapted to very fast experiments and invalidating one of the ‘selling’ arguments of the PSD, its stationarity. Also, it is prone to mechanical and electronic problems, as the PSD needs to move all the time.
Therefore, a new PSD has been built, based on the meanwhile well-proven ‘trench’ multi-wire proportional counter technology (used on XtremeD and D16). The new PSD has been completed, tested and is ready to replace the former PSD on D20 before reactor operation in 2025.
Some flagship results of 25 years of powder diffraction at D20 shall be presented, D20’s particular scientific challenges, the working principles of its current PSD, its problems and how one can overcome them by data acquisition strategies and data reduction. Finally, the respective differences of the new PSD, its working principles, its production and results of first tests shall be shown.

With the transformative development of event-based detectors, new perspectives for detection systems for various types of radiation were opened up. A recently developed event-driven imaging system based on Timepix3 sensor technology is capable of observing and time-stamping the optical signal induced by particle interactions in scintillator materials with nanosecond temporal and micrometer spatial resolution, providing a pathway to fuse the benefits of integrating camera type with counting type detectors. In this approach, the reconstruction of the interaction position of a neutron with the scintillator with sub-pixel accuracy can provide a precise determination in location, as well as in time-of-arrival of the individual neutrons. Utilizing such a principle, it was shown that spatial and temporal resolution can be improved beyond the classical limits of “regular” neutron imaging. Additionally, a significant increase of signal-to-noise ratio was achieved using the unique potential of event-mode detection to discriminate gamma background from neutron signal based on the spatiotemporal signature of single neutron events produced in the scintillator. Here, we present the most recent results in utilizing this concept for imaging applications and scintillator characterization measurements. It is considered that this novel concept will replace regular cameras in neutron imaging detectors as it provides superior detection capabilities compared to conventional camera systems.

After the licensing of lipid nanoparticles (LNPs) comprising messenger RNA (mRNA) for vaccination against COVID-19, nanoparticles comprising mRNA for pharmaceutical application have been gaining increasing attention in the scientific community.

mRNA is a single stranded RNA, which is the template for the synthesis of proteins by the cell. For its use as the active ingredient in pharmaceutical products, the molecular properties of mRNA have been optimized in terms of stability and activity. Several different mRNA formats, such as modified RNA (mRNA), which was used in the first COVID vaccines, self-amplifying RNA (saRNA), or circular RNA (circRNA) are by now considered for pharmaceutical applications. Virtually any protein can be expressed by mRNA, and various types of therapeutic intervention, including cancer therapy, protein replacement, gene editing, and vaccination against infectious diseases.

LNPs as used in the COVID-19 vaccines consist of four lipid components, namely an ionizable lipid, a phospholipid, cholesterol and a polyethylenimine-functionalized lipid (PEG-lipid) in a relatively narrow range of molar composition. LNPs have been intensely investigated, including by use of small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS), leading to some common consensus on their key structural features. While for vaccines against viral infections, LNPs in combination with modified mRNA (modRNA) have proven to be successful, for other applications, and other mRNA formats, other types of delivery systems may be more appropriate.

Here we give examples where SANS, in combination with SAXS, light scattering, and other techniques, was used for extended characterization of potential next-generation delivery systems for mRNA. Different types of lipid- and polymer-based nanoparticles and different mRNA formats were investigated. The structure and molecular organization could be accurately resolved and correlated with biological activity. Such insight can be the basis for assembly of tailored delivery systems for future applications, when certain structural features are required of the intended targeting and release characteristics.

Neutrons, by virtue of their non-destructive non-ionising nature, can provide a statistical and 3-dimensional perspective on structure in a range of model and industrial systems. Dairy gels, where the formation of a network of casein micelles from milk forms a barrier to mass transport, are the basis of major class food products manufactured from. Herein we follow on from our previous work examining the link between the mechanical properties of these gels and structure of the underlying fractal network [1]. The Bonse-Hart ultra-small angle neutron scattering (USANS) technique at the instrument KOOKABURRA (ANSTO, Australia) [2] utilizes two-channel cut (111) Si crystals to provide extremely good angular resolution of scattered neutrons in the horizontal direction but poor resolution in the vertical direction. KOOKABURRA provides well normalized slit smeared scattered intensity over a range of scattering vectors, 3 x 10$^{-5}$ Å$^{-1}$ < q < 0.01 Å$^{-1}$. In the present work, we exploit the non-ionizing technique to probe the formation of milk gels in-situ by actively metabolizing microbial systems, and modelling the slit-smeared scattered intensity with the network model of fractal aggregation by Teixeira [3]. We discuss the formation of a gel network and the broader application of this approach to food gels.
References:
[1] Ramya K. A., F. Boue, M. Strobl, L. de Campo, and C. Garvey, Manuscript in Preparation, 2024.
[2] Rehm, C., L. de Campo, A. Brule, F. Darmann, F. Bartsch, and A. Berry, Journal of Applied Crystallography 51 (1), 1-8, 2018.
[3] Teixeira, J., Journal of applied crystallography 21 (6), 781-785, 1988.

Amyloid β42 (Aβ42), a neurodegenerative peptide, undergoes various morphological changes in the pathway of forming plaques, a principal cause of Alzheimer's disease, and can alter the membrane integrity. Furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) are the most widely prescribed for their anti-inflammatory, antipyretic, analgesic and antiplatelet characteristics. The influence of Aβ42 and NSAIDs on the dynamics of single lipid membrane mimetic systems is widely studied. However, a single lipid membrane mimetics system is not an ideal representative of a multicomponent and complex cell membrane. Here, we have investigated the influence of Aβ42–monomer (m), aspirin (Asp), diclofenac (Diclo) and ibuprofen (Ibu), at different concentrations, on the dynamics and structure of BLs-ULVs using quasielastic neutron scattering (QENS), neutron spin echo (NSE) and small angle neutron scattering (SANS). We have prepared unilamellar vesicles (ULVs) using brain lipids (BLs), extracted from the porcine brain tissues, representing a physiologically relevant membrane system. Normalized QENS spectra showed that Aβ42–m induces higher QE broadening, suggesting substantially faster dynamics than pure BLs. For NSAIDs, higher QE broadening is observed for Asp at 10 and 30mol%, Diclo at 10mol% and Ibu at 10 and 20 mol%. This suggests that each NSAIDs at a different concentration has a unique effect on the BLs dynamics. The QENS spectra corresponding to BLs with and without Aβ42–m, Asp, Diclo and Ibu are described by two Lorentzian such that there are motion on two different time scales slow lateral and fast internal motion of BLs. Variation of half width half maxim (HWHM) shows that Aβ42–m mainly enhances internal motion (Гint) and does not affect the lateral motion (Гlat). In the case of NSAIDs, Гlat and Гint are increases in the presence of Asp at 10 and 30mol%, and Ibu at 10 and 20mol%. Whereas, Diclo does not affect the Гlat but enhances Гint at 10mol%. NSE spectra, described by the Zilmann and Granek model, showed that Aβ42–m does not affect the bending rigidity modulus (κKBT). Whereas, Asp enhances the κKBT at all concentrations and Diclo and Ibu reduce and increase the κKBT at 30 and 20mol%, respectively. The SANS result showed that Aβ42–m and NSAIDs do not affect the BLs-ULV structures. This study provides insights into the influence of Aβ42–m and NSAIDs on the dynamics of physiologically relevant BLs-ULVs membrane systems.

Glycolipids are known to stabilize biomembrane multilayers through preferential sugar-sugar interactions that act as weak transient membrane cross-links. Here, in order to obtain structural insights into this phenomenon, we utilize neutron reflectometry in combination with a floating lipid bilayer architecture that brings two glycolipid-loaded lipid bilayers to close proximity. We find that selected glycolipids with di-, or oligosaccharide headgroups affect the inter-bilayer water layer thickness and appear to contribute to the stability of the double-bilayer architecture by promoting adhesion of adjacent bilayers even against induced electrostatic repulsion. However, we do not observe any redistribution of glycolipids that would maximize the density of sugar–sugar contacts. In addition, we use small-angle and quasi-elastic neutron scattering on oligolamellar phospholipid vesicles containing defined glycolipid fractions in order to elucidate the influence of glycolipids on membrane mechanics and dynamics. Small-angle neutron scattering (SANS) reveals that the oligolamellar vesicles (OLVs) obtained by extrusion are polydisperse with regard to the number of lamellae, n, which renders the interpretation of the quasi-elastic neutron spin echo (NSE) data nontrivial. To overcome this problem, we introduce a method to model the NSE data in a rigorous fashion based on the obtained histograms of n and on their q-dependent intensity-weighted contribution. This procedure yields meaningful values for the bending rigidity of individual lipid membranes and insights into the mechanical coupling between adjacent membrane lamellae, including the effect of the glycolipids.

Mucins are a family of water soluble, and heavily glycosylated, proteins which, as the major macromolecular constituent of mucous, have a general function in forming wet physiologically relevant chemical and physical barriers in animals.1 Apart from the ability to form limited cross-links, gelation behavior, an important structure motif is the bottle-brush structure formed by the pendant glycosylations around the extended unfolded protein core consisting largely of serine and threonine. At neutral pH the glycosylations are largely uncharged. In this study we aim understand the dynamics of the water binding to the glycosylations in water, and eventually the coupling of water binding to the overall flexibility of the mucin backbone through the excluded volume interactions between the hydrated pendant glycosylations. Biological variability is often a problem for the relevance of these studies, for this reason we have utilized a commercial product available as lyophilized powder, pig gastric mucin (PGM). Differential scanning calorimetry (DSC) results suggest that the PGM can hold approximately 0.51 g of bound water per g of dry PGM.2 At this moisture content it is suggested that there is glass transition at approximately 25oC. Our initial studies on temperature dependance of QENS using hydrated powders of PGM below a moisture content suggest by DSC with the direct geometry time of flight spectrometers: FOCUS (Paul Scherrer Institute, Villigen, Switzerland); and IN5 (Institute Laue-Langevin, Grenoble France). The IN5 samples consisted of pairs of matched hydration where all available exchangeable H has been exchanged with D by exchange with D2O and samples prepared in natural abundance H2O. Together with fixed elastic window scans on the thermal backscattering spectrometer IN13 (Institute Laue-Langevin, Grenoble France) we are able to demonstrate a layer of water which is strongly coupled to the dynamics of the pendant glycosylations on the mucin backbone.

We have investigated the magnetic microstructure of two-phase Fe-Nb-B based Nanoperm alloys using unpolarized small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Our SANS analysis reveals a significantly large magnetic scattering contribution due to spin misalignment, primarily originating from the substantial jump in the longitudinal magnetization at the interfaces between the particles and the matrix. The magnetic scattering exhibits an angular anisotropy that resembles a clover-leaf-type pattern, consistent with the predictions of micromagnetic SANS theory. Analysis of the one-dimensional SANS data yields values for the exchange-stiffness constant and the average anisotropy and magnetostatic fields. The micromagnetic correlation lengths for all three samples are of similar magnitude and exhibit a field variation with sizes ranging between about 10-30 nm. We also find that the nuclear and magnetic residual scattering component of the SANS cross section exhibits a similar q dependency as the SAXS data. These findings further validate the applicability of micromagnetic SANS theory, and the mesoscopic information obtained is crucial for the advancement of the soft magnetic properties of this class of material.

Complex perovskite La2(Al1/2MgTa1/2)O6 (LAMT) crystallizes in a monoclinic unit cell with space group P21/n at room temperature. Due to little scattering contrast between the neighbouring elements Mg and Al of the periodic table, conventional X-rays could not properly resolve the mixed occupation on the B-site. Hence, complementary neutron powder diffraction studies were carried out to verify the exact B-site cation ordering in the unit cell. In this specific configuration of the B-cations, with its occupancy ratio and the presence of a heavy element Ta as well as neighbouring elements Mg and Al, only the strategy of a combined Rietveld analysis using both the X-ray and neutron powder diffraction data simultaneously succeeded in elucidating an accurate B-site cation ordering in this complex perovskite system. A full occupancy of Mg on the 2c-Wyckoff position and each a half occupancy of Al and Ta on the 2d-Wyckoff position could be resolved for the rock-salt-type ordering of the B-site cations in the monoclinic unit cell of LAMT.

Very cold neutron (VCN) sources present an exciting opportunity for scientists to access unprecedented length and time scales, and achieve improved sensitivity in neutron experiments. VCNs are defined over a wide spectral range, from 1 meV (9 Å) down to a few hundred neV (> several 100 Å). Wavelengths of up to several tens of Å are of particular interest to many research communities. Recently, thermal scattering kernels were developed for candidate VCN moderator and reflector materials within the scope of the HighNESS project and beyond. These advances present an opportunity for the conceptual design of VCN sources at newly emerging high-current accelerator-driven neutron sources (Hi-CANS) like the High Brilliance neutron Source (HBS). The HBS is a Hi-CANS project which hosts a linear accelerator delivering a pulsed proton beam of energy, 70 MeV, and peak current, 100 mA, to a novel high-power tantalum target and compact target-moderator-reflector (TMR). The production of competitive and brilliant cold neutron beams from a low dimensional parahydrogen source has been designed and its stable operation at 18 K subsequently demonstrated at the Big Karl platform in December 2023. A concept for a compact very cold neutron source based on the low dimensional parahydrogen cold source for the HBS will be presented, wherein a methane disk moderator is embedded within a parahydrogen cold moderator. As methane is known to produce a colder neutron spectrum when compared with parahydrogen, it is considered in this concept to shift the cold neutron spectrum generated by the parahydrogen cold moderator. Results from a full optimization of the geometry of the very cold neutron moderator concept, by coupling the Monte Carlo transport code PHITS with Dakota, with the single objective of boosting the neutron intensity within the range 9-18 Å for a small angle scattering instrument will be presented.

Waterborne latex films, obtained from the dispersion of latex particles are of particular interest due to the non-content of volatile organic compounds (VOC), often mandatory under environmental legislation (Konko et al. Langmuir. 2019, 35, 6075). However, abrupt water penetration inside the films restricting their lifespan and deteriorating the shining of the coating. In order to prepare efficient and solvent-free coatings with the low glass-transition temperature (Tg < the drying temperature) but with higher mechanical strength, we have integrated hydrophilic layers (Acrylic acid/ Poly(acrylamide)) around the hydrophobic cores (mixture of Methyl methacrylate and Butyl acrylate) and also hard shell around the soft core in the latex film. Latex particles with different morphology (hairy layer variants and core-shell particles) have been synthesized using emulsion polymerization (Abdeldaim et al. Macromolecules. 2023, 56, 3304). Polymer latex films have been prepared in the next step by evaporating water in a thermo-humidistatic chamber at temperature 25 oC. The structure formation of polymer latex films in the dry state (crystallinity) and in re-swelled state (change in crystallinity and whitening or blushing) have been studied to propose a recipe for the preparation of efficient latex coatings. The Small-Angle Neutron Scattering (SANS) study shows the FCC-like structure formation by the latex film, which become more organized with the inclusion of the hydrophilic shell. The hydrophilic shell also promotes the formation of the homogeneously water-swollen film and slows down the development of water “pockets”, preventing the deterioration of the latex film over time. On the other hand, the inclusion of hard shell protects the latex films from water whitening and provides additional mechanical strength. The interdiffusion between the latex particles has been analyzed by mixing H/D polymers. The transfer of polymer chains through interparticle boundaries that vanishes the crystalline structure and results in a formation continuous material.

Rare earth orthoferrites, RFeO$_3$ (R = rare earth element), have been model systems for studies and theoretical considerations of magnetic structures since the 1960s [Whi69, Mar70, Ber68]. They have regained considerable interest in the last decade due to their complex multiferroic and magnetocaloric properties, which make them potential candidates for modern applications, e.g. in the field of spintronics [Tok12, Lee11].

We have recently completed an extended project, "Mechanisms for multiferroicity in rare earth orthoferrites: Role of the Dzyaloshinskii-Moriya interaction", funded by the DFG (SA-3688/1-1). In this project we have used various experimental methods, mainly neutron scattering, to obtain an overview of the magnetic interaction parameters, structure and magnetic phase diagrams for different RFeO$_3$ compounds. The exchange within the Fe subsystem is the strongest, the Dzyaloshinskii-Moriya interaction leads to a spin canting, the single-ion anisotropy stabilises the system and the exchange interactions of the R-Fe and R-R type lead to a change in the energy balances of the systems, causing spin reorientation transitions. A detailed quantitative study and comparisons with literature data show that the interaction parameters differ significantly between individual members of the RFeO$_3$ family [Ovs22a, Ovs22c]. This leads to a fragile balance between the parameters and results in very different magnetic phase diagrams, e.g. for HoFeO$_3$, TbFeO$_3$ and YbFeO$_3$ [Ovs22a, Art12, Ovs22c]. We found a new low-symmetry magnetic phase in HoFeO3 [Ovs22b], the temperature range of which coincides with the temperatures of a reported large magnetocaloric effect in this compound. In addition, we have also looked at TmFeO$_3$, DyFeO$_3$ and LuFeO$_3$ as part of our project and have been able to obtain some initial information for them. In our presentation we give an overview of the results of the orthoferrites we have investigated.

[Art12] S. Artyukhin et al.; Nature Mater. 11 (2012) 694.
[Ber68] E.F. Bertaut; Acta Cryst. A 24 (1968) 217.
[Lee11] J.-H. Lee et al.; Phys. Rev. Lett. 107 (2011) 117201.
[Mar70] M. Marezio, J.P. Remeika and P.D. Dernier; Acta Cryst. B 26 (1970) 2008.
[Ovs20] A.K. Ovsyanikov et al.; J. Magn. Magn. Mater. 507 (2020) 166855.
[Ovs22a] A.K. Ovsianikov et al.; J. Magn. Magn. Mater. 557 (2022) 169431.
[Ovs22b] A.K. Ovsianikov et al.; IEEE Trans. Magn. 58 (2022) 2500105.
[Ovs22c] A.K. Ovsianikov et al.; J. Magn. Magn. Mater. 563 (2022) 170025.
[Tok12] Y. Tokunaga et al.; Nat. Phys. 8 (2012) 838.
[Whi69] R. White; J. Appl. Phys. 40 (1969) 1061.

Leveraging the unique interaction of neutrons with matter, neutron scattering techniques allow for the investigation of structural and dynamic properties that are often inaccessible by other means. Inelastic neutron scattering (INS) probes the vibrational modes of a system without the constraints of optical selection rules and is particularly effective in examining hydrogen-rich materials due to the large incoherent neutron scattering cross-section of hydrogen atoms. In the particularly small energy transfer regime, quasielastic neutron scattering (QENS) essentially studies the broadening of the elastic band given by the neutron scattering process [1]. This technique covers a sufficiently broad range in space and time to be able to study different dynamical processes, from fast vibrations and rotations to slow modes such as diffusion.

Here we present our recent study [2], in which we have used INS spectroscopy augmented by gas-phase and solid-state computational simulations to investigate the vibrational dynamics of methyl-β-D-ribofuranoside, a biologically significant carbohydrate with complex dynamic properties due to its five-membered furanose ring. Utilising the high-resolution capabilities of the TOSCA [3,4] spectrometer at the ISIS Pulsed Neutron and Muon Source, we obtained detailed INS spectra covering all vibrational modes up to approximately 500 meV with a good spectral resolution of 1.25% ΔE. Combining this with low temperature Raman and IR measurements, the dominating modes in condensed phase were characterised and spectroscopic evidence for a specific intermolecular H-bonding interaction in the unit cell was identified.

