MORIS user workshop

26 Apr 2023, 12:00 → 27 Apr 2023, 15:15 Europe/Berlin

UYL 04 20 - JCNS Meeting room (MLZ)

Peter Müller-Buschbaum (TU München, Physik-Department, LS Funktionelle Materialien), Martin Müller (Helmholtz-Zentrum hereon GmbH)

MLZ aims for a comprehensive refurbishment program, MORIS, in order to consolidate the instruments suite, identify and address potential long term reliability issues and provide an opportunity to implement new concepts or technologies, be it for beam delivery, at the core of the instruments or at the sample environment level.

MORIS stands for "MLZ Organized Refurbishment of the Instrument Suite". This project roots on proposals made by the MLZ scientists but, in accordance to our mission as a user facility, we are seeking a strong cooperation with the neutron community as a whole.

At this workshop, we would like to discuss our plans and ideas for the upgrade and further developments of our instrument suite in view of the anticipated scientific questions of the coming years. The workshop will take place at the MLZ in Garching on April 26-27^th (lunch to lunch meeting, the timetable can be found here). 

The workshop comprises plenary and parallel sessions with contributions from the user community as well as a presentation of the envisioned projects. The parallel sessions are structured along the experimental methods given below. For each topical session, scientific talks will highlight the pertinent questions of current and future research and how the instrument development can address these questions.

The parallel session will cover:

    * Spectroscopy of Soft Matter

    * Spectroscopy of Hard Matter

    * Large Scale Structures

    * Structure

    * Analytical Methods, Positrons, Imaging (API)

Ample time will be dedicated to open discussion, in order to ensure that the proposed upgrades satisfy the needs raised by the present trends and future challenges. The outcome of the discussion will be the baseline for the science case of our upgrade programme MORIS.

So, be part of this initiative to shape the future of neutron science at the European level and join us for this workshop where we will set the next steps towards a better user facility!

Looking forward to meeting you in Garching,

20230418-MORIS-pre-project-description_V2.0.pdf

Wednesday 26 April

12:00 → 13:00 Lunch and registration

13:00 → 13:30 Welcome, Motivation and tasks

Speakers: Prof. Martin Müller (Helmholtz-Zentrum hereon GmbH), Peter Müller-Buschbaum (TU München, Physik-Department, LS Funktionelle Materialien), Stephan Förster (Forschungszentrum Jülich)

13:30 → 14:30 New instruments

Convener: Markus Braden (Universität zu Köln)

13:30 FLASH-NT – A new imaging instrument on a cold neutron guide

Neutron imaging is an invaluable tool for many applications where X-rays fail to provide sufficient contrast, or penetrate at all. Together with recent achievements in high-resolution detectors and the development of advanced imaging techniques, many novel fields of applications become possible. High resolution neutron imaging has shown great potential in the optimization of the water management in anionic exchange membrane fuel or electrolyzer cells, which is a key feature for their large-scale application in a fossil-free chemical industry. Similarly, the visualization of lithium transport phenomena and dendrite growth with highest possible spatial resolution provides novel insights for the improvement of safety and lifetime of Li-ion batteries. Moreover, the use of modern and advanced neutron imaging techniques helps to find solutions for many important scientific challenges. These are e.g. the study of magnetic domains in electric steels using neutron grating interferometry (nGI) with the aim of developing electric drives with higher efficiency or the spatially resolved investigation of magnetic properties of weakly ferromagnetic materials using polarized neutrons that may eventually lead to the development of novel storage devices. Additionally, the spatially resolved determination of phase composition or strain mapping in alloys using Bragg edge imaging provides tremendous potential particularly for industrial applications.
We propose to build the additional neutron imaging instrument FLASH-NT, which is complementary to the higher energy spectrum at NECTAR and ANTARES, at an end position of a cold neutron guide. FLASH-NT will provide a fully moderated cold neutron spectrum with a minimum wavelength of ~2 Å, combined with an extremely low background. The instrument will be optimized for applications requiring highest possible spatial resolution down to the single µm range and applications using advanced imaging techniques that will benefit most from the broad spectral range and the low background at a neutron guide, thus adding new possibilities to the portfolio of neutron imaging applications at MLZ.

Speaker: Michael Schulz

13:50 Bonse-Hart USANS, the missing link for heirachical materials at MLZ?

Hierarchical materials, which contain structural organisation at many different length scales, are an important aspect of biomaterials and natural systems. Recent developments in technology, for example additive manufacturing, are enabled by the power of structural hierarchies. A Bonse-Hart diffractometer provides an effective means of bridging the gap between real space, imaging, and reciprocal space, small angle scattering, in structural investigations of isotropic materials at micron plus length-scales. The aim of this project is to complement existing and proposed instrumentation at the MLZ in a way that expands the relevance of neutron scattering for industrial applications.

Speaker: Christopher Garvey (MLZ)

14:10 Indirect-geometry crystal spectrometer Mushroom

Magnetic systems are a 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 and electronic applications. 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 such exotic excitations is by far more challenging, as they show broad distribution in the energy and momentum space. Complex dispersion relations require long measurement times and great effort when measured on triple-axis spectrometers that can only scan through the (Q, E)-space point by point. Compared to this the proposed indirect-geometry spectrometer Mushroom with a time-of-flight primary chopper spectrometer, a large super-cone crystal analyzer covering the upper part of the instrument and a large flat detector area below the sample position for the secondary spectrometer, can measure the excitations over a broader range in the (Q, E)-space at once. In the presented design nested mirror optics assure the sample illumination with an extremely well defined phase space volume. Thanks to this, the prismatic focusing crystal analyzer provides excellent energy resolution. The versatile chopper system adds flexibility in terms of resolution and bandwidth to this innovative instrument concept.

Mushroom would provide all necessary information within a much shorter time frame, only at the cost of a slightly reduced energy and momentum resolution as compared to a triple-axis spectrometer and significantly better than direct TOF instruments. Furthermore, it can be built relatively compact as the main dimension of the secondary spectrometer is given by the dome of PG crystals above the sample. The accessible wavelength band is 1 – 10 Å with an adjustable wavelength resolution of 1%- 5%. The instrument would be in total 20 m long and 4 m wide.

It is worth mentioning that in the current instrument suite of MLZ there is no such instrument for providing the out-of-plane full coverage of (Q, E)- space.

Speaker: Robert Georgii

14:30 → 15:00 Plenary user presentations

Convener: Markus Braden (Universität zu Köln)

14:30 Strategies to use neutrons as an industrial problem-solving tool- Plenary talk

For how trivial or provocative it can sound, the best neutron spectrometer in the world does not produce science and technology by itself. By definition of “Materials Science”, neutron scattering data on engineering materials must be used as a tool to understand, and even tailor, materials performance. In order for this to happen, neutron data need to be
1. Acquired under the most relevant condition possible
2. Coupled to other experimental techniques
3. Capitalized by means of proper simulations and data analysis
Point 1- calls for an intense use and the development of top-notch of in-situ techniques; Point 2- means that the sole use of neutron data will not lead to any solution of a global problem; All points above hint to the fact that access to neutron sources is not routine, and therefore it is imperative to search ways to make neutron data rentable and sustainable for the material science and industrial research community.
In this presentation, and based on two examples, we will show a couple of strategies to combine neutron data with other experiments, and with theoretical models to raise the validity of experiments to the level of problem-solving. As one might imagine, these are only a few among the almost infinite combinations possible to help improving material properties, performance, and safety, i.e., ripe for everyday use.

Speaker: Prof. Giovanni Bruno

15:00 → 15:30 Coffee break

15:30 → 18:00 Analytics, Positrons and Imaging (API)

Convener: Nikolay Kardjilov (Helmholtz-Zentrum Berlin)

15:30 Investigation of water transport in anion-exchange membrane electrolyzers via neutron imaging

In anion-exchange membrane (AEM) electrolysis, the hydrophilic nature of hydrocarbon ionomers and membranes poses a major challenge. Although reinforcements and modified polymer chemistry have improved stability, the operation mode and water management within the membrane-electrode-assembly (MEA) still strongly influence durability and performance.

Dry cathode operation in AEM water electrolysis, where only the anode side is supplied with liquid electrolyte (KOH), minimizes the contamination of the generated hydrogen. However, this introduces unique challenges for non-fluorinated anion-exchange polymers, whose conductivity and mechanical properties are strongly influenced by water content. High-
resolution in situ neutron imaging (~6 µm effective resolution) was utilized to show that varying the anion-exchange capacity of the cathode binder ionomer can help retain membrane humidification, which improves efficiency, by lowering the overpotential and decreasing the high-frequency resistance(1).

