Table of contents

This volume contains proceedings of ECNS 2011, held in Prague, Czech Republic, 17–22 July 2011. ECNS 2011 was the fifth Conference in a series of meetings organized in various European cities under patronage of the European Neutron Scattering Association, and was preceded by the European Neutron Scattering Conferences in Interlaken (1996), Budapest (1999), Montpellier (2003) and Lund (2007).

The positive atmosphere of the Prague meeting of the neutron community can certainly be attributed to recent progress in the extension of the European neutron experimental base, in particular the completion of the ISIS second target station and considerable progress in the European Spallation Source project in Lund. The success of ECNS 2011 has been manifested by the participation of 698 scientists from 36 countries, who presented 231 talks and 534 posters. This proceedings contains 112 papers from authors who wished to have the written versions of their contributions published. The contributions illustrate the broad scale of scientific problems investigated by neutron scattering methods and give a picture of growing activities in the field.

The conference chairmen wish to express their thanks to all colleagues who contributed to the organization and preparation of ECNS 2011, in particular the members of the International Advisory Committee, the International Program Committee and the Local Organizing Committee. We very much appreciate the role of Professor Michael Steiner, the President of ENSA, and all ENSA representatives who contributed valuable conceptual input and advice in the preparatory phase of the conference organization. Special thanks go to the editors and all the referees who helped us to publish the ECNS 2011 Proceedings in such a short time.

Vladimír Sechovský Petr Lukáš Conference chairmen

The PDF contains photographs from the conference and a full list of participants.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Low temperature superconductors ideally exhibit the Meissner-effect, i.e. magnetic flux is expelled from the material during superconducting transition. We report about the complete suppression of the Meissner-effect in two differently surface-treated niobium samples by means of polarized neutron radiography. Both samples were studied in the Meissner phase, T < T_c = 9.25[K] with an external magnetic field B_ext = 6.3mT and for T < T_c and B_ext = 0. Neutron radiographs of both samples were recorded, imaging the depolarization of the neutron spin for T > T_c and Bext = 6.4mT, T < T_c and B_ext = 6.3mT, and for T < T_c and B_ext = 0. After turning off B_ext at a temperature below T_c strong position dependent flux pinning was observed in the untreated sample and more uniform flux pinning in the case of the surface - BCP treatment.

This article presents the new Small Angle Neutron Scattering (SANS) instrument PA20 which will replace the PAXE instrument at LLB-Orphée. SANS is well-known to be especially well adapted to research in soft matter, materials and nanosciences and SANS is particularly powerful in the studies of complex systems, with isotopic labeling and contrast variation method, but also for large-scale structures (magnetic or not). PA20 is part of the LLB instrumental upgrade program "CAP2015". PA20 will not only maintain LLB's capabilities in SANS, but also considerably extend them in terms of SANS for magnetism with a polarized neutron option and Grazing Incidence SANS (GISANS), with an improved dynamical Q-range. The total length of PA20 will be 40 m, including a 19 m collimation length, a 20 m detector tank containing high-resolution/high-emciency XY detectors, and a casemate containing a monochromator (velocity selector λ = 0.3 − 2 nm), a chopper system for Time-of-Flight (TOF) mode, a polarizer and an RF spin flipper. PA20 will allow faster measurements, with "single-shot" access to a wider range of scattering vectors, on possibly small samples (few mm in size). In addition, polarized neutrons will enable magnetic studies in both SANS and GISANS configurations. Studies of nanostructured surfaces and interfaces (deposited or embedded nano-objects), magnetic domain formation, multilayered materials or magnetic thin films through specular and off-specular signals will be possible through GISANS setups. The versatility of PA20 should contribute to both enlarge the neutron user community, especially in expanding areas like nanosciences, and offer improved services for users in the years to come.

The thermal triple-axis spectrometer TAIPAN is the first instrument for inelastic neutron scattering at the new Australian research reactor OPAL. TAIPAN started operation in February 2009 and is in full user service since November 2010. Conceptually, it is similar to the triple-axis spectrometers IN8 (ILL) and PANDA (FRM-II) with variable incident and final energies and a secondary spectrometer with a single detector. The instrument can be operated either in a high flux mode with a double-focusing monochromator and analyser, or with Soller collimators - gaining resolution at the expense of intensity. Presently the PG (002) double-focusing monochromator and analyser are in use. The incident energy range on the TAIPAN TAS is from ∼5 meV up to ∼100 meV with neutron flux at sample position of 2.4≤10⁷ n/cm²/s at incident energy of 14.8 meV. First experiments were performed with superionic conductor Cu_2−δSe. The measurements reveal the presence of a soft mode related to ordering of Cu atoms followed by α - β phase transition at a lower temperature. The evolution of the magnetic structure with temperature in a magnetically modulated FePt₃ thin film was investigated in the diffraction mode of TAIPAN. The results show that the film fabricated by modulation of the chemical order parameter consists of a magnetic FM/AFM superlattice in single-crystalline FePt₃. The spin wave and phonon dispersion was recently investigated in TbVO₃ single crystal. The acoustic and optical magnon branches were observed in the same energy range. This indicates that the 'orbital Peiers state' also exists in TbVO₃.

We report on the procedure to treat neutron diffraction data, in order to obtain the differential cross sections, a step that is essential in the analysis of structural information for liquids and amorphous materials. The treatment is applied to new measurements that have been made on the D4C diffractometer for eight different isotopic compositions of H₂O/D₂O mixtures at ambient temperature. The procedure is based on Monte Carlo simulations to perform multiple scattering, attenuation and detector efficiency corrections, applied iteratively. The normalization process allows the direct comparison of measured data from different samples, and requires the knowledge of the total cross-section at the incident neutron energy. They high contrast between the cross sections (coherent and incoherent) for heavy and light water allows to test the procedure under very different conditions of multiple scattering effects.

Project INDECS (Integrated Neutron Diffraction Experiment Control System) is a newly developed software system created for the purpose of data acquisition from, and controlling of the upgraded version of the KSN-2 powder neutron diffractometer equipped with Position Sensitive Detectors. The KSN-2 neutron diffractometer (belonging to LND, DSSE, FNSPE, CTU in Prague, CZ, placed at the NRI, Řež near Prague, CZ) was recently upgraded with the possibility to contain up to three parallel linear PSDs which can be mounted on the detector arm instead of the original single counter detector. That was the motivation for the project INDECS to be started. For the actual data acquisition and initial data analysis of the raw sampled signals within the project INDECS a special modular structure called the PSD Acquisition Path (or PSDAP) was designed. Raw sampled signals from either end of the PSD are taken as the main input to the subsystem. The signals are then split into multiple events, analyzed for the position of the obtained events on the PSD, and a histogram of the diffraction events is created as the main output of this subsystem. Moreover, the PSDAP is capable of storing the raw signals either before event splitting or after, so that later the whole process of acquisition can be replayed in software, perhaps with different settings of the processing parameters or perhaps even algorithms. It can also be switched into a mode where under special conditions a correction curve specific for the given PSD can be constructed and later in normal operation it can be used to do the corrections of detected event positions to enhance the results on that particular PSD. This whole subsystem then acts as a single modular command unit (External Execution Module or EEM) within the entire system of project INDECS.

We developed AFP NMR in an aluminum container for polarized noble gas nuclei. The radio frequency magnetic field inside the aluminum container was designed from computer simulations. The polarization loss by the AFP spin flip of ³He was measured to be as low as 3.8×10⁻⁴. With this technique, a compact in-situ polarizing ³He neutron spin filter with AFP NMR is demonstrated.

Ultra-small-angle scattering of polarised neutrons (USANSPOL) allows for the study of magnetic structure in the micrometre range. The technique takes advantage from the narrow angular width of the Bragg reflection curve of perfect crystals and is employed in a double-crystal configuration of channel-cut perfect silicon crystals. Polarisation of the neutron beam is obtained by placing magnetic prisms, which act as birefringent regions, between the monochromator and analyser crystal. Samples are placed between the polariser prisms and the analyser crystal. Scattering of spin-up and spin-down neutrons is recorded in a single measurement and identified by an angular shift of their respective scattering curves. We have developed a prototype sample environment and handling system by which anisotropic samples may be aligned in different orientations and be subjected to external magnetic fields and stresses. Here, we present new experimental results on iron-boron ribbons of varying composition with remarkable magnetostriction properties, highly promising for technological application, and methodic development.

High-pressure research is one of the fastest-growing areas of natural science, and one that attracts as diverse communities as those of physics, bio-physics, chemistry, materials science and earth science. In condensed matter physics there are a number of highly topical areas, such as quantum criticality, pressure-induced superconductivity or non-Fermi liquid behaviour, where pressure is a fundamental parameter. Reliable, safe and user-friendly high pressure gas handling systems with gas pressures up to 1GPa should make a significant impact on the range of science possible. The ISIS facility is participating in the NMI3 FP7 sample environment project supported by the European Commission which includes high pressure gas cell development. In this paper the progress in designing, manufacturing and testing a new generation of high pressure gas cells for neutron scattering experiments is discussed.

Most neutron facilities have a fleet of cryostats providing low temperature and high magnetic fields for sample environment. This large scale usage of cryogenic equipment requires significant resources and can create a number of problems including health and safety issues and the considerable cost of the required cryogens. The last problem has become more significant due to the increasing costs of liquid helium caused by global helium supply problems. The ISIS facility has an internal development programme intended to gradually substitute all conventional cryogenic systems with cryogen free systems preferably based on the pulse tube refrigerator. The programme includes a number of development projects which are aiming to deliver a range of cryogen free equipment including a top-loading 1.5 K cryostat, superconducting magnets in re-condensing cryostats and cryogen free dilution refrigerators. Here we are going to describe the design of these systems and discuss the results of prototype testing.

Neutron imaging using pulsed neutron sources coupled with a 2-dimensional position sensitive detector applicable to the time-of-flight method can give information on the crystal texture of coherently scattering materials, dynamical information of incoherently scattering materials such as hydrogen, and magnetic field information. Bragg edges appeared at cold neutron region reflect the preferred orientation, crystallite size, and lattice spacing. To deduce such information from the neutron transmission data depending on the position we have developed a data analysis code, and applied this code to data of a welded iron sample. Furthermore, as examples of more realistic materials we have investigated quenched iron rods. The quenched region was clearly demonstrated by the lattice space distribution. Furthermore, difference in the bound state of water or hydrogen in wet and dry cement pastes have been observed by analyzing the gradient of the neutron transmission cross section at the cold neutron region. The magnetic field has been also measured by using the polarized neutrons, and the strength of the field was estimated easily by analyzing the wave length dependent data.

We present a tool to investigate neutron depolarisation effects with 10⁻⁴ precision. The test bench consists of two opaque ³He cells with in-situ adiabatic fast passage flipping of the helium spin. The cells polarise a neutron beam to more than 99.99 % and analyse its polarisation with high accuracy. For depolarisation studies, a sample can be inserted between the two cells and its effect on a primarily highly polarised beam is analysed. The test bench has been validated at the cold neutron beam PF1B at Institut Laue-Langevin, France. We present here preliminary results for the wavelength range from 5Å to 7Å. Polarisation with super mirrors is limited to about 99.7%. Direct evidence of depolarisation in the order of 10⁻³ in polarising super mirrors was found by the test bench.

