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The results obtained in the initial step of studying the effect of external proton irradiation on the properties and structure of simulated borosilicate and aluminophosphate glasses and of internal irradiation on the active glass arranged in the repository of the radiochemical plant of the Mayak Production Association are reported. These results show that the glass melting technologies used at the Mayak Production Association can reliably ensure the environmental safety of the glass incorporating the high-level waste. [ABSTRACT FROM AUTHOR]

This report presents the physics design and optimization of the neutron chopper and optics systems for the CENTAUR instrument, a multifunctional small-angle and wide-angle neutron scattering diffractometer for the Spallation Neutron Source Second Target Station. This instrument will offer a wide range of capabilities, including small-angle neutron scattering with wide Q coverage (e.g., 0.001–20 Å−1), providing a tool to investigate structures from atomic to mesoscopic scales simultaneously. To efficiently transport desired neutrons from the compact high-brightness cold source, several innovative designs are utilized: a time-zero chopper with a straight guide system for short-wavelength neutrons, octagonal guides for higher flux, and a correlation chopper to reduce inelastic scattering. The optimization process considers factors such as useable time-integrated flux, instrument resolution, brilliance transfer, divergence, and acceptance diagram uniformity. The overall design prioritizes flexibility to accommodate diverse user requirements. [ABSTRACT FROM AUTHOR]

Hydrogen atoms and hydration water molecules in proteins are essential for many biochemical processes, especially enzyme catalysis. Neutron crystallography enables direct observation of hydrogen atoms, and reveals molecular recognition through hydrogen bonding and catalytic reactions involving proton-coupled electron transfer. The use of neutron crystallography is still limited for proteins, but its popularity is increasing owing to an increase in the number of diffractometers for structural biology at neutron facilities and advances in sample preparation. According to the characteristics of the neutrons, monochromatic or quasi-Laue methods and the time-of-flight method are used in nuclear reactors and pulsed spallation sources, respectively, to collect diffraction data. Growing large crystals is an inevitable problem in neutron crystallography for structural biology, but sample deuteration, especially protein perdeuteration, is effective in reducing background levels, which shortens data collection time and decreases the crystal size required. This review also introduces our recent neutron structure analyses of copper amine oxidase and copper-containing nitrite reductase. The neutron structure of copper amine oxidase gives detailed information on the protonation state of dissociable groups, such as the quinone cofactor, which are critical for catalytic reactions. Electron transfer via a hydrogen-bond jump and a hydroxide ion ligation in copper-containing nitrite reductase are clarified, and these observations are consistent with the results from the quantum chemical calculations. This review article is an extended version of the Japanese article, Elucidation of Enzymatic Reaction Mechanism by Neutron Crystallography, published in SEIBUTSU-BUTSURI Vol. 61, p.216–222 (2021).

Aim. In response to increased clinical performance of ceramic restorations, the aim of this study is to test, analyze and compare the physical and chemical properties of pressed ceramics and zirconium oxide. Material and method. For this comparative analysis, three ceramic materials were studied, pressed ceramic (IPS E. max Ceram) and zirconium oxide (Ceramill zolid FX and BruxZir) and a dilatometer, the scanning electron microsope and a diffractometer were used for their physico-chemical properties analysis. The morphology of the materials was determined by scanning electron microscopy (SEM images), their elementary composition by X-ray spectroscopy (EDX analysis), the chemical composition by X-XRD diffraction, their behavior at different temperatures by dilatometry. Results and discussions. According to SEM images, the three materials have different morphology, with different phases and it was found that zirconium oxide has the highest mechanical strength, being formed only of the crystalline phase. EDX ANALYSIS identified that silicon dioxide (SiO2) forms of glassy network, and sodium (Na) and potassium (K) oxides are modifiers of the glassy network. By dilatometry, it was possible to analyze the sensitive behavior of the three ceramics at high temperatures up to 700 °C, finding that zirconia ceramics was least affected and is the most resistant to thermal shock. Conclusion. Both pressed ceramics and zirconium oxide have high aesthetic qualities, but the latter shows a higher mechanical strength and high thermal shock resistance.