Taking advantage of the capabilities of QENS instruments to directly measure diffusive motions and dynamic processes of hydrogen-rich molecules over pico- to nanosecond timescales [5], we plan to combine the detailed vibrational information from INS with the dynamic data from QENS to study materials particularly relevant to catalysis research. Such studies will have broader implications in fields such as energy storage and sustainable chemical processes development.

References
[1] V. G. Sakai et al., Current Opinion in Colloid & Interface Science, 2009, 14, 381. [2] M. Pascariu et al., J. Phys. Chem. A, 2024, 128, 2111. [3] S. F. Parker et al., J. Phys.: Conf. Ser., 2014, 554, 012003. [4] R.S. Pinna et al., Nuclear Instruments and Methods in Physics Research, A, 2018, 896, 68. [5] M. Kruteva, Adsorption, 2021, 27, 875.

We showcase a method development in neutron powder diffraction, primarily driven by the future time-of-flight diffractometer POWTEX, developed in collaboration with Forschungszentrum Jülich at FRM-II in Garching. Within the DAPHNE project, we are expanding these methods for wider applications, emphasizing sustainability.
There is significant interest in actively researching multidimensional data-reduction and Rietveld refinement techniques, applicable not only to POWTEX but also to instruments such as POWGEN and SNAP at SNS, ORNL, USA, and future TOF diffractometers at ESS, Sweden. Recent advancements enable multidimensional data reduction with the Mantid program package. As of today, multidimensional refinement routines are being incorporated into a customized GSAS-II version, currently undergoing testing with real-world samples.
The first successful application of the aforementioned methods dealt with POWTEX data collected at SNS, ORNL [1]. Herein, we report the first multidimensional refinement of a two-phase sample using high-pressure diffraction data from SNAP, also at SNS, ORNL. The results are illustrated by a comparison between conventional and multidimensional data refinement and discussed based on the structural peculiarities of PbNCN under pressure [2].
[1] Houben, A., Meinerzhagen, Y., Nachtigall, N., Jacobs, P., Dronskowski, R., POWTEX visits POWGEN, J. Appl. Cryst. 2023, 56 , 633–642.
[2] Meinerzhagen, Y., Eickmeier, K., Müller, P.C., Hempelmann, J., Houben, A., Dronskowski, R., Multidimensional Rietveld Refinement of High-Pressure Neutron-Diffraction Data of PbNCN, J. Appl. Cryst., submitted.

Aditi Gujare1, Jonas Runge2, Stefanie Uredat2, Julian Oberdisse1, Domenico Truzzolillo1, Thomas Hellweg2

1 Soft Matter Physics, Laboratoire Charles Coulomb, University of Montpellier, Montpellier, France
2 Physical and Biophysical Chemistry, Bielefeld University, Bielefeld, Germany

Smart membranes have applications in wastewater treatment and separation[1]. These membranes show permeability depending on the external stimuli, such as thermoresponsive microgel-based membranes. Such membranes can be prepared by UV cross-linking, electron beam cross-linking, or chemical cross-linking. A free-standing membrane made of NIPAM microgels has been reported, which are cross-linked with a secondary UV-sensitive crosslinker HMABP. These free-standing thermoresponsive membranes are resistant above their VPTT(33°C) and show permeability of ions below it[2].

To understand the incorporation of HMABP in the microgel particles, we performed contrast variation Small Angle Neutron Scattering(SANS) experiments. We synthesized microgels with deuterated monomers (NIPAM/NIPMAM) and non-deuterated cross-linkers BIS and HMABP. We performed contrast-matching experiments to see how these cross-linkers are distributed within a microgel particle(Figure-1). With changing scattering length densities of the solvent, the particles show similar scattering behavior when the D-monomers are scattering, thus confirming that they form the microgel. Whereas when the deuterated monomers are matched, and the cross-linkers are highlighted (which is at 100%D2O), there is a change in the scattering behavior which suggests an inhomogeneous distribution of the cross-linkers inside the microgels.

In the high-q region, both the NIPAM and NIPMAM-based microgels show similar scattering behavior at different solvent scattering length densities(except at 100%D2O). But in the low-q region, the scattering behavior of NIPMAM-based microgels, the samples above 50%D2O when the cross-linkers are highlighted, scatter very differently. This again suggests the inhomogeneous distribution of cross-linkers, which is different in NIPMAM- as opposed to NIPAM-based microgels.
It is hoped that these distributions of cross-linkers in microgels based on deuterated monomers can be used to describe the distribution of cross-linkers in non-deuterated microgels as these are comparable in size and also show similar thermoresponsive behavior with a VPTT between 33°C-44°C (depending on the monomer NIPAM/NIPMAM) and reach a fully collapsed state at 60°C. However, the scattering behavior is different when comparing the deuterated microgels with non-deuterated ones because, in a given solvent scattering length density(100% D2O), the non-deuterated monomers are highlighted along with the cross-linkers while the deuterated ones are contrast matched with the solvent.

[1]S. Uredat, A. Gujare, J. Runge, D. Truzzolillo, J. Oberdisse T. Hellweg, Phys.Chem.Chem.Phys.26(2024)2732
[2]M.Dirksen, T. Brändel, S. Großkopf, S. Knust, J.Bookhold, D. Anselmetti, T. Hellweg, RSCAdv.11(2021)22014-22024.

Barocaloric refrigeration leverages the adiabatic temperature and isothermal entropy changes of materials under external hydrostatic pressure, presenting a promising energy-efficient and eco-friendly refrigeration technology. Among the materials considered for barocaloric applications, Spin Crossover (SCO) compounds have recently gained attention due to their unique properties.

SCO compounds are characterized by a transition of the central metal ion between a low spin (LS) state, favored by low temperature and high pressure, and a high spin (HS) state, favored by high temperature and low pressure. This transition is accompanied by significant changes in entropy, which are crucial for barocaloric applications. However, understanding the microscopic mechanisms underlying the HS-LS transition remains challenging.

Our research focuses on the SCO compound [Fe(Pm-Bia)₂(NCS)₂], where (Pm-Bia) stands for (N-(2′-pyridylmethylene)-4-amino-biphenyl). This compound crystallizes in two polymorphs that exhibit distinct spin state transitions. We investigate these transitions using magnetization and DSC measurements, as well as powder and single-crystal X-ray diffraction, under varying temperature (80-300 K) and pressure (0-2 GPa) conditions.

The orthorhombic polymorph of [Fe(Pm-Bia)₂(NCS)₂] exhibits a sharp HS-LS transition within 1 K when subjected to temperature changes. However, applying external pressure does not induce a spin transition in this polymorph; instead, it leads to the formation of a superstructure at 2.02(4) GPa. In contrast, the monoclinic polymorph shows a gradual HS-LS transition over a broad temperature range (~100 K) and undergoes a transition to the LS state upon the application of pressure up to 1.36 GPa at room temperature.

In this study, we highlight the role of intermolecular interactions in determining the nature of the spin transition. We discuss and compare our observations in the context of cooperativity and spatial requirements, providing deeper insights into the structural changes associated with the HS-LS transitions in SCO compounds.

This research contributes to the understanding of SCO compounds for barocaloric applications, emphasizing the importance of structural analysis and the role of different perturbations on spin state transitions.

We present a combined first principle-based molecular dynamics (AIMD) simulations and experimental study of Al-Fe melts. Measurements were performed using quasi elastic neutron scatting (QENS) to obtain the self-diffusion coefficients of Fe at different Al-Fe compositions as a function of temperature.

A Quenching and Deformation Dilatometer (TA instruments DIL805A/D/T) operates at the MLZ for performing in-situ neutron diffraction (phase, texture, stress/strain) at STRESS-SPEC and small-angle neutron scattering (nanostructure) at SANS-1. A similar instrument operates at beamline P07 HEMS (DESY) for in-situ x-ray scattering studies. The combination of the scattering and dilatometry measurements yields a unique view on the microstructural evolution under thermomechanical treatment of the studied materials.
In this work, we will show the parameters of the dilatometer and its possibilities to be used for in-situ scattering characterization. Besides we will present some results of different materials, i.e. high entropy alloy (HEA), light weight TiAl alloy and Cu - Ce$_{0.8}$Gd$_{0.2}$O$_{2-\delta}$ (CGO) composites. Our analysis utilizing both dilatometry and in-situ diffraction enables precise evaluation of phase transformations (type and temperature) in AlCrFeNiTi HEA. TiAl alloy study will be focused on the bulk texture evolution induced by hot compression performed with the dilatometer. The aim is to investigate the mechanisms of hot compression and further to optimize the mechanical properties. Last example is the results on Cu-CGO composites for high temperature green energy applications (solid oxide fuel cells, electrolyzers and catalytic membrane reactors). Here we studied the thermal expansion coefficient of the Cu-CGO cermets as a bulk at the same time as we obtain in-situ high temperature microstructural information on both Cu and CGO phases in order to select the best electrode composite from the thermomechanical point of view.

The current trend of usage of fossil fuels to satisfy the ever-growing energy demand is expected to cause an irreversible increase in temperature. Alternative fuels like hydrogen can be a solution to this problem due to its high gravimetric energy density.
However, the low volumetric density of hydrogen in gas and liquid phases incurs problems related to storage [C.Pistidda]. In this work, the possibility of storing hydrogen as a metal hydride is explored. In particular, a mixture of MgNH₂, LiBH₄, and LiH was interesting and was investigated using Small Angle Neutron Scattering (SANS) [N.aslan et al.]. The SANS data were later explained using simulations.

SANS is traditionally known for the investigation of nanoscopic structures. In this work, a unique measurement method was applied to accomplish in situ measurement revealing information about the process as well. However, the measurements do not allow a direct deduction of the process or structure. Therefore, several models were created based on different hypotheses and the measured data was calculated from the simulation for comparison with experiments. The finite size effect within the calculated data, prevalent in the small angle region, was removed using $Q$ - clean method [Majumdar et al.]. As the simplest possible model, diffusion of hydrogen into and out of a spherical isotropic grain of hydrogen storage material was hypothesized. The disparity between the simulation data and the experiment shows that a more complicated model has to be used for the description of the sample. Therefore, micro-structures of absorbed and desorbed states were generated probabilistically. The calculated data from the simulation was compatible with the experiments after the addition of micro-structural details.

The overall conclusion of this work is that SANS probes the sample at a length scale that detects the nanoscopic microstructure of the hydrogen storage material. The information obtained from SANS can contribute significantly to a simulation at a bigger engineering scale, where the storage material can be approximated as an isotropic material.

Li-ion batteries as energy storage devices play a significant role in the global agenda to mitigate emissions, move to sustainable energy sources, and fight climate change. In recent years, new battery formats have emerged intending to increase energy. Moving from the conventional cylindrical 18650 design to the 21700 format can achieve higher energy content per cell.[1] These batteries are used in different scopes, such as electric vehicles in the automotive industry.
By scaling up the size of the battery, effects such as temperature and electrolyte distribution or inhomogeneities are gaining more influence on the cycling behaviour of the battery in comparison to smaller lab-size batteries.[2] Therefore, studying commercial cells to understand the lithiation and ageing mechanisms inside the electrodes is essential.
Here, in-operando neutron diffraction experiments were conducted on 21700 cells with NCM as a cathode material and graphite as an anode material at the DMC instrument at the Paul Scherrer Institute (PSI). By comparing three different states of health, the influence of cyclic ageing on the electrodes could be investigated.
The loss of capacity can be seen in the electrochemical data and the structural change of the electrodes. The movement of the 113 NCM-peak is reduced for the aged cell, indicating that unit cell change is restricted due to the loss of Li. Simultaneously, the range in which the lattice parameters move during cycling shifts to lower values for the aged cells, suggesting that the cathode is pushed to higher potentials. For the anode, the amount of the LiC6 phase is decreased for the aged cells, which confirms the loss of Li and is in accordance with the results from the cathodes.

[1] J. B. Quinn, T. Waldmann, K. Richter, M. Kasper, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2018, 165, A3284-A3291.
[2] D. Beck, P. Dechent, M. Junker, D. U. Sauer, M. Dubarry, Energies 2021, 14, 3276.

With extremely high elastic modulus, super strength, outstanding thermal and electrical properties, Carbon nanotubes (CNTs) are considered as one of the most potential reinforcements for composites. Our studies indicate that hybrid Mg MMCs, reinforced with SiCp and CNTs, have shown superior tensile properties. This is mainly attributed to the addition of CNTs to SiCp with CVD method.
In this contribution, we will present first a brief introduction on a novel fabrication process of the CNTs reinforced Mg-Zn matrix composites, and then the characterizations of their microstructures and phase by lab X-ray. In-situ tensile deformation test of these composites was performed using neutron diffraction at STRESS-SPEC (MLZ, Garching). Peak position variation with the tensile strain of each phase was analyzed. Bulk texture of both the initial and the tensile to broken samples was also investigated ex-situ by neutron diffraction.
X-ray results showed that in both as-cast and as-extruded materials there exists a precipitate of MgZn2 which are formed during both casting and extrusion processes. The MgZn2 was the only precipitate in ZK60 alloy and composites. The measured pole figures indicated no obvious change of the samples with the addition of CNTs.
Lattice strain evolution via in-situ test indicated SiCp and CNTs reinforcement played a role in carrying internal stress during tensile deformation, and lattice strain showed shaper increase in CNTs reinforced composite than that in SiCp composite and ZK60 alloy, indicating CNTs bear the forces in whole tensile process.

While being largely associated with the most electronegative elements N, O, and F, hydrogen bonding occurs in a variety of circumstances - one of the more exotic cases being bonding to the electron cloud of π systems of aromatic molecules. Here, we use total neutron scattering to study intermolecular interactions between benzene and ammonia. Solutions of benzene in ammonia (~1:12) were studied at room temperature and pressure of 10 bar revealing the presence of N-H···π bonds. These bonds are slightly longer than O-H···π bonds in a similar system of benzene in methanol, as would be expected due to lower electronegativity of nitrogen compared to oxygen. However, despite the increase in the distance between the atoms participating in this interaction, our findings suggest that the N-H···CoR (centre of ring) contact stays exceptionally linear similarly to the benzene-methanol system.

The world transitions toward sustainable energy sources. In this context, hydrogen plays a key role.$^{[1]}$ Efficient storage and release of hydrogen are essential for its practical application in various fields, including fuel cells and transportable energy storage systems.$^{[2]}$ Here, energy transport and storage via liquid organic hydrogen carrier (LOHC) systems is a significant vector.$^{[3]}$ Notable LOHC systems include toluene/methylcyclohexane and dibenzyltoluene (H0-DBT)/perhydro dibenzyltoluene (H18-DBT).$^{[4]}$ Understanding the diffusion behavior of this hydrogen storage molecules is critical for optimizing materials and systems to enhance performance, safety, and cost-effectiveness.$^{[5]}$

We investigate the diffusion of the LOHC molecule dibenzyltoluene (DBT) and of water in porous monoliths by neutron radiography. The technique leverages the fact that the neutron absorption cross section of hydrogen is approximately 1000 times greater than that of deuterium (D or $^{2}$H).$^{[6]}$ The resulting contrast in radiographic imaging allows for the observation of time-dependent concentration profiles arising from self-diffusion of the molecules within a monolith. The process is induced by controllably bringing the deuterated liquid in contact with a non-deuterated liquid ensuring an initially sharp boundary at a well-defined starting point.

Preliminary results will be presented. We anticipate that this method will enable fast, straightforward, and accurate determination of the diffusion of hydrogen carrier molecules in porous systems of different pore size and surface chemistry, providing novel insights into the transport mechanisms of LOHCs. Additionally, this method will be explored to measure the surface-, bulk- and wetting dynamics of LOHCs in porous systems.

[1] B. Pivovar et al., Electrochem. Soc. Interface 27, 47 (2018).
[2] A. Saberi Mehr et al., Int. J. Hydrogen Energy 70, 786-815 (2024).
[3] H. Jorschick et al., Int. J. Hydrogen Energy 45, 29,14897-14906 (2020).
[4] T. Rüde et al., Sustainable Energy Fuels 6, 1541-1553 (2022).
[5] K. Koizumi et al., Phys. Chem. Chem. Phys. 21, 7756-7764 (2019).
[6] V.F. Sears, Neutron News 3, 29 (1992).

We propose to implement a new modulation technique at the NREX reflectometer (MLZ) adding time resolution to polarized neutron reflectometry (PNR). The new technique is based on intensity modulation by a radio-frequency (RF) spin flipper, and shares some basic concepts with the MIEZE spin-echo technique and with AC-Polarized-Neutron-Reflectometry (AC-PNR). The aim is to resolve the kinetics of the nuclear and magnetic scattering length densities in periodic processes with a time resolution of a few micro-seconds, corresponding to an improvement of two orders of magnitude compared to conventional techniques. One main application of this new technique will be the study of so called magneto-ionic (MI) materials, which have a high potential in ultra-low-power neuromorphic computing applications. The electric and magnetic properties of magneto-ionic materials can be tuned or switched by a small gating voltage, which drives the transport of ions perpendicular to the layer boundaries. Oxygen, nitrogen, lithium, or hydrogen were used as mobile ions in MI materials, where hydrogen shows the highest mobility and thus allows for fast switching. Time resolved PNR will be a unique tool to study the switching process in MI materials in-situ, as both the hydrogen and the magnetization profiles can be determined with high accuracy. In addition, H/D contrast variation will permit to distinguish hydrogen migration from concurrent parasitic transport of other ions such as oxygen, a process which typically occurs in oxide materials.

Grazing Incidence Small Angle Neutron Scattering (GISANS) and Polarized Neutron Reflectivity (PNR) are employed in this study to investigate the structural and magnetic properties of magnetic multilayers deposited onto highly ordered nanosphere arrays. The multilayers, composed of (Co/Pd) multilayers with different numbers of repeats, were deposited using Molecular Beam Epitaxy (MBE) on a flat silicon (Si) substrate and on densely packed two-dimensional arrays of silica nanospheres with diameters of 50 nm and 200 nm, formed using an improved drop-casting method [1].
The use of highly ordered nanosphere arrays as substrates introduces a periodic nanostructure that significantly modifies the morphology and magnetic behavior of the multilayers. GISANS provides detailed insights into the lateral structural organization, revealing pronounced periodic ordering influenced by the underlying nanospheres. This lateral order affects the magnetic domain configuration and anisotropy. PNR offers depth profiles, showing increased interfacial roughness and altered magnetic coupling between layers due to the nanosphere-induced topography.
The findings demonstrate that highly ordered nanosphere arrays enhance interfacial roughness, alter magnetization reversal processes, and induce spatial variations in magnetic anisotropy, leading to modified magnetic domain structures. These results highlight the potential of using highly ordered nanosphere arrays to engineer magnetic materials with tailored properties for specific applications. This study advances the understanding of magnetism in curved nanostructured systems and paves the way for designing advanced magnetic materials with optimized functionalities.

References
[1] A. Qdemat, et.al., RSC Adv., 10, 2020.