Neutron Larmor Diffraction is a relatively new concept in neutron scattering which allows high resolution studies of subtle structural features in condensed matter. Several setups exist in various neutron facilities around the world. One of them is the Zero-field spin-Echo for Triple-Axis option (ZETA), available on the thermal triple-axis spectrometer IN22 (CEA-CRG beamline at Institut Laue Langevin). We have used ZETA to study thermal evolution of lattice constants in serveral systems of physical interest. Among them, the BaM₂(XO₄)₂ family is a serie of compounds which have been intensively studied for three decades, mainly because of their fundamental though puzzling magnetic properties. In this paper, we aim to shed a new light on the physical understanding of those systems by investigating the link between structural and magnetic ordering. The magnetoelastic effect is found to be weak but can be resolved thanks to the high resolution provided by NLD.

The use of non-linear tapered neutron guides has been extended over the last years and there are many examples of their performance and potential in several neutron scattering facilities around the world. However, the potential of these geometries is not fully explored. On the other hand, the increasing demand of neutron scattering instruments creates the need of more space for more instruments. One way to obtain it is by guide splitting. In this report we propose a guide splitter using a parabolic mirror. We make an analytical study and Monte Carlo simulations in order to observe its properties, performance and potential. The advantages of this configuration are clear: the filtering of unwanted neutrons in a shorter space than the traditional curved guide sections, the low divergence of the obtained beam and the lack of making larger moderators. However, the main disadvantage is the non-uniform divergence distribution of the beam.

In this paper some properties of the dispersive double-bent-crystal setting are described. Thanks to an easy manipulation with focusing of the monochromatic beam, high reflection probability of both bent crystals and very narrow (1-3 mm) obtained monochromatic beam such an arrangement could be attractive for an employment. We tested the properties of the double-bent-crystal setting of the bent Si(111) + bent Si(220) slabs on the diffractometer at the neutron wavelength of 0.163 nm for various curvatures of the Si(220) slabs. By using a standard polycrystalline sample of Fe it has been found that besides an excellent resolution the neutron current is sufficient even for powder diffraction experiments.

Multiple Bragg reflections (MBR) realized in one bent-perfect crystal (BPC) slab by sets of different lattice planes behave differently in comparison to the case of perfect nondeformed or mosaic crystal. Individual sets of lattice planes are mutually in dispersive diffraction geometry and the kinematical approach can be applied on this MBR process. It has been found that contrary to the perfect nondeformed or mosaic crystal, individual reflections participating in the MBR process can be spatially separated.

An aspherical supermirror is one of the most useful neutron-focusing optics. We aim to develop multiple aspherical supermirror devices using high-precision figured aspherical focusing supermirrors to focus neutron beams with high intensities, because multiple mirrors collect a very large beam divergence. Thin mirrors with a millimeter thickness are required to minimize the absorption loss of incident neutron beams since the thickness of a mirror shadows the reflective area of the other mirrors. However, it is difficult to fabricate thin mirror substrates with a form accuracy of sub-micrometer level by conventional machining. Conventional machining deforms a substrate by machining force and spring back after machining causes figure error. Furthermore the deposition of supermirrors deforms the mirror substrate by film stress. Thus, we developed a new process of fabricating a precise millimeter-thick elliptical supermirror. This process consists of noncontact figuring by the numerically controlled local wet etching technique and the ion beam sputter deposition of NiC/Ti multilayers on both sides of the mirror substrate to compensate for film stress. In this paper, we report on the fabrication results and focusing performance of elliptical supermirrors with a thickness of 1.5 mm.

This paper presents a new single crystal neutron scattering data analysis program, Mufit. The program can be used to refine spherical neutron polarimetry (SNP) data as well as nuclear and magnetic single crystal diffraction data. The article presents a brief overview of the SNP process and the core mathematics used to calculate the SNP matrices and gives an example of data that has been fitted using the MuFit package, which is available on request from the author: Bertrand.Roessli@psi.ch.

Novel multiplexing techniques, such as Repetition Rate Multiplication and Wavelength Frame Multiplication imply the use of a set of monochromatic wavelengths or a set of wavelength bands coming from the same source pulse by using novel combinations of standard mechanical neutron choppers. In this case the instrumental parameters, such as wavelength resolution, wavelength band, repetition rate are not any more determined by the source parameters, but can be flexibly defined by the chopper frequencies, speeds and slits. Here we report about the first experimental implementation of Repetition Rate Multiplication (RRM) and Wavelength Frame Multiplication (WFM). For this purpose the TOF spectrometer NEAT at HZB, Berlin and TOF diffractometer at BNC, Budapest have been used in non-standard modes of operation. Our results provide full proof-of-principle of the RRM and WFM methods and clearly show the extensive capability of these methods to achieve multiply enhanced data collection rates by individually tuning for each experiment the pulse length and/or pulse repetition rate within broad limits and independently from the actual source pulse parameters.

Horizontal focusing properties of a new neutron monochromator geometry are investigated by Monte Carlo simulations. The geometry is based on the Rowland circle, which satisfies ideal focusing conditions, as opposed to standard planar monochromator devices. For asymmetric geometries one can get optimised conditions for both intensity and energy resolution for such a "Rowland monochromator", in contrast to standard planar arrays. Energy resolution gains are also found for symmetric geometries, in particular for cold neutrons. Additional advantages include a symmetric beam well centered in energy. No changes are observed in integrated intensities.

The "whispering gallery" effect has been known since ancient times for sound waves in air, later in water and more recentiy for a broad range of electromagnetic waves from the radiofrequency region, through visible light to X-rays. It consists of wave localization in the vicinity of concave surfaces. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present the observation and theoretical description of such an effect.

Neutron focusing devices can be used to enhance neutron instruments when measuring small samples. However, for an optimum performance they need to be as close as possible to the sample which, in most situations, conflicts with the need for sample environment such as pressure cells, cryostats or magnets. In this paper we explore the potential and feasibility to incorporate a neutron lens based on supermirror technology into a cryostat containing a Paris-Edinburgh pressure cell. We present experimental results on the performance of super-mirrors between 5 and 300 K. Based on the experimental results we estimate the expected gain factors for a setup with a parabolic lens and a pressure cell in a cryogenic environment using Monte Carlo simulations.

The transmission spectrum of cold and thermal neutrons displays sudden intensity changes, known as Bragg edges, whose appearance is connected to the crystallographic structure of the investigated sample. However, many difficulties in interpreting and understanding the detected signal exist, in particular when results are evaluated quantitatively. We measured strain and texture properties of different samples utilizing the Bragg edge method on the CONRAD and VSANS instruments at Helmholtz Centre Berlin as well as on ENGIN-X at ISIS, UK. The different results will be compared and validated with conventional diffraction measurements and theoretical considerations. According to this, a Bragg edge neutron transmission simulation was developed to include instrument effects together with sample characteristics. Therefore, a neutron ray-tracing simulation package was applied to emulate the employed instruments in combination with the Bragg edge transmission technique. A new sample module has been created to realize energy-dependent transmission simulations based on neutron cross sections calculations. Towards the analysis of the conducted experiments the virtual sample features the expected strain and texture parameters. The results of the simulation are in good agreement with the experiments and will be discussed with regard to the prospects and limitations of this measurement method and the utilized instruments.

Most of diffractometers have collimators in front of detectors either to reduce the background contribution or to increase the angular resolution. These collimation devices are designed to collect only the neutrons coming from the sample position. When a sample environment is required, its walls are close to the sample position and produce some unwanted effects on the diffractograms. A simple geometrical model allows a description of the observed patterns in the two-axis diffractometer D4 (ILL, Grenoble, France). The calculated effects are compared with experimental data for a vanadium bar as measured in the standard cryostat of that instrument. This kind of measurements allows the experimental determination of the sample transmission.

The substantial upgrade in new-generation reactor-based time-of-flight spectrometers lies in their hugely increased detection area ensuring high neutron-collection power and remarkably good count statistics in relatively short times. Dealing with thousands of time channels and several tens of thousands of detection pixels is, however, quite punishing for data handling and correction. Real-geometry multiple scattering evaluation, even in an approximate way, is often the most demanding step in the treatment of inelastic neutron data, and becomes a very hard task in widely-extended detection geometries, as those of spectrometers like BRISP, IN4 or IN5 at the Institut Laue Langevin in Grenoble. We refreshed our approach to multiple scattering calculations, in order to obtain reasonably accurate real-geometry results in nearly real-time conditions. Our new code, originating from a long standing experience in the application of Monte Carlo (MC) integration techniques to multiple scattering calculations, is now made particularly efficient in computing time both by a careful application of the MC importance sampling method, and by the use of programming languages allowing for an efficient use of matrix algebra to avoid the far slower nested-loop logic of more traditional languages. The concepts at the basis of the algorithm and several implementation details are presented, together with the application to a real experimental test case.

Through thickness strain distribution of 50 mm thick welded ferritic steel (bcc) plate was studied using diffraction reflections 211 and 110 and neutron wavelengths of 1.55 and 2.39Å, respectively. Experimental results showed that for stress measurements in a possibly maximum thick weld, the different strain components should be measured with different reflections 211 and 110. The strains measured with these reflections for the same component are close. Since planes (211) and (110) of bcc ferrite have the same diffraction elastic constants the appropriate values of stresses could be derived from strains measured with reflections 211 and 110.

The characteristics of a Q-space focusing configuration are given. The procedure to get inverse space conditions is given also. Both the diffraction and inelastic scattering are considered. For the neutron diffractomerry both instruments with one crystal monochromator and with two crystals monochromators are taken into consideration. The time of flight diffractometers both for a pulsed neutron source and a steady state one is considered also. For inelastic scattering the inverse space focusing conditions for triple axis spectrometers are givene line-width

Although scanning small-angle x-ray scattering (SAXS) instruments are available, almost no attempt has been made to realize scanning small-angle neutron scattering (SANS) instruments because of rather low flux available in the case of neutron scattering. We propose the use of a multi-pinhole collimator–pinhole combination to reduce the beam size to about 1–2-mm diameter immediately in front of a sample. With such small pinholes, we can produce a rather short instrument, on the order of 1–2 m, to have access to conventional minimum Q of about 0.03 nm⁻¹. Because multiple beams hit the same detector at different parts of the detector, the obtained SANS patterns mutually overlap. However, using a wavelength-dependent SANS pattern, we were able to resolve the overlap in theory. We conducted a proof-of-principle type of experiment at the Hokkaido University electron linear accelerator based pulsed cold neutron source (HUNS) facility. We made several multi-pinhole plates with thin beam holes arranged in hexagonal patterns. By changing the moderator and detector pixel size and the instrument overall size, we can optimize the pinhole size and their layout. We conducted experiments using welded steel samples and seek the difference in SANS pattern in the welded and non-welded parts, as well as the heat-affected zone between them. We demonstrated the principle of resolving overlapped SANS patterns from the adjacent beams using wavelength-dependent scattering.