The general performance of diffractometers at the first long pulse spallation source ESS, is compared with their counterparts at J-PARC, a short pulse spallation source. The difference in the inherent pulse structure of these neutron sources presents opportunities for new concepts for instrumentation, where performance does not scale simply with source power. The article describes advantages and disadvantages of those diffractometers, adapting to the very different source characteristics. We find that the two sources offer comparable performance in flux and resolution when operating in high-resolution mode. ESS offers significant advantages in tunability and flexibility, notably in the ability to relax resolution in order to increase flux for a given experiment. The slow repetition rate of ESS favors long instruments. On the other hand, J-PARC instruments perform very well in spite of the lower source power and allow better access to epithermal neutrons, of particular interest for PDF analysis of diffraction data. [ABSTRACT FROM AUTHOR]

Neutron crystallography enables direct observation of hydrogen atoms which play crucial roles in the physiological functions of enzymes, including molecular recognition through hydrogen bonding and catalytic reactions involving proton-coupled electron transfer. Now neutron crystallography is a limited method for protein structure determination, but steadily catholicizes with an operation of diffractometers for bio-macromolecules at neutron facilities and accumulated techniques for sample preparation. In this article, we give a commentary on the current status of neutron crystallography for bio-macromolecules in the world, and illustrate our recent results, neutron structural analyses of copper amine oxidase and copper-containing nitrite reductase, which provide in-depth understandings of the enzymatic reaction mechanism. [ABSTRACT FROM AUTHOR]

High-resolution diffractometer is one of the first instruments of the set of 15 priority neutron scattering instruments to be installed at the Brazilian Multipurpose Reactor (RMB). A basic project of this instrument consists of the existence of three guides through which neutrons pass from source to sample to guarantee maximum neutron flux at the sample position. In this study, we investigate guide geometry performance considering fixed diffractometer geometry and spatial arrangement. Comparisons between different guide shapes and supermirrors are performed using software based on the Monte Carlo method, McStas. Our conclusion shows that a better solution is splitting the initial flux into two different guides to obtain the maximum flux at the sample position.

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to be used to evaluate specific aspects of the instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 640f, the seventh generation of this powder diffraction SRM, which is designed to be used primarily for calibrating powder diffractometers with respect to line position; it also can be used for the determination of the instrument profile function. It is certified with respect to the lattice parameter and consists of approximately 7.5 g of silicon powder prepared to minimize line broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the Si powder. Both statistical and systematic uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.5431144 ± 0.000008 nm. [ABSTRACT FROM AUTHOR]

Aim. In response to increased clinical performance of ceramic restorations, the aim of this study is to test, analyze and compare the physical and chemical properties of pressed ceramics and zirconium oxide. Material and method. For this comparative analysis, three ceramic materials were studied, pressed ceramic (IPS E. max Ceram) and zirconium oxide (Ceramill zolid FX and BruxZir) and a dilatometer, the scanning electron microsope and a diffractometer were used for their physico-chemical properties analysis. The morphology of the materials was determined by scanning electron microscopy (SEM images), their elementary composition by X-ray spectroscopy (EDX analysis), the chemical composition by X-XRD diffraction, their behavior at different temperatures by dilatometry. Results and discussions. According to SEM images, the three materials have different morphology, with different phases and it was found that zirconium oxide has the highest mechanical strength, being formed only of the crystalline phase. EDX ANALYSIS identified that silicon dioxide (SiO2) forms of glassy network, and sodium (Na) and potassium (K) oxides are modifiers of the glassy network. By dilatometry, it was possible to analyze the sensitive behavior of the three ceramics at high temperatures up to 700 °C, finding that zirconia ceramics was least affected and is the most resistant to thermal shock. Conclusion. Both pressed ceramics and zirconium oxide have high aesthetic qualities, but the latter shows a higher mechanical strength and high thermal shock resistance. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to evaluate specific aspects of instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 660c, the fourth generation of this powder diffraction SRM, which is used primarily for calibrating powder diffractometers with respect to line position and line shape for the determination of the instrument profile function (IPF). It is certified with respect to lattice parameter and consists of approximately 6 g of lanthanum hexaboride (LaB6) powder. So that this SRM would be applicable for the neutron diffraction community, the powder was prepared from an isotopically enriched 11B precursor material. The microstructure of the LaB6 powder was engineered specifically to yield a crystallite size above that where size broadening is typically observed and to minimize the crystallographic defects that lead to strain broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the LaB6 powder. Both Type A, statistical, and Type B, systematic, uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.415 682 6 ± 0.000 008 nm (95% confidence). [ABSTRACT FROM AUTHOR]

