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Monochromator
Kinds of Monochromator Selected AbstractsA comparison of a microfocus X-ray source and a conventional sealed tube for crystal structure determinationJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2009Thomas Schulz Experiments are described in which a direct comparison was made between a conventional 2,kW water-cooled sealed-tube X-ray source and a 30,W air-cooled microfocus source with focusing multilayer optics, using the same goniometer, detector, radiation (Mo,K,), crystals and software. The beam characteristics of the two sources were analyzed and the quality of the resulting data sets compared. The Incoatec Microfocus Source (IµS) gave a narrow approximately Gaussian-shaped primary beam profile, whereas the Bruker AXS sealed-tube source, equipped with a graphite monochromator and a monocapillary collimator, had a broader beam with an approximate intensity plateau. Both sources were mounted on the same Bruker D8 goniometer with a SMART APEX II CCD detector and Bruker Kryoflex low-temperature device. Switching between sources simply required changing the software zero setting of the 2, circle and could be performed in a few minutes, so it was possible to use the same crystal for both sources without changing its temperature or orientation. A representative cross section of compounds (organic, organometallic and salt) with and without heavy atoms was investigated. For each compound, two data sets, one from a small and one from a large crystal, were collected using each source. In another experiment, the data quality was compared for crystals of the same compound that had been chosen so that they had dimensions similar to the width of the beam. The data were processed and the structures refined using standard Bruker and SHELX software. The experiments show that the IµS gives superior data for small crystals whereas the diffracted intensities were comparable for the large crystals. Appropriate scaling is particularly important for the IµS data. [source] Using the general equation of a conic for the calculation of the instrument function of a Bragg,Brentano diffractometerJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2008A. D. Zuev The general equation of the conic representing the intersection of the receiving-slit plane with the diffraction cone as well as with the reflection cone of a plane crystal monochromator are given for a diffractometer in Bragg,Brentano geometry. Apart from the fact that this equation can be easily used to calculate the total instrument function as well as specific instrument functions for diffractometers in Bragg,Brentano geometry, it also provides tools for elucidating different aberrations of the diffractometer in Bragg,Brentano geometry. [source] The new very-small-angle neutron scattering spectrometer at Laboratoire Léon BrillouinJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007S. Désert The design and characteristics of the new very-small-angle neutron scattering spectrometer under construction at the Laboratoire Léon Brillouin are described. Its goal is to extend the range of scattering-vector magnitudes towards 2 × 10,4,Å,1. The unique feature of this new spectrometer is a high-resolution two-dimensional image-plate detector sensitive to neutrons. The wavelength selection is achieved by a double-reflection supermirror monochromator and the collimator uses a novel multibeam design. [source] Calculation of the instrumental function in X-ray powder diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2006A. D. Zuev A new method for calculating the total instrumental function of a conventional Bragg,Brentano diffractometer has been developed. The method is based on an exact analytical solution, derived from diffraction optics, for the contribution of each incident ray to the intensity registered by a detector of limited size. Because an incident ray is determined by two points (one is related to the source of the X-rays and the other to the sample) the effects of the coupling of specific instrumental functions, for example, equatorial and axial divergence instrumental functions, are treated together automatically. The intensity at any arbitrary point of the total instrumental profile is calculated by integrating the intensities over two simple rectangular regions: possible point positions on the source and possible point positions on the sample. The effects of Soller slits, a monochromator and sample absorption can also be taken into account. The main difference between the proposed method and the convolutive approach (in which the line profile is synthesized by convolving the specific instrumental functions) lies in the fact that the former provides an exact solution for the total instrumental function (exact solutions for specific instrumental functions can be obtained as special cases), whereas the latter is based on the approximations for the specific instrumental functions, and their coupling effects after the convolution are unknown. Unlike the ray-tracing method, in the proposed method the diffracted rays contributing to the registered intensity are considered as combined (part of the diffracted cone) and, correspondingly, the contribution to the instrumental line profile is obtained