Since long neutron spin resonance in an arrangement of crossed homogeneous and spatially alternating transversal magnetic fields is known to allow for wavelength-selective polarisation manipulation. Combined with a pair of highly efficient polarising supermirrors it is an elegant method to single out a specific wavelength from an initially polychromatic polarised neutron beam, based upon the fact that in its rest frame each neutron creates its individual frequency. A spin flip process can then take place only if this individual frequency equals the neutron LARMOR frequency in the homogeneous field. Here, we present the first experimental results we have obtained with a conceptually novel type of such spatial spin resonator, consisting of a series of separate modules which can be controlled independently from each other. Thus it becomes possible to vary e.g. the amplitude distribution of the spatially alternating transversal field without any geometric modification of the setup. Moreover this device fulfils the requirements for fast electronic switching of each module, which will be an important asset for the possible decoupling of the minimal neutron pulse duration and the achievable wavelength resolution. We compare the actual performance of this prototype resonator system with the theoretically expected behaviour.

We report on phase-space optimizations for neutron scattering instruments employing horizontal focussing crystal optics. Defining a figure of merit for a generic virtual source configuration we identify a set of optimum instrumental parameters. In order to assess the quality of the instrumental configuration we combine an evolutionary optimization algorithm with the analytical Popovici description using multidimensional Gaussian distributions. The optimum phase-space element which needs to be delivered to the virtual source by preceding neutron optics may be obtained using the same algorithm which is of general interest in instrument design.

The dependence of the neutron spin polarization on the difference of the magnetic field integrals along the precession fields before and after the sample gives rise to a spin-echo signal. In neutron spin-echo (NSE) experiments with non-polarizing samples, a single spin-echo group is observed (or two in case of some magnetic sample systems). However, in NSE experiments using polarizing samples, three different groups appear: i) the spin rotation (SR) group, ii) the antiparallel echo (APE) group and iii) the parallel echo (PE) group. The echo groups contain information on the life time of the excitations from which the intermediate scattering function S(Q,t) can be derived. In this article, we discuss the basic strategies for NSE measurements using the 2-, 4-, and 20-point method. Finally, we report on quasi elastic NSE experiments on a polarizing magnetic sample MnSi, which stabilizes a single-handed spin spiral. Here, the overlap of the spin rotation and spin-echo group for small spin-echo times requires a measurement of the NSE signal over a wide range of phase angles.

For holographic gratings recorded in superparamagnetic nanoparticle-polymer composites the diffraction efficiency should – next to grating spacing, nanoparticle concentration and grating thickness – depend on the strength of an external magnetic field and the incident neutron spin state. As a consequence, diffraction gratings should be tunable to act as mirrors for one spin state, while being essentially transparent for the other. Thus, polarizing beam splitters for cold neutrons become feasible.

A new time-of-flight neutron reflectometer GORIZONT with vertical scattering plane was constructed and tested at the IN-06 spallation pulsed neutron source at the Institute for Nuclear Research RAS. The instrument can be used also as a small angle neutron instrument. Due to the vertical scattering plane it is well-suited for the studies of free-liquid surfaces. A Monte-Carlo simulation and experimental testing of instrument have been performed. The neutron spectra at the guide exit and at the sample position and beam profiles were measured. Based on the experimental data the momentum transfer range and the instrument resolution were estimated.

An efficient Monte Carlo algorithm has been developed aimed at simulating neutron tracing in a liquid or amorphous sample, during a diffraction experiment. At odds with approximated analytical estimates, such a method allows to easily take into account some physical and geometrical features, which play an important role in determining the measured scattered neutron intensity.

Some general laws giving the multiple scattering intensity, in terms of few adimensional parameters, are provided. In particular, it results that the most relevant quantity involved in the neutron transport is the mean free path (defined as the inverse of the attenuation factor), which can be helpfully assumed as natural length unit. This yields to some important consequences: for istance, in the case of absorbing or structured samples, the mean free path can strongly depend on the neutron energy and this should be considered in the choice of the experimental apparatus.

Reflective optics is one of the most useful techniques for focusing a neutron beam with a wide wavelength range since there is no chromatic aberration. Neutrons can be focused within a small area of less than 1 mm² by high-performance aspherical supermirrors with high figure accuracy and a low smooth substrate surface and a multilayer interface. Increasing the mirror size is essential for increasing the focusing gain. We have developed a fabrication process that combines conventional precision grinding, HF dip etching, numerically controlled local wet etching (NC-LWE) figuring, low-pressure polishing and ion beam sputtering deposition of the supermirror coating to fabricate a large aspherical supermirror. We designed and fabricated an piano-elliptical mirror with large clear aperture size using the developed fabrication process. We obtained a figure error of 0.43 μm p-v and an rms roughness of less than 0.2 nm within an effective reflective length of 370 mm. A NiC/Ti supermirror with m = 4 was deposited on the substrate using ion beam sputtering equipment. The results of focusing experiments show that a focusing gain of 52 at the peak intensity was achieved compared with the case without focusing. Furthermore, the result of imaging plate measurements indicated that the FWHM focusing width of the fabricated mirror is 0.128 mm.

The neutron interference imaging experiment with two absorption gratings has been done. We develop new way to fabricate absorption gratings for neutron with the pitch of 150 μ m, 180 μ m, and 200 μ m. Compact imaging detector system is developed, whose weight is 2kg. Small break in an acrylic plate, the welded place of Nb plate were observed, it reveals that the neutron interference imaging method can become new method of a nondestructive inspection for reinforced plastics and composite material such as CFRP and so on.

In the neutron resonance spin echo method the information about sample dynamics is encoded in the neutron beam polarization measured in the analyzer-detector unit. Thus, the method is not applicable for sample systems and environments, which depolarize the neutron beam strongly. To over come this draw back a neutron analyzer directly before the sample position may be installed to perform MIEZE-I experiments. We compared the performance of a transmission polarizer and a solid-state bender at this position for the neutron resonance spin echo spectrometer RESEDA by Monte Carlo simulations. It turned out, that the polarization as well as the intensity transmitted to the sample position is more advantageous for the transmission polarizer as for the bender. In addition, we present measurements of the polarization and intensity performance of the transmission polarizer already installed at RESEDA to polarize the neutron beam coming from the reactor FRM II. The measurements are in good agreement with Monte Carlo simulations.

At the Materials and Life science experimental Facility (MLF) in J-PARC, an experiment of detecting a neutron polarizing ability caused by a neutron-nuclear spin correlation at a resonant peak of ¹²⁹Xe is planned. We evaluated measurable quantities based on a neutron optical theorem, developed a polarized Xe gas system, and carried out a feasibility test of our apparatus.

The time-of-flight diffractometer Epsilon-MDS at the modernised pulsed reactor IBR-2M at Dubna is designed for the detection of residual and applied strains in polycrystalline materials. The instrument allows the recording of diffraction patterns with high resolution (Δd/d = 5×l0⁻³ to the best) over a wide wavelength band (λ_max = 7.8 Å; d_max = 5.6 Å). Complicated polyphase materials like rocks consisting of minerals with large unit cells and low crystal symmetry can be investigated. The diffractometer is equipped with 81 detectors positioned behind nine radial collimators at a unique Bragg angle of 2θ = 90° for the central detector and at different radial angles allowing the simultaneous measurement of nine sample directions. A pressure device for the in situ investigation of intra-crystalline strain under uniaxial load up to 150 MPa on cylindrical samples is available. The macroscopic strain on the sample surface can be determined simultaneously by means of a laser extensometer. The sample can be rotated around its axis, i.e. limited information on texture can be obtained. The simultaneous strain and CPO measurements are helpful for a better understanding of the deformational behaviour of polycrystalline materials, e.g. to investigate elastic processes in rocks before, during and after rock failure.

We have measured the optical thickness of a phase object for the first time using multilayer cold neutron interferometer. The measured phase shift of 15.1 ± 1.9 wavelength agreed with the expected value of 17.4 ± 0.7 wavelength due to an about 600-μm-thick silicon plate. This demonstration reconfirmed that two paths in our new interferometer were completely separate, and showed its applicability into various precise measurements.

SENJU is a state-of-the-art single crystal time-of-flight Laue diffractometer in Materials and Life Science Experimental Facility at Japan Proton Accelerator Research Complex (J-PARC). The diffractometer is designed for precise crystal and magnetic structure analyses under multiple extreme conditions, such as low temperature, high-pressure, high-magnetic field. Measurements using small sample less than 1.0 mm³ will be also realized, which allows us to study wide variety of materials. SENJU is using a poisoned decoupled moderator to obtain peak profiles of Bragg reflection, and intensity distributions of superlattice reflections and diffuse scatterings with good accuracy. At the beginning, the diffractometer will have 31 two-dimensional scintillator detectors to cover wide area of reciprocal lattice space by a single measurement. The instrument is currently under construction and is scheduled to start on-beam commissioning in February 2012.

Optical materials that emit from the visible to the near-infrared spectral region are of great interest due to their possible application as tunable radiation sources, as signal transmission, display, optoelectronics signal storage, cellulose industry as well as in dosimetry. One important family of such systems are the spinel compounds doped with Cr³⁺, in which the physical the properties are related to the insertion of punctual defects in the crystalline structure. The purpose of our work is two fold. First, we compare the luminescence of the MgGa₂O₄-Ga₂O₃ system with the single phase Ga₂O₃ and MgGa₂O₄ and relate structural changes observed in MgGa₂O₄-Ga₂O₃ system to the optical properties, and secondly, to compare the neutron powder diffraction results obtained using two diffractometers: D2B located at the ILL (Grenoble, France) and Aurora located at IPEN (São Paulo, Brazil). In the configuration chosen, Aurora shows an improved resolution, which is related to the design of its silicon focusing monochromator.

Already at the end of the last century theory predicted that the wave number and frequency of any wave will change when passing an accelerating refractive medium. The effect was calculated both for electromagnetic and neutron waves. As a refractive index may be introduced for waves of any nature one can speak about a very general Accelerating Medium Effect. As far as we know this effect has not yet been observed for light. Here we report on a neutron-optics experiments performed with ultra-cold neutrons where this effect has been demonstrated for the first time ever. The maximum energy transform in the experiment was ± (2÷6) ×10⁻¹⁰ eV which agrees with theory within less than 10%. Possibilities for future investigations of the Accelerating Medium effect will be discussed.

If a new light boson existed, it would mediate a new force between ordinary fermions, like neutrons. In general such a new force is described by the Compton wavelength λ_c of the associated boson and a set of dimensionless coupling constants. For light boson masses of about 10⁻⁴ eV/c², λ_c is of the order millimeters. Here, we propose a table-top particle physics experiment which provides the possibility to set limits on the strength of the coupling constants of light bosons with spin-velocity coupling. It utilises Ramsey's technique of separated oscillating fields to measure the pseudo-magnetic effect on neutron spins passing by a massive sample.