Secondly, electrochemical reduction of CO$_{\mathrm{2}}$ is a crucial technology for the defossilization of the chemical industry, but salt precipitation and water management remain major challenges. High-resolution neutron imaging of a zero-gap CO$_{\mathrm{2}}$ electrolyzer operating at 200 mA cm$^{\mathrm{−2}}$ and 2.8 V reveals salt precipitation penetrating the cathode gas diffusion layer, which blocks CO$_{\mathrm{2}}$ gas transport and causes the commonly observed decay in Faraday efficiency. Salt accumulation is observed to be higher under the cathode channel of the flow field than the land. The findings suggest that resolving the water management and salt precipitation issues is crucial for advancing the commercialization of CO$_{\mathrm{2}}$ electrolysis technology(2).

References
(1) Koch, S.; Disch, J.; Kilian, S. K.; Han, Y.; Metzler, L.; Tengattini, A.; Helfen, L.; Schulz, M.; Breitwieser, M.; Vierrath, S. Water management in anion-exchange membrane water electrolyzers under dry cathode operation. RSC Adv 2022, 12, 20778–20784.
(2) Joey Disch; Luca Bohn; Susanne Koch; Michael Schulz; Yiyong Han; Alessandro Tengattini; Lukas Helfen; Matthias Breitwieser; Severin Vierrath; Disch, J. et al. High-resolution neutron imaging of salt precipitation and water transport in zero-gap CO2 electrolysis. Nat Commun 2022, 13, 6099.

Speaker: Susanne Koch

16:00 A dedicated polarization analysis setup for ANTARES

The outstanding transmission characteristics of the neutron combined with its magnetic moment render it a unique probe for the determination of magnetic properties of bulk ferromagnetic materials. While neutron scattering techniques probe magnetism from an atomic length scale up to a few 100 nm, neutron imaging has been shown to provide complementary information from macroscopic length scales down to a few 100 µm. Imaging with polarized neutrons can be employed to directly visualize large individual magnetic domains as e.g. found in grain oriented electric steel typically used for transformers. Moreover, the spatial variation of magnetic properties of samples arising e.g. from stress introduced during manufacturing or chemical inhomogeneity can be probed.
Currently, the spatial resolution with polarized neutrons at ANTARES is limited to ~0.5 mm mainly by the large distance between the sample and the detector that is required for the placement of the polarization analyzer, which has a length of ~500 mm. Moreover, since the polarizer and analyzer available at ANTARES are not optimized for the spectrum of the instrument, the polarization reaches only ~70% at a wavelength of 4.3 Å, where the flux is only 10% of the peak flux. We propose to design and acquire dedicated polarizers and analyzers for ANTARES in order to strongly improve the spatial resolution, flux and polarization at the same time. The same setup could in the future also be used for polarized imaging experiments at the proposed new imaging instrument FLASH-NT.

Speaker: Michael Schulz

16:30 Neutron Imaging of Electrochemical Devices

Electrochemical storage systems, such as lithium batteries and fuel cells, have become an increasingly important pillar in a zero-carbon strategy for curbing climate change, with their potential to power multiscale stationary and mobile applications. Immense progress has been made in electrochemical storage technology during the past decades, but significant challenges remain and new development strategies are required to improve performance, fully exploit power density capacity, utilize sustainable resources, and lower production costs. Suitable characterization techniques are crucial for understanding, inter alia, 3D diffusion processes, formation of passivation layers or dendrites in batteries or visualize the water management in fuel cells. Studies of such phenomena typically utilize 2D or 3D imaging techniques, offering locally resolved information. Over the last decades neutron imaging has been steadily growing in many disciplines as a result of improvements to neutron detectors and imaging facilities, providing significantly higher spatial and temporal resolutions. The high sensitivity for light-Z elements, in particular hydrogen and lithium, makes neutron imaging to the perfect probe to study inter alia, changes of the media distribution and transport mechanisms in electrochemical components.
All of that provides a platform for studying dynamic and structural process with a high local resolution making neutron imaging to a rising investigation tool in energy research. An overview of latest neutron battery and fuel cell research will be presented, providing a deep insight in dynamic, multi-dimensional, complementary neutron imaging and structural analysis with focus on direct probing in 3D and 4D with the fourth dimension being time or energy. The main challenges for neutron imaging of electrochemical devices will be outlined and an outlook on development methods in the field and their potential and significance for future research on electrochemical devices will be discussed.

Speaker: Dr Ralf Ziesche (Helmholtz-Zentrum Berlin)

17:00 Gamma-Ray Analysis from Inelastic Neutron Scattering (GRAINS)

The major reaction of fast neutrons at NECTAR is inelastic scattering, in which a lower-energy neutron and a medium-energy gamma photon is produced. The gamma rays are characteristic, i.e. they identify the emitter nuclide. Using the coincidence detection of these particles, elemental or isotope mapping of complex samples would be possible. Based on this approach, we propose an upgrade to the existing imaging capabilities at NECTAR, providing bulk isotope concentration determination to complement existing high resolution imaging capabilities at the instrument. Examples of this technique would range from: archeology, where the samples composition could be determined in 3D; batteries and fuel cells, where the chemical composition could be mapped in full size cells; industrial applications, where e.g. scintillators could be inspected for inhomogeneities in composition; all the way to inspection of hazardous materials that cannot be opened, e.g. nuclear waste forms.

Speaker: Adrian Losko (Technische Universität München, Forschungs-Neutronenquelle MLZ (FRMII))

17:30 ---

15:30 → 18:00 Large scale structures

Convener: Tobias Unruh (FAU Erlangen-Nürnberg)

15:30 Hierarchical structures in life sciences - probing different length scales in bulk and at interfaces

We will discuss challenges when it comes to revealing structures in life science associated with the hierarchical structure of these systems.
First we will discuss revealing the structure of lipid self assembly structures at interfaces. Here in particular we will discuss the structure formed by non-lamellar lipid liquid crystalline phases on surfaces as revealed by Grazing Incidence Small-Angle Neutron Scattering on a nanometer length scale. The limitation in terms of low scattering intensity and high background will be discussed, but also the potential of fully reveal these types of structures with neutron techniques.
Starch particles have been used to stabilize O/W food emulsions. This is because starch is a naturally occurring polysaccharide that is safe to use in foods and because it is abundant, biodegradable and inexpensive. The can be modified The for emulsification most suitable starch granules are in the order of 1 micrometer, which is a challenging size range for study the internal structure as it requires a wide Q-range. Initial SANS data will be presented and challenges in terms of interpretation of the data is discussed. The case for being able to measure at lower q for in particularly at low q will be given.

Speaker: Tommy Nylander (Lund University)

16:00 Refurbishement of the optics at REFSANS, the TOF-reflectometer with GISANS option

In a wide variety of fields, the properties of a system are controlled by the structure of interfaces: e.g. electrochemical systems, corrosion, bio-membranes, catalysts. Neutron reflectometry is a fundamental tool for the investigation and characterization of those interfaces: this technique is nondestructive; its resolution is well adapted to the length-scales of interest; it probes a large surface of the sample thereby providing a statistically relevant information in a single measurement. Beside the classical specular reflectivity mode of operation, modern 2D detectors make it easy to collect the diffuse off-specular scattering characteristic of long range in-plane correlations. Grazing incidence small angle scattering pushes the limits of off-specular reflectometry by drastically improving its resolution. Those aspects and the broad scientific community potentially interested by this technique are the reasons for which neutron facilities typically offer several reflectometers. Among those, the instruments with horizontal sample geometry based on the time of flight mode of operation occupy a specific niche and are recognized as an indispensable component of an instrument suite. Initially developed to perform measurements on liquid-air interfaces for which angular scanning is not practical, they have widened their use case by making it easy to perform in situ time-resolved experiments. Moreover, they constitute a natural and ideal test bench for the development of techniques to be used at pulsed sources. REFSANS is the horizontal TOF reflectometer at MLZ, offering a unique GISANS option.
This improvement project consists of two independent work packages, both aiming to increase the flux at the sample position, reducing the measurement time and improving the time resolution; the first one being the refurbishment of the instrument’s primary neutron delivery system whose performance has declined over time. Extensive simulations and measurements have demonstrated that the already implemented technical solution should still be used in the future. The second work package aims at optimizing the secondary optics for smaller samples, thereby answering the modern needs of the whole user community. On the one hand a modification of the collimation will enable a wider range of accessible vertical divergences and, on the other hand, an in-plane focusing solution reducing the beam width by half will be implemented by using parabolic nested mirror optical devices.
The refurbishment of the primary delivery system should improve the intensity by a factor 2 while together, the in-plane focusing and increased vertical divergent option would bring an additional factor 2 to 4 thereby positioning the MLZ horizontal TOF reflectometer on par with its international competitors.