Iron oxide nanoparticles (IONPs) are vital in many applications ranging from biomedicine to heterogeneous catalysis. While their structure is well-studied, the interfacial dynamics of surface molecules have been barely addressed up to now. Quasielastic neutron scattering (QENS), though, is highly suited to access the dynamics of water and ligand molecules on surfaces of metal oxide nanoparticles. For instance, rotational and translational diffusion dynamics of interfacial water molecules on the surface of TiO2 nanoparticles were shown to be different from bulk water [1,2]. Recently, we disentangled magnetic signatures from water and ligand diffusive modes on the surface of iron oxide nanoparticles from QENS data – yet for comparably dry powders equilibrated at 8 % RH (relative humidity). [3]
Here, we report on QENS experiments on 7 nm IONPs performed at IN16B at ILL using fixed window scans (FWS) and a wavelength of 6.271 Å. The IONPs were synthesized according to ref 4, are stabilized with the ligand citrate and equilibrated at four distinct RH, reflecting different numbers of water layers on the IONP surface: from nominally dry powders at 8 %RH, via 75 and 85 % RH to multilayer water coverage at 98 %RH. FWS were carried out at the elastic line and at an energy offset of 3 µeV. A temperature range of 2 – 373 K and a Q-range of 0.19 – 1.83 Å-1 were used.
The elastic and inelastic FWS allow us to quickly identify distinct differences in the diffusion dynamics of samples equilibrated at different RH. While at very low RH of 8 %, we are also highly sensitive to the dynamics of magnetism and the citrate ligand, with increasing RH these contributions to the quasielastic signal decrease. Compared to the 8% RH sample, the FWS of the IONPs equilibrated at 75 % RH already show on first sight the dominating contribution of diffusion dynamics of water molecules. Activation energies and relaxation times are derived from refinements of the FWS.

References:
[1] E. Mamontov, L. Vlcek, D. J. Wesolowski, et al., J. Phys. Chem. C 2007, 111, 4328-41.
[2] A. G. Stack, J. M. Borreguero, T. R. Prisk, et al., Phys Chem Chem Phys 2016, 18, 28819-28
[3] M. S. Plekhanov, S. L. J. Thomä, A. Magerl, et. al., J. Phys. Chem. C 2024, accepted manuscript
[4] M. Eckardt, S. Thomä, M. Dulle, et al., ChemistryOpen, 2020, 9, 1214–122

Slowing and stopping the ongoing rapid climate change necessitates the reduction of CO2 emissions and, therefore, fossil fuel consumption. Transportation, particularly motorized private transport, contributes significantly to fossil fuel consumption. Here, transitioning to battery elec-tric vehicles (BEVs) is an option to reduce the consumption of fossil fuels, assuming a CO2-free electricity production. Compared to conventional vehicles, BEVs have a reduced range due to a lower energy density in the battery. Next to the development of higher capacity batteries, an avenue for a higher range is to improve the efficiency of the electric drive. In our DFG-supported project, we investigated the improvement of electric drives by targeted residual stress.
Electric drives, i.e. synchronous motors, used in BEVs require the careful guidance of the magnetic flux in the rotor. The rotor comprises a stack of non-oriented electrical steel (NOES) sheets. Conventionally, material is removed from the sheets to create flux barriers. These removed areas are called cutouts and reduce the mechanical strength and, hence, the achievable rotational speed of the drive, which affects its power density and efficiency. Here, we showed that residual stress introduced by embossing, a local forming process, locally reduces the magnetic permeability. Inverse magnetostriction describes the change of magnetic permeability due to residual stress. The locally reduced permeability displaces the magnetic flux from these regions and concentrates it in other areas. Neutron grating interferometry (nGI), an advanced neutron imaging technique, is uniquely capable of mapping the magnetic flux displacement with high spatial resolution in the bulk of electrical steel, as shown in Fig. 1.
In our contribution, we will present how polychromatic and energy-resolved nGI allowed us to verify the magnetic flux guidance by mapping the dependence of magnetic domain size and orientation on material parameters and applied magnetic field. Further, we will present our current DFG-supported industry transfer project. Here, we are working with our collaborators from mechanical and electrical engineering and an industry partner to use the previously gained insights to build more efficient electric drives using residual stress to guide the magnetic flux.

Polysaccharide polymers constitute the fundamental building blocks of life and display a diverse set of conformations resulting in complex viscoelastic behaviour in their solutions; the origins of which need further understanding. Utilising a model high molecular weight, high Trouton ratio 'pectin' polysaccharide extracted from okra (Abelmoschus esculentus) mucilage, we combine computational (molecular modelling and dynamics simulation) and experimental (rheology, calorimetry, and small-angle scattering) investigations, to unveil the underlying microscopic hydrodynamic origins of polysaccharide conformation. In miscible heterogenous solvents of water and glycerol, we observe that the polysaccharide chain undergoes a non-monotonic conformational transition from flexible-to-swelled-to-collapsed configurations, resulting in pronounced viscoelastic responses. The conformational transition is entropy-driven. Although Kirkwood-Buff integrals and preferential binding coefficients indicate preferential exclusion being more significant for water compared to glycerol, molecularly adsorbed water molecules within ca. 0.40 nm of the chain surface have increased 'residence time' with an increase of glycerol in the solvent composition. We postulate that this increased water residence elicits an entropically unfavourable dynamic solvent heterogeneity, which is ameliorated by swelling and collapse of polysaccharide chains. Our results offer new fundamental insights which were previously inaccessible through mean-field assumptions.

see attached

We investigate the signature of magnetic surface anisotropy in nanoparticles in their spin-flip neutron scattering cross section. Taking into account the isotropic exchange interaction, an external magnetic field, a uniaxial or cubic magnetic anisotropy for the particle’s core, and several models for the surface anisotropy (Néel, conventional, random), we compute the spin-flip small-angle neutron scattering (SANS) cross section from the equilibrium spin structures obtained using the Landau-Lifshitz equation. The sign of the surface anisotropy constant, which is related to the appearance of tangential- or radial-like spin textures, can be distinguished from the momentum-transfer dependence of the spin-flip signal. The data cannot be described by the well-known and often-used analytical expressions for uniformly magnetized spherical or core-shell particles, in particular at remanence or at the coercive field. Based on a second-order polynomial expansion for the magnetization vector field, we develop a novel minimal model for the azimuthally averaged magnetic SANS cross section. The theoretical expression considers a general magnetization inhomogeneity and is not restricted to the presence of surface anisotropy. It is shown that the model describes very well our simulation data as well as more complex spin patterns such as vortexlike structures. Only seven expansion coefficients and some basis functions are sufficient to describe the scattering behavior of a very large number of atomic spins.

Microplastics, defined as plastic particles smaller than 5 mm, are a grave concern due to their accumulation in marine and terrestrial environments, posing significant ecological and health risks and potential to enter the food chain. Various strategies are being employed to combat this issue, including filtration, bioremediation, coagulation, and flocculation [1-3]. Herein, we have developed a model microplastic system comprised of 140 ± 6 nm polystyrene spheres dispersed in water and flocculated using Nanofloc®. Here, the polystyrene particles are analogs to the microbeads in commercial face washes. The role of Nanofloc® in this system is to induce flocculation, a process crucial for the aggregation and removal of the model microplastic from aqueous suspensions.
The polystyrene particles are negatively charged with Zeta potential - 58 mV for a particle volume fraction 1e-5. The Nanofloc® solution is highly positively charged; a 0.17 vol/vol % solution showed Zeta potential 56 mV. We prepared a series of polystyrene colloids and investigated their flocculation using scanning electron microscopy (SEM) and small-angle neutron scattering (SANS). The flocculation occurs within 10 seconds of adding Nanofloc®. SEM image of the suspension (inset, Fig 1), which exhibited complete flocculation, shows that the Nanofloc® uniformly covers the polystyrene particles with an interconnected network of compact and denser flocs. SANS studies were carried out as a function of polystyrene and Nanofloc® concentration. Fig.1 shows the SANS curve of the polystyrene particles with and without the addition of Nanofloc®. For samples with a high concentration of Nanofloc®, the intensity is random due to the quick settling of the flocs (data not shown). The scattering data for the particles with Nanofloc® was fitted using the Teixeira model for fractal aggregates, and a fractal dimension of 2.3 was obtained from the fit. This implies a faster diffusion process and the flocculation proceeds via reaction-limited cluster aggregation (RLCA).
References
1. Lapointe, M., Farner, J.M., Hernandez, L.M. and Tufenkji, N., Environmental science & technology, 54(14), 8719 (2020).
2. Rajala, K., Grönfors, O., Hesampour, M. and Mikola, A., Water Research, 183, 116045 (2020).
3. Risch, P. and Adlhart, C., ACS Applied Polymer Materials, 3(9), 4685 (2021).

The single-crystal diffractometer HEiDi at MLZ has been designed for a wide range of scientific applications, offering a broad spectrum of thermal and hot neutrons, excellent resolution, access to a large region of reciprocal space, low absorption and high sensitivity for light elements. This makes HEiDi a versatile tool for extended studies on many structures for nowadays topics in physics, chemistry and mineralogy, e.g. investigations of a wide variety of magnetic compounds, components for batteries as well as geomaterials and small molecular structures. In addition to atomic positions, details like mean square displacements or (partial/local) disorder and incommensurability and twinning are also thoroughly analyzed.

The sample environment of HEiDi plays a key role for these studies: our options for temperature-dependent measurements have been continuously optimized to perform low-temperature measurements down to ~2 K, e.g. on magnetic structures in the case of a recently finished DFG project on orthoferrites (SA 3688/1-1) [Cha17]. Also, a mirror furnace has been developed allowing not only measurements of the position and mobility of ions like lithium or oxygen in potential battery materials up to 1300 K but also enabling studies on excess oxygen incorporation in brownmillerites as part of another DFG project (ME 3488/2-1), generating a better understanding of the underlying diffusion processes and structural changes [Mag21].

The recent optimisation of HEiDi for tiny samples << 1 mm³ was accompanied by introducing high-pressure cells within two BMBF projects (05K16PA3, 05K19PA2), establishing isotropic high-pressure experiments on single crystals up to 10 GPa as new application on HEiDi [Grz20]. Aside from new diamond anvil cells and clamp cells, the later project contained the development of a prototype of an Li-glass based area detector (PSD, in collaboration with JCNS) optimized for short wavelengths in order to enable more efficient detection of reciprocal space and weak signals.

Concerning HEiDi’s future, we intend to build a larger version of the PSD prototype in order to further increase its efficiency and range of possibilities. To combine its short wavelengths with a large PSD enables us to support the growing scientific demand for total scattering studies, namely by offering PDF analysis (pair distribution function) to study locally disordered materials (including those for technological advances) as new application on HEiDi.

[Cha17] T. Chatterji et al. (2017); AIP Advances , 045106
[Mag21] F. Magro et al.(2021); J. Appl. Cryst. 54, 822-829.
[Grz20] A. Grzechnik et al (2020); J. Appl. Cryst. 53(1), 1-6 2020.

Background from sample environment may be a relatively important issue in the measurements with small and low scattering samples. It can be present in the form of sharp peaks as a function of nominal energy transfer E and scattering wave vector Q. The intensity of this parasitic intensity can be well comparable to the measured inelastic signal. The main reason for this complex Q-E structure of the sample environment background appears to be related to multiple elastic scattering (diffraction) of the incident beam on the internal structure of a cryostat comprising several temperature screens and walls of vacuum vessels even if they are made as a rule from relatively low scattering aluminium alloys. We show that this parasitic scattering can be reduced by introducing neutron absorbers inside the cryostat, in the most internal volume, on the side opposed to the used scattering side. This will imply rotating the sample with the sample stick, independently of the static cryostat thus changing the “classical” mode of operation. In fact, such systems are already being routinely used at ILL with different sample environments such as cryomagnets, for instance. If combined with a single crystal alignment device Goniostick developed at ILL, the experimenters recuperate the full flexibility of the sample movements inherent to measurements on three-axis spectrometers - now with reduced background that stem from sample environment.

Neutron and X-ray scattering experiments provide valuable insights into the nanoscopic properties of matter, a scale that is also accessible through Molecular Dynamics (MD) simulations. If the simulations reproduce the experiments, they can give greater insight into the material properties on the nanoscopic scale than traditional data analysis methods. However, existing MD forcefields are primarily optimized to reproduce macroscopic quantities.
In our work we establish a connection between published experimental data from neutron and X-ray experiments, specifically focusing on diffuse scattering and quasielastic neutron scattering, and MD simulations.
We integrate tools for MD simulation (LAMMPS) and scattering curve computation (Sassena) in a custom built Bayesian framework that employs a Markov Chain Monte Carlo approach to sample a parameter space. Our approach explores a broad range within the parameter space, enhancing the likelihood of finding the global minimum of forcefield parameters. This approach is highly versatile and can be adapted to different systems. We compare this approach to a simple brute force method of finding an adequate fit. In this work, we utilize liquid water as a proof of concept.

Calibrating the neutron optical path of EMD is a complicated process. To enhance the measurement accuracy of residual stress, it is required that the neutron beamline, sample stage rotation center axis, and radial collimators’ focal points are all focused on the center of the gauge volume defined as the scattering center. Initially, a high-precision laser tracker is used to position the neutron optical components along the path. Subsequently, the neutron beam is used to validate and possibly fine-tune optical components. Finally software calibration aligns ±90° spherical detectors with the scattering center using standard sample. Another critical goal is to minimize the experimental time. EMD employs three neutron slits to optimized the combinations of resolution and integrated peak intensity based on the best figure of merit.
After calibration, the neutron optical path of EMD has been optimized, with a neutron flux of 6×106 n/s/cm² and resolution of 0.3-0.38% @ d-spacing: 0.5-2.6 Å. The determination of the gauge volume center was highly accurate, the deviation of the peak position in the LaB6 diffraction patterns obtained from detectors on both sides after translation to a strain value is only 6 microstrains. After debugging and trial operation for one year, the EMD instrument demonstrates excellent physical performance. Currently, EMD can accurately measure residual stresses in engineering components and conduct in-situ neutron diffraction experiments for both uniaxial and biaxial tension.

Infrared spectroscopy serves as local probe reporting on specific vibrations in some side chains which are spectrally distant from the complicated infrared spectrum of a protein in solution. But it can also serve as a global probe using the coupling of the amide I or amide II vibrations of the protein backbone. Here, infrared spectroscopy can give information on the fold of the protein and also follow aggregation phenomena. Small angle neutron scattering (SANS) also reports on the global structure of proteins in solution and can give information on the shape of growing aggregates or folded proteins in solution. Both techniques prefer heavy water as a solvent for biological samples over normal water. This makes it so attractive to explore the combination of these two techniques with respected to biological processes.
In this study we would like to explore the capabilities of quantum cascade laser (QCL) based infrared spectrophotometry in combination with small angle neutron scattering (SANS). The advantages of QCLs over conventional infrared light sources are their superior beam characteristics and spectral density. Their disadvantage is the more complicated mode of operation and the limited spectral width they can cover.
As first scientific sample the effect of pH on protein aggregation and amyloid like structure formation in insulin was investigated. The sample was dissolved in phosphate buffer adjusted pH to 2. The sample was pumped constantly through varying combinations of flow through cells of the following techniques: FTIR spectrophotometer, the QCL based infrared spectrophotometer, the UV-Visible spectrophotometer, small angle neutron scattering or the static light scattering device. Thereby we could follow the amyloid like structure formation on the very same sample using different techniques in parallel. For example, we could follow the unfolding of the protein insulin and its formation of an amyloid like structure by the observation of an increasing absorption at 1627 cm-1 in the infrared spectral range and correlate this process with an increase in low momentum transfer scattering of the SANS technique, indicative of the formation of large protein assemblies.

The High Brilliance Neutron Source (HBS) [1] project aims to develop a High-Current Accelerator-driven Neutron Source (HiCANS) for neutron scattering, analytics, and imaging. It will feature several cold neutron sources, including a liquid para-hydrogen moderator. At the Forschungszentrum Jülich, time-of-flight measurements were performed with the prototype of such a cryogenic moderator for different ratios between para- and ortho-hydrogen. In order to optimize the design of future instruments that will use this cold neutron source, an accurate description of the source characteristics is necessary, which requires simulations of the neutron transport to the detector for a comparison of simulated and experimental data.

This work focuses on the comparison of various simulated spectra against experimental ones for different para- and ortho-hydrogen ratios. Several Monte Carlo codes, including MCNP, PHITS, McStas, VITESS, and KDSource, and nuclear data from the ENDF/B-VII.1, JENDL-4.0 and JENDL-5.0 libraries were utilized. The simulations started with the comparison of the proton-neutron yield spectra, continued with coupling the event files before and after the modeling of the neutron guide, and ended with the neutron time distribution at the detector. A good agreement between simulations and experiments was obtained, with a relative error below 20%.

The results provide insights into the strengths and limitations of each Monte Carlo code and nuclear data library combination. Not only the observed discrepancies are discussed, but also the potential sources of uncertainty are identified. Also, the conclusions will help to improve the accuracy and reliability of neutron cold moderator designs, especially for projects that will deploy a para-hydrogen cold source such as the HBS.

[1] T. Brückel et al, 2022. Technical Design Report High Brilliance Neutron Source. Forschungszentrum Jülich. https://doi.org/10.34734/FZJ-2023-03722

Both Microemulsions and Polyelectrolytes are part of formulations in detergency and personal care products. Therefore, it is rather surprising that only little is known about their interactions. Here, we investigate the interactions of slightly positively charged oil in water droplet microemulsions consisting of the surfactants tetrradecyldimethylamine oxide and tetradecyltrimethylammonium bromide (TDMAO, TTAB 95:5 mol:mol), the cosurfactant 1-hexanol and the oil decance with different anionic polyelectrolytes.
Small angle neutron scattering (SANS) measurements show the formation of elongated aggregates. Measurements of the dynamics on different time and length scales through neutron spin-echo spectroscopy (NSE, up to hundreds of nanoseconds and tenths of nanometres) and dynamic light scattering (DLS, milliseconds and hundreds of nanometres) show qualitatively different behaviour. While NSE measurements show a bimodal relaxation with a fast mode corresponding to the diffusion of free ME droplets and a slower mode corresponding to the diffusion of the aggregates, DLS measurements show a monomodal decay with a diffusion coefficient between the two values obtained from NSE. This finding suggests that the aggregates observed by SANS are highly transient, with a life time between the nanoseconds time scale of NSE and the milliseconds timescale of DLS [1].
Simplistic random walk simulations show that the observed SANS patterns are compatible with free microemulsion droplets which are slowed down by a fixed factor in the immediate vicinity of the PE chain. This means that the formation of aggregates can be observed in SANS without any attractive interactions between the microemulsion droplets.

References
[1] M. Simon, M. Gradzielski. I. Hoffmann, Nanoscale Adv., 2020, 2, 4722.

Focusing on the prominent technique of neutron diffraction for phase identification, the principal goal is to autonomously identify the presence of different crystalline phases such as: Al2O3, LiAlH4, TiO2, ZnS, etc., efficiently and without being dependent on a reference database. Although deep learning approaches require high amount of training data, they only use the learned weights and biases during inference which makes them rapid and robust solutions. Being known for their high throughput rates, they were employed in this study as a path to efficiently recognize phases of a neutron diffraction pattern without rule-based methods.