Entanglement is a remarkable peculiarity in quantum mechanics. It occurs in quantum systems that consist of space-like separated parts, or in systems whose observables belong to disjoint Hilbert spaces. The latter is the case in single-neutron systems. Entangled states are renowned for exhibiting non-classical correlations between observables of individual sub-systems. In a perfect Si-crystal interferometer experiment entanglement between three degrees of freedom in a single-neutron system is created. The prepared entanglement of spin, path and energy is induced by interaction with an oscillating magnetic field. The generated Greenberger-Horne-Zeilinger (GHZ) state is analyzed with an inequality derived by Mermin, yielding a value M = 2.558(4) 2, which exhibits a clear violation of the classical assumption. In addition observation of a GHZ entanglement, consisting of spin, momentum and total energy, in a neutron polarimetric experiment is presented. Here the advantages of neutron polarimetry, such as high contrast or insensitivity to ambient disturbances, are utilized resulting in final value of M = 3.936(2) 2.

We give a short overview of the gravity resonance spectroscopy methods used recently by the qBounce experiment. It has been demonstrated that mechanically induced transitions between bound neutron states in the gravitational field can be observed. Applications of this new method test Newton's gravity law, search for extra dimensions of space-time, and study the neutrality of the neutron.

In situ neutron diffraction measurements of adsorbed carbon dioxide in an ordered mesoporous carbon (CMK-1) have been carried out along an isotherm at 253 K and at a range of pressures up to 18 bar. The experiment has been performed with the aid of a novel high-pressure adsorption apparatus and the GEM diffractometer (ISIS, Rutherford Appleton Laboratory, UK). Diffraction measurements of bulk liquid carbon dioxide have also been carried out. The structure factors and the total differential correlation functions of the adsorbed carbon dioxide suggest that the confined fluid has liquid-like properties at all thermodynamic states studied; however, some subtle differences were observed pointing to enhanced adsorption because of the presence of micropores.

To study the n+d→p+n+n breakup reaction the experimental setup allowing registration of all secondary particles in different kinematical arrangements was installed at the neutron channel of the Moscow Meson Factory of the Institute for Nuclear Research. The experiment is performed in broad energy range of neutrons (20-100 MeV) incident on deuterium target. The first preliminary data on neutron-neutron scattering length a_nn obtained in the final state interaction (FSI) geometry are presented. For E_n = 40 MeV and ΔΘ = 6° the value a_nn = -17.9 ± 1.0 fm is obtained. Test measurements in the np quasi-free scattering (QFS) arrangement showed that we are able to obtain data on nn QFS in a broad range of neutron energy.

The PERC collaboration will perform high-precision measurements of angular correlations in neutron beta decay at the beam facility MEPHISTO of the Forschungs-Neutronenquelle Heinz Maier-Leibnitz in Munich, Germany. The new beam station PERC, a clean, bright, and versatile source of neutron decay products, is designed to improve the sensitivity of neutron decay studies by one order of magnitude. The charged decay products are collected by a strong longitudinal magnetic field directly from inside a neutron guide. This combination provides the highest phase space density of decay products. A magnetic mirror serves to perform precise cuts in phase space, reducing related systematic errors. The new instrument PERC is under development by an international collaboration. The physics motivation, sensitivity, and applications of PERC as well as the status of the design and preliminary results on uncertainties in proton spectroscopy are presented in this paper.

In situ neutron diffraction measurements of adsorbed carbon dioxide in an ordered mesoporous silica (MCM-41) have been carried out along an isotherm slightly above the critical point (308 K) and at a range of pressures below and above the critical one (30-125 bar). The experiment has been performed with the aid of a novel high-pressure adsorption apparatus and the GEM diffractometer (ISIS, Rutherford Appleton Laboratory, UK). Diffraction measurements of both bulk supercritical and bulk liquid carbon dioxide have also been carried out. The structure factors and the total differential correlation functions of the adsorbed carbon dioxide suggest that the confined carbon dioxide has liquid-like properties. However, some differences are observed when the confined phase is compared to those of bulk liquid and bulk supercritical fluid respectively, mainly arising from orientational correlations between adsorbed molecules. These differences could be attributed either to strong interactions between the silica walls and CO₂ molecules or to the confinement of the fluid combined with the relatively large quadrupole moment of carbon dioxide.

We have analysed the effect of non-Newtonian gravity on the amplitude of neutron reflection from bulk materials. We found that the first-order contribution of non-Newtonian gravity is significant when the neutron wavelength is nearly equal to the radius of curvature of the neutron refractive index due to non-Newtonian gravity and that it becomes negligible when the neutron wavelength is much smaller than the radius of curvature.

Clathrate hydrates, depending on the guest molecule type, generally exhibit one out of three different crystal structures: two cubic structures, sI and sII and one hexagonal structure, sH. In the past, our inelastic neutron scattering measurements on hydrogen clathrates have provided information on the quantum dynamics of the guest molecules in the water cages. Besides the guest dynamics, the dynamics of the water lattice itself has a large interest, due to the analogy with ice (e.g. proton disorder), and to the existence of various possible structures. Additionally, in these inclusion compounds, a coupling between the host and the guest motions is generally observed, and is considered to be relevant to explain the anomalous features of some macroscopic properties, such as thermal conductivity. Here, we present a systematic study of the H-projected phonon density of states (H-PDoS) of the lattice modes in clathrate hydrates. We have experimentally investigated the three existing structures (i.e. sI, sII, and sH) through inelastic neutron scattering measurements, and we have extracted the acoustic-optic and the librational H-PDoS's. By using proper isotopic substitutions, we have been able to tune the host scattering intensity with respect to the guest one. The studied samples consisted in three clathrates made of light water (namely, simple sI structure with Xe, simple sII structure with fully deuterated THF, and binary sH structure with MTBE and D₂), and two made of heavy water (namely, simple sII structure with Ne, and simple sII structure with fully deuterated THF). The experimental results have been compared with lattice dynamics simulations performed by us.

In the development of new high-temperature alloys for gas turbine applications various candidates are under consideration. This contribution deals with a CoRe based alloy strengthened by Cr₂₃C₆ type carbide and Cr₂Re₃ type σ phase precipitations (here designated as CoRe-1 alloy). High-temperature cycling experiments show how the influence of heating, cooling and the hcp<->fcc phase transformation of the Co-matrix on the stability of these phases. Neutron diffraction experiments with high-temperature vacuum furnace show that Cr₂₃C₆ carbides starts to dissolve around 1100°C and above 1250°C are almost completely dissolved. On the other hand σ phase is still present at 1300°C. This contribution describes the evolution of the different phases during the heating and cooling cycles which are repeated two times. Further, the influence of boron addition to CoRe-1 alloy was studied for samples in the first heating/cooling cycle. A newly developed tensile rig was also tested up to 980°C to combine in situ loading and heating for the neutron diffraction measurements.

The present work describes the application of a tubular reactor that allows in-situ neutron diffraction on working catalysts at high pressures. The designed reactor enables the application to a sample of industrially-relevant reaction conditions, i.e., in a temperature range up to 330° C and 60 bar pressure, coupled with online gas-analysis. Application of the cell is demonstrated by ammonia synthesis over a commercial catalyst with diffraction data obtained from the high-resolution powder diffractometer, Echidna, at the Australian Nuclear Science and Technology Organisation, ANSTO.

Inelastic neutron scattering experiments were performed to investigate the phonon dispersion relations along the [1,0,0], [1,1,0] and [1,1,1] directions in cubic PbTiO₃. All of the transverse optic (TO) branches soften significantly toward the zone center around T_c. The zone-center TO mode stiffens considerably at 1173 K. The energies of the [ξ, 0, 0] TO branch for PbTiO₃ measured at 793 K are considerably higher than those for Pb(Zn_1/3Nb_2/3)O₃ at 423 K in the entire zone. The [ξ, 0, 0] transverse acoustic (TA) branch is found to soften slightly at 793 K. The [ξ, ξ, ξ] TA branch exhibits two minima at the middle point (1/4,1/4,1/4) and the zone boundary (1/2,1/2,1/2). These two modes are weakly temperature dependent up to 1173 K.

The neutron diffraction study has been performed on a single crystal specimen of yttrium doped compound Bi₂Sr₂Ca_0.4Y_0.6Cu₂O_8+δ, which is a structural analog of the Bi-2212 superconducting cuprates. The average structure is orfhorhombic of Fmmm symmetry (a = 5.448 Å, b = 5.439 Å and c = 30.416 Å). Two kinds of distortion are observed. The first one, manifested by satellite reflections of wavevector [τ,0,1] with τ = 0.220, is associated with an incorporation of extra oxygen (δ∼0.44) into BiO bilayer. The respective modulation consists of a flexing of the bilayer and corrugation of other structural layers with period 4.5a. The second distortion is associated with displacements in the BiO planes due to Bi³⁺ bonding and lone pair ordering, which results in common cases in a formation of infinite ribbons of Bi-O-Bi- chains and decrease of average symmetry to Amaa. In the present system, the reflections characteristic for Amaa are absent and, instead, a diffuse scattering along the [001] direction is observed, pointing to a presence of 2-dimensional superstructure with in-plane period 9.0a – twice the one of the regular modulation. Based on these data, we propose a structural model in which bonding chains in the BiO planes of Bi₂Sr₂Ca_0.4Y_0.6Cu₂O_8.44 are segmented and rearranged in a tweed pattern.

Yttrium doped ceria materials (Ce_1−xY_xO_2−x/2) are widely studied for their application in Solid Oxide Fuel Cells devices. An anomalous decrease in the isothermal ionic conductivity at increasing Y³⁺ concentration above a critical value has been observed and attributed to the formation of defect clusters / domains at the nanometric scale, the crystallographic structure of which is still under debate. In this context we present a combined Synchrotron Radiation and Neutron Powder Diffraction study. In particular, neutrons allow to determine accurately oxygen related parameters, the contribution of which in terms of X-ray scattering power is almost negligible when compared to that of cations. The effect of doping on the average structure is investigated using conventional Rietveld analysis, while the Pair Distribution Function (PDF) technique is used to explore structural distortions and the spatial extent of disorder as well. The local structure observed in the real space is not consistent with the mean crystallographic one and is better modeled considering a biphasic model.

We report structural changes in amorphous hydrated zirconia caused by high intensity ultrasonic treatment studied by means of small-angle neutron scattering (SANS) and X-ray diffraction (XRD). It was established that sonication affects the mesostructure of ZrO₂×xH₂O gels (i.e. decreases their homogeneity, increases surface fractal dimension and the size of monomer particles). Ultrasound induced structural changes in hydrated zirconia governs its thermal behaviour, namely decreases the rate of tetragonal to monoclinic zirconia phase transition.

Synchrotron X-ray and neutron diffraction measurements were carried out for (⁷Li₂S)_x(P₂S₅)_100−x glasses and a ⁷Li₇P₃Sn₁₁ metastable crystal. The Reverse Monte Carlo (RMC) modeling provided us the three-dimensional structures of (⁷Li₂S)_x(P₂S₅)_100−x and ⁷Li₇P₃S₁₁, particularly the distribution of Li⁺ cations.