analytically for this part of the diffracted cone and not for a diffracted unit ray as in ray-tracing simulations. [source] Cold pressing of copper single crystals for a large-area doubly focusing monochromatorJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2004D. F. R. Mildner The design for a large-area doubly focusing neutron monochromator consists of a large number of small square copper single crystals mounted onto thin aluminium blades that both buckle and rotate independently. This avoids the need for large individual alignment mechanisms for each crystal that introduce unacceptably high levels of background. However, it does require that the crystals be oriented such that the diffracting crystallographic planes are parallel to the crystal face. Cold pressing broadens the natural narrow mosaic of the virgin crystal discs to increase the diffracted intensity. This introduces anisotropy into the crystal that determines its orientation in the final monochromator. The alignment procedure used for each crystal before cutting out the square tile in the correct orientation is described. A few crystals are characterized in detail by neutron diffraction at various stages of the operation, revealing the variation in the mosaic width and the angular position of the reciprocal-lattice vector as a function of the azimuthal angle by rotating the crystal about the normal to its face. The twofold symmetry of the mosaic width of the pressed crystal is modulated by the 2, periodicity introduced by the precession of the reciprocal-lattice vector around the crystal face normal. Satisfactorily aligned crystals have a variation in the angular position for diffraction within the allowed tolerance. [source] Hot pressing of germanium monochromator crystalsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2004S. F. Treviño The method and parameters for vacuum hot pressing of single-crystal germanium, suitable for a large-area double-focusing neutron monochromator, are presented. The square virgin crystals have a mosaic that is less than 0.01° and isotropic. After appropriate pressing at high temperature (1073,K at a pressure of 10.7,MPa) the mosaic becomes anisotropic, about 0.5° in one direction and 0.2° in the other. The distribution of the mosaic widths of the crystals in the two directions are given, together with their composite values. [source] Scan profiles for neutron spectrometers.JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2003The recent development of neutron collimators with rectangular transmission profiles (intensity versus angular divergence) extends hope of improved count rates on neutron scattering instruments. It is usually assumed that a more effective use of beam angular spread in these devices should increase count rates by about a factor of two. However, real beams have both angular and wavevector spread and both these spreads are governed by the allowed collimation. In this extended view, the gains from ideal rectangular-profile elements (angle filters) are shown to be much larger (about a factor of four). The mirror reflections used to achieve the rectangular profiles in real devices complicate the resolution effects. Specifically, the reflections disturb the wavevector,angular divergence correlation in the beams, leading to unusual peak shapes characterized by triple peaks on powder diffractometers. Thus, these reflecting collimators are likely to be universally useful only before the monochromator and immediately preceding the detector, where wavevector,angle correlations have no effect. This reduces the potential gains to a factor of two or so. Note that the gains are as previously expected but for quite different reasons than imagined. This remains a very significant gain in a field where most work is intensity-limited. [source] Scan profiles for neutron spectrometers.JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2003Newly developed reflecting neutron collimators promise increased detector count rates in a field where most work is intensity-limited. The effects of such elements on instrument resolution are complicated and appear to be even more subtle than previously imagined. Numerical tests using the McSTAS ray-tracing program (http://neutron.risoe.dk/mcstas) are reported which support and extend the recent analysis of these effects. If reflecting collimators are used in all instrument positions they give unusual scan profiles. Using reflecting collimators only before the monochromator and immediately before the detector has no deleterious resolution effects and increases count rates by a factor of more than two on powder diffractometers. [source] A high sensitivity pinhole camera for soft condensed matterJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Thomas Zemb A significant improvement in the sensitivity of a Huxley-Holmes design for a small angle X-ray scattering camera is obtained by separating the mirror and the monochromator. The "separated optics" camera described in this paper involves a long X-ray mirror close to a point X-ray source associated with a curved focusing crystal located close to the sample. The sample area is located at half the distance between the source and detector planes. Diffuse scattering produced by the mirror is not incident on the