High-Current Accelerator-driven Neutron Sources (HiCANS) are seen as the next-generation medium sized neutron sources working in the same league as the shut down BER II reactor in Berlin or ORPHÉE reactor in Saclay. In Germany, the Jülich High Brilliance neutron Source (HBS) has been developed at Forschungszentrum Jülich (FZJ) and has been published in a technical design report in 2023 [1] containing 4 volumes (‘Accelerator’, ‘Target Stations and Moderators’, ‘Instrumentation’ and ‘Infrastructure and Sustainability’).
The technological feasability has been proven at the JULIC facility at FZJ. The next step will be to build the HBS Science Demonstrator to prove that such a neutron source enables a large variety of scientific measurements. It is supposed to have about 1% of the neutron flux expected for the HBS and 5 instruments: a diffractometer, a SANS instrument, a reflectometer, an imaging instrument und an analytics instrument.
The diffractometer is designed as a flexible instrument running with different source frequencies, operation modes and detector arrangements, which will enable different kinds of measurements: powder diffraction, single crystal diffraction, engineering diffraction and maybe even PDF measurement for local structure determination. A preliminary design and first virtual powder diffraction experiments are presented to give a flavor of the instrument performance and to start a discussion about the instrument requirements to enable the foreseen measurements, which will be the basis for the final design.
[1] T. Brückel, T. Gutberlet (Eds.), "Technical Design Report HBS", Schriften des Forschungszentrums Jülich, General Vol. 9 (Forschungszentrum Jülich GmbH, 52425 Jülich, 2023).

In order to provide users of the neutron scattering instruments at the MLZ with the appropriate partially or fully deuterated materials the JCNS built up a deuteration service, primarily from our core competence areas of polymers and ethoxylation. Similar services exist at other neutron sources, such as the ILL, ISIS or ANSTO. However, we are the first dedicated deuteration laboratory for neutron users in Germany.
As the FRM II reactor at the MLZ is currently not running we currently accept proposals for users who wish to measure their samples at different neutron sources.
During the Deutsche Neutronenstreutagung we want to present our services and capabilities to the German user community. We will also detail how people can access our services.
We offer the deuteration of various soft matter systems, including polymers, surfactants and a variety of small molecules. We are capable of conducting different methods of controlled polymerizations, such as anionic or RAFT polymerizations, to generate polymers with narrow polydispersities and precise molecular weights. In addition, we are equipped to work with deuterated ethylene oxide in order to synthesize PEO and perform ethoxylations. Our catalogue of small molecules includes various deuterated monomers, surfactants as well as deuterated phase transfer catalysts.
We are looking forward to discuss with different neutron users from all over Germany about their needs in terms of deuterated compounds and are also open to talk about long term cooperations.

The boron based multi stage tracking detector (BASTARD) is a neutron detector with high spatial resolution and high rate capability.
It consists of a multi layer gaseous detector with a boron coated cathode for neutron conversion.
The boron captures the neutrons and decays into helium and lithium ions.
The Ions are detected with the GEM based anode, giving a position resolution of 100 micrometers.
The readout allows for a rate of 10 Mhz and is realized with VMM3a hybrids via the RD51 Scalable Readout System.
A prototype detector with an active area of 10cm x 10cm is under development.
Currently the GEM foils and cathodes are framed, the first layer is beeing assembled and the readout hardware is tested.
The next steps include the design of the platform hardware and tests with a neutron beam.
The final detector will be expandend to an active area of 30cm x 30cm with a total of up to ten layers.

The scientific objective of this project is to craft a modular sample environment that facilitates the utilization of small-angle neutron scattering (SANS), a potent technique for probing the mesoscopic structural intricacies of soft matter systems amidst non-equilibrium conditions. Moreover, the design of the sample environment should enable the integration of spectroscopic measurements, such as fluorescence, UV-Vis, and infrared spectroscopy, for simultaneous monitoring of kinetics to gain complementary insights into structural evolution at molecular length scales. The integrated approach of characterizing soft matter systems simultaneously with complementary techniques is crucial because various soft matter systems not only depend on precise control of sample parameters, such as temperature, pressure, pH etc., but also are strongly sensitive to the parameter history. Thus, the modular sample environment being developed will ensure precise control of temperature and flexibility in modifying the systems composition, enabling SANS and spectroscopic observations of non-equilibrium soft matter samples in a flow-through cell in a continuous fashion. Such studies will aid in unraveling the fundamental mechanisms governing the evolution of soft matter systems, which is particularly crucial for the development of tailored materials with specific functionalities in fields ranging from drug delivery to advanced materials engineering.

Beginning in 2013 when the shut-down of the Berlin Experimental Reactor (BER II) was announced for December 2019, the management of Helmholtz-Zentrum Berlin (HZB) was offering HZB’s highly competitive, in part unique neutron scattering instrumentation and sample environment to neutron scattering facilities all over the world. A large number of collaborating institutions concluded contracts with HZB, so that hopefully all BER II instruments (but eventually 1) plus a substantial part of the neutron guides and shielding find new homes at collaborating neutron science centers in Germany, in Europe and overseas. Until now, 20 instruments have been delivered out of
which 6 instruments have already taken up user service again at their new destinations. A team of scientists, units of the administration and the technicians that once guaranteed for the continuous successful operation of the instruments at BER II reoriented to the necessary processes that ensure successful transfer of the experimental stations to their new locations. We describe these processes and the status of the transfer project which is an enormously important activity for keeping the valuable BER II experimental facilities available to the international user community.

Kinetic-quantum-sieving-assisted H2:D2 separation in flexible porous materials is more effective than the currently used energy-intensive cryogenic distillation and girdle-sulfide processes for isotope separation. It is believed that material flexibility results in a pore-breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum-sieving phenomenon at each stage of gas separation. However, only a few studies have investigated kinetic-quantum-sieving-assisted isotope separation using flexible porous materials. Here, we present the quasi-elastic neutron scattering (QENS) data showing a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures. Unlike rigid structures, the extracted diffusion dynamics of hydrogen isotopes within flexible frameworks show that the diffusion difference between the isotopes increases with an increase in temperature confirmed by measured QENS data. Owing to this unique inverse trend, a new strategy can be proposed for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal-organic framework system.

DAPHNE4NFDI is a consortium within the Nationale Forschungsdaten Infrastuktur (NFDI) in Germany, dedicated to the development of data management tools and best practices for research data from Photon and Neutron (PaN) sources. One of the tasks of the consortium is centered around data and metadata capture during the experiment with the aim to develop the FAIRness (Findability, Accessibility, Interoperability, and Reuse) of data. Here we present draft recommendations for the captured, aggregated and stored metadata of experiments at PaN large scale infrastructure facilities.

In recent years, RFeO3 systems have gained significant interest because of antiferromagnetic ordering correlation with next-generation high-density and high-speed magnonics applications [1, 2]. DyFeO3 is the first orthoferrite among the RFeO3 family to possess an incommensurate magnetic order of the rare earth sublattice under zero field conditions [3]. In DyFeO3 crystal system, there exist two magnetically ordered sublattices formed by rare earth Dy3+ ions and by Fe3+ ions. The magnetic transition temperature for ordering the Fe sublattice in Γ4 (GxAyFz) state is at TN1 ∼ 650 K and for ordering Dy sublattice it is TN2 ∼ 4 K. The Fe3+ magnetic order transform from Γ4 (GxAyFz) to Γ1 (AxGyCz) state at TSR ~ 73 K which is called as the spin reorientation transition. We report here the unusual incommensurate (IC) phase in the single crystalline DyFeO3 using our measurement at inelastic neutron scattering instrument (IN12, ILL) operated with zero energy transfer mode. Based on these measurements, higher harmonics (up to 7th order) of (001) magnetic peak corresponding to Dy order has been observed below 4 K. Similar higher order harmonics have been observed for Tb magnetic order in TbFeO3 single crystal with application of magnetic field parallel to c-axis [4]. Dy orders in incommensurate magnetic structure with k = [0, 0, L] where, L is the modulation length of IC phase. The modulation length L changes as a function of temperature over the 1 to 4 K with L = 0.0188 (1) at 2 K. Ritter et al. has reported the L = 0.028 at 2 K for the same compound in polycrystalline form [3]. The incommensurate periodicity of this IC phase is found to be approximately 53 units cells or ~ 405 Å in our study. Based on our analysis of neutron measurement, we conclude the co-existence of commensurate and IC phases of Dy ordering below 4 K.

FIG 1 : The scan measured at 3.66 K with various harmonics (+k, +3k, +5k, and +7k) reflection labeled accordingly.
FIG 2 : The variation of modulation length corresponding to Dy order as a function of temperature.

Reference :
[1] J. R. Hortensius, et al., Nat. Phys. 17, 1001 (2021).
[2] W. Lin, et al., Nat. Phys. 18, 800 (2022)
[3] C. Ritter et al., J. Phys. Cond. Matt. 34, 265801 (2022).
[4] S. Artyukhin et al., N. Mat. 11, 694-699 (2012)

This comprehensive study delves into the complex magnetic properties and interactions of the perovskite-like compound CaCu$_3$Ti$_4$O$_{12}$, employing advanced neutron diffraction and spectroscopy to explore the underlying spin-orbital coupling and single-ion anisotropy. By synthesizing high-quality single crystals and utilizing a four-circle neutron diffractometer, we capture sufficient magnetic reflections to accurately determine the magnetic structure. In-depth investigations using a neutron three-axis spectrometer reveal the exchange interactions and anisotropic energies, elucidating the spin wave spectrum and highlighting the significant role of indirect exchange interactions mediated through Ti$^{4+}$. This research provides crucial insights into the exchange model and magnetic interactions within CaCu$_3$Ti$_4$O$_{12}$, contributing to a deeper understanding of its unique properties and refining the theoretical frameworks applicable to similar complex oxides.

Foams are a complex material with a rich structural hierarchy. Aqueous foams in particular change their structure over time due to processes like gravitational drainage, Ostwald ripening and coalescence. Because of this complex structure, modelling SANS curves obtained from foams is challenging. Here, we employ a recently developed model, describing SANS data of foams. The model takes into account the geometry of the foam bubbles and is based on an incoherent superposition of reflectivity curves, arising from the foam films, and a small-angle scattering (SAS) contribution from the Plateau borders. We present results obtained from foams stabilized by ($i$) a standard cationic surfactant ($C_{14}$-TAB), ($ii$) temperature responsive pNIPAM-microgels and ($iii$) protein ($β$-lactoglobulin, casein, bovine serum albumin and lupine) stabilised foams i.e. drainage states, that provides information about the thickness. The numerous examples underline the models generality and thus gives valuable new insight of the foam aging process.

A persistent challenge for the inelastic neutron scattering technique is the low scattering cross-section of neutrons, necessitating larger sample sizes compared to other techniques. Focusing the neutron beam is a viable method to increase the flux reaching the sample. However, previous techniques have limitations concerning beam size and quality or require positioning excessively close to the sample, which interferes with sample environments. The nested mirror optic (NMO) is an ideal solution to overcome these challenges, providing a small, well-behaved beam at the sample position while maintaining space for sample environment equipment.
The development of supermirror coatings with large m-values has opened the possibility of applying this technique to the thermal TAS instrument PUMA at MLZ. While monochromator focusing with PUMA yields a beam size of about 20 mm x 20 mm at the sample position, the ongoing NMO project seeks to develop, install, and commission an NMO setup that will reduce the beam size to 5 mm x 5 mm while preserving 50% of the incoming neutrons, resulting in an 8-fold increase in flux on small samples. Additionally, it will provide space for the sample environment and will be straightforward to mount and dismount to adjust for the needs of each user.
The use of novel and complex optics necessitates developing new tools to understand the beam characteristics, such as the beam shape and resolution function. The McStas neutron simulation package offers a general tool for Monte Carlo simulations of neutron scattering instruments and experiments. By integrating with the McStasScript Python API, we have built a user-friendly GUI for simulating the PUMA instrument with McStas, including the new NMO optics. This combined program enables the simulation of neutron scattering experiments on a virtual PUMA instrument. For staff, a virtual instrument is useful for testing optics, particularly the NMO arrays. For users, a virtual instrument allows simulating experiments to test instrument parameters and acquire resolution functions. For students, a virtual instrument serves as a learning platform for neutron scattering, allowing them to practice alignment or take measurements without needing to be at the instrument.
We will discuss the planned setup and our current progress in designing the NMO setup for PUMA, along with the scientific case for this device, highlighting several planned use cases. Additionally, we will showcase the progress on the McStasScript-PUMA integration and discuss the planned features and capabilities.

The instrument ERWIN, currently being assembled at the MLZ, is a high-efficiency diffractometer designed for rapid data collection, time-resolved measurements, parametric studies and investigations on small samples. ERWIN is characterized by a large two-dimensional wire chamber detector with a virtually seamless coverage of 135° and a vertical angle range of 15° which will allow the characterization of powder samples, textured bulk samples and single crystals. The spectrum of applications ranges from time- and spatially-resolved investigations of battery materials to the kinetics of hydrogen storage materials and deformation mechanisms of engineering materials under the influence of external loads. In this contribution we will present the scientific applications, specifications, current developments and planned expansion stages.

One of the most promising cases of magnetic hyperthermia is using magnetic nanoparticles (MNPs) in cancer therapy. In this treatment, MNPs are immersed into tumours and, by heating with external magnetic fields, typically 100-900 kHz, destroy cancer cells. Since it is a clinical application, optimising field parameters and, in turn, the heating power is crucial to maintain both safety and high efficiency. Safety dictates an upper limit of the applied magnetic field. Hence, for a successful application, the heating power needs to be improved by optimising the MNP structure.
Moreover, recent studies have shown a massive increase in magnetic heating by the excitation of transversal spin modes in MNPs in the low GHz range. An ideal tool for characterising such MNPs is small angle neutron scattering (SANS), with the extended functionality provided by the MIEZE technique. Our ERUM-Pro HYMN project aims to develop a novel, unified experimental and computational toolbox for in-situ magnetic hyperthermia experiments under clinical conditions, utilising the SANS and MIEZE-SANS techniques combined with nanomagnetic simulations. This will be achieved by developing two custom-made setups for operation in the 100-450 kHz (up to 30 mT) and 0.5-4 GHz (up to 2 mT) range. We present the first SAXS and SANS results, where we used in-situ RF heating at 450 kHz to examine magnetite nanocubes with 12, 34 and 53 nm sizes. For these samples, we have found promising indications of dynamic structure formation.

Superparamagnetic iron oxide nanoparticles (SPIONs) are promising nano-vehicles for biomedical applications such as drug delivery, imaging, and magnetic hyperthermia. However, one of the limitations of these systems is their tendency to agglomerate, which has a direct impact on the efficiency of their performance. One way to overcome this limitation is to apply a coating during synthesis. In this work, we have investigated the effect of three biocompatible coatings on controlling the agglomeration of iron oxide nanoparticles. The biocompatible coatings used are sodium citrate, (3-aminopropyl)triethoxysilane (APTES), and dextran. The structural and magnetic properties of the coated nanoparticles are characterized using various experimental techniques, including cryogenic transmission electron microscopy (cryo-TEM), magnetometry, Mössbauer spectroscopy, and small-angle X-ray and neutron scattering. The results show that the coatings effectively stabilize the nanoparticles, and lead to clusters of different sizes which then modifies their magnetic behaviour due to magnetic inter-particle interactions. We also investigated the oxidation kinetics of the nanoparticles prepared with the various coating materials as a function of time to characterize the oxidation behaviour and stability. This research provides valuable insights into the design of an optimized nanoparticle functionalization strategy for biomedical applications.

The nanoscale microstructures and their evolution under multi-field coupling condition are vital to materials’ property and service stability. However, most of the “structure-property” studies were carried out for ex-situ condition, because it is difficult to in-situ investigate the microstructures evolution under complicated fields. Small angle neutron scattering (SANS) has been widely used to probe the nanoscale structures in different materials. Due to the high penetration of neutrons, it is a powerful technique for in-situ experiments with complicated sample environments, such as load frame and furnaces. Based on small angle neutron diffractometer at China Spallation Neutron Sources (CSNS), we build up an in-situ stress-temperature loading equipment. Its maximum load capacity is 10 kN, and the available temperature range is from -70 to 400 ºC. In-situ SANS experiments on composites, polymer networks, hydrogels and alloys under thermal-mechanical coupled field loading conditions were carried out by using this equipment. The SANS 2D scattering pattern was found to evolve from isotropic to anisotropic with stress loading, which reveals the morphology and spatial orientation change of the nanoscale aggregation in the specimen.

The complex interplay in 4d-5d based heterostructure thin films is a prominent topic in contemporary spintronics, particularly for the development of magnetic skyrmions within ultra-thin oxide films. For the stabilization of magnetic skyrmions, heterostructures must exhibit coexisting electron-electron correlations, large perpendicular magnetic anisotropy (PMA), interfacial Dzyaloshinskii-Moriya interaction (DMI), and strong spin-orbit coupling (SOC) (Pham et. al., science, 384, 2024). In such systems, inversion symmetry can be artificially broken using the SOC/ferromagnetic interface (J. Matsuno et.al. Sci. Adv., 2 (7), 2017). Magnetic skyrmions are primarily probed using Magnetic Force Microscopy (MFM) and their electrical detection via the Topological Hall Effect (THE) (Meng et. al. Nano lett., 19(5), 2019). This study focuses on ultra-thin SrIrO3 (SIO) and SrRuO3 (SRO) multilayer interfaces on TiO2-terminated STO (001) substrate.
In epitaxial SRO/SIO multilayers, the strong DMI acts as the driving force for the formation of magnetic skyrmions (J. Matsuno et.al. Sci. Adv., 2 (7), 2017). SRO films are deposited using high oxygen pressure sputtering (HOPS), while SIO is deposited using Molecular Beam Epitaxy (MBE). By varying the deposition time, different thicknesses of SRO thin films are achieved, and their magnetic and transport properties are studied to observe changes in their physical properties. Consequently, the evolution of the Hall effect is studied in SRO thin films with decreasing thickness.
Studies on 4d/5d based multilayer epitaxial thin films, provide an ideal playground for investigating the interplay between ferromagnetism and strong SOC. This research advances our understanding of the fundamental mechanisms driving skyrmion formation and stability, potentially leading to innovations in magnetic memory devices.

Smart microgel membranes have a wide range of applications. They can be used for water treatment or gas separation due to their ability to change their gating behaviour.(1) To form membranes from microgels, a secondary crosslinker is required. Different types of secondary crosslinkers require different types of comonomers. In this case 2-hydroxy-4-(methacryloyloxy)-benzophenone (HMABP, Figure 1) is used as a comonomer with N isopropylacrylamide (NIPAM), which is activated by UV light.(2)

For a better understanding of the membrane formation of secondary cross-linkable microgels, the microgel structure should be customisable. We can thus follow in different solvents if this distribution changes as a function of synthesis conditions, and how it can be made, e.g., more homogeneous, or specifically heterogeneous, with all the UV crosslinkers on the outside. The localisation of the crosslinker is crucial. Therefor SANS contrast matching experiments can be performed. (3)

Acknowledgements: The DFG and the ANR are thanked for funding the "SmartBrane" project.