The deuterated form of ammonium iron(III) bis (hydrogenphosphate), ND₄Fe(DPO₄)₂, was investigated in detail from neutron powder diffraction data with a wavelength λ = 4.724 Å. The material undergoes two successive magnetic phase transitions which are associated with the Fe³⁺ magnetic moments. One at T_C = 17.82 ± 0.05 K is attributed to the ferrimagnetic order with the magnetic moments, μ_FI = 4.19 ± 0.02 μ_B at 4 K, lying on the crystallographic plane ac. The other transition is found to be at T_t = 3.52 ± 0.05 K due to an antiferromagnetic arrangement, with an equal moment antiphase structure that is characterized by a long-period propagation vector close to _AF ≈ (1/16,0,1/16) and a magnetic moment for the Fe³⁺ ions of μ_AF = 4.41 ± 0.03 μ_B at 1.5 K. The low symmetry of its triclinic crystal structure and the complex pattern of competing superexchange pathways seem to be responsible for the existence of this double magnetic phase transition.

The magnetic excitations of charge-stripe ordered La₂NiO_4.11 where investigated using polarized- and unpolarized-neutron scattering to determine the magnetic excitations of the charge stripe electrons. We observed a magnetic excitation mode consistent with the gapped quasi-one-dimensional antiferromagnetic correlations of the charge stripe electrons previously observed in La_2−xSr_xNiO₄x = 1/3 and x = 0.275.

Neutron scattering experiments were performed on single crystals of magnetic impurity doped cobalt oxides La_1.5Ca_0.5CoO₄ to characterize the charge and spin orders. We newly found contrasting impurity effects. Two types of magnetic peaks are observed at q = (0.5,0,L) with L = half-integer and integer in La_1.5Ca_0.5CoO₄, while magnetic peak at L = half-integer (integer) was only observed in Mn (Fe)-substituted sample. Although Mn and Fe impurities degrade charge and magnetic order, Cr impurity stabilizes the ordering at x = 0.5. Based on the crystal structural analysis of Cr doped sample, we found that the excess oxygen and change of octahedron around Co³⁺ were realized in Cr doped sample.

Delafossite compound CuFeO₂ is a spin-driven magneto-electric multiferroic, in which magnetic field-induced or nonmagnetic impurity-induced proper helical magnetic ordering generates a spontaneous electric polarization through the spin-orbit-interaction mediated modulation of Fe 3d-O 2p hybridization. As is expected from spin-lattice tightly coupled character of this system, we found an enhancement of spin-driven ferroelectric polarization under [10] uniaxial stress as spin-mediated piezoelectric effect. Preparing almost mono-domain state for multiferroic CuFe_1−xGa_xO₂ sample with x = 0.035, we have performed polarized neutron diffraction and in-situ ferroelectric polarization measurements to investigate how the helical magnetic structure is modified and how much ferroelectric polarization increases under application of [10] uniaxial stress up to 100 MPa. The uniaxial-stress variation of magnetic structural parameters characterizing helical magnetic ordering suggests decreasing of the ferroelectric polarization according to the calculation on the basis of d-p hybridization mechanism. Therefore, it is suggested that the enhancement of ferroelectric polarization originates not in variation of the magnetic structure but in the enhancement of the d-p hybridization coupling constants.

Using the unique coverage of (Q, ω) space available on the BRISP spectrometer, we have investigated the low Q dynamical response of a single crystal of UFe₂. A strong inelastic signal was found with a dispersion corresponding to the transverse acoustic phonon branch, forbidden in the first Brillouin zone. A detailed analysis of the neutron intensities as a function of temperature reveals a possible magnetic contribution superposed to this signal, which could originate from the magnon-phonon interaction, explaining the anomalous magnetoelastic behavior in this compound.

Binary intermetallic compound Nd₇Rh₃, crystallizes in a Th₇Fe₃ type hexagonal structure in space group P6₃mc and has been reported to show two antiferromagnetic (AFM) phase transitions at 32 K and 10 K from magnetic susceptibility, and a field induced first-order magnetic transition at a field strength of 1 Tesla at 2 K from magnetization measurements. These magnetic properties are different from the isostructural counterparts like Tb₇Rh₃, Ho₇Rh₃, and Nd₇Ni₃. In order to understand the differences in the magnetic behaviour between Nd₇Rh₃ and other isostructural compounds, we have carried out neutron diffraction (ND) studies on polycrystalline Nd₇Rh₃, at various temperatures between 2 and 45 K. ND patterns were also recorded at T = 2K in the presence of applied magnetic fields from 0 to 1.5 Tesla. ND spectra on Nd₇Ni₃ and Ho₇Rh₃, for example, at 2 K in zero magnetic field exhibit a strong AFM peak at a Q ( = 4πSinθ/λ) value of 0.32 and 0.38 Å⁻¹, respectively. However, ND spectra on Nd₇Rh₃, carried out at Focusing Crystal Diffractometer (FCD-Dhruva-Mumbai), diffractometers E6 and E9 (HZB-Berlin) using wavelengths λ = 1.48Å, 2.45Å and 2.8Å respectively, at T = 2K in zero field do not exhibit any AFM peaks in the entire Q-range studied. Instead, long-range ferromagnetic order is established as evidenced by the intensity enhancement of the nuclear Bragg peaks. The lack of extra peaks in the ND patterns would imply that the magnetic order seen in magnetization could be of a k = 0 type which changes from one type to another on the application of magnetic field. The results of nuclear and magnetic structure refinement are discussed to explain the magnetic behaviour of Nd₇Rh₃, at low temperatures.

Neutron diffraction measurements were performed on the iron borate DyFe₃(BO₃)₄ to investigate details of the crystallographic structure, the low temperature magnetic structure and its magnetic properties. DyFe₃(BO₃)₄ adopts at room temperature the P3₁21 symmetry and becomes antiferromagnetic below T_N = 39 K. Both, the rare earth and the iron sublattice, follow the same magnetic propagation vector τ = [0, 0, ½] which leads to a doubling of the crystallographic unit cell in the c-direction. The easy axis anisotropy of the rare earth determines the moment orientation to be mainly along c. No spin reorientation is found between T_N and 1.5 K, however, a small anomaly in the thermal dependence of the unit cell a-parameter is found at about 27 K which could be connected to repopulation of low lying Kramers doublets of Dy³⁺. The magnetic moment value of the Fe-moment is at 1.5 K with μ_Fe = 4.5 μ_B only slightly smaller than expected for an S = 5/2 ion while the Dy moment is strongly reduced and amounts only to μ_Dy = 6.4 μ_B.

We studied the spin-5/2 antiferromagnetic (AF) linear trimer substance SrMn₃P₄O₁₄ using neutron powder diffraction and inelastic neutron scattering (INS) techniques. We determined the magnetic structure below T_N1 = 2.2(1) K. Ordered magnetic moments have x and z components. The angle between two neighboring moments in the trimer is 164 or 166° at 1.5 K, indicating that the intra-trimer (J₁) interaction is AF as expected. The propagation vector is expressed as k = [0, k_y, 0]. The value of k_y is 0.317 at 1.5 K, indicating an incommensurate magnetic structure. The value of k_y changes abruptly between 1.7 and 1.8 K and reaches values close to 0.33 above 1.8 K, indicating another phase transition at T_N2 = 1.75(5) K. We observed plural magnetic excitations. The peak positions are 0.46, 0.68 and 1.02 meV. Our INS results are consistent with those expected in the trimer model. We evaluated the J₁ value as 0.29 meV (3.4 K).

The incommensurate helimagnetic structure (IHS) in the Lu₂Fe₁₇ intermetallics has been induced at 5 K by hydrostatic pressure above 0.3 GPa and characterized by a propagation vector (00t_z). The observed dependence of t_z on external variables is discussed within a simple model based on a complex dependence of exchange interactions J_n,m (n, m = f, j, k and g) on distances between Fe-atoms in inequivalent positions 4f, 12j, 12k and 6g of the hexagonal P6₃/mmc crystal structure. To verify this model, we have studied magnetization and representative neutron reflections of Lu₂Fe₁₇ single crystals under high hydrostatic pressure and uniaxial compression with stress σ || a-axis and σ || c-axis. Both, the metamagnetic transitions and magnetic satellites of the (00t_z) type that verify the presence of IHS in Lu₂Fe₁₇ at 5 K were observed under hydrostatic pressure and under uniaxial stress σ || c-axis only. We show that the dominant role in an appearance of IHS in the Lu₂Fe₁₇ under compression is played by the J_ff and J_fj exchange interactions.

Magnetic structures in TbIG and in terbium-yttrium ferrite garnet Tb_0.37Y_2.63IG are revisited using Bertaut' representation analysis for the highest crystallographic subgroups of the space group Ia d with the wave vector k = 0. Powder neutron diffraction experiments performed only on TbIG are combined with single crystal magnetization measurements. Three field-induced phase transitions are observed at 4.2 K in high magnetic fields up to 150 kOe along the <001> direction while <111> remain the easy axis of magnetization. New parameters of the previous Tb³⁺ double umbrella magnetic structure are found at 5 K in a modified model of the rhombohedral subgroup Rc . From magnetizations on Tb_0.37Y_2.63IG single crystal, non collinear magnetic structure is evidenced at 4.2 K along the easy axis <001>. The parameters of a 'square pyramid' umbrella are predicted using both the basis vectors of the tetragonal subgroup I4₁/acd and a model based on the effective spin Hamiltonian with anisotropic exchange and magnetic tensors with the requirement g_yG_y < g_zG_z ≪ g_xG_x. Anisotropy of magnetization is observed by comparison with the hard axis <111> below Ta = 80 K where the earlier spin reorientation phase transitions <001>↔<uuw>↔<111> occur between T₁ = 40 K and T₂ = 140 K. The basis vectors of the monoclinic subgroup C2/c are tentatively proposed for the low symmetry angular phases <uuw>. All results are compared to previous works.

There are various representations for the long time evolution and the dynamics of spin glasses, but a coherent, overall accepted real space description remains lacking. Small-Angle Neutron Scattering measurements reveal the long range spin-spin correlations from which the correlation length as a function of the temperature, time or magnetic field can be deduced. The scattering of the amorphous Fe₉₀Zr₁₀ alloy during zero magnetic field cooling arises from long range correlations described by a Lorentzian function and scattering from spin clusters. From the temperature dependence of the correlation length two transitions are observed without, however, the correlation length to diverge. The application of magnetic field suppresses the transitions. The experimental findings are discussed in conjunction with different theoretical models.

Results of X-ray, neutron, magnetization and Mössbauer measurements on polycrystalline samples of Fe_3−xCr_xAl_0.5Si_0.5 (x = 0, 0.125, 0.250, 0.375 and 0.5) alloys are presented. The alloys crystallize in the structure of DO₃ type, and their unit cell volumes are practically independent of the chromium concentration. X-ray and neutron diffraction confirmed the phase homogeneity of all the samples. Neutron and Mossbauer measurements disclosed that Cr atoms occupy preferentially B-sites, while D sites are almost entirely occupied by Al and Si. The total magnetisation as well as the site and individual magnetic moments μ_Fe(A,C), μ_Fe(B) and μ_Cr(B,D) have been found to be linearly dependent on the chromium concentration.