The Neogene sediments were interpreted to understand the clay mineral paragenesis in rocks using x-ray differaction technique. The process was conducted with an x-ray diffractometer, Anode = Cu (Cu Kᾳ = 1.541871 A� ), Filter = Ni, Current = 15 mA and Voltage = 35 kv. The clay mineral assemblages in the rocks indicates that the neogene sediments were derived from the preexisting sedimentary, metasedimentary, metamorphics and igneous rocks and formed in different climes in the continental environment. The illite crystallinity (IC) value (0.2165 Δ°2θ CuKα) in the area correspond exactly with the epizonal metamorphic conditions.

High energy resolution silicon semiconductor detectors are developed and used in RADIAN X-ray diffractometers. The use of these detectors reduces the requirements for monochromators and β-filters, simplifies the optical scheme of a diffractometer, increases the peak-to-background ratio, and decreases the radiation source power and sizes of a diffractometer. To select useful events, a tunable differential discriminator with a reconfigurable energy window is used in the detector. The detector can operate with different X-ray tube anode materials. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1879b, the third generation of this powder diffraction SRM. SRM 1879b is intended for use in the preparation of calibration standards for the quantitative analyses of cristobalite by X-ray powder diffraction in accordance with National Institute for Occupational Safety and Health (NIOSH) Analytical Method 7500, or equivalent. A unit of SRM 1879b consists of approximately 5 g of cristobalite powder bottled in an argon atmosphere. It is certified with respect to crystalline phase purity, or amorphous phase content, and lattice parameter. Neutron powder diffraction, both time-of-flight and constant wavelength, was used to certify the phase purity using SRM 676a as an internal standard. A NIST-built diffractometer, incorporating many advanced design features was used for certification measurements for lattice parameters. [ABSTRACT FROM AUTHOR]

Herein, we describe the development of a novel dual air-bearing fixed-X diffractometer for beamline I19 at Diamond Light Source. The diffractometer is designed to facilitate the rapid data collections possible with a Dectris Pilatus 2M pixel-array photon-counting detector, while allowing remote operation in conjunction with a robotic sample changer. The sphere-of-confusion is made as small as practicably possible, through the use of air-bearings for both the ω andφ axes. The design and construction of the new instrument is described in detail and an accompanying paper by Johnson et al. (also in this issue) will provide a user perspective of its operation. [ABSTRACT FROM AUTHOR]

Herein, we describe the development of a novel dual air-bearing fixed-x diffractometer for beamline I19 at Diamond Light Source. The diffractometer is designed to facilitate the rapid data collections possible with a Dectris Pilatus 2M pixel-array photon-counting detector, while allowing remote operation in conjunction with a robotic sample changer. The sphere-of-confusion is made as small as practicably possible, through the use of air-bearings for both the ͎ and ⇎ axes. The design and construction of the new instrument is described in detail and an accompanying paper by Johnson et al. (also in this issue) will provide a user perspective of its operation. [ABSTRACT FROM AUTHOR]

A scalable 16-ch thermal neutron detection system has been developed in the framework of the upgrade of a neutron diffractometer. The detector is based on a ZnS: 6 LiF scintillator with embedded WLS fibers which are read out with SiPMs. In this paper, we present the 16-ch module, the dedicated readout electronics, a direct comparison between the performance of the diffractometer obtained with the current 3 He detector and with the 16-ch detection module, and the channel-to-channel uniformity. [ABSTRACT FROM AUTHOR]