References
(1) Uredat, Stefanie et al. ”A review of stimuli-responsive polymer-based gating membranes” Phys. Chem. Chem. Phys., 26, 2732-2744, 2024.
(2) Dirksen, Maxim et al. “UV cross-linked smart microgel membranes as free-standing diffusion barriers and nanoparticle bearing catalytic films.” RSC advances, 11,36, 22014-22024, 2021.
(3) Cors, Marian et al. “Determination of Internal Density Profiles of Smart Acrylamide-Based Microgels by Small-Angle Neutron Scattering: A Multishell Reverse Monte Carlo Approach” Langmuir 2018, 34, 50, 15403–15415, 2018

Acknowledgements: The DFG and the ANR are thanked for funding the "SmartBrane" project.
References
1 Uredat, Stefanie et al. ”A review of stimuli-responsive polymer-based gating membranes” Phys. Chem. Chem. Phys., 26, 2732-2744, 2024.
[2] Dirksen, Maxim et al. “UV cross-linked smart microgel membranes as free-standing diffusion barriers and nanoparticle bearing catalytic films.” RSC advances vol. 11,36 22014-22024, 2021.

Nuclear medicine diagnostics that are integral to modern healthcare, heavily rely on the radionuclide 99Mo, traditionally produced in nuclear reactors through the fission of 235U [1, 2, 3]. However, the complex radiochemical processing involved generates substantial radioactive waste, necessitating a shift towards more sustainable practices. This poster presents the 99Mo Best joint project, an initiative focused on developing an innovative, cost-efficient concept for the production and utilization of 99Mo-based radiodiagnostics, utilizing the 98Mo(n, γ)99Mo reaction eliminating fissile materials and minimizing radioactive waste.
The project comprises three key sub-projects:
1. Process Optimization: This involves refining the processes for generating 99Mo-based radiodiagnostics, as well as improving their processing and utilization in clinical settings.
2. Neutron Target Technology: Developing high neutron flux density neutron target technology is crucial for irradiation with reduced radiation doses, ensuring safe handling and processing of Mo samples post-irradiation.
3. Radiation Protection and Disposal: Addressing safety concerns, this sub-project aims to determine radiation protection and disposal issues pertinent to the novel 99Mo production process, ensuring a secure and sustainable approach.
This comprehensive approach aims to create a paradigm shift in the field of nuclear medicine by offering a sustainable and efficient alternative to traditional 99Mo production methods, mitigating environmental impact and advancing the application of accelerator-based neutron radiation sources in medical radioisotope production.

Oil droplets in food emulsions, such as milk, are typically stabilized with proteins and phospholipids, which influence the interface and emulsion stabilization mechanism on microscopic and macroscopic length- and time-scales. With neutron scattering techniques including contrast variation, details of the interface of an oil-water emulsion stabilized with the milk protein b-lactoglobulin have been investigated. Combining structural information on molecular length scales from small angle x-ray and neutron scattering (SAXS and SANS) [1] with time dependent neutron spin echo spectroscopy (NSE) allows to expand our understanding towards intermolecular interactions within the interface. These interactions are linked to the emulsion stability – the elastic properties of the protein or protein/phospholipid stabilized oil/water interface on molecular length scales.
NSE provides the time dependent correlation function of the proteins and the emulsion interface in reciprocal space, S(q,t), on molecular length scales and time scales in the nanosecond range relevant for thermally driven motion of such mesoscopic systems. Insights into the interfacial elasticity can be drawn from the NSE experiments.
Connecting these emerging results with classical characterizations such as interfacial tension or viscoelasticity helps understanding the complex mechanisms of interfacial stability and may contribute to a knowledge driven development of sustainable food emulsions.

[1] T. Heiden-Hecht et al., Journal of Colloid and Interface Science, 655, 319-326 (2024).

Heterostructures (HS) composed of conventional superconductors (SC) and ferromagnets (FM) reveal intriguing effects resulting from the interaction and proximity of these two opposing phases of matter. Our interest is focused on proximity effects in HS based on high critical temperature (T$_c$) SC and FM with perpendicular magnetic anisotropy, particularly oxides. SrRuO$_3$ (SRO) emerges as a suitable FM candidate due to its strong PMA with narrow domain walls and excellent lattice match with the high-T$_c$ SC YBa$_2$Cu$_3$O$_{7-x}$ (YBCO). Moreover, SRO exhibits interesting quantum properties, such as high spin-orbit coupling, anomalous Hall effect, and Berry effects. Such properties in combination with conventional and unconventional superconductors motivate the exploration of topological superconductivity [1]. We have observed indicators of proximity effects in an epitaxial YBCO/SRO bilayer HS characterized by (i) a reduction in the SC T$_c$ and (ii) an inversion of the magnetoresistance signal at the superconductivity onset. These global features invite a more detailed microscopic understanding. Polarized Neutron Scattering (PNR) provides insights into the structural and magnetic properties of the high-T$_c$ SC/FM bilayer HS with depth resolution, elucidating the spatial distribution of SC and FM regions and identifying interfacial effects. Off-Specular Neutron Scattering (OSS) offers additional depth- and lateral-resolved characterization of magnetic properties, allowing a more detailed understanding of the magnetic domain structures and interfacial interactions within the YBCO/SRO bilayer HS. In this work, we report magnetotransport results of YBCO/SRO bilayer HS prepared on low miscut SrTiO$_3$ (001) single crystals by high oxygen pressure sputtering. Additionally, through simulations, we present how PNR and OSS can be useful to investigate whether the formation of an interfacial magnetic dead or depleted layer contributes to the reduction of the SC T$_c$, and to characterize the formation of magnetic domain structures in this YBCO/SRO bilayer HS. This work contributes to a deeper understanding of the complex interplay between magnetism and superconductivity in the high-T$_c$ SC/FM systems and sheds light on future materials for quantum electronics.

[1] M. Cuoco; A. Di Bernado, APL Materials, v. 10, n. 9, p. 090902 (2022).

Invitation to the MLZ User Meeting

The High-Brilliance neutron Source (HBS) project [1] develops a High-Current Accelerator-driven Neutron Source (HiCANS) with a pulsed proton beam, a peak current of 100 mA and an average power at the target of 100 kW. The concept of such a HiCANS was published some years ago [2] indicating the feasibility of such a facility with all of its components: high-current accelerator, target station with integrated moderator-reflector assemblies and neutron instruments. All components require engineering development and testing. The JULIC Neutron Platform was thus developed as a testbed for all components and the investigation of their interplay.

The JULIC Neutron Platform uses a cyclotron providing a tunable pulsed proton beam with a low current but a variable frequency and pulse length to a spacious experimental area. A target station shielding is placed in its center with an empty inner core of 1 m3, able to accommodate different moderator-reflector assemblies as well as cryogenic moderators. The target station uses a tantalum target for the conversion of protons to neutrons and has eight spacious ducts where moderator plugs for neutron extraction or blind plugs are placed.

First beam on target was achieved in December 2022 and in 2023 a total of 7 weeks of beamtime have been used for a variety of different experiments with the help of up to 5 external guests: reflectometry, diffractometry, fast and thermal imaging, moderator and reflector material tests, dosimetry and detector tests.

At DN2024, we will present the JULIC Neutron Platform and the experiments performed. We will evaluate the possibilities an accelerator-driven neutron source offers.

References
[1] P. Zakalek, et al, J. Phys.: Conf. Ser., 1401, 012010 (2020)
[2] T. Brückel, et al. Conceptual Design Report Jülich High Brilliance Neutron Source (HBS), Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich (2020)

KOMPASS is a polarized cold-neutron three axes spectrometer (TAS) currently undergoing its final construction phase at the MLZ in Garching. The instrument is designed to exclusively work with polarized neutrons and optimized for zero-field spherical neutron polarization analysis for measuring all elements of the polarization matrix. In contrast to other TASs, KOMPASS is equipped with a unique polarizing guide system. The static part of the guide system hosts a series of three polarizing V-cavities providing a highly polarized beam. The exchangeable straight and parabolic front-end sections of the guide system allow adapting the instrument resolution for any particular experiment and provide superior energy- and Q-resolution values when compared with the existing conventional guide and instrument concepts [1, 2]. In combination with the end position of cold neutron guide, the large doubly focusing HOPG monochromator and analyzer, the V-cavity for analysis of polarization of scattering beam, the KOMPASS TAS will be very well suited to study various types of weak magnetic order and excitations in variety of complex magnetic structures and indeed first successful experiments on chiral magnets or very small crystals could already be performed.
[1] M. Janoschek et al., Nucl. Instr. and Meth. A 613 (2010) 119.
[2] A. C. Komarek et al., Nucl. Instr. and Meth. A 647 (2011) 63.
The construction of KOMPASS is funded by the BMBF through the Verbundforschungsprojekt 05K19PK1.

KWS-1 is a small-angle scattering instrument with variable wavelength resolution dedicated to experiments with polarised neutrons and polarisation analysis [1].
The instrument commences with a velocity selector positioned in the middle of the "S-shaped" neutron guide, approximately 16 meters away from the collimation line. The neutron flux is monitored both before and after the selector. Upon reaching the end of the "S-shaped" neutron guide, the neutrons enter the chopper chamber, where their continuous flux can be shaped to pulses. Subsequently, they pass through the neutron polarizer chamber. A radio-frequency spin flipper, situated immediately after the polarizer chamber, allows flipping of the neutron polarization. Finally, the neutrons proceed to the collimation line, where the beam shape is configured. As the neutrons traverse the neutron lens chamber at the end of the 18-meter-long collimation line, they scatter on the sample and are then detected by a detector housed in a 20-meter-long evacuated detector tube.
During the autumn of 2018, a state-of-the-art $^3$He detector, designed by Reuter-Stokes, was integrated. This advanced detector boasts an impressive counting rate capability, handling several MHz of scattered neutrons. Additionally, the active detection area has been expanded to approximately 1 m$^2$, encompassing nearly the entire inner diameter of the detector tube.
The neutron polarisation analysis setup integrated into KWS-1 is compatible with 3 T HTS magnet, thanks to its remarkably low stray fields. This compatibility is achieved using in-house manufactured $^3$He cells made from GE180 glass, specifically optimized for the wavelength and scattering angle used. Positioned directly in front of the detector tube, the analyser allows the measurement of all four spin-flip and non-spin-flip channels (I$^{++}$, I$^{+−}$, I$^{−+}$, I$^{−−}$). Recently, the polarisation analysis setup has been equipped with an in-situ pumping of the $^3$He cell, eliminating the need for time-dependent corrections in the analysis of neutron experiments conducted using this method.
In collaboration with the IT and Sample Environment groups, we designed and put into operation an automated sample changer tailored for the 3 T magnet. Rigorous testing conducted at the sample position demonstrated the robotic arm's ability to independently retrieve samples from storage, position them in the beam for measurement, and subsequently return them. This guarantees that samples susceptible to alterations in magnetic fields remain within a non-magnetic environment both prior to and following the measurements.

[1] A. Feoktystov, H. Frielinghaus, Z. Di, et al., J. Appl. Cryst., 48, 61 (2015).

The mullite-type PbMnBO4 and PbFeBO4 phases have been considered as excellent playground to follow the Goodenough–Kanamori–Anderson spin rules to understand the antiferromagnetic (AFM) and ferromagnetic (FM) microscopic features. We report inelastic neutron scatterings (INS) of PbFeBO4, PbMnBO4 and Pb(Fe0.5Mn0.5)BO4 powder samples between 1.5 K and 520 K. The Stokes and anti-Stokes spectra are collected on IN4C@ILL and IN6@ILL, respectively. The temperature-dependent dynamic structure factor S(Q,E) demonstrates clear changes of phonon dynamics across the magnetic phase transitions at the respective TC. The INS profile of PbFeBO4 exhibits steep magnon excitations up to E ≃ 15 meV at the momentum transfer of Q = 1.1(1), 1.6(1) and 2.7(1) Å-1, which are corresponding to acoustic spin-waves centered at (010), (111) and (113) AFM Bragg reflections, respectively. An AFM spin-wave velocity at d = 0.57(1) nm is estimated to be 653(24) ms-1. The analysis of the temperature-dependent low-frequency phonon profile is challenging below and above the TC due to magnon-phonon coupling and strong paramagnetic background, respectively. However, phonon density of states (PDOS) of the isostructural non-magnetic PbAlBO4 and PbGaBO4 phases help understand the associated phonons across the respective TC. Ab-initio lattice dynamical calculations of PDOS enables microscopic interpretations of the observed data. The calculations well reproduce the observed vibrational features and provide the partial vibrational components. Temperature-dependent PDOSs demonstrate that the optically silent phonon features exhibit negative mode Grüneisen parameter, which are responsible for the axial negative thermal expansion for all relevant mullite-type compounds.

Determining an unknown crystal structure from powder diffraction may be considered an ill-defined problem that requires experienced users to make strategic choices. Therefore, investigating the viability of the Machine Learning (ML) models for inferring structural information from powder-diffraction patterns is a highly coveted goal. Due to the limited availability of labeled experimental data, self-supervised representation learning pipelines are designed to evaluate the efficacy of using simulated diffraction patterns of known structures from crystallographic databases for training. Detailed simulation pipelines are developed that follow the evolution of constant-wavelength X-ray diffraction (XRD) while extensively modeling sample and instrumental effects. Several training and testing standards are introduced to ensure that the model learns representations obeying both invariances and equivariances attributable to instrumental and sample effects, respectively. The initial focus is to use these representations to make accurate predictions of the space group and lattice parameters of phase-pure XRD measurements. Subsequently, these representations shall be used as feature embeddings for training generative models, and they shall also be extended to accommodate neutron-diffraction measurements.

Para-hydrogen has very different mean free paths for thermal neutrons (ca. 1 cm) and cold neutrons (ca. 10 cm). This unique feature makes it possible to design and construct low-dimensional moderators which are elongated along the cold neutron extraction direction(s) but compact along the thermal neutron feeding directions. The small luminous surface together with the directed emission of cold neutrons leads allows to extract cold neutron beams with high brilliance.
Here, we will present the concept of low-dimensional moderators as developed within the HBS project for a HiCANS neutron source as well as the experimental realization of a 1-dimensional para-hydrogen cold moderator and first experimental results obtained at the JULIC Neutron Platform.

Small-angle neutron scattering (SANS) is one of the most important techniques for microstructure determination, which is used in a wide range of scientific disciplines such as materials science, physics, chemistry, and biology. Conventional SAS can probe microstructural (density and composition) inhomogeneities in the bulk and on a mesoscopic length scale between a few and a few hundred nanometers. Being sensitive to magnetism, small-angle neutron scattering (SANS) also provides a unique magnetic contrast.
Despite drastic improvements over the last decades, SANS is inherently flux limited, similar to any other neutron scattering technique, caused by the limited brilliance of todays neutron sources, that is essentially given by the properties of the target or core materials.
We show first results of a recently popular approach to optimize the usage of SANS beamtime. In this project, we use algorithms based on machine learning to optimize and automatize the measurement strategy of a pinhole SANS instrument, based on a set of exemplary standard SANS samples. Our model includes the desired statistical resolution, intensity and Q-resolution for the different geometrical setting of the instrument and is able to provide reduced I(Q) data of a set of samples as an output. In combination with machine-learning-based analysis of the measurement-data we work on an AI-based optimization of the measurement strategy.
Therefore our project may form an important contribution to developing a fully autonomous SANS experiment.

One of the most promising medical applications of magnetic nanoparticles (MNPs) is cancer therapy through magnetic hyperthermia and externally controlled drug delivery. The latter could be achieved by a phase transition of lipid nanoparticles with embedded iron oxide nanoparticles, as demonstrated in [1,2]. In such systems, external high-frequency magnetic fields can generate the heat required for the phase transition. Optimizing the field parameters is crucial, as the ultimate goal is clinical application. Small angle neutron scattering (SANS) is an ideal technique for the in-situ characterization of the magnetic response of MNPs. However, creating and controlling the magnetic field and heating power of the MNPs requires a dedicated setup compatible with the conditions of a neutron beamline.

To address this, a custom setup was prepared and used at the SANS instrument ZOOM ISIS Neutron and Muon Source research center in the UK. This proof of concept involved an AC oscillating circuit for field generation and an externally mounted pyrometer for heating control. The setup is an LC-resonator driven by a generator and amplifier. It includes a rotary capacitor with adjustable capacity and a coil. The setup is optimized for frequencies ranging from (50-600) kHz and can generate field amplitudes up to 60 Gauss. We present the experimental results, where the setup was used to examine the phase transition of a lipid nanoparticle solution under the influence of the RF magnetic field.

[1] Mendozza, M., et al. (2018). Nanoscale, 10(7), 3480–3488. https://doi.org/10.1039/c7nr08478a
[2] Caselli, L., et al. (2021) International Journal of Molecular Sciences, 22(17). https://doi.org/10.3390/ijms22179268

We present a neutron-sensitive MicroChannel Plate (MCP) detector integrated with a Timepix3 readout system. This study aims to combine the high gain and low background noise of the MCP with the excellent time and position resolution of the Timepix3. The MCP is doped with boron-10, which captures neutrons and decays into lithium ions and alpha particles. Within the microchannels, these charged particles are converted to electrons and amplified. The Timepix3 readout, offering a time resolution of 1.56 ns and a spatial granularity of 55 µm, is positioned very close to the MCP to collect the signal and record the neutron positions. Utilizing four Timepix3 chips results in an active area of 28 mm x 28 mm. The detector is sensitive to thermal neutrons, and previous studies indicate that the detector can achieve up to 10 µm spatial resolution with more than 50% thermal neutron detection efficiency. These features make our detector a promising candidate for neutron imaging and radiography applications.

Currently, the mechanical construction of the detector is complete, and vacuum and high voltage tests have been performed. We are now focusing on the design of the electronics and the integration of the Timepix3 readout. This poster will present the principles, construction stages, and future plans for our neutron-sensitive MCP detector system.

Polarized neutron diffraction is a powerful tool for studying magnetic structure and to probe the spin and orbital properties of unpaired electrons. POLI is a polarized neutron single crystal diffractometer built on the hot neutron source at MLZ [1]. Currently three standard setups are implemented on POLI: 1) zero-field spherical neutron polarimetry using CRYOPAD; 2) polarized neutron diffraction in magnetic fields; 3) non-polarized diffraction under various conditions.
We recently implemented a new actively shielded asymmetric split-coil superconducting magnet with a maximal field of 8T [2]. The magnet is designed to facilitate polarized neutron diffraction with low stray fields, a large opening (30° vertical) and a large sample space suitable for e.g., piezo goniometers, and pressure cells. We also built a compact-size solid-state supermirror bender polarizer optimized for short neutron wavelengths to provide high neutron polarization in the vicinity of the magnet. An in-situ SEOP polarizer and analyzer will be available soon which maintains high levels of neutron polarization and intensity over long periods of time. The SEOP polarizer are well shielded magnetically and can be used with the large magnet. Transferring the BIDIM26 area detector of size 26cm by 26cm from LLB to MLZ is in progress [3].
[1] V. Hutanu, J. Large-Scale Res. Facil. 1, A16 (2015).
[2] V. Hutanu et al., IEEE Trans. Magn. 58, no. 2, pp. 1-5, (2022).
[3] A. Gukasov et al., Physica B 397, 131 (2007).