Speakers: Gaetano Mangiapia (German Engineering Materials Science Centre (GEMS) am Heinz Maier-Leibnitz Zentrum (MLZ)), Dr Jean-Francois Moulin (Hereon)

16:30 Structure and dynamics of supramolecular poly(alkyl ether)-based polymers: insights from neutron scattering and complementary methods

In this talk, a number of key results converged from neutron scattering, rheology and dielectric relaxation spectroscopy (DRS) on the association and chain structure of supramolecular polymers from the bulk to the diluted state in the melt will be highlighted. These consist of well-defined hydrogenated (H) polymers with a polyethylene oxide (PEO) and polypropylene oxide (PPO) backbone (molar mass is 2000 g·mol-1), carrying at the ends either two different hydrogen bonding (H-bonding) functional groups types (H-bond pair diaminotriazine (DAT) and thymine-1-acetic acid (THY) or homoassociative 2-ureido-4[1H]-pyrimidinone (UPY)) differing in both association pattern and strength. Small angle neutron scattering (SANS) results in the bulk reveal that while PEO and PPO functionalized with THY/DAT self-assemble as linear chains, PEO and PPO functionalized with UPY form spherical UPY clusters responsible for the physical crosslinks of the formed transient network [1,2]. Also in the bulk, a molecular view on the association lifetimes for the supramolecular PEO and PPO functionalized with the pair THY/DAT is provided by neutron spin echo spectroscopy (NSE) in combination of rheology and DRS [1]. For a better insight at a molecular level on the association dynamics of UPY based supramolecular polymers, PEO functionalized with UPY functional groups is diluted in deuterated (D) covalent short linear non-functionalized PEO chains in the melt (the non-functionalized (D) PEO chains molar mass is 500 g·mol-1). It is observed that upon dilution the supramolecular PEO functionalized with UPY changes from spherical ring-like to linear conformation, which is confirmed as well by NSE and rheology analysis [3]. Ultimately, it is concluded that at sufficient dilution the structure and dynamics of supramolecular PEO polymers become independent on the H-bonding type and association strength.

[1] A. R. Brás, A. Arizaga, D. Sokolova, U. Agirre, M.T. Viciosa, A. Radulescu, S. Prévost, M. Kruteva, W. Pyckhout-Hintzen, A. M. Schmidt, Macromolecules, 2022, 55, 10014.
[2] A. Brás, A. Arizaga, U. Agirre, M. Dorau, J. Houston, A. Radulescu, M. Kruteva, W. Pyckhout-Hintzen, A. M. Schmidt, Polymers 2021, 13, 2235.
[3] A R. Brás, R. Pasquino T. Koukoulas G. Tsolou, O. Holderer, A. Radulescu, J. Allgaier, V. G. Mavrantzas W. Pyckhout-Hintzen, A. Wischnewski, D. Vlassopoulos, D. Richter Soft Matter, 2011, 7, 11169.

Speaker: Ana Brás Würschig (University of Cologne)

17:00 Faster Kinetics followed by SANS

Upgrade of KWS-1
Science Case
In the past, the exchange kinetics of polymers between different polymer micelles have been resolved using SANS. The option of selective deuteration has a huge potential to look at any exchange process in the future. Usually, one starts with two differently labelled, but otherwise structurally the same entities that by the time exchange their building blocks and, therefore, lose the contrast between them. The science field is now moving to smaller molecules like lipids that have much faster exchange kinetics than the slow polymers. Therefore, experimentally shorter time scales have to become accessible for kinetic measurements.
Apart from kinetic measurements, even in static measurements, one wants to measure much faster in order to explore a larger parameter space at a given time. The results will be fed to industrial optimization processes that often are supported by artificial intelligence that even require much more experimental data.
One prominent example of the past is the Covid vaccine using mRNA embedded in lipid particles. Here, one needed to study the drug delivery processes and the ideal compositions (with many more ingredients). So, lipids as formulation component and as interacting material are becoming more and more important for the industry.
Technical realization
To follow kinetic processes using SANS, the provided intensity if often not enough. One either has to perform a lot of repetitions or is limited to rather short times (~10s+) in a single shot experiment. Therefore, it highly important to optimize the beam preparation section of an instrument (including the velocity selector and the collimation) and maximize the detector area (for optimal data collection).
Beam preparation part will already be tackled in the course of 2023 on internal funding including a tilt option for the selector for 20% wavelength spread and an exchangeable beam stop to allow for sample apertures of 2.5 x 2.5 cm2 (instead of 1 x 1 cm2). The intensity gain will be 2 x 6 = 12.
The remaining portion is the extension of the detection area by implementing a near-field detector with a hole in the centre for the small-Q information. This additional detector will cover an area of 1 x 1m2 and, therefore, will allow for an approx. 2-fold higher detection of neutrons.

Speaker: Henrich Frielinghaus (JCNS)

17:30 Fast kinetics in thin films

We propose to upgrade and optimize NREX for studying the interaction of hydrogen with surfaces and thin film structures. The main goals of the upgrade are: (i) to increase the sensitivity and time resolution for single shot experiments by one order of magnitude compared to existing neutron techniques, with the aim to detect changes of the hydrogen concentration with a sensitivity better than 1%at. in less than one second. (ii) to improve the time resolution for periodic gating experiments by two orders of magnitude, from currently 1ms to 5µs. Technically, the enhanced performance relies on the design of optimized samples with resonator structures, and on fast neutron beam intensity modulation by radio-frequency spin flippers. The performance of the polarization analysis is not affected by this intensity modulation, this means that both the kinetics of the hydrogen concentration and of the magnetization reorientation can be studied simultaneously. The methods are also applicable to other ions and dopants, in particular oxygen and lithium.

Speaker: Thomas Keller (MPI for Solid State Research, Stuttgart)

15:30 → 18:00 Spectroscopy (hard-matter)

Convener: Petr Čermák (MGML, Charles University)

15:30 Covalent counterparts of van-der-Waals magnets

This talk provides an overview about magnetic and spectroscopic properties of a new class of magnets, TM2Mo3O8, composed of decorated honeycomb layers of transition metal (TM) ions. Although in terms of chemical bonding these compounds are three dimensional, the magnetic interactions have a strongly two-dimensional character, making them similar to van-der-Waals magnets. The two-dimanesional nature of the interactions combined with frustration arising from competing anisotropies gives rise to various exotic states and dynamical phenomena.

Speaker: Istvan Kezsmarki (Uni Augsburg)

16:00 DNS-WAPA: A cold-neutron xtal-TOF spectrometer with wide-angle polarization analysis

Unravelling emergent excitations and exotic quasiparticles in frustrated and topological quantum magnets represents a tremendous challenge experimentally, since the relevant inelastic scattering signals are very weak, often very broad in Q-space, and may be highly anisotropic in spin-space or strongly bond-direction dependent. A dedicated cold-neutron TOF spectrometer that combines with a new-generation wide-angle polarisation analysis (WAPA) can meet this challenge. The primary consideration of the DNS-WAPA project is to upgrade DNS to a more dedicated cold-neutron xtal-TOF spectrometer that would become internationally competitive among similar instruments for the measurement of magnetic excitations, meanwhile, to retain its world-leading position in polarised magnetic diffuse scattering.

Speaker: Dr Yixi Su (JCNS-MLZ)

16:30 New Magnets for Correlated Electron Systems at MLZ

Strongly correlated electronic systems from the field of magnetism and superconductivity are one of the key fields of research where neutron diffraction and spectroscopy play a pivotal role. At MLZ, several high impact discoveries have been achieved over the last decade directly revealing new functionalities towards future data storage or logical devices. Further, new instrumental concepts and more brilliant neutron sources enable the detection of even weaker, often diffuse signals. This provides a key step towards the exploration of new physics by extending the available parameter range of the sample environment – particularly for (quantum) disordered systems or exotic electronic ordering phenomena. Besides temperature, pressure and electrical field, the application of magnetic fields plays a pivotal role in tuning the properties of strongly correlated electronic systems. Within the MORIS program, we propose the purchase of three new magnets, all based on new, dry cryogen free high temperature superconducting (HTS) technology.
These are:
(i) A 10T high performance compensated, asymmetric horizontal magnet optimized for small angle neutron scattering (SANS), reflectometry and the resonance spin echo technique MIEZE.
(ii) An ultra-low background magnet for time-of-flight (TOF) neutron scattering.
(iii) A dedicated triple-axis-spectroscopy horizontal magnet with a large-opening-angle and a field strength of ~5T with a dilution unit.