The Bruker AXS SMART BREEZE™ system is a single-crystal X-ray diffractometer designed to collect data from crystals of small organic or inorganic compounds. It is typically equipped with a Molybdenum-anode sealed tube to facilitate data collection from small unit cells. We recently acquired this system, but chose to have it installed with a copper-anode sealed tube with the hope of using it to collect data from larger unit cells such as those found in crystals of proteins or other macromolecules. This is the first and only BREEZE™ system installed by Bruker AXS with a copper-anode to date. Here we show that this system is capable of efficiently collecting quality X-ray diffraction data from crystals of the enzymes lysozyme and xylanase. This capability to collect diffraction data from both macromolecular and small-molecule crystals greatly expands the scope of undergraduate research projects that can be addressed using this instrument. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1878b, the third generation of this powder diffraction SRM. SRM 1878b is intended for use in the preparation of calibration standards for the quantitative analyses of α-quartz by X-ray powder diffraction in accordance to National Institute for Occupational Safety and Health Analytical Method 7500, or equivalent. A unit of SRM 1878b consists of approximately 5 g of α-quartz powder bottled in an argon atmosphere. It is certified with respect to crystalline phase purity, or amorphous phase content, and lattice parameter. Neutron powder diffraction, both time of flight and constant wavelength, was used to certify the phase purity using SRM 676a as an internal standard. A NIST-built diffractometer, incorporating many advanced design features was used for certification measurements for lattice parameters. [ABSTRACT FROM AUTHOR]

A number of measures to increase the quality of data recorded with an improved Balzers Eldigraph KD-G2 gas-phase electron diffractometer are discussed. The beam-stop has been decoupled from the sector enabling us recording the current of the primary beam and scattered electrons during the experiment. Different beam-stops were tested for use in the present setup. Modifications of the nozzle tip of an earlier described medium temperature nozzle are reported. The measures lead to reduced exposure times and reduced amount of sample necessary for complete data collection. [ABSTRACT FROM AUTHOR]

Herein, we describe the development of a novel dual air-bearing fixed-χ diffractometer for beamline I19 at Diamond Light Source. The diffractometer is designed to facilitate the rapid data collections possible with a Dectris Pilatus 2M pixel-array photon-counting detector, while allowing remote operation in conjunction with a robotic sample changer. The sphere-of-confusion is made as small as practicably possible, through the use of air-bearings for both the ω and φ axes. The design and construction of the new instrument is described in detail and an accompanying paper by Johnson et al. (also in this issue) will provide a user perspective of its operation.

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1976b, the third generation of this powder diffraction SRM. SRM 1976b consists of a sintered alumina disc, approximately 25.6 mm in diameter by 2.2 mm in thickness, intended for use in the calibration of X-ray powder diffraction equipment with respect to line position and intensity as a function of 2θ-angle. The sintered form of the SRM eliminates the effect of sample loading procedures on intensity measurements. Certified data include the lattice parameters and relative peak intensity values from 13 lines in the 2θ region between 20° and 145° using CuKα radiation. A NIST-built diffractometer, incorporating many advanced and unique design features was used to make the certification measurements. [ABSTRACT FROM PUBLISHER]

The Parallel Robotics Inspired Goniometer (PRIGo) is a novel compact and high-precision goniometer providing an alternative to (mini-)kappa, traditional three-circle goniometers and Eulerian cradles used for sample reorientation in macromolecular crystallography. Based on a combination of serial and parallel kinematics, PRIGo emulates an arc. It is mounted on an air-bearing stage for rotation around ω and consists of four linear positioners working synchronously to achieve x, y, z translations and χ rotation (0-90°), followed by a ϕ stage (0-360°) for rotation around the sample holder axis. Owing to the use of piezo linear positioners and active correction, PRIGo features spheres of confusion of <1 µm, <7 µm and <10 µm for ω, χ and ϕ, respectively, and is therefore very well suited for micro-crystallography. PRIGo enables optimal strategies for both native and experimental phasing crystallographic data collection. Herein, PRIGo hardware and software, its calibration, as well as applications in macromolecular crystallography are described. [ABSTRACT FROM AUTHOR]