focusing crystal, thus reducing the background signal. Complete elimination of hard X-rays allows precise calibration and hence absolute determination of sample cross-section by means of a semi-transparent beam-stop. In pinhole geometry, the flux corresponds to a ca. 107 photons/s through the sample, collimated to q=10 -2 Å -1 in scattering vector range. This allows determination of scattered intensities of the order of 10 -3 cm -1, corresponding to the scattering related to isothermal compressibility of less than 0.1 mm of pure water. Values of absolute intensities for water as well as convenient widespread buffer solutions are shown, in order to be usable for calibration as secondary standards. As solid reference sample, the widely studied Lupolentm, a semi-crystalline polymer- is calibrated. The high- q limit (q, 4.5 nm,1 ) of a porous calcite sample can be used as a secondary standard for specific area determination of solid/solid or solid-liquid dispersions. [source] Deconvolution of instrumental aberrations for synchrotron powder X-ray diffractometryJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2003T. Ida A method to remove the effects of instrumental aberrations from the whole powder diffraction pattern measured with a high-resolution synchrotron powder diffractometer is presented. Two types of asymmetry in the peak profiles caused by (i) the axial-divergence aberration of the diffractometer (diffractometer aberration) and (ii) the aberration of the monochromator and focusing optics on the beamline (beamline aberration) are both taken into account. The method is based on the whole-pattern deconvolution by Fourier technique combined with the abscissa-scale transformation appropriate for each instrumental aberration. The experimental powder diffraction data of LaB6 (NIST SRM660) measured on beamline BL-4B2 at the Photon Factory in Tsukuba have been analysed by the method. The formula of the scale transformation for the diffractometer aberration has a priori been derived from the instrumental function with geometric parameters of the optics. The strongly deformed experimental peak profiles at low diffraction angles have been transformed to sharp peak profiles with less asymmetry by the deconvolution of the diffractometer aberration. The peak profiles obtained by the deconvolution of the diffractometer aberration were modelled by an asymmetric model profile function synthesized by the convolution of the extended pseudo-Voigt function and an asymmetric component function with an empirical asymmetry parameter, which were linearly dependent on the diffraction angle. Fairly symmetric peak profiles have been obtained by further deconvolution of the empirically determined asymmetric component of the beamline aberration. [source] A novel lattice-spacing comparator with resolution of 10,8JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2003Xiaowei Zhang A novel, fast and stable system for measuring the lattice spacing of a silicon crystal with a precision of 10,8 is described. Self selection of monochromatic X-rays by a monolithic double channel-cut crystal monochromator (MDCM), producing silicon 264 and 624 diffraction, may lead to a stable, highly collimated and narrow-bandwidth beam. When utilizing the 264 and 624 Bragg reflections of a silicon sample, the angular distance between the two associated Bragg peaks must be extremely small, so that the diffraction angle can be determined with high precision and the traveling time from one peak to the other can be considerably reduced by the order of at least three compared with the established classical Bond method. This so-called self-reference comparator method can dramatically save measurement time and can provide an absolute measurement on the basis of the known X-ray wavelength available from the MDCM. Thus a lattice-spacing measurement with resolution of 10,8, within a few tens of seconds for an area of 1,mm2 on a silicon sample, has been realised. [source] Instrument line-profile synthesis in high-resolution synchrotron powder diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2003O. Masson An accurate method for synthesizing the instrumental line profile of high-resolution synchrotron powder diffraction instruments is presented. It is shown that the instrumental profile can be modelled by the convolution of four physical aberration functions: the equatorial intensity distribution, the monochromator and analyser transfer functions, and the axial divergence aberration function. Moreover, each equatorial aberration is related to an angle-independent function by a scale transform factor. The principles of the instrument line-profile calculation are general. They are applied in the case of the angle-dispersive powder X-ray diffraction beamline BM16 at the ESRF. The effects of each optical element on the overall instrument profile are discussed and the importance of the quality of the different optical elements of the instrument is emphasized. Finally, it is shown that the high resolution combined with the precise modelling of the instrument profile shape give access to a particle size as large as 3,µm. [source] A high-resolution X-ray diffractometer for the study of imperfect materialsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2002A. Boulle