Speaker: Sebastian Muehlbauer

17:00 Polychromatic chopper system for TOPAS

TOPAS was conceived to increase the capability to study high energy excitations at the MLZ.
While the thermal three axis spectrometer PUMA is ideal to study coherent excitations in condensed matter tuning the instrument to the respective reciprocal space region, TOPAS aims for mapping large regions in reciprocal space or the study of localized excitations, where one can benefit from the massive coverage of the approx. 16 m2 position sensitive detector.
While TOPAS is still waiting for commissioning, the development of the T-REX spectrometer for ESS has opened a route to optimize the instrument even more for the study of very high energy exchange, i.e. very large neutron energy loss.
This optimization will allow the study of high energy excitations with improved flux/resolution conditions important e.g. for small single crystal specimen.
One of the unique features of TOPAS, the provision of neutron polarization analysis at large energy transfer even beyond 100 meV will benefit in particular from the increased intensity in the large neutron energy loss dynamic range.

TOPAS was built to explore the dynamics in the thermal neutron energy range. In particular it aimed to complement and increase the capabilities of the MLZ instrument suite at high energies. The position sensitive detector is perfectly suited to map out the coherent excitation landscape in the energy range up to 100 meV, while localized excitations with relaxed requirements on momentum resolution can be explored even at higher energy. The optimization towards neutron energy loss and hence low final neutron velocity resulted in a comparably compact secondary spectrometer with a sample to detector distance L${_SD}$ = 2.5 m. The chopper system was matched to this requirement as the pulse length ratio of the resolution defining choppers was matched according to Lechners formula for λ' / λ=2.
$$ \frac{\tau_1}{\tau_2} = \frac{L_{12}}{L_{2s} + (\lambda\prime/\lambda)^3 L_{SD} +1} $$ Here L${12}$ denotes the distance between the two choppers, L${2S}$ is the distance between the sample and the last chopper and $\tau_i$ are the respective pulse lengths of chopper 1 and 2. On the other hand, a direct geometry chopper spectrometer is characterized the secondary bandwidth Δλ=h/m_n (νL${SD})^{-1}$ with the repetition rate ν and the sample-to-detector distance L${SD}$, e.g. TOPAS features Δλ' = 3.956Å, for a repetition rate of 400 Hz. These rather broad bandwidth implies, that primary and secondary energy resolution are matched only for a small fraction of the available dynamic range. In the course of the conceptualisation of the spectrometer T-REX it became clear, that repetition rate multiplication is not just a tool to improve the duty cycle of the instrument. RRM implies, that the initial neutron wavelength λ is increased step-like during one period of the neutron source as indicated by the different color of the initial wavelength λ in Fig. 1. Hence the dynamic range of each pulse has already been probed by the previous pulsed, but with relaxed energy resolution. By optimizing the very high relative neutron energy loss λ'/λ > 4 with the chopper settings we provide ideal conditions to study high energy excitations, but still cover a large dynamic range employing matched initial wavelength λ. The optimization of large neutron energy loss requires very strict λ resolution constraints, requesting a larger distance L$_{12}$ between the choppers, while the secondary resolution can be relaxed, allowing a larger pulse length $\tau_2$, which in the present design is the limiting factor of the reachable energy resolution.

For the technical realization it is necessary to adapt the chopper system of TOPAS by replacing the Fermi Chopper FC1 by a pair of disc choppers moving upstream significantly, probably into the experimental hall.
The higher order removal chopper has most likely to be equipped with a different slit pattern to provide the appropriate band selection.

Speaker: Jörg Voigt (Forschungszentrum Jülich)

17:30 The power of combining various neutron spectrometer types

Quantum materials often reveal ground states with deeply intertwined electronic charge, orbital, spin and lattice degrees of freedom. Their interplay can stabilize novel collective phenomena that can be understood by microscopic studies susceptible to the various degrees of freedom, and by their dependencies on external tuning parameters such as pressure, magnetic field and chemical substitution. In this talk I will show how the combination of various neutron spectrometers equipped with different sample environments allowed us to clarify the microscopic multiferroic properties of Ni3TeO6. Our studies show that its non-chiral crystal structure gives raise to non-reciprocal chiral low-energy magnons, whose condensation trigger a direct coupling between the various degrees of freedom.

Speaker: Daniel Mazzone (Paul Scherrer Institut)

15:30 → 18:00 High resolution spectroscopy

Convener: Arantxa Arbe (Centro de Fisica de Materiales CSIC-UPV/EHU)

15:30 Dynamics of amyloid fibers and their hydration water as studied by neutron spectroscopy

Protein amyloid fiber formation is the pathological hallmark in various neurodegenerative diseases such as Parkinson’s and Alzheimer’s. The physico-chemical origin of protein fibrilation, as well as the role that hydration-water might play remain elusive. We combine elastic and quasi-elastic neutron spectroscopy and molecular dynamics simulations on the intrinsically disordered proteins α-synuclein (involved in Parkinson disease) and tau (involved in Alzheimer disease) to investigate both structural and dynamical properties of the protein-hydration water system. One of our findings is an increased water translational diffusion on fiber surfaces, suggesting that hydration-water entropy might be one of the driving forces for amyloid fiber formation.

Speaker: Martin Weik

16:00 Considerations for achieving polarization analysis for high resolution QENS

Polarization analysis provides profound additions in knowledge for the field of soft condensed matter research. The ability to study dynamics of incoherent and coherent scattering contributions separately gives unique information on the cooperative vs local dynamics of a system. The JCNS is interested in exploring new instrumentation ideas as a polarization analysis upgrade to our SHPERES backscattering instrument. We will discuss the current concepts and simulations on ways of achieving polarization analysis for the high resolution regime, i.e \DeltaE<1\mu eV on a traditional backscattering instrument such as SPHERES at MLZ.

Speaker: Earl Babcock

userworkshop.pptx

16:30 Present and Perspectives in Neutron Scattering for Molecular Biophysics

In my talk I will highlight ongoing work in my group concerning structure and dynamics of the intrinsically disordered myelin basic protein (MBP) and its interaction with biomimetic myelin membranes as well as effects of macromolecular crowding on the liquid liquid phase transition of MBP. Additionally, I will present recent work on changes of molecular dynamics of a blue light sensitive photoreceptor protein through its photo-cycle investigated by a combination of kinetic QENS and NMR experiments. Furthermore, I will present planned work in the field of molecular biophysics that relies on the application of neutron spectroscopy, small-angle scattering as well as neutron reflectometry.

Speaker: Andreas Stadler (FZ Jülich)

17:00 Passive Magnetic Shielding for the J-NSE “PHOENIX”

The current J-NSE represents at the moment the best known design of an NSE Spectrometer, enabling measurements with correlation times up to several 100 nanoseconds in routine operation. An important area of science at the J-NSE is the investigation of domain motion in large proteins under physiological conditions, a unique capability of NSE, requiring extremely high precision measurements since deviations in relaxation from diffusive behavior needs to be quantified.
However, a major source of instrument downtime or increased sources of noise and systematic error in the data are magnetic field variations in the area of the J-NSE spectrometer coming from sources like magnets, the crane, relocated steel plates, moving polarization analyzers. Measures have been started to reduce the influence of those stray fields, which affect the NSE already on scales down to mG.
The most elegant and robust solution, which proved to work excellently for NSE instruments, is the double layer µ-metal housing as it is provided for the SNS-NSE in Oak Ridge. It has to surround the full instrument, also the floor needs to be included into the housing, and the housing needs to be large enough such that the mirror fields inside the cage do not reduce the resolution of the instrument. Options and requirements for such a magnetic shielding at the J-NSE "PHOENIX" will be presented.
Precision measurements of small effects at highest resolution in the dynamics would gain significantly in quality with such a passive magnetic shielding.