A new diffractometer for microcrystallography has been developed for the three macromolecular crystallography beamlines of the Swiss Light Source. Building upon and critically extending previous developments realised for the highresolution endstations of the two undulator beamlines X06SA and X10SA, as well as the super-bend dipole beamline X06DA, the new diffractometer was designed to the following core design goals. (i) Redesign of the goniometer to a sub-micrometer peak-to-peak cylinder of confusion for the horizontal single axis. Crystal sizes down to at least 5 µm and advanced sample-rastering and scanning modes are supported. In addition, it can accommodate the new multiaxis goniometer PRIGo (Parallel Robotics Inspired Goniometer). (ii) A rapidchange beam-shaping element system with aperture sizes down to a minimum of 10 µm for microcrystallography measurements. (iii) Integration of the on-axis microspectrophotometer MS3 for microscopic sample imaging with 1 µm image resolution. Its multi-mode optical spectroscopy module is always online and supports in situ UV/Vis absorption, fluorescence and Raman spectroscopy. (iv) High stability of the sample environment by a mineral cast support construction and by close containment of the cryo-stream. Further features are the support for in situ crystallization plate screening and a minimal achievable detector distance of 120 mm for the Pilatus 6M, 2M and the macromolecular crystallography group's planned future area detector Eiger 16M. [ABSTRACT FROM AUTHOR]

Tin oxide thin film was synthesized on glass and quartz substrate by sol-gel dip coating process taking tin (II) chloride as precursor and methanol as solvent. XRD study confirmed the tetragonal rutile structure of SnO2. It was concluded that the transmission was higher and grain size was bigger in case of quartz than glass substrate from the study of optical characteristics by UV/VIS Spectrophotometer and SEM micrographs. CO gas sensing property of SnO2 thin film was studied and it was revealed that the sensitivity of SnO2 thin film grown on quartz substrate shows better performance than the film grown on glass substrate under the same conditions. Sensitivity of the film to CO gas was measured at different temperatures and was found to be highly sensitive at 220 °C for glass substrate and 210 °C for quartz substrate, at 50 ppm concentration. The result of change in conductivity of the sensors in presence of CO gas was also reported. [ABSTRACT FROM AUTHOR]

The resonant scattering and diffraction beamline P09 at PETRA III is designed for X-ray experiments requiring small beams, energy tunability, variable polarization and high photon flux. It is highly flexible in terms of beam size and offers full higher harmonic suppression. A state-of-the-art double phase-retarder set-up provides variable linear or circular polarization. A high-precision Psi-diffractometer and a heavy-load diffractometer in horizontal Psi-geometry allow the accommodation of a wide variety of sample environments. A 14 T cryo-magnet is available for scattering experiments in magnetic fields. [ABSTRACT FROM AUTHOR]

Copper sulfide chalcogenide thin films have been successfully deposited on glass substrates using copper II chloride, thiourea, TEA and ammonium hydroxide in a solution bath. Structural and optical characterizations were carried out with the aid of X-ray Diffractometer and Unico-UV-2102PC spectrophotometer respectively. The effects of varying the annealing temperatures on the structural and spectral properties were also investigated. The presence of both chalcocite (Cu1.96S) and digenite (Cu9S5) phases of the copper sulfide thin films with average grain sizes between 12.55nm and 14.22nm were confirmed by XRD analysis. The thermally treated CuxS thin films have very high transmittance, between 85% and 95%, and low reflectance, less than 21% at both the visible and the NIR regions of the electromagnetic spectrum. They have optical band gap energy between 2.1eV and 2.5eV. The refractive index, extinction coefficient, optical conductivity and the dielectric properties were also studied. The analysis show that the thin films could serve as good materials for the fabrication of solar cell and other optical devices. [ABSTRACT FROM AUTHOR]

This paper reviews some of the modelling and experimental techniques recently employed by the authors for the analysis of the macro- and mesoscopic behaviour of polycrystalline aggregates. A joined-up approach is used for assessing the deformation behaviour of polycrystalline materials at the macroscopic and grain levels, based on combining modelling using the crystal plasticity finite element (CPFE) method with experimental characterization by in situ loading and continuous lattice strain measurement by diffraction. The complementarity of the two methodologies is emphasized, as it helps to improve understanding of the physics underlying inelastic deformation, damage mechanisms, and fatigue crack initiation. The proposed approach is part of the attempt to develop a general framework that will enable reliable and accurate determination of the inhomogeneous fields of plastic strain, the regions of localized plasticity, and intergranular residual stresses. Examples are given of microscopically calibrated CPFE simulations being used to match the experimentally observed evolution of lattice stresses and strains in advanced structural alloys of industrial interest. [ABSTRACT FROM AUTHOR]