In this contribution, we present a new approach to the classical treatment of total scattering data obtained from the ILL's hot neutron diffractometer. This software is based on a Python package and the use of Jupyter notebooks, providing maximum flexibility and allowing step-by-step monitoring of the entire process. At any point in the process, modifications can be made to suit the user's specific needs.
We present the current progress of the project, which currently allows for the necessary corrections to account for background contributions, attenuation, multiple scattering, and inelasticity, enabling the extraction of the total coherent elastic contribution from the sample. In addition to the classical approach for making these corrections (as with the well-known CORRECT code), the inclusion of Monte Carlo simulations is planned to achieve more refined results.
This package also facilitates the normalisations leading to the differential cross-section and the determination of the static structure factor. Finally, the Fourier transform of this structure factor enables the extraction of pair correlation functions.
For the time being, this code is specific to two-axis diffractometers, which are the standard instruments at steady-state neutron sources, such as those available in research reactors.
This technique, known as total scattering or PDF (Pair Distribution Function), has traditionally been applied to the study of the structure of liquid or amorphous systems. However, its field of application has extended to systems that exhibit long-range disorder but are ordered at short distances. Among these systems are quasicrystals and nanoparticles, where structural information is not limited to diffraction, but also includes diffuse scattering.

We present a new development of aerodynamic levitation for neutron scattering experiments,being developed in order to process both oxide and metallic melts, with a good signal with background ratio by introducing a new type of chamber. This setup enables levitation of
metallic spheres up to 4 mm in diameter under a controlled and vacuum-tight atmosphere. The system employs two 100W lasers heating the spherical samples from above and below to reduce the temperature gradient throughout the sample. First experiments have been carried out to study the crystallization behavior of lunar regolith relevant for additive manufacturing under space conditions, as well as studying liquid structure of PdNiS glass forming alloys in order to understand the impact of sulfur on glass formation.
The compactness and reliability of our aerodynamic levitation facility make it a valuable tool for neutron scattering experiments, particularly with a focus of in-situ, time resolved studies.
Future development includes experiments on time-of-flight spectrometers for studying melt dynamics. Looking ahead, this facility will be available for user access at the Institut Laue-Langevin (ILL), providing the scientific community with a new resource for their experimental needs.

Incommensurate spiral magnets have raised tremendous interest in recent years, mainly motivated by their wealth of spin structures with potential non-trivial topology. A second field of interest is multiferroicity: Helical spin structures are in general ferroelectric[1]. Both fields present enormous potential for future devices, where spin and charge degrees of freedom are coupled. Antiferromagnetic $Ba_{2}CuGe_{2}O_{7}$, characterized by a quasi-2D structure with Dzyaloshinskii-Moriya interactions (DMI) combines these regards with a third one: a variety of unconventional magnetic phase transitions. $Ba_{2}CuGe_{2}O_{7}$ is an insulator characterized by a tetragonal, non-centrosymmetric space group (P-421m) with lattice parameters a = 8.466 Å and c = 5.445 Å. The magnetic structure is mainly due to the square arrangement of Cu2+ ions in the tetragonal (a,b) plane with dominant nearest-neighbor AF exchange along the diagonal in the plane and much weaker FM exchange between planes. Below the Néel temperature $T_{N}$ = 3.05K, the DMI term leads to a long-range incommensurate, almost AF spin cycloid with the spins (almost) confined in the (1,-1,0) plane [2,3].
At zero external field, neutron diffraction is used for a careful examination of the distribution of critical fluctuations in reciprocal space, associated with the paramagnetic to helimagnetic transition of $Ba_{2}CuGe_{2}O_{7}$. Caused by the reduced dimensionality of $Ba_{2}CuGe_{2}O_{7}$, a crossover from incommensurate antiferromagnetic fluctuations to 2D antiferromagnetic Heisenberg fluctuations is observed, highlighting the rich cornucopia of magnetic phase transitions in spiral magnetic textures.
Recently, a new phase with a vortex-antivortex magnetic structure has been theoretically described[4]. It has been experimentally confirmed in a phase diagram pocket at around 2.4K and an external field along the crystalline c-axis of around 2.2T. A lack of evidence for a thermodynamic phase transition towards the paramagnet in high resolution specific heat measurements and a finite linewidth in energy and momentum of the incommensurate peaks in neutron scattering, as opposed to the cycloidal ground state, seem to mark the vortex phase as a slowly fluctuating structure at the verge of ordering. Polarization measurements and neutron experiments including electrical field to investigate its interplay with an external magnetic field are planned and will allow for further pinning down multiferroic properties of $Ba_{2}CuGe_{2}O_{7}$ [5].
[1] M. Mostovoy. Phys. Rev. Lett., 96:1–4, 2006.
[2] S. Mühlbauer et al, Rev. Mod. Phys, 91, 015004 (2019)
[3] A. Zheludev, et al. Phys. Rev. B, 54 (21):15163- 15170, (1996).
[4] B. Wolba. PhD thesis, KIT, 2021.
[5] H. Murakawa et al. Phys. Rev. Lett., 103(14):2–5,2009.

We present a novel application of neutron volume detectors to be realized for the TOF neutron powder diffractometer POWTEX [1, 2]. This application leverages the detector’s additional depth dimension needed to reconstruct neutron trajectories and enhance analytic capabilities.
The key advantage lies in exploiting the extra spatial dimension in order to extract information about the origin of the scattering source within the experiment. While directly detecting the neutron’s path is not achievable, the volume detector allows us to statistically correlate multiple neutron events within its depth to a single neutron trajectory. That is to say that a neutron trajectory can be imagined as a collection of neutrons, all having undergone identical diffraction conditions and all behaving identically within experimental resolution.
The volume detector’s ability to capture events along the depth direction serves to correlate these events to the same neutron trajectory. This correlation also allows for distinguishing “good” neutrons (those following the expected diffraction pattern) from “bad” outliers.
By identifying and removing these outliers automatically, the volume detector significantly improves data quality. This translates into cleaner datasets and facilitates superior analysis, ultimately leading to deeper scientific insights in neutron powder diffraction experiments. Furthermore, it alleviates the burden on researchers by automating the removal of “bad” events, traditionally identified and removed by hand. This application is expected to enhance the data treatment and refinement, both for conventional and multi-dimensional approaches [3]. It may also hold potential for the entire neutron science community, offering researchers a powerful tool to unlock new avenues of analysis and discovery.

[1] Houben A., Schweika W., Brückel Th., Dronskowski R., Nucl. Instr. and Meth. A 2012, 680, 124.
[2] Modzel G., Henske M., Houben A., Klein M., Köhli M., Lennert P., Meven M., Schmidt C. J., Schmidt U., Schweika W., Nucl. Instr. Meth. A 2014, 743, 90.
[3] Houben, A., Jacobs, P., Meinerzhagen, Y., Nachtigall, N., Dronskowski, R., J. Appl. Cryst. 2023, 56, 633–642.

Open Science Clusters’ Action for Research and Society (OSCARS) is a EU-funded project that will bring your research data to new audiences and target new use-cases. FAIR (Findable, Accessible, Interoperable, Reusable) data allows research data to be used in new and novel ways, with increased citations acknowledging the original researchers and facilities that provided that data.

OSCARS covers a broad range of science activities, including Humanities and Social Sciences, Life Sciences, Environmental Sciences, Astronomy, and Neutron and Photon Science. This allows adoption and tailoring of existing services to match photon science needs.

OSCARS builds on the EOSC (European Open-Science Cloud) science clusters' outcomes to support open science, by enhancing communication between these clusters (WP1), improving the outcomes of the clusters' software and services (WP2), connecting EOSC funded activities and projects (WP3) and providing direct funding for open science projects (WP4).

WP1 will establish a specific domain-orientated community-based competence centre for the science clusters' facilities. These competence centres will focus on the community's specific achievements and skills, addressing their scientific needs. This will encourage and strengthen intra-cluster collaboration, the sharing of best practices, services and strategy development.

WP2 takes a catalogue of existing services, data hubs and analysis platforms of varying maturity and will identify how they might be composed, possibly when enhanced, to provide broader support for scientific investigation. This might involve services and software from different science clusters, breaking down barriers that prevent cross-domain research and allowing new research. OSCARS will enhance specific tools to show the benefits to researchers.

WP3 will build connections between OSCARS and other EOSC projects, task forces and related work. This ensures OSCARS benefits from existing work, aligns OSCARS activity with effort elsewhere, and increases the uptake of OSCARS outcomes. WP3 will also establish testing methodology to drive up the quality of the project’s outcomes.

WP4 oversees a funding programme, split into two rounds. Each call will be open for two months and will accept a wide range of proposals that target open science and the FAIR data environment. At the time of SRI 2024, the first call will have closed; however, the second call will open in November 2024. Successful proposals will be funded for 1–2 years, with a budget of 100–250 k€.

Here, we will present the strategy within OSCARS and provide the anticipated impact within the photon science community, as core members of the Photon and Neutron Open Science Cloud (PaNOSC).

Small-Angle Neutron-Scattering (SANS) with polarization analysis is a powerful technique to investigate magnetic order in hard condensed matter systems on the nanometer and mesoscopic length scales. Especially for magnetic chiral structures, polarized SANS and its surface sensitive counterpart Grazing-Incidence-SANS (GISANS) are effective tools to determine their lateral and depth magnetic profiles. At the European Spallation Source (ESS), the expected high neutron flux coupled with novel instrumentation that will be supported by a wide variety of sample environments, will be combined with neutron polarization analysis on many instruments [1], enabling exciting new science projects.
Firstly, I will present an example system for future science projects at the ESS using polarized GISANS, and its impact on instrumentational considerations. Thin film Nb/FePd exhibits coexisting superconducting and ferromagnetic phases, affecting both the superconducting and the magnetic order around its superconducting Tc [2]. Although a Dzyaloshinskii–Moriya Interaction (DMI) leading to magnetic chirality is not expected in the L10-structured FePd, its domain walls obtain a preferred chiral direction, unveiled by polarized GISANS [3].
Secondly, comprehensive and user-friendly procedures for the collection, reduction, and analysis of polarized SANS data have to be established for ESS instruments. I will present the status of polarized SANS development on ESS instruments, including design, the data reduction protocols for polarized SANS and its future implementation into the data reduction software Scipp [4].

[1] W. T. Lee et al., EPJ Web of Conferences 286, 03004 (2023).
[2] A. Stellhorn et al., New Journal of Physics 22, 093001 (2020).
[3] A. Stellhorn, PhD thesis, RWTH Aachen University (2021).
[4] https://scipp.github.io/ess/

Polyelectrolytes (PE) are polymeric macromolecules in aqueous solution characterized by their chain topology and intrinsic charge in a neutralizing fluid. Structure and dynamics are related to several characteristic screening length scales determined by electrostatic, excluded volume and hydrodynamic interactions. We examine PE dynamics in dilute to semidilute conditions using dynamic light scattering, neutron spinecho spectroscopy and pulse field gradient NMR spectroscopy. We connect macroscopic diffusion to segmental chain dynamics revealing a decoupling of local chain dynamics from interchain interactions. Collective diffusion is described within a colloidal picture including electrostatic and hydrodynamic interactions. Chain dynamics is characterized by the classical Zimm model of a neutral chain retarded by internal friction. We observe that hydrodynamic interactions are not fully screened between chains and that the internal friction within the chain increases with increasing ion condensation on the chain.

Interchain Hydrodynamic Interaction and Internal Friction of Polyelectrolytes; Buvalaia, E., Kruteva, M., Hoffmann, I., Radulescu, A., Förster, S., & Biehl, R.; ACS Macro Letters, 22, 1218–1223

Printed Neutron Converter Foils

Can conventionally printed neutron converters substitute costly coating processes?
The cost increase of helium-3 has sparked the development of alternative detection technologies, specifically the use of boron carbide (B4C) converters is one of the pillars of next-generation neutron detectors.
While producing high-quality films, sputter-deposition is limited in the deposition area, and requires costly and energy-intensive vacuum processing. Lithium fluoride (LiF) can reach a similar performance to 1.5 μm B4C at around 20 μm layer thickness. While its lower melting point and lower costs are advantageous, there are currently no ideal film deposition techniques for this material. Therefore, the investigation of new approaches for the fabrication of neutron converter foils are necessary to improve fabrication costs, deposition over large areas and explore a larger palette of materials.
The field of Functional Printing offers several advantages to face these challenges. It provides the cost-efficient, high throughput and large area fabrication inherent to printing techniques and enables the resource efficient deposition of functional materials. Furthermore, all processes are compatible with mechanically flexible substrates, which allows the converters to be inserted into different types of detectors.
In our recent project, we investigate the deposition of B4C and LiF materials via screen printing and bar coating to fabricate high performance neutron sensing flexible films. The aim is to investigate the correlation between printing process, film properties and neutron detection efficiency and to establish the material-process-functionality relations necessary to optimize the detector performance, specifically in terms of outgassing. First small-scale samples show encouraging results in terms of performance and mechanical stability. Thanks to the industrial readiness of printing technology we expect a potential pathway towards developing a new generation of printed neutron converter foils to support the development of state-of-the-art large-area instruments.

We present a classification model consisting of an ensemble of Convolution Neural Networks (CNNs) to recommend the small angle scattering (SAS) model from the inspection of two-dimensional images generated by the position sensitive detector in small angle neutron scattering experiments. This recommendation system ranks the highest scores in the SoftMax layer of the ensemble and can provide 5 models with an accuracy of 99% that the correct model is found between the selected ones. We describe the training procedure on 260.000 images generated by means of Monte Carlo simulations. This database was generated from virtual experiments of the KWS-1 instrument at FRM-II, Garching, in Germany, in which the instrument configuration was varied between 12 setups and the SAS model of the sample was varied between 46 different models (database available in Zenodo). We also interpret the results obtained by means of explainable Artificial intelligence algorithms and discuss the possibilities of using generative adversarial networks to bring experimental features into simulated data.

The cold triple-axis spectrometer (TAS) FLEXX at HZB is a well-designed and upgraded instrument [1-4]. There was a strong wish that this excellent instrument should be preserved for the community. One attractive gap in the present instrumentation suite of MLZ, is the Larmor-diffraction technique [5-6] (LD) and, as a natural extension, cold neutron resonant spin echo (NRSE). TAS comes at no extra cost, as it is the main backbone of such an instrument.
The instrument will be placed on a cold neutron guide. Further, new developments are under way to allow for application of magnetic fields at the sample, hitherto not possible [7-9]. This opens up new vistas in the exploration of materials. A last attractive option is the possibility to combine high magnetic fields together with cold TAS.

[1] M. Skoulatos et al., NIMA 647, 100 (2011).
[2] M.D. Le et al., Nucl. Instr. Meth. Phys. Res. A 729, 220 (2013).
[3] F. Groitl et al., Rev. Sci. Instrum. 86 025110 (2015).
[4] K. Habicht et al., EPJ Web of Conferences 83, 03007 (2015).
[5] M.T. Rekveldt, Jour. Appl. Phys. 84, 31 (1998).
[6] M.T. Rekveldt et al., Europhys. Lett. 54, 342 (2001).
[7] Neutron Spin Echo - Proceedings of a Laue-Langevin Institut Workshop, Grenoble, Springer- Verlag, Ed:
F. Mezei (1980).
[8] M.T Rekveldt et al., Jour. Appl. Cryst. 47, 436 (2014).
[9] K. Habicht, “Neutron-Resonance Spin-Echo Spectroscopy: A High Resolution Look at Dispersive Excita-
tions”, Habilitation, University of Potsdam (2016).

The gas phase sorption of small molecules into solid soft matter materials has important effects on the transport and mechanical properties of the material. This bulk behavior is often framed at the microscopic level in terms of the activation of certain molecular scale dynamics by the sorbed molecules in a manner analogous to temperature, sometimes referred to plastisization. Thus the tight control of the temperature and gaseous composition during a neutron spectroscopy measurement may provide important molecular scale understanding. Practical outcomes of the perspective may include the role of sorbed water in: the stability and barrier properties of foods and pharmaceutical excipients; rehydration of bacteria and its applications to biotechnology; and the environmental stability of packaging materials. While often cryostats are used in conjunction with neutron spectroscopy to understand the thermal activation of important dynamics, the deployment of a sample environment for the control of the gas phase environment and temperature around the sample would seem important. Here we show our current state of development of such a sample environment within the geometric measurement constraints of a range of spectrometers: the two-circle cold diffractometer MORPHEUS (Paul Scherrer Institute, Villigen), and two spectrometers at the Heinz Maier-Leibnitz Zentrum (Garching) time-of-flight TOFTOF, and a cold triple axis spectrometer, LaDIFF. The platform, involving 3D printing of the sample chamber, and control of gas mixing system in a flow through system is under active development.

QtiSAS is a cross-compiled program designed for the graphical visualization, reduction, analysis, and fitting of data produced by a small-angle neutron scattering (SANS) instrument [1,2]. Initially, QtiSAS was developed to analyze data produced by SANS instruments of the Jülich Centre for Neutron Science (JCNS) at the high flux reactor FRMII at the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany. However, most of the tools can also be used for data analysis generated by any SANS instrument or data unrelated to SANS.
The current status and future options will be presented.

[1] Web page: qtisas.com
[2] Repository: iffgit.fz-juelich.de/qtisas/qtisas

The SPectrometer for High Energy RESolution SPHERES at MLZ is a third generation backscattering spectrometer with focusing optics and phase-space transform (PST) chopper. Both these main components have been upgraded over the years, resulting in a more than doubled intensity. The latest upgrade encompassed the introduction of a background chopper, allowing for a low background operation with a significantly increased signal-to-noise ratio.
SPHERES enables investigations on a broad range of scientific topics. It provides high energy resolution with a good signal-to-noise ratio and is a versatile instrument for the investigation of atomic and molecular dynamics on a μeV scale. It is particularly sensitive to the incoherent scattering from hydrogen and allows to access dynamic processes up to a timescale of a few ns. It is therefore well suited to study the dynamics in soft matter materials like polymers and nanocomposites or the motions in biological systems such as proteins. Another import application is the investigation of energy materials, for instance the study of diffusion processes in fuel cells. Other typical applications are hyperfine splitting in magnetic materials or rotational tunneling and molecular reorientations.

As a novel option for the next generation of neutron sources, the development of High-Current Accelerator-driven Neutron Sources (HiCANS) has received growing interest. High neutron yields can be achieved by irradiating metal targets with proton beams with energies in the MeV range and currents of several tens of milliamperes. In alignment with this concept, the High Brilliance Neutron Source (HBS) project has been developed at Forschungszentrum Jülich to provide a high neutron flux and brilliance for a variety of scattering, analytical, and imaging instruments.
With the aim of keeping the dose rate in the monitored areas of HBS well below the radiation protection limits, minimising background radiation from neutrons and gamma to ensure high-quality measurements and reducing material activation to minimise decommissioning waste the shielding of the HBS target station has been developed and optimised.
To achieve a most compact and modular biological shielding design, the HBS shielding prototype was realised with a multi-layer structure comprising several layers of lead and borated polyethylene supported by a suitable stepped structure. The performance of the shielding prototype was tested in 2023 on the JULIC neutron platform, which was established within the HBS project for the testing and operation of components of neutron sources based on pulse accelerators. The concept of biological shielding was verified, and its performance evaluated, demonstrating its effectiveness in meeting the desired level of radiation protection.
The analysis of the distribution of the neutron and gamma dose rate in the target station and in the experimental hall will be presented from the perspective of radiation protection. The dosimetry experiment on the JULIC platform will be given and the Monte Carlo simulation in comparison to the measurements and the subsequent analysis will be discussed.