Speaker: Olaf Holderer

17:30 Hemoglobin diffusion and polymerization in HbFxHbS1-x compounds

Sickle cell disease (SCD) is a genetic blood disorder, inducing severe anemia. It results from the polymerization of the oxygen-carrying protein hemoglobin found in red blood cells (RBC), which leads to a deformation of the cells to rigid, sickle-like shape under certain circumstances that will obstruct capillaries vessels, and will ultimately induce the disease of different organs. The hemoglobin (HbS), that is at the origin of this blood disorder, is a variant of normal human hemoglobin A0 (HbA0) whose sequence only differs by two amino acids over the 574 of the protein. Human that are homozygote of HbS gene (inherited from both parents) suffer from a severe anemia. SCD was the first identified molecular disease by Linus Pauling, in 1949 [1]. The pharmacological treatments for sickle cell disease include hydroxyurea, a molecule that promotes the synthesis of fetal hemoglobin (HbF) that leads to a hemoglobin mixture HbFxHbS(1-x) in blood with HbF partially or fully inhibiting HbS polymerization depending on its concentration. We have shown previously that diffusion inside the red blood cells is similar to that in solution at the same concentration [2]. From the concentration dependence of the diffusion coefficient and using a simple model developed for oxygen uptake in the lungs [3] we have stressed that not only the diffusion of hemoglobin is necessary to obtain the full oxygenation of the RBC during the limited time of transit in the capillary close to the alveolar sac [4] but the concentration of hemoglobin inside RBC corresponds to an optimum oxygen transport for an individual under physical activity. We investigated the structure and the dynamics of HbS and HbF mixtures to better understand 1- how HbF will inhibit HbS polymerization, under which concentration and partial oxygen pressure. The impact of oxygen partial pressure is fundamental, because in the body it differs from the alveoli (PO2=160 mm.Hg) down to the heart (PO2=10-20 mm.Hg). And 2- gain insight on the oxygen exchange process at the RBC level. We will present how the intermediate scattering function is strongly affected by the oxygen partial pressure and the fraction of HbF present in solution (x). Moreover, we will show how the free (non polymerized) Hb diffusion is affected by polymerization and discuss the physiological implications.

[1] L. Pauling et al. Science 110, 543–548 (1949).
[2] W. Doster and S. Longeville, Biophys. J. 93 (4) , 1360-1368 (2007)
[3] A. Clark et al., Biophys. J., 47, 171 (1985).
[4] S. Longeville et al., Scientific Report, 7, 10448 (2017)

E-mail for corresponding author: slongeville@cea.fr

Speakers: Prof. Pablo Bartolucci (3UMGGR - Unité des maladies génétiques du globule rouge), Stéphane Longeville (CEA-LLB)

15:30 → 18:00 Structure

Convener: Prof. Holger Kohlmann (Universität Leipzig)

15:30 Neutron diffraction competing with high resolution X-ray diffraction: Any chances?

Structural investigations on functional ceramics is an important tool for material characterisation and tailoring of properties for specialised applications. This frequently requires high angular resolu-tion to resolve highly correlated phase coexistences or subtle structural features. The most com-mon tool is high resolution X-ray or synchrotron radiation. Especially for in situ investigations in transmission geometry synchrotron facilities are the usual choice due to high absorption. In special cases even optimised setups with 2D detectors are not able to resolve weak reflection splitting of phase coexistences. Then analyser detectors with a resolution at the physical limit are necessary. However, with increasing brilliance and decreasing beam sizes at the synchrotron sources, the grain statistics become a significant challenge and in some cases the feasible experiments are limited to microstructures with grain sizes in the low μm range.
Since many material systems exhibit grain sizes well above this limit, other characterisation meth-ods are necessary. Here the unique properties of neutron instruments can be exploited. Due to the usually rather high wavelengths, the minimum in the curve of reflection widths lies at relatively high angles. Together with the high reflection intensities at high diffraction angles, these setups can be a real competitor for synchrotron instruments. We will demonstrate this with two examples in the material systems potassium sodium niobate and barium titanate.

Speaker: Dr Manuel Hinterstein (Fraunhofer IWM)

16:00 SPODI multidetector upgrade

Historically high-resolution neutron diffractometers create the large portion of scientific output at large scale facilities. This holds true for both steady-state and pulsed neutron sources, as reflected in the publication statistics arising from monochromatic (D2B, BT1, ECHIDNA) and time-of-flight (POWGEN, HRPD, S-HRPD) high-resolution machines. Instrument SPODI fits well into the selection of high-resolution neutron diffractometers in terms of the resolution, performance, user request, output etc.
After almost 20 years of successful operation the instrument upgrade is proposed in two stages. Transfer of FIREPOD and corresponding upgrade of shielding, primary and secondary optics at SR8 will bring the neutron optics at SPODI to the modern state, creating the best compromise between the achieved neutron flux at the sample position and the Q-resolution in the broad range of momentum transfer. If the efficiency of SPODI data collection is aimed to be increased, only the remaining option\target is the modification of SPODI multidetector, which is the topic of the current contribution.

Speaker: Anatoliy Senyshyn

16:30 Automated sample change systems for SPODI/FIREPOD/ERWIN

Automatic sample changers not only improve the efficiency in the usage of measurement slots, they also widen the scope of scientific applications. In particular, robotic systems enable to measure large series of samples prepared by different processing routes or by varying the chemical composition. Exemplary small series of such measurements on Li-ion batteries, solar-cell or engineering materials at room temperature have already been carried out using a semi-automated 10-sample carousel. However, there is also a high demand for measurements involving a large number of samples with multiple temperature points. Thus, a large number of proposals would benefit greatly from an automatic cryogenic or a high temperature sample changer.

Therefore we envision that all three powder diffractometers at the new beamline SR8 should use one common pool of automatable sample environments (both for low and high temperatures) including automatic sample changing systems. The technical details of this proposal will be presented in this talk.

Speaker: Christoph Hauf

17:00 HEiDi: Large Area Detector for High Q Studies

Using the hot source of FRM II the single crystal diffractometer (SCD) offers a high flux of unpolarized neutrons down to short wavelengths well below 1 Å, for instance at 0.55 Å. Shorter wavelengths give access to a large Q ranges, which provide very detailed/precise information, for instance, about partially disordered compounds like new materials for energy storage [e.g. G. Redhammer et al., Acta Cryst B 77 (2021), Adv. Mat. Interfaces 7 (2020)).
To take full advantage of the shorter wavelengths on HEiDi and for as many scientific cases as possible, we propose a large 2D Position Sensitive Detector (PSD) with high sensitivity in this neutron energy range. This increases the efficiency of the instrument for faster and more accurate data collection. Furthermore, the improved detection/separation of Bragg and diffuse scattering from the sample vs. modulated background by a PSD and the large Q range of ~22/Å at 0.55 Å will enable HEIDI to study additional scientific cases that benefit from modern methods like total scattering / pair distribution analysis (PDF) with neutrons for both powders ( nPDF) and single crystals (3D Δ-PDF) [e.g. T. Whitfield et al., IUCrJ (2016), Dove & Li, Nucl. Analysis 1 (2022), Weber & Simonov, Z. Krist. (2012)).
The ideal PSD offers a high sensitivity > 50% at 0.55 Å, a beam angle of 130° horizontal x 13° vertical coverage and - due to the limited experimental field of HEiDi - a small installation depth. Given these requirements, we currently favour a 6Li scintillator-based system derived from a prototype currently under construction, (collaboration with JCNS detector group), although we also explore other options.
This presentation provides more details on the proposed PSD, an overview of the project timeline, estimated cost and resources required to successfully embed this project into the MLZ landscape.

Speaker: Dr Martin Meven (RWTH Aachen University, Institute of Crystallography - Outstation at MLZ)

17:30 ---

19:00 → 22:00 Dinner at Gasthof Neuwirt, Garching

Thursday 27 April

09:00 → 10:00 Plenary user presentations

Convener: Markus Braden (Universität zu Köln)

09:00 Neutron studies of SrCu2(BO3)2 under extreme conditions – a fruit fly for quantum many body physics

Neutron spectroscopy offer a unique insight into the emergent quantum phases and entangled dynamics in quantum materials.
A textbook example is offered by the compound SrCu2(BO3)2 realizing the theoretical Shastry-Sutherland model, which reveal a plethora of intriguing phenomena including: bosonic flat bands; a zoo of entangled bound states; correlated decay of magnons; valence bond solid of plaquette singlets; a quantum equivalent to the critical point of water; a putative deconfined quantum critical point; fractional magnetization plateaus and bosonic BEC of triplet bound states. Exploring this rich physics in parallel illustrates the challenges and rewards of technological advancements in neutron instrumentation and pushing the capabilities of extreme condition sample environments.
I will present some of the remarkable findings in SrCu2(BO3)2 and illustrate what outstanding questions can be answered through technological advancements like the MORIS programme.