HANARO is a 30 MW multi-purpose research reactor located at the Korea Atomic Energy Research Institute (KAERI) with a maximum thermal flux of 5.4 × 1014 n/cm2/s. It reached first criticality in 1995. As part of its present cold neutron project, the KAERI selected disk chopper time-of-flight (DC-TOF) spectrometer as one of the day-one instruments. In this report, we present the current design of our DC-TOF. In order to optimize the design parameters of DC-TOF and its guide layout, we made full use of two Monte-Carlo simulation codes, VITESS and McStas. We have also optimized technical parameters using analytical tools, whenever possible. [ABSTRACT FROM AUTHOR]

MC simulations of neutron diffractometer have been performed using the VITESS software package to check the feasibility of the frame multiplication concept and to compare a powder instrument installed on a long pulse target station (LPTS) with an equivalent instrument installed on a decoupled poisoned moderator of a short pulse target station (SPTS) of the same power. The simulations show that frame multiplication can be realised, if five choppers are used to determine the frame. For the same FWHM peak width, the LPTS yields comparable peak intensities for wavelengths of about 1 Å, much higher intensities than the SPTS for long wavelengths, and a quite symmetric peak shape for all wavelengths. Therefore, a combination of high-energy LPTS and pulse shaping choppers can be used instead of a decoupled poisoned moderator of a SPTS to run a TOF powder diffractometer. It is the better choice (than the SPTS solution), because it matches the performance of SPTS in the case most favourable for SPTS: highest resolution offered by the poisoned moderator, has the capability of easily increasing the intensity by its variable resolution and gives superior intensity for longer neutron wavelengths. [ABSTRACT FROM AUTHOR]

The new diffractometer EXED at HMI designed for high resolution and extreme environments (like very high magnetic fields) has been simulated in detail using the software package VITESS. The simulation includes the beam extraction system, beam splitter, kink, chopper system, sample and detector. Many parameters like coatings, kink angle, etc. were varied to improve the instrument. The chopper system was checked and a focussing guide optimized. Finally, powder diffraction patterns of an aluminium sample show that a resolution of Δ d / d - 4 will be feasible at 176° detector angle. The data collection time is estimated on the basis of the simulation results for the flux at sample. [ABSTRACT FROM AUTHOR]

The synthesis, X-ray structure and role of intermolecular interactions have been studied in case of 1,3-diphenyl-urea, owing to its medicinal importance. The compound crystallizes in orthorhombic crystal system space group, Pna21) with unit cell parameters, a = 9.118(3), b = 10.558(2), c = 11.780(3) Å and Z = 4. The structure has been solved by direct methods and refined to a final R-value of 0.0316. The oxygen atom of the carbonyl group is responsible for the existence of two N-H…O intermolecular interactions. [ABSTRACT FROM AUTHOR]

We will report on the current configuration of the X-ray facility of the University of Ferrara recently used to perform reflectivity tests of mosaic crystals and to calibrate the experiment JEM–X aboard Integral. The facility is now located in the technological campus of the University of Ferrara in a new building (named LARIX laboratory= ̳LARge ̳I talian ̳X-ray facility) that includes a tunnel 100 m long with, on the sides, two large experimental rooms. The facility is being improved for determining the optical axis of mosaic crystals in Laue configuration, for calibrating Laue lenses and hard X-ray mirror prototypes. [ABSTRACT FROM AUTHOR]

Abstract: During the past two decades, 1D and 2D semiconductor photon-counting detectors found applications, e.g., in detection of elementary particles and in medicine. More recent is their use for the X-ray diffraction and spectroscopy, where they become highly competitive with other detector types. Practical applications of such 1D detectors, built from up to about a hundred (at laboratory diffractometers) to several hundred (at a synchrotron beamline) of strips of size of the order 0.1×10mm, to diffraction purposes started at the turn of the century. In the present study, selected properties of a laboratory X-ray powder diffractometer equipped with a linear photon-counting detector and a primary-beam Johansson monochromator are described. Aberrations characteristic to Bragg–Brentano instruments equipped with linear detectors are experimentally shown to be weak for 2.1° angular range covered by the detector used in this study. The counting statistics provided by this setting is shown to largely outperform that obtained with the settings equipped with point detectors. Consequently, diffraction peaks are detectable down to the level of 0.1% intensity, permitting for identification of minor impurity phases. Using illustrative examples, it is demonstrated that, with the described instrument, phase analysis of bulk polycrystals and thin polycrystalline layers is facilitated, and that structure refinement of collected data can be successfully performed. [Copyright &y& Elsevier]