We have determined the magnetic structure of the intermetallic compound HoGa by high-resolution neutron powder diffraction. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and the magnetic structure comprises ferromagnetic order of the Ho sublattice along the c-axis. The Curie temperature is 66(3) K. Upon cooling below 20 K, the Ho magnetic moments cant away from the c-axis towards the ab-plane. At 3 K, the Ho moment is 8.8(2) μ_B and the Ho magnetic moments point in the direction θ = 30(2)° and ϕ = 49(4)° with respect to the crystallographic c-axis. The observation of an ab-plane component at around 50° from the a-axis is in contrast with the suggested magnetic structure of ac order (θ = 32° and ϕ = 0°) reported by Delyagin et al. [1] on the basis of a ¹¹⁹Sn Mössbauer spectroscopy study of a Sn-doped HoGa sample. However, we find that these two sets of orientations are in fact indistinguishable by Mössbauer spectroscopy.

Previous neutron scattering experiments on single crystal of Sendust alloy (73.5 at. % Fe, 17 at. % Al, and 9.5 at. % of Si) revealed extremely high spin wave damping at room temperature. The aim of present studies was to test if the spin wave damping originates from lattice disorder or comes from mutual spin waves interactions or other excitations that would be temperature dependent. The spin wave dispersion relation and damping were studied in temperature range from 8 to 295 K. No regular changes of both spin wave damping and stiffness constant (which characterises dispersion relation) with temperature were found. Thus, within this temperature range, spin waves interactions with dynamical excitations of all kinds must be negligible, and their damping is most likely produced by lattice disorder alone. It is of interest to note that the inelastic background intensity below the spin wave peaks increases with temperature and for energy transfers higher than 30 meV this increase is larger than that of spin-wave peak intensity.

The influence of Nd magnetic impurities on the spin dynamics of CeCoIn₅ was studied by inelastic neutron scattering. In the Nd-substituted compound Ce_0.95Nd_0.05CoIn₅, the spin resonance peak (observed at Ω_res = 0.55 meV in the pure system) is shifted to lower energies but the ratio Ω_res/k_BT_c remains almost unchanged. These observations are compared with non-magnetic La-substitution.

While the high transition temperatures suggest that the conventional BCS phononmediated mechanism may not provide the main pairing mechanism in the recently discovered RFeAsO_1−xF_x (1111-type) superconductors, there is, as yet, no consensus, despite extensive experimental and theoretical study. We report here the results of an inelastic neutron scattering investigation of an overdoped polycrystalline sample of LaFeAsO_1−xF_x with x = 0.15 (T_c = 26 K). Four excitation peaks were observed at 13.6±1.5, 24.2±0.8, 32.2±0.5, and 41.4±1.0 meV. They were identified as phonon modes based on their wavevector and temperature dependence. The peak positions agree well with first-principles calculations of phonon density of states as well as experimental data on both the insulating parent and optimally doped LaFeAsO_1−xF_x compounds. No evidence for the presence of a resonance mode was found. We found that the phonon density of states of the x = 0.15 sample remains unchanged below T_c and is similar to samples with other fluorine concentrations. This suggests that a standard electron-phonon pairing mechanism cannot explain the high transition temperatures observed in these materials.

Low-energy spin excitations on polycrystalline LaFeAsO_1−xF_x samples have been studied by inelastic neutron scattering. The Q-integrated dynamical spin susceptibility χ"(ω) at 11 meV decreases with increasing fluorine content x across the phase transition from antiferromagnetic to superconducting phases. For superconducting samples, a peak in χ"(ω) develops at ω = E_res below T_c, accompanied by its reduction below E_res. Fe 3d orbital contribution on the dynamical spin susceptibility and the electron scattering between Γ and M Fermi surfaces are discussed.

A time-honoured approach to single-molecule, or self, dynamics of liquids is based on the so-called Gaussian approximation (GA), where it is assumed that, in the whole dynamical range between hydrodynamic diffusion and free-particle streaming, the motion of a particle is fully determined by a unique function of time directly related to the velocity autocorrelation function. An evident support to the GA is offered by the fact that the approximation becomes exact in both above limit conditions. Yet, experimental inquiries into the presence of non-Gaussian dynamics are very scarce, particularly in liquid parahydrogen in spite of its importance as the prototype of a "quantum Boltzmann liquid" which has also served as a benchmark for the development of quantum dynamics simulation algorithms. Though experimental evidence of the breakdown of the GA was obtained by some of the authors a few years ago, the localization in Q space of non-Gaussian behaviour was still undetermined, and no quantitative assessment of the effect was ever obtained. These issues have been tackled and solved by a new neutron investigation, which provides the first determination of non-Gaussian behaviour in the framework of the well-known theoretical approach by Rahman, Singwi and Sjölander.

Here we report temperature dependent self-diffusion coefficients of liquid aluminium measured on absolute scale by using incoherent quasielastic neutron scattering at temperatures of 980K, 1020K, and 1060K. Aluminium self-diffusion coefficients follow an Arrhenius law with an activation energy of 280±70 meV. The Sutherland-Einstein equation relating viscosity to the diffusion coefficient well captures the temperature dependence and absolute values of the here reported aluminium self-diffusion coefficients using the covalent radius of aluminium. A comparison to published molecular dynamics simulation data helps to further narrow down the choice of the potential.

Using inelastic neutron scattering, we have investigated the elementary excitations of an isotropic two-dimensional Fermi liquid, ³He adsorbed on graphite. We provide in this article a detailed account of the principles and methods which allowed measuring for the first time inelastic spectra on a liquid monolayer of ³He, a strong neutron absorber. We also summarise the results presented at this Conference, and review our recent experimental and theoretical work on this this interacting many-body system. At low wave-vectors, near the edge of the particle-hole band, a mode identified as the zero-sound excitation by comparison to our theoretical calculations, is found as predicted at energies much lower than in bulk ³He. The mode enters the particle-hole band, where it undergoes Landau damping. Surprisingly, however, intensity is observed in the neutron spectra at wave-vectors larger than twice the Fermi wave-vector. This new branch is interpreted as the high wave-vector continuation of the zero-sound mode, in agreement with the theory. The results open new perspectives in the understanding of the dynamics of correlated fermions.

The structure of liquid Bismuth is probably the best-studied among elemental liquid metals because of a combination of the interesting physical properties of Bismuth and its excellent neutron scattering properties. Over the last six decades there have been more than 10 independent studies of the structure of liquid Bi, near the melting temperature. This remarkable number of measurements provides an opportunity to compare these results and to analyze the different sources of error contributing to the calculated pair distribution function. In the present contribution we analyze possible sources of error by varying the analysis procedure for a given measurement. By repeating a previous measurement in a new experimental configuration we demonstrate that an invariant (i.e. up to an absolute error) structure factor can be obtained. Transforming the structure factor into the radial distribution introduces new sources of error which causes the scatter to be greater than that required to resolve issues such as the existence of liquid-liquid phase transitions in Bi and to obtain correlation between thermo-physical properties and structure. We consider the contribution of different parameters when transforming the structure factor to the radial distribution function.

Quasi-elastic neutron scattering spectra of liquid Se₂Br₂ at 298 K, 373 K and 473 K were measured by utilizing the cold-neutron disk-chopper spectrometer AMATERAS in J-PARC. The obtained dynamic structure factors are reproduced well by a two-Lorentzian model consisting of slow and fast modes. With increasing temperature, the maxima in the Q-dependence of the magnitude for both modes shift to a low Q direction, while the temperature dependence of the magnitude is opposite between slow and fast modes. The temperature dependence of the magnitude and the analysis of the energy width for these modes reveal that the fast mode is originated from dynamics in strongly interacted neighbouring molecules, while the slow mode is derived from inter-molecular dynamics without the strong interaction.

Liquid structure of Bi₅₀Zn₅₀, which is situated at around the Bi-rich end of miscibility gap in Bi-Zn system, has been investigated by neutron and x-ray diffraction experiments and following analysis using reverse Monte Carlo (RMC) structural modelling. Among the partial correlations calculated from the structural model obtained by RMC, the Zn-Zn partial has a large temperature variation. It is found that there are medium-range fluctuations in Zn distribution which have a scale of 10 Å.

We present a data treatment procedure, based on an iterative technique, properly developed to subtract the multi-phonon contributions from the dynamic structure factor in a self-consistent way. With this technique, we derive the one-phonon vibrational density of states from the dynamic structure factor of different disordered systems, in the framework of the incoherent scattering approximation. We present results on glassy glucose (C₆H₁₂O₆), a nearly perfect incoherent scatterer, due to high hydrogen content. The data treatment procedure has been found to work well also for the more complex case of dry and hydrated DNA.

To assess the structure of complex biomembranes, the use of asymmetric model systems is rare, due to the difficulty of realizing artificial membranes with desired heterogeneous composition and applicable for single membrane structural investigation. We developed an experimental model with a single macroscopic bilayer floating on top of another adhering to a silicon flat surface, prepared by Langmuir-Blodgett Langmuir-Schaefer technique, then investigated by neutron reflectivity. On the way to more complex systems, containing lipids of different nature, we tested whether a simple imposed asymmetry is kept in time and whether it can stand some standard experimental protocols commonly employed in treating model membranes. We focused on cholesterol, a basic component with a transverse distribution that is not symmetric in biomembranes, and may assume specific location in functional domains. So we forced different asymmetries in the "adhering + floating" bilayers system composed of phospholipids and cholesterol in bio-similar mole ratios. The neutron reflection accessible length-scale and its sensitivity, enhanced by the possibility to play with deuteration, allowed assessing the cross profile of the membrane and revealing that lipid redistribution can occur.

Experimental results on neutron reflection from a magnetic film placed in an oscillating magnetic field are reported. We found evidence for neutron spin resonance in the film and observed a spatial beam-splitting. The beam-splitting finds its origin in the exchange of an energy quantum ℏω between the oscillating field and the neutron.

Magnetization reversal of the exchange-coupled granulated ferromagnetic (GF) CoCu and ferromagnetic (F) Co nanolayers is studied by polarized neutron reflectometry. The main parameters that specify the structure and saturation magnetization of the GF and F layers are determined for Si(substrate)/Co_0.5Cu_0.5(5nm)/Co(x)/Si(3nm) samples with a thickness x varying from 6 to 20 nm. Neutron data allow some suggestions to be made about the features of the GF/F bilayer magnetization reversal. For small x the main mechanism of the magnetization reversal is the domain wall motion hindered by the exchange interaction between GF and F. As a consequence, the magnetization of the Co layer contacting with numerous granules is reversed in fields exceeding its own coercivity by an order of magnitude. For large x the magnetization reversal undergoes several stages conditioned by interaction of GF and F nanolayers. These stages may be characterized by three fields. For an oppositely magnetized sample, when the field approaches H₁, there appear regions with flipped moments coupled to non-flipped moments in neighboring regions ("lateral magnetic springs") in the F layer. The field H₁ sets off the overturn of magnetic moments of the granules, which is accompanied by the pinning of the regions with reversed magnetization in the F layer. The fields H₂ and H₃ tag the completion of the overturn of the F layer magnetization and the granule moments, respectively. When the applied field reaches H₃, any further change of the magnetic state is due to a reversible rotation of the granule moments and the F layer magnetization. The reversibility of magnetic states persists with fields both increasing above H₃ and decreasing down to 0 and further to -H₁.