Speaker: Henrik Ronnow (EPFL and ENSA)

09:30 Neutron scattering in soft matter

We attempt to present a comprehensive view on the opportunities in studying structure and dynamics using neutron scattering, with a focus on soft and complex materials. We discuss in particular the combination of small-angle scattering with energy-resolved techniques (time of flight, backscattering, spin echo). We also comment on the value of complementary techniques(SAXS, IR, rheology, size exclusion chromatography, ...), which might be employed simultaneously with neutrons.Examples will derived from work on biomolecules (M. Grimaldo et al, Quart. Rev. Biophys. 52 (2019) e7, 1) as well as nanoparticle systems (T. Seydel et al, Chem. Sci. 11 (2020) 8875).
Finally, some remarks will be made on big data challenges and solution strategies.

Contributions by numerous collaborators are gratefully acknowledged, as is financial support by the BMBF and the DFG.

Speaker: Prof. Frank Schreiber (Uni Tübingen, Angewandte Physik)

10:00 → 10:15 Break

10:15 → 11:45 Analytics, Positrons and Imaging (API)

Convener: Nikolay Kardjilov (Helmholtz-Zentrum Berlin)

10:15 Two Key Challenges towards a More Sustainable World: Light-Weight, High Load Bearing Structural Materials and High-Efficiency, Functional Materials for Energy Storage

Tailoring properties of structural and functional materials is strongly based on atomic defect analysis. Occurrence of these defects is in most cases associated with open volume for which positrons are an ideal and specific probe, e.g., by applying energy spectroscopy of the Doppler broadening of the two gamma photons of the positron-electron annihilation in general and in coincidence (CDB). It allows for specific analysis of defects and their kinetics in structural bulk materials as well as in functional thin films. In the ideal case, high spatial, surface and subsurface depth resolution in the micrometer range is achieved. Examples of own research will be given for in-situ, fast defect annealing in strongly deformed metals [1], precipitation hardening of light-weight aluminum alloys [2], and charging/discharging processes in thin film battery materials [3]. From the experience as long-term chairman of a review panel for this world-wide unique high-intensity positron beamline, future prospective applications with respect to the widening fields of light-weight structural materials as well as for materials for energy conversion and storage will be outlined. Demand for further improvements in resolution (time, lateral, and in-depth) of the beamline will be sketched. Also a sensitivity increase of the CDB method will be highly beneficial for the characterization of the chemical environment of atomic defects, i.e., vacancies.

References
[1] B.Oberdorfer, EM.Steyskal, W.Sprengel, W.Puff, P.Pikart, C.Hugenschmidt, M.Zehetbauer, R.Pippan, R.Würschum, In-Situ Probing of Fast Defect Annealing in Cu and Ni with a High-Intensity Positron Beam
Physical Review Letters 105 (2010) 146101 // DOI 10.1103/PhysRevLett.105.146101
[2] L.Resch, T.Gigl, G.Klinser, C.Hugenschmidt, W.Sprengel, R.Würschum, In-situ monitoring of artificial aging and solution heat treatment of a commercial Al(Mg,Si) alloy with a high intensity positron beam
Journal of Physics Condensed Matter 32 (2020) 085705 // DOI:10.1088/1361-648X/ab556d
[3] R.Würschum, S.Topolovec, G.Klinser, W.Sprengel, H.Kren, S.Koller, H.Krenn, C.Hugenschmidt, M.Reiner, T.Gigl, F.Berkemeier, M.Fiedler, Defects and Charging Processes in Li-Ion Battery Cathodes Studied by Operando Magnetometry and Positron Annihilation
Materials Science Forum 879 (2016) 2125-2130 // DOI:10.4028/www.scientific.net/MSF.879.2125

Speaker: Wolfgang Sprengel (Graz University of Technology, Institute of Materials Physics)

10:45 Spatially Resolved and Element-Sensitive Defect Analysis with Positrons

The Coincidence Doppler Broadening (CDB) spectrometer with its monoenergetic scanning positron beam allows the investigation of defect distributions in three dimensions (3D) and the elemental surrounding of open-volume defects. With our instrument we address the following scientific questions:

• Homogeneity of samples, i.e. depth and lateral distribution of lattice defects. Examples are (laser beam or friction stir) welded technical alloys, irradiated materials, superconducting and (doped) thin semiconducting films.
• Defect kinetics and fast defect annealing at high temperatures, e.g. of samples after severe plastic deformation or plasma-facing materials for fusion reactors
• Vacancy-solute complexes and nano-clusters in, e.g. doped semiconductors or precipitation-hardened alloys
• In-operando defect analysis of samples, which are not stable in vacuum, exposed to gases and/or during application of electric fields. Examples are electrode materials or aging of thin polymer films in various atmospheres
• Fundamental research with otho-Positronium (o-Ps).

In order to cope with the forefront research questions we plan to upgrade the CDB spectrometer by considerably enhancing its performance in terms of (i) spatial resolution, (ii) measurement time and signal-to-noise, and (iii) high sample temperature. The upgrade project comprises the (i) implementation of a novel two-fold positron remoderation stage, (ii) optimum coverage of the field-of-view by extension of the detection system, and (iii) installation of an infrared laser for contact-less sample heating.

Speaker: Christoph Hugenschmidt

11:15 In Search of Confirmation - Traceability of Resource Analytical Methods

A modern circular economy for metallic and mineral raw materials requires the use of both primary and secondary raw materials, since it is impossible to operate without losses. The conversion of energy production to renewable energy sources envisaged in Germany and Europe demands the use of a large number of metallic raw materials, starting with commodities such as copper and steel and ending with critical metals such as Li, Co, In, Ga or Ge in significantly higher quantities than required by traditional technologies. An energy transition to renewable energies that is consistently thought through to its end requires planning for the recycling of the raw materials used for this from the very beginning.
This poses enormous challenges for resource analytics, a means of providing critical information for the development of energy-efficient and resource-saving technologies. In addition to high-precision standard chemical and phase analysis methods, this involves the use of spatially resolved, automated, imaging analysis methods, in-situ analyses using portable instruments, and various qualitative and quantitative process analytical methods.
Neutron activation analysis and prompt gamma activation analysis methods will rarely be used as near-process methods with short response times, but have the potential to solve fundamental challenges in resource analysis, such as:

• Characterization of different types of reference materials for
  recycled materials, especially those for difficult-to-analyze
  elements.
• Ensure traceability of resource analytical methods for the detection of halogens (F, Cl, Br, and I) in wide concentration ranges in difficult matrices such as plastics, black mass of battery recycling, electronic scrap, or shredder fines,
• Ensure traceability of resource analytical methods for detecting trace levels of critical metals in intermediate and final products of pyrometallurgical and hydrometallurgical processes,
• Control analyses to determine the origin of raw materials as well as intermediate and end products in the sense of ensuring sustainable and secure supply chains as required by the industry due to current national and international regulations.

Speaker: Dr Axel Renno

10:15 → 11:45 Large scale structures

Convener: Tobias Unruh (FAU Erlangen-Nürnberg)

10:15 Mesoscale structures investigated with USANS - use for studies of food and environment

Modern materials are often effective because of their structure and many important processes and substances have significant length scales that range from nanometres to tens of micrometres. Examples are flocculation of particles during water purification, food such as emulsions and bakery products, and freeze-dried materials. The range of components and heterogeneity make the contrast variation available with neutron techniques very valuable in these studies. In particular, studies in these areas using ultra small-angle neutron scattering (USANS) complement SANS, VSANS and imaging as well as other probes with X-rays and light microscopy. Illustrative examples will be shown for societal relevant studies related to water purification, freeze drying and food.

Speaker: Adrian Rennie (Uppsala University)

10:45 SANS-1MAX: Massive Q-Range Upgrade

The SANS-1MAX proposal aims both at extending the dynamical Q-range and increasing the maximal momentum transfer Q. The SANS-MAX proposal consists of two independent two subprojects. (i) The replacement of the S-bender neutron guide with an optimized version will shift the wavelength cut-off down to ~2.5 Å. (ii) The installation of a second, high-Q detector bank at short detector distances on a second, independent detector carriage will largely improve the dynamic range.

Both upgrades will enable the access to new fields of research, particularly for modern engineering materials science and metallurgy applications and energy materials. The increased dynamical Q-range is particularly beneficial for the growing demand of in-situ measurements of irreversible processes, e.g., precipitation growth in high performance alloys, quenching of alloys, rapid heating and cooling processes and the mimicking of metal process chains, in particular in combination with sample environment like the dilatometer. Accessing larger Q allows measuring even smaller correlations of a few atoms to study the early growth of precipitates. A maximum momentum transfer of 2.2 Å^-1 of the SANS-1MAX proposal will finally allow covering the first Bragg peaks of typical alloys like e.g. Ni or Co based superalloys and their main precipitates. This option will enable coherent investigations of early stage precipitation covering the SANS and diffraction region in a single measurement. It hence allows an analysis of the size, size distribution, shape and the crystalline properties of precipitates. Besides materials science, SANS-1MAX will also tremendously increase the overall efficiency of SANS-1.