Room temperature powder neutron diffractions have been performed to investigate the structure of (AgI) 0.8 -(NaPO 3 ) 0.2 and (AgI) 0.7 -(NaPO 3 ) 0.3 composites consisting of AgI crystalline precipitated in a glassy NaPO 3 network. Unlike (AgI) 0.8 -(NaPO 3 ) 0.2 and most silver-based superionic materials, (AgI) 0.7 -(NaPO 3 ) 0.3 contains Ag 5 IP 2 O 7 instead of βAgI and less γAgI. The diffuse background levels of both composites are similar and largely dominated by NaPO 3 amorphous phase. [ABSTRACT FROM AUTHOR]

We report crystalline phases in the melt-quenched (AgI)0.8–(NaPO3)0.2 and (AgI)0.7–(NaPO3)0.3 superionic composites at room temperature as studied by VEGA powder neutron diffraction of KEK. (AgI)0.8–(NaPO3)0.2 contains γAgI and βAgI with a 70:30 ratio, which is similar to that found in pure AgI. On the other hand, (AgI)0.7–(NaPO3)0.3 contains AgI and Ag5IP2O7 with a 53:47 ratio, without any indication of βAgI presence. Due to the overall broad line widths and the hexagonal-related orthorhombic unit cell of Ag5IP2O7, VEGA was indispensable to probe its existence in (AgI)0.7–(NaPO3)0.3 at room temperature. The disappearance of βAgI in (AgI)0.7–(NaPO3)0.3 in favour of Ag5IP2O7 containing more oxygens indicating that the phosphate chains have been oxidized to P2O7 pairs of phosphate tetrahedra. [Copyright &y& Elsevier]

We will report on the equipment and performance of the X-ray facility of the University of Ferrara. Initially developed to test the PDS (Phoswich Detection System) instrument aboard the BeppoSAX satellite and to perform reflectivity measurements of mosaic crystal samples of HOPG (Highly Oriented Pyrolytic Graphite), with time the facility has been improved and its applications extended. Now these applications include test and calibration of hard X-ray (> 10 keV) detectors, reflectivity measurements of hard X-ray mirrors, reflectivity tests of crystals and X-ray transparency measurements. The facility is being further improved in order to determine the optical axis mosaic crystals in Laue configuration within a project devoted to develop a hard X-ray (> 60 keV) focusing optics (Pisa, A. et al.: in press, Feasibility study of a Laue lens for hard X-rays for space astronomy, SPIE Proc., 5536). [ABSTRACT FROM AUTHOR]

The newly installed, much-improved single-crystal diffractometer, SXD at ISIS, received its first neutrons in May 2001. The detector area now covers slightly more than 2π steradians in solid angle. High-pressure research using single crystals is becoming an increasingly important part of the user programme and thus, efforts are underway to provide a new sample environment as well as state-of-the-art data analysis software to open new opportunities in high-pressure single-crystal diffraction. Recently, a new gas-pressure cell with pressures up to 0.5 GPa has been successfully commissioned. First results from a series of molecular compounds containing short hydrogen bonds are presented. More recent developments at ISIS include a sapphire anvil cell for pressures up to 8 GPa, which has been successfully tested on the GEM powder diffractometer. It will shortly also be tested on SXD, as well as a modified Paris-Edinburgh cell to take 5-15 mm 3 single-crystal samples to pressures of more than 10 GPa. [ABSTRACT FROM AUTHOR]