Neutron reflectometry is found to be quite sensitive to oxidation of very thin layers of Ti. Preliminary results of the study of oxidation of thin Ti films in air are represented. The thickness of the oxide layers formed in air at room temperature on Ti films of thickness 20, 10 and 5 nm (as sputtered) is found to be 2.9±0.3, 3.6±0.3 and 6.1±0.3 nm, respectively. The annealing at temperatures in the range 100-300°C leads to the growth in the oxide layer thickness and in roughness of both (air/oxide and oxide/metal) interfaces. The study of the oxidation of thin Ti films is of interest for improvement of polarizing neutron mirrors and supermirrors.

In the present study, [bmim][PF₆] ionic liquid (IL) was introduced into the pores of two ordered mesoporous silicas (MCM-41 and SBA-15) having different pore sizes by means of two different processes: a) with physical imbibition from a methanol solution under high vacuum and b) by chemically immobilising the IL with silanisation of the pore surface followed by reaction with butyl-methyl imidazolium chloride and anion exchange with PF₆, the process termed as the "grafting to" method. Both the extent of IL entrapment and the structural properties of the IL phase under confinement were investigated by SANS, contrast-matching SANS, XRD and nitrogen adsorption measurements. The results show that the pores of chemically prepared samples are not totally filled by IL and also suggest for ordering of the silylated IL phase. On the other hand, the physically prepared samples are almost or totally filled with IL whereas no evidence for ordering of the confined IL phase was observed.

On a hydrophilic substrate the growth of a Bragg peak was observed at Q≈0.05 Å⁻¹ which we attribute to a layering of micelles. This ordering is destroyed when the system is sheared. When shear is removed, it builds up and reaches equilibrium at ambient temperature after approximately 700s. However, there is a waiting time of 200s before any structure becomes visible again. When lower shear rates are applied the ordering recovers more quickly, but it does not build up to the same extent.

Control and optimization of polymer properties require the global knowledge of the constitutive microstructures of polymer morphologies in various conditions. The microstructural features can be typically explored over a wide length scale by combining pinhole-, focusing- and ultra-small-angle neutron scattering (SANS) techniques. Though it proved to be a successful approach, this involves major efforts related to the use of various scattering instruments and large amount of samples and the need to ensure the same crystallization kinetics for the samples investigated at various facilities, in different sample cell geometries and at different time intervals. With the installation and commissioning of the MgF₂ neutron lenses at the KWS-2 SANS diffractometer installed at the Heinz Maier-Leibnitz neutron source (FRMII reactor) in Garching, a wide Q-range, between 10⁻⁴Å⁻¹ and 0.5Å⁻¹, can be covered at a single instrument. This enables investigation of polymer microstructures over a length scale from lnm up to 1μm, while the overall polymer morphology can be further examined up to 100μm by optical microscopy (including crossed polarizers). The study of different semi-crystalline polypropylene-based polymers in solution is discussed and the new imaging-SANS approach allowing for an unambiguous and complete structural characterization of polymer morphologies is presented.

A series of Polyvinyl alcohol (Mowiol 5-88) – Bentonite nanocomposite films with predefined clay loading (up to 0-20%), were prepared via solvent casting technique. The developed films, due to the favourable polymer-particle interactions, revealed excellent dispersion of the clay particles in the polymer matrix and improved properties. Furthermore, the properties of PVA/clay nanocomposites as well as their structural changes as a function of the relative humidity were thoroughly investigated using neutron membrane diffraction experiments. The samples prior their measurement were equilibrated at different relative humidity levels (%RH) using either H₂O or D₂O. The application of contrast variation technique enabled us to investigate the contribution of both the polymer and the clay particles to the diffraction spectra. Thus, the use of H₂O enlightened the low Q region, providing information about the structure of the inorganic phase and specifically the stacking of the clay platelets. The diffraction patterns in this region obtained from perpendicular and in-plane sample positions revealed that there is a specific orientation of bentonite plates, parallel to the film surface. This conclusion is in agreement with the results obtained from XRD and gas permeability technique, in which the well organized and dispersed impermeable inorganic layers, increase the resistance in flow through the nanocomposites film, acting as gas barriers. On the other hand, diffraction experiments on pre-equilibrated with D₂O samples revealed the structural changes in polymeric matrix, due to hydration. The obtained peak revealed the presence of a new crystalline phase, presumably induced by the presence of the silicates, which is in agreement with DSC data reported in previous studies.

Water dynamics plays a fundamental role for the fulfillment of biological functions in living organisms. Decades of hydrated protein powder studies have revealed the peculiar dynamical properties of hydration water with respect to pure water, due to close coupling interactions with the macromolecule. In such a framework, we have studied coherent collective dynamics in protein and DNA hydration water. State-of-the-art neutron instrumentation has allowed us to observe the propagation of coherent density fluctuations within the hydration shell of the biomolecules. The corresponding dispersion curves resulted to be only slightly affected by the coupling with the macromolecules. Nevertheless, the effects of the interaction appeared as a marked increase of the mode damping factors, which suggested a destructuring of the water hydrogen-bond network. Such results were interpreted as the signature of a "glassy" dynamical character of macromolecule hydration water, in agreement with indications from measurements of the density of vibrational states. Extending the investigations to living organisms at physiological conditions, we present here an in-vivo study of collective dynamics of intracellular water in Escherichia coli cells. The cells and water were fully deuterated to minimise the incoherent neutron scattering background. The water dynamics observed in the living cells is discussed in terms of the dynamics of pure bulk water and that of hydration water measured in powder samples.

Changes of molecular dynamics associated with amyloid fibril formation were explored using apomyoglobin as a model system. Protein dynamics was measured using elastic incoherent neutron scattering. The formation of amyloid fibres was evidenced by the presence of characteristic signatures in the X-ray diffraction pattern.

In the present contribution, a procedure for molecular motion characterization based on the evaluation of the Mean Square Displacement (MSD), through the Self-Distribution Function (SDF), is presented. It is shown how MSD, which represents an important observable for the characterization of dynamical properties, can be decomposed into different partial contributions associated to system dynamical processes within a specific spatial scale. It is also shown how the SDF procedure allows us to evaluate both total MSD and partial MSDs through total and partial SDFs. As a result, total MSD is the weighed sum of partial MSDs in which the weights are obtained by the fitting procedure of measured Elastic Incoherent Neutron Scattering (EINS) intensity. We apply SDF procedure to data collected,by IN13, IN10 and IN4 spectrometers (Institute Laue Langevin), on aqueous mixtures of two homologous disaccharides (sucrose and trehalose) and on dry and hydrated (H₂O and D₂O) lysozyme with and without disaccharides. It emerges that the hydrogen bond imposed network of the water-trehalose mixture appears to be stronger with respect to that of the water-sucrose mixture. This result can justify the higher bioprotectant effectiveness of trehalose. Furthermore, it emerges that partial MSDs of sucrose and trehalose are equivalent in the low Q domain (0÷1.7) Å⁻¹ whereas they are different in the high Q domain (1.7÷4) Å⁻¹. This suggests that the higher structure sensitivity of sucrose should be related to the small spatial observation windows. Moreover, the role of the instrumental resolution in EINS is considered. The nature of the dynamical transition is highlighted and it is shown that it occurs when the system relaxation time becomes shorter than the instrumental energy time. Finally, the bioprotectants effect on protein dynamics and the amplitude of vibrations in lysozyme are presented.

Based on X-ray crystallographic data available at Protein Data Bank, we have built molecular dynamics (MD) models of homologous recombinases RecA from E. coli and D. radiodurans. Functional form of RecA enzyme, which is known to be a long helical filament, was approximated by a trimer, simulated in periodic water box. The MD trajectories were analyzed in terms of large-scale conformational motions that could be detectable by neutron and X-ray scattering techniques. The analysis revealed that large-scale RecA monomer dynamics can be described in terms of relative motions of 7 subdomains. Motion of C-terminal domain was the major contributor to the overall dynamics of protein. Principal component analysis (PCA) of the MD trajectories in the atom coordinate space showed that rotation of C-domain is correlated with the conformational changes in the central domain and N-terminal domain, that forms the monomer-monomer interface. Thus, even though C-terminal domain is relatively far from the interface, its orientation is correlated with large-scale filament conformation. PCA of the trajectories in the main chain dihedral angle coordinate space implicates a co-existence of a several different large-scale conformations of the modeled trimer. In order to clarify the relationship of independent domain orientation with large-scale filament conformation, we have performed analysis of independent domain motion and its implications on the filament geometry.

Neutron diffraction is a very powerful tool in texture analysis of zirconium based alloys used in nuclear technique. Textures of five samples (two rolled sheets and three tubes) were investigated by using basal pole figures, inversion pole figures, and ODF distribution function. The texture measurement was performed at diffractometer KSN2 on the Laboratory of Neutron Diffraction, Department of Solid State Engineering, Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague. Procedures for studying textures with thermal neutrons and procedures for obtaining texture parameters (direct and inverse pole figures, three dimensional orientation distribution function) are also described. Observed data were processed by software packages HEXAL and GSAS. Our results can be summarized as follows: i) All samples of zirconium alloys show the distribution of middle area into two maxima in basal pole figures. This is caused by alloying elements. A characteristic split of the basal pole maxima tilted from the normal direction toward the transverse direction can be observed for all samples, ii) Sheet samples prefer orientation of planes (100) and (110) perpendicular to rolling direction and orientation of planes (002) perpendicular to normal direction, iii) Basal planes of tubes are oriented parallel to tube axis, meanwhile (100) planes are oriented perpendicular to tube axis. Level of resulting texture and maxima position is different for tubes and for sheets. The obtained results are characteristic for zirconium based alloys.

The neutron diffraction and acoustic emission (AE) techniques have been used for in-situ investigation of deformation twinning activity in cast polycrystalline magnesium at room temperature. The combination of these two techniques results in obtaining complementary information about the twinning mechanism during the straining. It is shown that loading mode significantly influences the twin nucleation and the twin size. In tension, the twin nucleation is observed during the entire test, while in compression only at the beginning of the plastic deformation. Nevertheless, the overall twinned volume does not differ. The optical micrographs support the above mentioned conclusions.

We present here results of small-angle neutron scattering (SANS) investigation of partially and fully yttria stabilized zirconia (PYSZ and FYSZ, respectively) turbine blade coatings (TBC). The samples have been prepared by electron beam physical vapour deposition method (EB-PVD) with various setup parameters. Structure parameters of porosity have been studied in-situ with high-temperature furnace. Temperature dependence of specific surface and anisotropy parameter of porosity has been obtained. Differences in character of microstructural morphology changing with in-situ thermal treatment as well as open and closed porosity ratio in PYSZ and FYSZ has been described and discussed.