Speaker: Sebastian Muehlbauer

11:15 Improving our fundamental understanding of novel superalloys by neutron scattering and diffraction

Superalloys are key materials of our modern society. They are not only used in harsh environments of power plants for energy conversion but also in aerospace or marine applications, as they combine excellent mechanical properties at high homologous temperatures with very good oxidation and corrosion resistance. To further improve the efficiency of engines, advanced superalloys with improved properties are needed that can operate at higher temperatures.
In this work, examples of new Ni- and Co-based superalloys are presented whose development and characterization was supported by neutron as well as X-ray diffraction and scattering methods. Results on the temperature-dependent lattice misfit between the main constituent phases of the investigated superalloys explains the observed precipitate morphologies and are used for calculating the force balance of interfacial dislocations. In-situ high-energy X-ray diffraction measurements revealed the deformation behaviour and formation of unwanted intermetallics phases during high temperature deformation. Finally, small angle neutron scattering results could be used to adjust the alloys’ heat treatments to optimize their mechanical properties.

Speaker: Steffen Neumeier (Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg)

10:15 → 11:45 Spectroscopy (hard-matter)

Convener: Petr Čermák (MGML, Charles University)

10:15 Mesoscale quantum textures

Mesoscale patterns are well-known in ferromagnets, ferroelectrics, superconductors, monomolecular films or block copolymers, where they reflect spatial variations of a pertinent order parameter at length scales and time scales that may be described classically. In the past thirty years increasing evidence has suggested the presence of mesoscale patterns near zero-temperature phase transitions, also known as quantum phase transitions. In recent years, the exploration of mesoscale textures under carefully controlled conditions near quantum phase transitions has entered a new phase, show-casing access to new phenomena such as emergent collective excitations reflecting Landau quantization, mesoscale quantum criticality, as well as dynamical forms of order when driven periodically. Neutron scattering represents an exceptionally powerful probe, uniquely suitable for the identification and exploration of the properties of mesoscale quantum textures.

Speaker: Christian Pfleiderer (TUM)

10:45 PUNC: PANDA Upgrade Primary Spectrometer (Neutron Channel)

PANDA is a world-leading cold three-axis spectrometer complementing TOF instruments in case of specific requests for resolution and related signal-to-noise ratio or demanding sample environments. Providing experiments with highest reliability since 2005, PANDA is always requested for newest scientific aspects in strongly correlated electron systems and on quantum magnetism, but serves for studies on phonons and their interaction with electronic degrees of freedom, too. PANDA improved on its secondary side (BAMBUS multi-channel-system) and due to providing a virtual twin as well as AI-assisted mapping mode for better performance already, but keeps limited by its primary flux. Improving this and concurrently the signal-to-noise ratio will allow more and better experiments but could also answer the increasing demand for high-end experiments. We suggest building a new neutron channel (beam port to drum) now with
i) installation of a velocity selctor,
ii) flux increase by state-of –the-art neutron-optical opportunities and
iii) shielding designed for giving frequent access to the VS and filter-collimation devices.

Speaker: Astrid Schneidewind (JCNS at MLZ, FZ Jülich)

11:15 Lattice dynamics using neutrons and x-rays

Neutron spectroscopy has played a pivotal role uncovering lattice dynamical properties from early studies of elemental superconductors to density-wave materials and current investigations of materials featuring intertwined ordering phenomena. Over the years, experimental goals have evolved from the basic determination of phonon dispersion to detailed mapping of phonon renormalization related to, e.g., lattice anharmonicity, spin-phonon coupling or exotic effects such as phonon-phonon nesting and signatures of gaps in the electronic band structure. In my presentation, I will explain how I use a combination of neutron time-of-flight, triple-axis and inelastic x-ray scattering spectroscopies to investigate superconducting, magnetic and density-wave materials backed-up by a ab-initio lattice dynamical calculations. Based on these science cases, I will discuss instrument features which are particularly useful for the investigation of lattice dynamics in solids.

Speaker: Frank Weber (Karlsruhe Institute of Technology)

10:15 → 11:45 High resolution spectroscopy

Convener: Arantxa Arbe (Centro de Fisica de Materiales CSIC-UPV/EHU)

10:15 dynamics of lqiuid alloys studied by quasielastic neutron scattering

We investigate mass transport and flow behaviour of liquid alloys, which are key properties for material processing. Quasielastic neutron scattering provides a unique possibility to access the dynamics of the melt on microscopic time and length scales. On the one hand, this allows the precise measurement of self-diffusion coefficients at elevated temperatures without any convective effect. On the other hand, the microscopic structural relaxation time provides hints on the correlation between different dynamical properties of the melt. While in densely packed, glass-forming alloys self-diffusion and melt viscosity are both governed by one dominant relaxation timescale, for more loosely packed Germanium alloys those processes appear to be less correlated. Technically, it is often necessary to process these alloy melts containerlessly in order to avoid contaminations, which simultaneously results in a good signal-to-background ratio. Currently, the use of aerodynamic levitation for metallic samples are being explored, which will extend the processability of different sample systems considerably.

Speaker: Fan Yang (Deutsches Zentrum für Luft- und Raumfahrt)

10:45 Upgrade concept for TOFTOF in the 21st Century

As a cold time-of-flight spectrometer TOFTOF’s impacts are felt across scientific areas including: biophysics, materials science; fundamental hard and soft condensed matter physics, chemistry and biology. Here we will discuss our idea for an upgraded TOFTOF. The upgrade addresses both the competitiveness of the instrument around existing scientific areas and aspires to address new questions/areas stemming from all the grand challenges for the MLZ and its user community. Specifically we seek to enhance the sample area, angular resolution and number of neutrons analysed by increasing the flux at the sample, decreasing background signal and increasing solid angle and angular resolution. Particular areas of scientific focus may be:
• The perspective on hydrogen dynamics, and the accompanying molecular dynamics, from TOFTOF on biological or soft matter material such as proteins, peptides, lipids and polymers is important for, e.g. gels, new drug release systems, polymer blends, liquids in confinement or organic solar cells. In health and the life-sciences dynamics are proving an important step forward from the structural view enabled by crystallography in understanding function.
• Neutron spectroscopy provides insight around molecular mobility in energy storage. Such as novel anode or cathode materials, electrolytes and the study of ion mobility in batteries under in-operando conditions may provide for improved electrochemical storage. Studies of hydrogen mobility and binding characteristics in solid-state hydrogen storage material characterise both chemisorption and physisorption. The perspective may enable efficient, sustainable and cheap catalysts in fuel.
• For materials science, the possibility to probe low-lying excitations (e.g. the phonon density of states) and measurements of diffusion coefficients will help to improve the understanding and development of novel materials.
• The study of quantum spin liquid and quantum spin ice phenomena in low dimensional and/or frustrated materials reveals rich physics and new concepts emerging from the quantum behaviour of many interacting particles.

Speaker: Marcell Wolf (TUM)

11:15 Experiences and challenges with QENS experiments under in-situ illumination

This contribution will discuss recent QENS experiments under in-situ illumination including sample structure, specific instrument setup and desirable future instrument options. As an example, data of the orange carotenoid protein (OCP) will be presented. OCP plays a vital role in the photoprotection of cyanobacteria and exhibits a significant structural change upon photoactivation. A rarely considered aspect is the importance of internal protein dynamics in facilitating the structural transition to the active state. Quasielastic neutron scattering under (in-situ) blue light illumination was used to probe the protein dynamics of the orange carotenoid protein in the dark-adapted and in the active states, respectively. It is shown that the localized internal dynamics of amino acid residues is significantly enhanced upon photoactivation. This is attributed to the photoinduced structural changes exposing larger areas of the protein surface to the solvent and, thus, resulting in a higher degree of motional freedom. However, the flexibility of the mutant W288A assumed to mimic the active state structure is found to be different, thus highlighting the importance of in-situ experiments.