The characteristics of a neutron diffractometer using a 3He one-dimensional position-sensitive detector (PSD) with delay line readout, a 200 (length) × 100 (height) mm2 active window and 2.5 mm spatial resolution have been studied and compared with those of the High-Resolution Powder Diffractometer (HRPD) of KAERI with 32 3He conventional tube (∅50 mm) detectors and Soller collimators (10′) before detectors. For the sample to PSD distance R=1200 mm, the PSD subtends 8° angle of 2θ and provides the resolution and the peak-to-background ratio close to that for HRPD. Time for scanning (with the same statistics) of a 0–160° interval is about 1.6 times longer and the multi-PSD system providing efficiency about 10 times higher than HRPD is proposed. Because of the small angle subtended by the PSD, the parasitic peaks from the sample environment are eliminated and operation without an oscillating radial collimator is possible. Additionally, the proposed diffractometer has an advantage for small samples. [Copyright &y& Elsevier]

Energy-dispersive powder diffraction (EDPD) has now been in routine use for over thirty years. During that time it has been applied to a wide range of academic and industrial problems. The advent of image plate and charged coupled device (CCD) area detectors has enabled the use of monochromatic radiation for many of the applications traditionally reserved for EDPD. Here the basic principles and major applications of EDPD are reviewed, the impact of image plate and CCD detectors is assessed and the possible future roles for EDPD is explored. [ABSTRACT FROM AUTHOR]

An automated, high-sensitivity Mössbauer powder diffractometer is described, and its performance demonstrated with a bcc 57Fe foil sample. Useful diffraction patterns are acquired in about 10 hours. The incoherent and coherent parts of the scattering are readily identified. Both are affected by thickness distortion, but the incoherent part is affected more strongly. [ABSTRACT FROM AUTHOR]

Abstract: Monte Carlo simulations may be used to model radiation shielding for neutron diffractometers. The use of the MCNP computer program to assess shielding for a diffractometer is discussed. A comparison is made of shielding requirements for radiation generated by several materials commonly used in neutron optical elements and beam stops, including lithium-6 based absorbers where the Monte Carlo method can model the effects of fast neutrons generated by this material. [Copyright &y& Elsevier]

Abstract: The new single crystal diffractometer RESI (REciprocal Space Investigator) at FRM-II has successfully passed the commissioning phase. With its unique setup of a kappa goniometer and a neutron sensitive imaging plate, it is very well suited for structure determination and the exploration of disorder phenomena. We will present first results from measurements on the new quasicrystalline phase of AlCoCu, showing the suitability of the instrument for fast collection of both Bragg and diffuse scattering data. [Copyright &y& Elsevier]

Abstract: In 1998, a prototype of a time-of-flight (TOF) powder diffractometer was built at KFKI in Budapest in collaboration with the Hahn-Meitner-Institut (HMI) in Berlin. At a reactor source the neutron pulses are produced by a chopper system, which allows for shorter pulses than those obtained at pulsed spallation sources in the wavelength range most relevant for diffraction work, i.e. λ⩾0.7Å. Furthermore, the chopper system provides an ideal symmetric line shape. First results proved the high potential of the approach, namely an excellent resolution of 1–5×10−3 for Δd/d was achieved. The prototype is presently rebuilt as a user instrument at the Budapest Neutron Centre. At HMI Berlin a new much more complex TOF powder diffractometer (EXED=extreme environment diffractometer) with higher resolution is under construction. It will benefit from variable resolution to achieve either ultrahigh resolution or very high intensities at conventional resolutions. EXED is devoted to studies under extreme sample conditions, for instance the TOF technique permits the access of a broad range of Q-values or d-spacing domains under scattering angle access strongly restricted by the use of highest field magnets. The whole instrument was simulated by Monte Carlo (MC) technique, and the simulations yield promising results. [Copyright &y& Elsevier]

Abstract: A high-intensity powder diffractometer (HIPD) with 8 position-sensitive detectors (PSD) separated with radial shielding walls is currently under construction at the HANARO reactor, Korea. Since the space at beam port ST-3 is limited the take-off angle 2θ M=90° and a comparatively short sample-to-detector distance of 1000mm were chosen. Experiments with mosaic Ge and bent perfect Si monochromators were carried out to determine optimal design characteristics for such a compact multi-PSD powder diffractometer with medium resolution of Δd/d≈3.5×10−3. The construction of HIPD is in final stage and commissioning of HIPD is scheduled to be in early 2006. [Copyright &y& Elsevier]