Al-Pb binary system is a suitable model system for testing liquid phase dispersion strengthening in bulk materials for structural applications. Liquid Pb islands can be finely dispersed in still solid Al matrix due to the substantial difference of melting points. The Al-Pb system prepared by means of Equal Channel Angular Pressing (ECAP) process was investigated by Small-Angle Neutron Scattering technique (SANS) which enables in-situ measurement of size and morphology parameters of Pb inclusions at elevated temperatures. It was observed that the lead particles were elongated roughly in the direction of ECAP. During the subsequent in-situ thermal cycle RT-400°C-RT, the elongated Pb particles transformed to nearly spherical shape. The change of scattering contrast during melting of Pb mapped the transform of the confined lead particles to the liquid phase. The center of the transition region is around 342°C (615K) for both the as-cast and the ECAP deformed samples, which is a significant shift with respect to the free Pb melting point 327°C (600K). For the ECAP sample, the transition is not sharp, indicating a broad size distribution of lead particles.

A specifically designed cruciform-shaped austenitic stainless steel AISI 321 sample was subjected to ex-situ biaxial tension-compression cycling to establish ferromagnetic martensitic phase conversion under the action of plastic deformation. The time-of-flight neutron diffraction technique was employed for in-plane residual stress determination in this sample for both the austenitic and martensitic phases. The 2D data enabled determination of macro-, micro-, hydro- and deviatoric contributions to the total phase stresses.

This paper studied for the first time peak intensity, peak position and FHWM pole figures with one time measurement at the neutron diffractometer STRESS-SPEC via in-situ tensile deformation on austenitic steel. Fibre distribution with its evolution from central tensile direction to normal direction of these three kinds of pole figures was obtained. Variation of peak position and FWHM can be correlated to the reorientation of the texture component.

Neutron and X-ray diffraction were used to study the residual and internal stress evolution during cold drawing in pearlitic steel wires. A selection of high strength filaments drawn to different reductions has been investigated. In order to compare the evolution of macro and micro residual phase stresses in ferrite, the lattice strain evolution has been studied in axial and transverse direction. In-situ neutron diffraction tests in "Poisson" geometry have been carried out at the TOF strain scanner POLDI at PSI, Switzerland. These tests revealed a significant scatter in mechanical response among differently oriented ferrite grains, including a peculiar response of the {200} reflection, cp. [1, 2].

The porosity of undoped and Zr- and Ti-doped graphites has been determined using small-angle neutron scattering measurements. To differentiate between open and closed pores in the neutron scattering measurements the contrast matching technique was employed. In the pore volume distribution three distinct sizes of pores are present. Doping increases the volume fraction of pores, shifts the mean size to lower values and makes the size distributions wider. In addition it enhances drastically the closed porosity.

Hydrogen and deuterium pressure-composition (P-C) isotherm measurements were carried out for Ti_0.31Cr_0.49V_0.20 bcc alloy. As a result, the residual hydrogen-to-metal ratio (H/M)_res was almost the same as the residual deuterium-to-metal one (D/M)_res; the (H/M)_res and (D/M)_res were approximately 0.5. Furthermore, the neutron scattering experiments were conducted with Ti_0.31Cr_0.49V_0.20 alloys including the residual hydrogen and/or deuterium. It was found that H atoms absorbed in the first absorption cycle up to H/M = 0.5 are hardly bound in the desorption cycle as the residual hydrogen, whereas D atoms are mainly bound in Ti_0.31Cr_0.49V_0.20 bcc alloy as the residual deuterium when D₂ gas is partially used in the H absorption reaction.

In angle-dispersive neutron strain scanning the information about residual strain comes from the whole gauge volume that is defined by slits in the incoming and diffracted beams. Since the intensity of the neutron beam decreases with the amount of material it has travelled, neutrons diffracted from different locations within the gauge volume contribute with different intensities to the recorded diffraction peak. This can lead to peak shifts, and thus apparent strains. The magnitude of this peak shift depends mostly on the beam attenuation and the size of the gauge volume, but also on the sample geometry and position of the gauge volume within the sample. The peak shift plays a significant role when the size of the gauge volume becomes large because of peak broadening by the sample. An analytic expression for the peak shift was derived for a simple geometry to evaluate a numerical simulation. The numerical simulation was developed to quantify necessary corrections in detail. The attenuation-induced peak shift was demonstrated by measurements on a strain-free powder sample and the results were compared with the numerical predictions.

Joining of pipes from stainless steel (SS) and titanium (Ti) alloy still experience serious technical problems. Recently, reliable and hermetic joining of SS and Ti pipes has been achieved with the explosive bonding technique in the Russian Federal Nuclear Center. Such adapters are earmarked for use at the future International Linear Collider. The manufactured SS-Ti adapters have excellent mechanical behavior at room and liquid nitrogen temperatures, during high-pressure tests and thermal cycling. We here report the first neutron diffraction investigation of the residual stresses in a SS-Ti adapter on the POLDI instrument at the SINQ spallation source. The strain scanning across the adapter walls into the SS-SS and SS-Ti pipes sections encompassed measurement of the axial, radial and hoop strain components, which were transformed into residual stresses. The full stress information was successfully determined for the three steel pipes involved in the joint. The residual stresses do not exceed 300 MPa in magnitude. All stress components have tensile values close to the adapter internal surface, whilst they are compressive close to the outer surface. The strong incoherent and weak coherent neutron scattering cross-sections of Ti did not allow for the reliable determination of stresses inside the titanic pipe.

The hydrogen diffusion from the gas phase into Zircaloy-4 solid cylinders was investigated at various temperatures between 823 and 1473 K. Diffusion coefficients were fitted using axial hydrogen distributions for all temperatures investigated. The activation energy of the hydrogen diffusion was calculated for temperatures at which the bcc β phase is stable. The determined value of 48.3 kJ mol⁻¹ K⁻¹ is significantly higher than values published by other authors. At lower temperatures the hydrogen uptake is connected with a phase transformation from the hep α- to the bcc β-phase. The spatial phase distribution and the hydrogen concentrations in the two phases were analysed.

Crystallographic preferential orientation (CPO) of metagabbro mylonite from the eastern part of Stare Mesto belt, Bohemian Massif, is investigated by means of neutron diffraction method. The experiments were performed on the KSN-2 neutron diffractometer situated at the research reactor LVR-15 in the Nuclear Research Institute, pic. Rez, Czech Republic. Based on the collected diffraction patterns, the orientation distribution function of crystalline grains is determined by Rietveld harmonic method for the principal mineral phases -amphibole and plagioclase - and used to calculate (001), (020), (021), (110), (111) (plagioclase) and (001), (11), (020), (110), (200) (amphibole) pole figures. Lattice parameters of the phases have been obtained from diffraction patterns of a powder specimen. Main features of the observed CPO are compared with results of electron back-scatter diffraction measurements performed formerly on the same sample and with other known data.

The present work deals with the carbonation process in cement based materials such as concrete. In order to clarify the evolution of the two main phases involved in the process, portlandite and calcium carbonate as a function of depth, spatially resolved neutron diffraction experiments have been performed at SALSA diffractometer at ILL in carbonated cement paste samples. Specimens submitted to different carbonation processes, both natural and accelerated, have been analyzed with this non destructive technique. The evolution of the main diffraction peaks of portlandite and calcite has been followed by means of neutron diffraction patterns measured at different depths. The results indicate that, in specimens subjected to CO₂ atmospheres for 24 and 48 hours, the amount of calcite increases from the centre of the specimen to the surface. In both type of specimens calcite is formed at all depths analyzed, with higher quantities for the ones submitted to the longest carbonation period. Regarding the evolution of portlandite in these specimens, it almost completely disappeared, with only a low amount of the phase constant throughout the sample. In specimens subjected to air in a closed chamber for 21 months, higher amounts of portlandite were observed throughout the sample and little increase of calcite in the outer part, pointing out a much less severe reaction. The absorption effects are characterized by measuring in perpendicular directions and an absorption coefficient is calculated for portlandite.

The Maya blue (MB) is an artificial pigment created between 500-800 A.D. and used in murals, pottery and sculptures by Mayas and other people in Mesoamerica. MB is resistant to age, acid, weathering, biodegradation and even modern chemical solvents, but the chemical reasons behind the resistance to chemical aggressions are still under debate. Water plays a fundamental role in the interactions between indigo and clay. The dynamics of the clay's zeolitic and structural water molecules during the formation of MB, usually stabilized by moderate heating, has been monitored by means of neutron inelastic scattering. Neutron incoherent scattering in these samples is only due to the hydrogen atoms, so the signal is very sensitive to the amount of released water, providing detailed information on the dehydration process. A simultaneous analysis of the coherent elastic scattering and the incoherent scattering allows observing and quantifying how the structure of the clay is affected by dehydration. Here we show that a quite resistant pigment can be obtained at room temperature simply by dehydrating a palygorskite-indigo mixture employing only vacuum, without any thermal treatment.

Similar to LaCoO_4.14, La_2−xSr_xCuO_4±δ shows oxygen diffusion at moderate temperatures. The Oxygen Isotope Back Exchange (OIBE) experiments are done in order to investigate the effect of strontium on the oxygen diffusion in as grown single crystals of La_2−xSr_xCuO_4±δ (x = 0, 0.05, 0.1, 0.15). Neutron diffraction data collected at TriCS@SINQ are in agreement with diffusion measurements achieved by oxygen back exchange. From ¹⁸O/¹⁶O isotope exchange between 40 °C to 1000 °C free oxygen mobility can be realized for x = 0, 0.05 below 500 °C but is depressed for x = 0.1 and 0.15. This gives evidence that low temperature oxygen mobility can be suppressed by replacing La with Sr. First crystal test using neutron single crystal diffraction proved the high quality of the samples.

Due to their high hydrogen content, tetraborohydrides are discussed as potential synthetic energy carriers. On the example of lithium borohydride LiBH₄, we discuss current approaches of direct, solvent free synthesis based on gas solid reactions of the elements or binary hydrides and/or borides with gaseous H₂ or B₂H₆. The direct synthesis from the elements requires high temperature and high pressure (700°C, 150bar D₂). Using LiB or AlB₂ as boron source reduces the required temperature by more than 300 K. Reactive milling of LiD with B₂H₆ leads to the formation of LiBD₄ already at room temperature. The reactive milling technique can also be applied to synthesize other borohydrides from their respective metal hydrides.

The characterization of ten ancient Greek silver coins from the Treasure collection of Gazoros (CH IX 61) found in Serres- North Greece; as well as two silver coin replicas, has been carried out using a polychromatic neutron beam of large cross-section to obtain diffraction patterns from the entire objects. The diffraction profiles indicate that there are three distinct categories of coins. The first one is a set of three coins consisting mainly of silver and copper alloy phases with high quantities of Cu₂O and CuCl . The second group is formed of coins with high silver/ copper alloy ratio and the third is a collection of five coins consisting of very high purity silver. The comparison between the diffraction profiles of the original coins to those of the replicas present distinct variations that may be used to differentiate the different groups.