Speaker: Jörg Pieper (University of Tartu)

10:15 → 11:45 Structure

Convener: Prof. Holger Kohlmann (Universität Leipzig)

10:15 Neutron crystallographic analysis of protein-ligand hydrogen bonding patterns in galectin-3 guides drug design

Galectin-3 is an important protein in molecular signalling events involving carbohydrate recognition, and an understanding of the hydrogen-bonding patterns in the carbohydrate binding site of its C-terminal domain (galectin-3C) is important for the development of potent new inhibitors. I will present neutron crystal structures of galectin-3C in three states: apo, in complex with the natural substrate lactose and with glycerol. These structures reveal the exquisite tailoring of the carbohydrate recognition site to recognise the hydrogen bonding patterns presented by galactose and glucose moieties. Comparison of the glycerol and lactose structures reveals the possible importance for molecular recognition of a hydrogen bond from arginine to the cyclic oxygen atom of galactose. The apo structure shows that, though water molecules occupy the positions of the most important oxygen atoms of the ligand [1], not all hydrogen bond directionality is preserved when the oxygen atoms are unconstrained by being “locked” in the ligand.
I will present some of the work required to achieve these structures, e.g. improvement in crystal size for perdeuterated galectin-3C by a crystal growth protocol involving feeding the crystallisation drops [2], which resulted in improved data quality and reduced data collection times. We collected five datasets at three different neutron sources from crystals of similar volume, which gives insights into the crystal volumes and times necessary for the same system at sources with different technologies and data collection strategies.
Finally, I will mention some ongoing work on the orientation of a crucial water molecule and its effect on the affinity of two very similar galectin-3C ligands.

References

1. F. Manzoni, J. Wallerstein, T. Schrader, A Ostermann, L Coates, M Akke, M Blakeley, E Oksanen & D.T. Logan. Elucidation of hydrogen bonding patterns in ligand.free, lactose- and glycerol-bound galectin-3C by neutron crystallography to guid drug design J. Med. Chem. 61, 4412-4420 (2018)

2. F. Manzoni, K. Saraboji, J. Sprenger, A.L. Noresson, U. Nilsson, H. Leffler, Z. Fisher, T. Schrader, A. Ostermann, L. Coates, M.P. Blakeley, E. Oksanen & D.T. Logan. Perdeuteration, crystallisation, data collection and comparison of five neutron diffraction datasets of human galectin-3C. Acta Cryst. D. Biol. Cryst. 72, 1194-1202 (2016)

Speaker: Derek T Logan (Lund University, Biochemistry and Structural Biology, Centre for Molecular Protein Science)

10:45 BIODIFF detector array renewal: tackling even larger unit cells

At the instrument BIODIFF, the incident wavelength can be freely selected between 2.7 Å and 5.6 Å. This is an essential unique feature of BIODIFF and allows it to adapt the wavelength to the unit cell size of the sample crystals. At a wavelength of 4.7 Å, unit cells with lattice constants up to 200 Å can be measured at BIODIFF. Up to now, only one other instrument in the world, MaNDi at ORNL, can perform high resolution structure determinations using neutrons on crystals with unit cells of that size. Recently, more and more proposals have been submitted with interesting projects that exceed this unit cell size, As the user community grows, the number of projects/proposals with larger unit cell crystals will continue to increase in the future. In order to serve such needs, it is essential to extend the capabilities of BIODIFF to allow data collection of larger unit cells. When using a longer wavelength - to counteract the reflex overlap on the detector in case of large unit cells - the maximum achievable resolution, will inevitably be cut. To overcome this limitation a new detector setup with a variable detector-to-sample distance should be realized. This will allow to compensate the reflex overlap on the detector for larger unit cells by increasing the detector-to-sample distance. Finally, this would enable the data collection from membrane protein crystals, a class of proteins so far not accessible to neutron single crystal diffraction due to their large unit cells.

Speaker: Tobias Schrader

11:15 Contribution of polarized neutron diffraction to the study of magneto-structural relationships of molecular magnetic compoundslk

PND has proved to be particularly suitable for the study of magnetic molecular compounds and the determination of the spin density. This provides unique information on the paths of magnetic interactions and the nature of magnetic intra-or intermolecular coupling [1]. In this talk, we show on several examples how we can go beyond the spin density reconstruction and use the local susceptibility tensor approach [2] and study the magnetic anisotropy in molecular compounds (Figure 1) [3-6].
This makes PND an excellent tool to help in the design of molecular-based magnets and especially single-molecule magnets for which strong uniaxial magnetic anisotropy is required.

References
[1] C. Aronica, E. Jeanneau, H. El Moll, D. Luneau, B. Gillon, et al., Chem. Eur. J., 2007, 13, 3666-3674 (https://doi.org/10.1002/chem.200601253)
[2] A. Gukasov and P. J. Brown, J. Phys-Condens. Mat. 2002, 14, 8831-8839.( https://doi.org/10.1088/0953-8984/14/38/307)
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Speaker: Prof. Dominique LUNEAU (Université Claude Bernard Lyon 1)

11:45 → 12:15 Coffee Break

12:15 → 13:15 Analytics, Positrons and Imaging (API)

Convener: Nikolay Kardjilov (Helmholtz-Zentrum Berlin)

12:15 Developments at PGAA and NAA

Prompt Gamma Activation Imaging (PGAI) is based on the narrow collimation of the neutron beam to, and of the gamma rays emitted from predefined spots of complex objects. We plan to reduce the long scanning time using a detector cluster consisting of seven HPGe detectors each of which would observe one voxel each along the line activated by the neutron beam also applying multiple collimator channels within the gamma shielding. The method will be beneficial in the investigation of complex and sensible archaeological objects.
To broaden the circle of the analyzed elements, our goal is to detect all emitted particles from the activation products, e.g. beta particles which in a few cases are not followed by gamma radiation. This would be important e.g. in determination of the phosphorus dopant in silicon semiconductors. This requires a combination of a scintillator counting in 4π solid angle with a HPGe detector.

Speaker: Dr Zsolt Revay (PGAA)

12:45 Wrap up

12:15 → 13:15 Large scale structures

Convener: Tobias Unruh (FAU Erlangen-Nürnberg)

12:15 Magnetic Small-Angle Neutron Scattering: A Probe for Mesoscale Magnetism Analysis

Small-angle neutron scattering (SANS) is a powerful technique for the investigation of magnetic materials, since it provides information from within the bulk of magnetic media and on the mesoscopic length scale, i.e., the size regime between a few nanometers and a few micrometers. In this talk we give an overview on recent theoretical and experimental work. This includes the study of the effect of the Dzyaloshinskii-Moriya interaction in microstructural-defect-rich materials, investigations of the spin structure of nanocomposites, and the usage of micromagnetic simulations for understanding the spin structure of nanoparticles beyond the single-domain form-factor concept.

Speaker: Prof. Andreas MICHELS (University of Luxembourg)

12:45 Wrap up

12:15 → 13:15 Spectroscopy (hard-matter)

Convener: Petr Čermák (MGML, Charles University)

12:15 Neutron velocity selector on thermal three axes spectrometer PUMA

The thermal-neutron three axes spectrometer PUMA at MLZ is designed to achieve high neutron flux at the sample position, making it a leading instrument in the worldwide research community for performing experiments with low inelastic scattering intensity, such as magnetic or phononic excitations. To further enhance its capabilities, the installation of a neutron velocity selector is proposed. The neutron velocity selector will improve the control of background levels by effectively eliminating unwanted higher-order neutrons and provide greater flexibility in inelastic neutron scattering measurements by allowing for more flexibility in choosing outgoing neutron wave vectors. Alongside the upcoming nested mirror optics on PUMA, the neutron velocity selector will bring a significant synergy effect, particularly in measuring a small-size sample under an extreme sample environment.

Speaker: Jitae Park (MLZ, TUM)

12:45 Wrap up

12:15 → 13:15 High resolution spectroscopy

Convener: Arantxa Arbe (Centro de Fisica de Materiales CSIC-UPV/EHU)

12:15 High resolution spectroscopy and Larmor diffraction

We present a major upgrade for TRISP. Through optimized beam geometry and development of a spin-echo multi-detector, gain factors of 5-50 are possible. The proposed multi spin-echo analyzer is both suited for continuous and TOF operation.

Speaker: Thomas Keller (MPI for Solid State Research, Stuttgart)

12:45 Wrap up

12:15 → 13:15 Structure

Convener: Prof. Holger Kohlmann (Universität Leipzig)

12:15 Upgrading POLI with a 2D detector

Polarized neutron single-crystal diffraction is known for studying the magnetic properties of materials. However, it is limited by the availability of intense polarized neutron resources and large crystals. New detector technologies have made high-resolution and high-efficiency large area detectors possible, which can speed up the data collection and enable more capabilities. We will report our 2D detector upgrade proposal for the polarized neutron single crystal diffractometer POLI at MLZ in the MORIS program which would enhance the data acquisition efficiency greatly for single crystal measurements and enable us to study powder samples.

Speaker: Jianhui Xu (MLZ, TUM)

12:45 Wrap up

13:15 → 13:45 Summary, closing

13:45 → 14:45 Lunch