We examine the chiral function in the polarized magnetic small-angle neutron
scattering (SANS) cross section resulting from vortex-type and skyrmion spin
structures through numerical micromagnetic simulations. Using the materials
parameters of FeGe and adopting a cylinder geometry, we consider the interplay
between the isotropic exchange interaction, the Dzyaloshinskii-Moriya interaction
(DMI), a uniaxial magnetic anisotropy, a Zeeman energy, and the magnetodipolar
interaction. We compare results with and without the DMI to understand its influence
on the emergence of skyrmions and their signature in the chiral function. Our
numerical computations are compared to an analytical trial field for the unit
magnetization vector that is able to reproduce vortices as well as Bloch and Néel
skyrmions. We show that, for the given system Hamiltonian and particle geometry,
pure Néel skyrmions do not correspond to an energy minimum and yield a vanishing
chiral function.

The Small-K Advanced Diffractometer (SKADI) is a small-angle neutron scattering instrument currently being constructed at the Eurpean Spallation Source (ESS) as a collaboration between the Forschungszentrum Jülich and the Laboratoire Leon Brillouin, France.
I will be general purpose polarized high-flux (7.7×10e8 n s-1 cm-2) and high resolution SANS instrument with a simultaneous Q-range of at least 3 orders of magnitude. It will use the cold spectrum over a wavelength band of 5 Å (10 Å in pulse skipping mode) from the cold moderator of ESS. The resolution will be ΔQ/Q = 1-7 %, depending on the specific chosen wavelength band and location on the detector.
As a general purpose SANS its science case encompasses soft matter, such as biological, medical or polymer samples, over hard matter with magnetic materials and metal samples to material science for virtually any material where the structure on a nanometer scale is of interest. Especially low background or weak scattering materials have been taken into account during the design.
For SKADI a dedicated detector, SoNDe (Solid State Neutron Detector), has been developed. This will allow SKADI to measure the primary beam directly, allowing high resolution access to low Q-values, also for weak scattering samples.
Construction and first installations at the ESS are just now taking place, and the instrument will be ready close to the beam-on-target date of ESS to accept first neutrons.
In this presentation insights into the design process and considerations will be provided, together with unique features of the instrument developed by the instrument team both at LLB and FZJ.

References
[1] JAKSCH, Sebastian, et al. Technical Specification of the Small-Angle Neutron Scattering Instrument SKADI at the European Spallation Source. Applied Sciences, 2021, 11, 8, p. 3620.

[2] JAKSCH, Sebastian, et al. Recent developments SoNDe high-flux detector project. NOP 2017 proceedings. 2018. S. 011019.

Microstructure at atomic- to nano- scale is one of the key factors that determining the mechanical and functional properties of matter. Therefore, accurate design and characterization of these microstructure are significant for properties’ manipulation in materials science. One of the novel nanostructure probe method is small-angle neutron scattering (SANS), which can unravel the fluctuation of composition, density and magnetism at 1~100 nm length-scale. Due to the high penetration, nondestructive and sensitivity to spin and light elements of neutrons, SANS finds a broad application in multidiscipline fields.
The SANS instrument at China Spallation Neutron Source (CSNS, located in Dongguan) has started to operate and open to international users from 2018. By using this instrument, we have conducted a series of off-site and in-situ SANS experiments under elevated temperature, cryogenic condition, mechanical stress and magnetic field loading [1]. These observations enable us a deep insight into the size, morphology and kinetic evolution of nanoheterogeneity in matters, including particles, precipitates, pores, and domains within hard matters as well as the macromolecule chain, aggregation, and self-assembly structure of soft matters.
A large amount of valuable users’ research has been completed and result in more and more publication in high impact journals. Based on its characteristics, the instrument specifications and research scope of SANS technique will be presented. Moreover, typical case study on SANS@CSNS will be demonstrated in the introduction of SANS application in multidisciplinary research.

In recent decades, analyzing complex, disordered systems posed a challenging yet highly rewarding endeavor in the field of physics [1]. One intriguing area of investigation involves spin disorder [2], particularly in the context of magnetic nanoparticles. They exhibit a reduced saturation magnetization compared to their bulk counterparts that is the result of a substantial degree of spin disorder. Polarized SANS with longitudinal polarization analysis (POLARIS) is a powerful technique to distinguish between spin configurations in nanoscale materials [3]. Whereas correlated spin canting near the particle surface was revealed in arrangements of nanoparticles [4,5], non-correlated spin disorder has been reported throughout non-interacting nanoparticles [6,7]. These observations indicate that interparticle interactions might play a pivotal role for correlated spin canting.

In this contribution, we will present the effect of decreasing interparticle distances, correlated with increasing dipolar interactions, on the magnetic SANS by iron oxide nanoparticles. By pyrolysis treatment of self-organized nanoparticle arrangements, a systematic increase of packing densities in nanoparticle assemblies was achieved and related to increased superparamagnetic blocking temperatures. We will present the results of a POLARIS experiment (D33/ILL) on the magnetic morphology of nanoparticles with varying interparticle interactions.

References

[1] Giorgio Parisi wins the 2021 Nobel Prize in Physics https://doi.org/10.1038/d43978-021-00122-6
[2] D. A. Keen et al. Nature 521, 303-309 (2015)
[3] S. Mühlbauer et al. Rev. Mod. Phys. 91, 015004 (2019)
[4] K. L. Krycka et al. Phys. Rev. Lett. 104, 207203 (2010)
[5] K. L. Krycka et al. Phys. Rev. Lett. 113, 147203 (2014)
[6] S. Disch et al. New J. Phys. 14, 013025 (2012)
[7] D. Zákutná et al. Phys. Rev. X 10, 031019 (2020)

Colloidal gelation, where colloidal scale particles aggregate and form a network, is a fundamental process with industrial relevance.(Jadrich et al., 2023) Following from our previous work on the structure formed by a simple system of gelling colloidal particles in a Couette shear field(de Campo et al., 2019, Muzny et al., 2023) we study the time evolution of the structure over an extended range of scattering vectors, 3x10-4 nm-1 < q < 3.1x10-1 nm-1. This range of scattering vectors contains information about the individual nano-scale sol particles and the network formed by the gelling particles. Two instruments at the Australian Centre for Neutron Scattering (Lucas Heights, Australia) were utilized: conventional pinhole SANS (BILBY(Sokolova et al., 2016)); and slit smeared intensity from a Bonse-Hart USANS (KOOKABURRA)(Rehm et al., 2018). Gelation was initiated from a model system of silica nanoparticles where a slight adjustment of the pH modulated interparticle interactions. In the absence of shear we observe that the sol rapidly increases in viscosity until flow is arrested, in the case of an applied shear we observe that viscosity rapidly increases until it reaches a maximum, and then viscosity decreases. Scattering curves at constant shear rate were modelled to yield the growth and volume fraction of clusters. Derived structural parameters were used to calculate viscosities from a simple theoretical model(Gillespie, 1983) which gives excellent agreement with measured viscosities.

de Campo, L., C. J. Garvey, C. D. Muzny, C. Rehm, and H. J. M. Hanley. 2019. Micron-scale restructuring of gelling silica subjected to shear. Journal of Colloid and Interface Science 533:136-143.
Gillespie, T. 1983. The effect of aggregation and particle size distribution on the viscosity of newtonian suspensions. Journal of Colloid and Interface Science 94(1):166-173.
Jadrich, R. B., D. J. Milliron, and T. M. Truskett. 2023. Colloidal gels. The Journal of Chemical Physics 159(9):090401.
Muzny, C., L. de Campo, A. Sokolova, C. J. Garvey, C. Rehm, and H. Hanley. 2023. Shear influence on colloidal cluster growth: a SANS and USANS study. Journal of Applied Crystallography 56(5).
Rehm, C., L. de Campo, A. Brule, F. Darmann, F. Bartsch, and A. Berry. 2018. Design and performance of the variable-wavelength Bonse-Hart ultra-small-angle neutron scattering diffractometer KOOKABURRA at ANSTO. Journal of Applied Crystallography 51(1).
Sokolova, A., J. Christoforidis, A. Eltobaji, J. Barnes, F. Darmann, A. E. Whitten, and L. de Campo. 2016. BILBY: Time-of-Flight Small Angle Scattering Instrument. Neutron News 27(2):9-13.

We investigate surface charged "starlike" micelles in aqueous solution formed by carboxy terminated n-octacosyl-poly(ethylene oxide) block copolymers, C$_{28}$-PEO5-COOH with 5 the PEO molar mass in kg/mol, by small angle neutron scattering (SANS), zeta-potential measurements and rheology. The –COOH end group was introduced by selective oxidation of the –CH$_2$ –OH end group of a C$_{28}$-PEO5-OH precursor using Bobbitt’s salt. Micellar solutions of different concentrations in the dilute and semidilute range were investigated at pH 2, 6 and 12 to vary ionic strength and the number of effective surface charges $Z_{eff}$. $Z_{eff}$ was further varied by using mixtures of C$_{28}$-PEO5-COOH and C$_{28}$-PEO5-OH at different mixing ratios. SANS measurements reveal that the intramicellar form factor $P(Q)$ is identical at the different pH-values which implies that the individual micellar structure is unaffected by the number of surface charges.
On the contrary, the intermicellar structure factor $S(Q)$ and the phase behavior show a strong dependence on $Z_{eff}$. In particular, we observe a distinct shift of the liquid - fcc crystal phase boundary. A quantitative analysis in terms of a screened Hard Sphere Yukawa otential reveals a very good agreement between experiment and theory. Because of this consistency and of the tunability of the n-alkyl-PEO starlike micelles we consider this system to be an excellent model for further studies on the interplay between steric and electrostatic interactions in soft colloids.

Macromolecules in press 2024

The cold neutron three-axis spectrometer IN12 is operated by the Juelich
Centre for Neutron Science (JCNS) in collaboration with the CEA-Grenoble as
a CRG-B instrument at the Institut Laue-Langevin (ILL) in Grenoble, France.

The instrument is situated in the guide hall ILL7 at the end position of a modern
state-of-the-art neutron guide.
With a virtual source concept and a double focusing PG monochromator
IN12 reaches a peak flux at the sample position of about 10$^8$ n/sec/cm around k = 2 Å$^{-1}$ with a simultaneously low background and good resolution.
A wavelength range far into the warmish region (max. k $\approx$ 5.1 Å$^{-1}$) is available.

A velocity selector in the guide ensures a clean beam, and a vertical guide
changing system with a transmission polarizing cavity guarantees an easy-to-use polarization set-up.

IN12 is one of the rare spectrometers that can use polarization analysis with a Mezei-spin-flipper in combination with horizontal and vertical high magnetic fields.
Different examples will be shown that demonstrate the versatility and excellence of IN12 in condensed as well as soft matter experiments.

In this reactor shutdown of the ILL we plan the installation of a second monochromator using perfectly bent Si(111) crystals. For lowest accessible wavevector range and energy transfer, it will provide a cleaner signal-to-noise ratio, clean tails of the elastic line and better energy resolution.
Its sharper focusing is advantageous when using high field magnets.
In addition the new Si-monochromator can be used also with polarized set-ups achieving excellent resolution in polarized neutron scattering experiments.

The concept of a novel cold neutron source allowing for the generation of wide neutron beams with simultaneously increased brightness and intensity compared to present-day para-hydrogen-based cold neutron sources with an equal cold neutron beam cross-section, whether flat or voluminous, is proposed.

The design employs chessboard or staircase assemblies of high-aspect ratio rectangular para-hydrogen moderators with well-developed and practically fully illuminated surfaces of the individual moderators. Model calculations indicate that gains of up to approximately 2.5 in both brightness and intensity are achievable.

An analytic approach for calculating the brightness of para-hydrogen moderators, which assumes the prevailing single collision process during thermal-to-cold neutron conversion, is introduced. The obtained results are in excellent agreement with MCNP calculations.

The concept of ‘low-dimensionality’ in moderators is explored, explaining why additional compression of the moderator along the longest direction, effectively giving it a tube-like shape ("finger moderators"), does not result in a significant brightness increase comparable to the flattening of the moderator.

The neutron time-of-flight engineering diffractometer BEER (Beamline for European Materials Engineering Research) is currently under construction at the European Spallation Source (ESS).
The main tasks of BEER are to enable fast in situ and in operando characterization of materials and their microstructure during processing conditions close to real ones and to provide state-of-the-art and fast analysis of residual stresses, phase analysis and microstructure/crystallographic texture characterization.
These tasks are supported by the instrument design. It enables, for example, to choose between a standard pulse shaping chopper technique or a newly developed technique called pulse modulation. The latter extracts several short pulses out of the long ESS pulse. Thus leading to a multiplexing of Bragg reflections and to substantial intensity gain for high symmetric materials while preserving the resolution. By the combination of both chopper techniques, BEER is a versatile engineering diffractometer providing easy tuneable resolution/flux ratios across wide wavelength and resolution ranges. Together with a large detector coverage, BEER enables sub-second in situ measurements for fast residual strain scans; texture analysis as well as phase analysis of complex composite systems where high resolution is needed. Advanced sample environments dedicated to thermo-mechanical processing, e.g. a quenching and deformation dilatometer, support these measurements.
Here, we present the current status of the BEER instrument and its features.

Inelastic neutron scattering techniques and the study of spin dynamics in magnetic materials have long driven each other's advancements. Traditionally, studies on ferromagnets like iron and nickel were limited by coarse resolution, even with state-of-the-art instruments. However, employing the modern neutron spectroscopy method MIEZE [1], we probed nickel's spin wave dispersion and paramagnetic spin fluctuations with unprecedented detail at small momentum and energy transfers.
The MIEZE technique, implemented at the resonance spin-echo spectrometer RESEDA, uniquely enables the investigation of magnetic phenomena despite depolarizing samples and environmental conditions [2]. Its versatility allows for studying weak and low-energy magnetic dynamics with reasonable measurement times, thanks to its tolerance for a broad wavelength spectrum and large neutron flux. Recent upgrades to the instrument have improved background suppression, $q$ coverage, and energy resolution.
Analyzing the spin wave dispersion of isotropic ferromagnets using the Holstein-Primakoff theory (HPT) reveals insights into weak dipolar interactions [3]. The dispersion should be quadratic for a pure Heisenberg-like ferromagnetic system for small $q$ values $E_\mathrm{SW} \propto q^2$. In contrast, HPT predicts a linear $q$ dependence of the dispersion due to the long-range dipolar interactions between the magnetic moments. In addition to the dispersion, influences on the lifetime of critical fluctuations above $T_\mathrm{C}$ are also expected because the length scale $q_\mathrm{D}^{-1}$ should enter the dynamical scaling function as a second scaling variable and separate longitudinal from transversal modes [4].

[1] R. Gähler et al., Phys. Lett. A 1, 13 (1987)
[2] C. Franz et al., NIM A 939, 22-29 (2019) 
[3] T. Holstein et al., Phys. Rev., 58, 1098 (1940)
[4] E. Frey et al., Phys. Lett. A 123, 1 (1987)

Neutron single crystal diffraction provides an experimental method for the direct location of hydrogen and deuterium atoms in biological macromolecules. At the FRM II neutron source the neutron single crystal diffractometer BIODIFF, a joint project of the Forschungszentrum Jülich and the FRM II, is mainly dedicated to the structure determination of enzymes. Typical scientific questions address the determination of protonation states of amino acid side chains in the active center, the orientation of individual water molecules essential for the catalytic mechanism and the characterization of the hydrogen bonding network between the enzyme active center and an inhibitor or substrate. This knowledge is often crucial towards understanding the specific function and behavior of an enzyme. BIODIFF is designed as a monochromatic diffractometer and is able to operate in the wavelength range of 2.4 Å to about 5.6 Å. This allows to adapt the wavelength to the size of the unit cell of the sample crystal. Data collection at cryogenic temperatures is possible, allowing studies of cryo-trapped enzymatic intermediates. Unit cells with lattice constants up to 200 Å can be measured at BIODIFF. Recently more and more proposals have been submitted with interesting projects that exceed cell constants of 200 Å. In order to serve such needs a potential detector upgrade for BIODIFF will be presented, which will expand the maximum unit cell limits.

We investigated the SARS-CoV2 membrane fusion timescale by means of small-angle neutron scattering (SANS) using hydrogen/deuterium contrast variation. After the successful production of virus-like vesicles and human- host-cell-like vesicles we were able to follow the fusion of the respective vesicles in real-time. This was done using deuterated and protonated phospholipids in the vesicles in a neutron-contrast matched solvent. The vesicles were identical apart from either the presence or absence of the SARS-CoV2 spike protein. The human host-cell-like vesicles were carrying an ACE2 receptor protein in all cases. In case of the absence of the spike protein a fusion over several hours was observed in agreement with literature, with a time constant of 4.5 h. In comparison, there was not time evolution, but immediate fusion of the vesicles when the spike protein was present. Those two figures, fusion over several hours and fusion below 10 s corresponding to the absence or presence of the spike protein allow an upper-limit estimate for the fusion times of virus-like vesicles with the SARS-CoV2 spike protein of 10 s. This very fast fusion, when compared to the case without spike protein it is a factor of 2500, can also help to explain why infection with SARS-CoV2 can be so effective and fast. In order to access very short timescales we also performed continuous flow experiments, which support the stopped flow and static experiments. This fusion process could be strongly influenced by a promising drug candidate, which inhibited the fusion process.

In addition to the time-resolved contrast matching SANS experiments we also performed neutron-spin echo experiments to investigate the dynamics of the membrane during the fusion process.

Studying spike protein variants using our method may explain differences in transmissibility between SARS-CoV2 strains. In addition, the model developed here can potentially be applied to any enveloped virus.

References
Hayward, D., Dubey, P. S., Appavou, M. S., Holderer, O., Frielinghaus, H., Prevost, S., ... & Jaksch, S. (2023). Timescales of Cell Membrane Fusion Mediated by SARS-CoV2 Spike Protein and its Receptor ACE2. arXiv preprint arXiv:2303.10746.

The Fe$_3$O$_4$/Nb:STO system has garnered significant attention due to its potential applications in spintronics and memristors. We present an investigation of a 30 nm Fe$_3$O$_4$ thin film deposited on a Nb-doped SrTiO$_3$ (Nb:STO) substrate using Polarized Neutron Reflectometry (PNR) and X-ray Reflectometry (XRR) at low temperatures. Around 105K, Nb:STO undergoes an antiferrodistortive transition, and the resulting faceting induces extra strain on the Fe$_3$O$_4$ films, and also affects the resolution and interpretation of PNR measurements [1]. Fe$_3$O$_4$, known for its Verwey transition around 120 K, exhibits changes in electronic conductivity and magnetic properties as the temperature passes through T$_V$ due to structural changes from cubic to monoclinic.

Our study reveals that low temperatures induce notable modifications in the roughness and density of the Fe$_3$O$_4$ film, driven by the transitions in both the Nb:STO substrate and the Fe$_3$O$_4$ film itself. The Verwey transition in Fe$_3$O$_4$ leads to marked changes in its magnetic profile, as observed through variations in the magnetic scattering length density.

These findings highlight the complex interplay between the transitions in Fe$_3$O$_4$ and Nb:STO, providing insights for the development of advanced memory and spintronic devices.

[1] Hoppler et al,PRB 78, 134111 (2008)

Surprisingly, recent inelastic neutron scattering experiments on the spin-1/2 triangular lattice antiferromagnet(TLAF) Ba$_{3}$CoSb$_{2}$O$_{9}$ reveal unconventional multiband higher energy excitations that might be relevant to quantum nonlinearity. To clarify whether this unconventional higher energy excitation continuum is universal for spin-1/2 triangular antiferromagnets or not, various high-resolution neutron spectroscopy measurements on polycrystalline Ba$_{3}$CoNb$_{2}$O$_{9}$ and Ba$_{3}$CoTa$_{2}$O$_{9}$ were performed and achieved an unprecedented energy and time scale.

In this poster, the magnetic excitations of the novel spin-1/2 TLAF Ba$_{3}$CoNb$_{2}$O$_{9}$ and Ba$_{3}$CoTa$_{2}$O$_{9}$ will be presented. The strong quantum fluctuations of the effective S-1/2 cobalt moments are evident by the higher energy continuum qualitatively observed in both compounds. A Heisenberg model will be discussed with spin wave theory. The physical interpretation of quantum fluctuation will be shown in detail.

Additionally, the updated work on a complementary neutron spectroscopy sum rule for frustrated magnets will be presented. This rule is an extension to the current version of total moment sum rule to the macroscopic measurable quantities. As an example, its application on Ba$_{3}$CoNb$_{2}$O$_{9}$ and Ba$_{3}$CoTa$_{2}$O$_{9}$ will be illustrated.

Photosynthesis is a biochemical process by which sunlight is converted into chemical energy. As a major input of energy into the terrestrial environment, where for example, the Archean origins of this process represent an important geological timescale event in the evolution of the terrestrial environment.1 The modern ecological relevance of understanding photosynthesis is evident in the impact of global warming is unpinned by such phenomena as coral bleaching.2 A reductionist view on photosynthesis is the storage of electrochemical potential by intra-cellular membranes. Small angle neutron scattering (SANS) is non-destructive structural probe, albeit of low information content, suitable for monitoring aspects of photosynthetic membrane organization in vivo in actively metabolizing cells. Information in SANS patterns is typically extracted by comparison of patterns with a model calculation by linear least squares fits. Real space information, for example TEM microscopy, provided a ready comparison with the reciprocal space SANS derived model consisting of stacks of bilayer enclosed compartments.3 When constrained by other sources of information modelling of SANS data is a convenient method for verifying structural hypothesis based on real space models of cell membrane organization. Here we report on SANS as a general method for analysis of bilayer organization in photosynthetic Symbiodinium algae, both in hospice in coral and anemone polyps, and isolated.

1. Fournier, G. P.; Moore, K. R.; Rangel, L. T.; Payette, J. G.; Momper, L.; Bosak, T., The Archean origin of oxygenic photosynthesis and extant cyanobacterial lineages. Proceedings of the Royal Society B: Biological Sciences 2021, 288 (1959), 20210675.
2. Sully, S.; Burkepile, D. E.; Donovan, M. K.; Hodgson, G.; van Woesik, R., A global analysis of coral bleaching over the past two decades. Nat. Commun. 2019, 10 (1), 1264.
3. Nallet, F.; Laversanne, R.; Roux, D., Modeling x-ray or neutron-scattering spectra of lyotropic lamellar phases - interplay between form and structure factors. J. Phys. II 1993, 3 (4), 487-502.

The cold neutron time-of-flight chopper spectrometer TOFTOF is versatile to address large parts of the relevant momentum and energy transfer range, with a tunable energy resolution, and it has a strong user base in the disordered materials community (materials sciences, soft matter, life sciences, magnetic materials). The instrument is in operation since 2005, and some critical components (chopper system, detector electronics) are likely to ultimately fail, with no possibility for repair or spare part supply. At the same time, advances in neutron optics technology and the use of position sensitive detectors will be made use of to further enhance the attractiveness of the instrument to an even broader user base. Both points shows that a rebuild is needed to ensure ongoing TOFTOF user operation with a state of the art instrument. Here we want to discuss our plans for the rebuild of the Instrument TOFTOF.

Since first years of exploitation in 1960-70, neutron scattering has emerged as a unique and non-destructive means to probing inside matter properties at the nanometer length scales. Because the neutron production is scarce and expensive, the detection has to be extremely efficient. We take advantage of the recent improvements of optical sensors in photon detection, to develop a position-sensitive neutron detector combining high detection efficiency and high spatial resolution. This 2D-neutron detector displays exceptional performances: Wide reciprocal space observation, spatial resolution lower than 0.5mm, low detection threshold (<1 neutron/cm2/s), reduced dimensions and a permanent upgrading. We underline the advantage of associating an accurate wavelength selection and point out the possibility to operate in time of flight mode. This type of instruments certainly foreshadows the future neutron scattering landscape, in particular in the view of future spallation sources.
P. Baroni, L. Noirez, American Journal of Applied Sciences,11(9):1558-1565 DOI: 10.3844/ajassp.2014.1558.1565.

Thermal moderators are a crucial component in the chain of neutron flux generation in neutron sources. Typically, the primary neutrons emitted from the nuclear reactions have energies in the MeV range. To be made useful for scattering or analytics experiments, their energies must decrease to reach values well belower 1 eV. The primary function of the thermal moderator is to facilitate this process while maintaining a compact neutron field. This ensures the extraction of high-intensity beams from the moderator region. Inserting a cryogenic moderator into compact neutron field of the thermal moderator allows a very efficient feeding of the cryogenic moderator and a further reduction of the neutron energy into the meV range. It is therefore crucial to understand the effects a thermal moderator has on the performance of an accelerator-driven neutron source.
A modifiable target station was thus setup at JULIC, the pre-accelerator of the COSY facility in Jülich. It provides a pulsed 45 MeV proton beam with adjustable pulse lengths and frequencies and allows extensive studies of moderator setups. This study aims to test the moderator and reflector design and materials to assess their suitability and feasibility. A polyethylene moderator and a lead reflector filled with neutrons emitted from a tantalum target have been chosen. By performing comprehensive simulations and experimental validations, we aim to verify that the thermal moderator meets the requirements for forthcoming scientific investigations and experiments.
At the DN2024, we will present the performed experiments as well as the validations with Monte Carlo simulations.

High-Current Accelerator-driven Neutron Sources (HiCANS) have been established as a promising option for a new generation of neutron sources. Within the framework of the high brilliance neutron source (HBS) project a powerful HiCANS is developed to serve as a user facility. One of the key components as well as a particular challenge is the development of a neutron target since it is the main power-limiting factor of this type of facility. This target releases neutrons via nuclear reactions from an impinging proton beam with energies well below the spallation threshold. The quite small neutron yield of these nuclear reactions is compensated by a high current. The unique requirements specified for the HBS neutron target are given by a 70 MeV pulsed proton beam with a peak current of 100 mA, an average thermal power of 100 kW on a target area of 100 cm² and a desired lifetime of about one year.
A solid tantalum target prototype with an innovative micro channel water cooling structure was developed, manufactured, and successful tested at operation conditions with an electron beam as well as destroyed in order to experimentally examine the targets limit. Known challenges from low energy targets like blistering, joining, lifetime, and heat dissipation, as well as particular challenges of the HBS target design like coolant erosion, thermomechanical stresses, and critical heat flux have been consequently considered during the development.
Here, we will present the HBS target design, explain various measures taken to solve the challenges mentioned, and show the successful high heat flux tests in the electron beam facility JUDITH 2.

The High Brilliance Neutron Source (HBS) project is developing a high-current accelerator-driven neutron source (HiCANS). It will facilitate three target stations with a large suite of instruments for neutron scattering, imaging and analytic. Each target station has its own optimized moderator structure and thus provides a high extractable neutron brightness. One target station will be dedicated to cold neutron instruments with a large pulse length and a large neutron bandwidth and therefore requires a cryogenic moderator. The existing moderator setups for low power CANS or spallation-based neutron sources need to adjusted to the specific characteristics of a HiCANS and the need to provide cold neutrons to a large number of instruments.
Following the basic principle of a low-dimensional moderator, three different liquid parahydrogen moderators have been investigated using Monte Carlo simulations: a one-dimensional moderator, a pancake moderator and a combination of both named star-like moderator. Each moderator shows a different coupling strength between the thermal water moderator and the parahydrogen due to the different surface-to-volume ratios. Our results show that increasing the thermal neutron feeding surface can significantly boost cold neutron brightness.
At the DN2024, we will present the simulations we have done. We will show that an optimized moderator structure shows very promising results for target stations that serve a large number of instruments.

The High Brilliance Neutron Source (HBS) aims to develop a High-Current Accelerator-driven Neutron Source (HiCANS) for neutron scattering, analytics, and imaging. Among the 25 instruments planned and described in the Technical Design Report [1], there will be at least 5 different neutron imaging instruments, covering a wide range of neutron energies from cold to fast, and dedicated to different applications such as hydrogen in metals, nuclear safety, battery processes, strain-phase mapping studies in engineering, automotive, aerospace, geology, and cultural heritage.

Each one of these imaging instruments will provide specific sample positions, which were chosen to optimize the flux, collimation, spatial, wavelength, and time resolutions (applies for the cold, diffractive, and resonance neutron instruments). To optimize the required neutronic parameters Monte Carlo simulations were used, starting from the source and ending at the sample position. For the source simulations, the PHITS code was used, while VITESS and McStas performed the ray transport through the instrument. Also, an open-source code called KDSource was used to increase the statistics by resampling new particles at a given point of the neutron beam trajectory. The obtained computational results were found to agree well with the expected values derived from analytical models.

Finally, in the framework of the HBS project, an experimental platform, the so-called JULIC Neutron Platform [2], was built at the Forschungszentrum Jülich. There, the proof-of-principle capabilities of this kind of platform to perform thermal and fast neutron imaging have been demonstrated.

The objective of this work is to present to the neutron scattering community the conceptual design of these neutron imaging instruments, along with the principal parameters, the potential capabilities, and the simulations performed. Also, the results obtained at the JULIC Neutron Platform will be shown.

[1] T. Brückel et al, 2022. Technical Design Report High Brilliance Neutron Source. Forschungszentrum Jülich. https://doi.org/10.34734/FZJ-2023-03722
[2] P. Zakalek et al, 2023. The JULIC Neutron Platform, a tested for HBS. UCANS10 proceedings.

Aiming to develop a high-current accelerator-driven neutron source (HiCANS), the High Brilliance Neutron Source (HBS) project has extensively detailed its technical aspects in the conceptual and technical design reports [1][2]. The facility, based on a high-power linear proton accelerator delivering a 70 MeV proton beam with a peak current of 100 mA, is designed to supply three distinct target stations operating at different pulse frequencies. Each target station will provide pulses optimized for specific instrument groups, ensuring efficient use of the available beam and supporting a competitive suite of instruments.
A next step is the realization of an HBS Science Demonstrator, which aims to assess the scientific potential of HiCANS, providing a proton beam power of approximately 10 kW. It will feature a selection of highly demanded neutron instruments, among them a small angle neutron scattering (SANS) instrument. For this, we will present a conceptual design including ray-tracing Monte Carlo simulations using the software VITESS to optimize instrument parameters. Virtual experiments on select samples, representing typical use cases, will be used to quantify the instrument performance.

[1] Thomas Brückel et al. Conceptual Design Report Jülich High Brilliance Neutron Source (HBS). Ed. by Thomas Brückel and Thomas Gutberlet. Vol. 8. Reihe Allgemeines/General. Schriften des Forschungszentrums Jülich, 2020. ISBN: 978-3-95806-501-7.

[2] Thomas Brückel et al. Technical Design Report HBS. Ed. by Thomas Brückel and Thomas Gutberlet. Vol. 8. Reihe Allgemeines/General. Schriften des Forschungszentrums Jülich, 2023. ISBN: 978-3-95806-711-0.

Surfactants are one of the most important product categories in chemical industry. Consumer care is a prominent area in the wide variety of commercial applications. In this study, the localization of dyes within surfactant micelles is studied utilizing small-angle neutron scattering (SANS) combined with contrast variation using deuterated surfactant molecules. Additional NMR measurements helped confirming the localization of dye molecules within the micelles.

In a first step, we characterized the self-assembly behaviour of three commercial azo hair dyes, of blue, yellow and red colour, using a NaHCO3/Na2CO3 buffered solution at pH 10.5 [1]. We could, with UV-vis spectroscopy and SANS, prove that despite their similar chemical nature, the three dyes behave differently: Whereas yellow does not self-aggregate, blue only forms dimeric assemblies, but red aggregates even further, into fractal-like structures which are composed of cylindrical segments.

Dyeing formulations and hair care products contain different types of surfactants. Therefore, we dissolved a dye in solutions of either a cationic (DTAB) [2, 3] or a nonionic surfactant (C12E5) [4]. Micelles formed between dye and the cationic surfactant adopt different morphologies, ranging from short elliptical micelles to wormlike structures, depending on the concentration ratio of dye to surfactant. The dye is located in the outer region of cationic surfactant micelles. Dissolving the dye in a nonionic surfactant solution, both temperature and pH become additional parameters that govern the adopted micellar shapes. The dye localization is seen to depend on the pH, moving from the interior via the palisade to the outer micellar region as the pH is increased.

References
[1] W. Müller et al., Soft Matter 19, 4579 (2023)
[2] W. Müller et al., Soft Matter 19, 4588 (2023)
[3] W. Müller et al. Nanoscale Advances 5, 5367 (2023)
[4] W. Müller et al. Langmuir (2024), in print

Diffusion of proteins is essential for transport and regulation in biology. Changes in the short time diffusion - where hydrodynamic and electrostatic interactions dominate whilst protein-protein collisions can be neglected - influence the long time diffusion. For monodisperse protein solutions, systematic studies in the short-time regime confirm a comprehensive picture in good agreement with colloid theory, describing the dependence on temperature, size, and volume fraction [1-3]. In contrast, biological systems contain differently sized particles in the solution. This polydisperse crowded environment influences the diffusion of individual tracers, depending on their size. Recently, the short-time diffusion of tracer proteins has been investigated in the presence of a naturally crowded environment both with quasielastic neutron backscattering and simulations, confirming a good agreement between experiment and model [4]. The simulations as well as further studies [5] showed that the short time diffusion of the tracers changes if the environment changes from a purely monodisperse to a polydisperse environment. Moreover, neutron backscattering spectroscopy on solutions containing proteins with two distinct hydrodynamic radii, namely bovine serum albumin (BSA) and immunoglobulin (IgG), provides additional access to the situation of differently sized tracers [6]. By changing both the total volume fraction as well as the fraction of BSA and by applying fits along energy and momentum transfer simultaneously, the global diffusion of both proteins can be separated from the internal diffusion and from the solvent contribution. The resulting diffusion coefficients for both proteins are in quantitative agreement with the predicted deviation from the monodisperse case of pure BSA and pure IgG, respectively. The methods developed also benefit systematic studies of protein cluster formation, including crowding- and salt-induced clusters [7-11], where the latter can be modeled as patchy colloids, as well as clusters of monoclonal antibodies [12]. References: [1] M.Grimaldo et al., Quart.Rev.Biophys. 52, e7 (2019), https://doi.org/10.1017/S0033583519000027 [2] M.Grimaldo et al., J.Phys.Chem.B 118, 7203 (2014), https://doi.org/10.1021/jp504135z [3] F.Roosen-Runge et al., PNAS 108, 11815 (2011), https://doi.org/10.1073/pnas.1107287108 [4] M.Grimaldo et al., J.Phys.Chem.Lett. 10, 1709 (2019), https://doi.org/10.1021/acs.jpclett.9b00345 [5] M.Wang et al., J.Chem.Phys. 142, 094901 (2015), https://doi.org/10.1063/1.4913518 [6] C.Beck et al., J.Phys.Chem.B 126, 7400 (2022), https://doi.org/10.1021/acs.jpcb.2c02380 [7] M.Braun et al., J.Phys.Chem.Lett. 8, 2590 (2017), https://doi.org/10.1021/acs.jpclett.7b00658 [8] C.Beck et al., J.Phys.Chem.B 122, 8343 (2018), https://doi.org/10.1021/acs.jpcb.8b04349 [9] F.Roosen-Runge et al., Sci.Rep.4, 7016 (2014), https://doi.org/10.1038/srep07016 [10] M.Grimaldo et al., J.Phys.Chem.Lett. 6, 2577 (2015), https://doi.org/10.1021/acs.jpclett.5b01073 [11] C.Beck et al., Soft Matter 17, 8506 (2021), https://doi.org/10.1039/D1SM00418B [12] I.Mosca et al., Mol.Pharm. 20, 4698 (2023), https://doi.org/10.1021/acs.molpharmaceut.3c00440

Saponins are ususally plant derived amphiphiles which exhibit strong physiological effects. In the present contribution we discuss the saponin ß-aescin with respect to its interaction with model membranes made of the negatively charged lipid 1,2-dioleoyl-sn-glycero-3-phosphoglycerol (DOPG). The study is conducted at a pH value at which aescin is negatively charged as well, and mixtures up to an aescin content of 50 mol% (equivalent to a molecular ratio of 1:1) were investigated, so that the cmc of aescin is exceeded by far. Analysis of the system by scattering and NMR methods was performed with respect to two reference systems made of the bare components: DOPG SUVs and aescin micelles. Wide-angle X-ray scattering (WAXS) was used to determine molecular correlation distances for both kinds of molecules, and small-angle neutron and X-ray scattering (SANS and SAXS) revealed a structural picture of the system, which was further confirmed by diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR). Contrary to the expected solubilization of the DOPG membrane, most probably none- or only weakly-interacting, separated DOPG SUVs and aescin micelles were found [1]. This is in line with prelimnary results from neutron spin-echo (NSE). The study highlights the importance of using independent methods to characterize a rather complex colloidal system in order to obtain a complete picture of the structures formed.

[1] F. Gräbitz-Bräuer et al.; Colloid and Polymer Science (2023) 301:1499–1512

Small-angle scattering is a commonly used tool to analyze the dispersion of nanoparticles in all kinds of matrices. Besides some obvious cases, the associated structure factor is often complex and cannot be reduced to a simple interparticle interaction, like excluded volume only. In recent experiments, we have encountered a surprising absence of structure factors (S(q) = 1) in scattering from rather concentrated polymer nanocomposites [1]. In this case, quite pure form factor scattering is observed. This somewhat “ideal” structure is further investigated here making use of reverse Monte Carlo simulations in order to shed light on the corresponding nanoparticle structure in space. By fixing the target “experimental” apparent structure factor to one over a given q-range in these simulations, we show that it is possible to find dispersions with this property. The influence of nanoparticle volume fraction and polydispersity has been investigated, and it was found that for high concentrations only a high polydispersity allows reaching a state of S = 1. The underlying structure in real space is discussed in terms of the pair-correlation function, which evidences the importance of attractive interactions between polydisperse nanoparticles. The calculation of partial structure factors shows that there is no specific ordering of large or small particles, but that the presence of attractive interactions together with polydispersity allows reaching an almost “structureless” state.

Figure 1. Apparent structure factor of nanoparticles in polymer melt, before annealing (S = 1), and after. The sketches on the left show snapshots of the corresponding particle distributions in space.

[1] A.-C. Genix et al, ACS Appl. Mater. Interfaces 11 (2019) 17863
[2] A. C. Genix and J. Oberdisse, EPJE 2023, 46(6), 46 (highlight, on the occasion of the 50th birthday of D11)