A high-resolution X-ray diffractometer devoted to the study of imperfect materials (mainly oxides and ceramics) is presented. It is based on a rotating anode generator, a four-bounce monochromator, a five-movement sample holder and a curved position-sensitive detector (PSD). This setup allows rapid acquisition of a reciprocal-space map (in less than 10,h) even for very poorly diffracting materials. The two-dimensional instrumental profile is calculated taking into account each optical element in the beam path. The one-dimensional instrumental profiles corresponding to widely used scans (, scan, ,,2, scan, rocking curve and powder scan) are also calculated. In the three former cases, the setup exhibits an excellent angular resolution (0.003°), whereas in the latter case the resolution is lowered by one order of magnitude at the benefit of a strong increase in the collected intensity. The possibilities of this diffractometer are illustrated with three examples: an epitaxic layer, a microstructured single crystal and a powder. [source] Performance of a confocal multilayer X-ray opticJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2002J. Kusz In recent years, several companies have developed the technique of arranging two multilayer mirrors in confocal optics for monochromatizing X-rays. In this study, a focusing device of Osmic Inc., with a source-to-focus distance of 1005,mm, has been used. The goal was to measure the homogeneity of the beam, the cross section at various distances from the focus and the efficiency of the optic when it is operated with vacuum and with air in the beam path. A small crystal sphere set at various distances is used to compare the intensities and the widths of reflections with those of a flat graphite monochromator. In a standard diffraction experiment (crystal size 0.25,mm), the gain factor with respect to graphite is roughly ten at a position where the beam plateau is 0.5,mm. The suppression of the Cu K, radiation and of higher harmonics of K, is very good. [source] A new single grating spectrograph for ultraviolet Raman scattering studiesJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2006Lutz Hecht Abstract A state-of-the-art single grating spectrograph for Raman scattering studies within the deep ultraviolet (DUV) region of the electromagnetic spectrum is discussed. It is based on a high throughput DUV version of a single-stage monochromator originally designed for use in the visible spectral region. Its key components are two identical, newly designed calcium fluoride camera lenses each consisting of five different individual optical elements. The first of these lenses collimates the Raman scattered DUV radiation entering the spectrometer through its entrance slit. The second lens focuses the collimated beam of dispersed Raman scattered DUV radiation emerging from a high-resolution reflection grating onto a charge coupled device (CCD) detector with enhanced DUV sensitivity. A novel high transmission edge filter is used as a blocking device for a sufficient rejection of the Rayleigh line generating a relatively sharp transmittance cutoff at a Stokes Raman wavenumber shift of about ,450 cm,1 employing 257 nm DUV excitation. Overall, this new spectrograph enables rapid collection of Stokes DUV Raman scattered photons at f/2 wide apertures with sufficiently large signal-to-noise ratios (SNRs) in relatively short acquisition times and with an effective spectral resolution of approximately ,6 cm,1. Backscattered Raman spectra of the following chemicals are presented as typical results illustrating the excellent performance characteristics of this new DUV spectrograph for a variety of experimental conditions within different scattering scenarios and for a relatively wide range of commonly used sample preparation techniques: neat cyclohexane, laboratory air, polycrystalline D -glucose, single crystal L -alanine and a dilute aqueous solution of 2,-deoxyadenosine. Copyright © 2005 John Wiley & Sons, Ltd. [source] Coherence and wavefront characterization of Si-111 monochromators using double-grating interferometryJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2010Ana Diaz A study of the coherence and wavefront properties of a pseudo-channel-cut monochromator in comparison with a double-crystal monochromator is presented. Using a double-grating interferometer designed for the hard X-ray regime, the complex coherence factor was measured and the wavefront distortions at the sample position were analyzed. A transverse coherence length was found in the vertical direction that was a factor of two larger for the channel-cut monochromator owing to its higher mechanical stability. The wavefront distortions after different optical elements in the beam, such as monochromators and mirrors, were also quantified. This work is particularly relevant for coherent diffraction imaging experiments with synchrotron sources. [source] The ID23-2 structural biology microfocus beamline at the ESRFJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2010David Flot The first phase of the ESRF beamline ID23 to be constructed was ID23-1, a tunable MAD-capable beamline which opened to users in early 2004. The second phase of the beamline to be constructed is ID23-2, a monochromatic microfocus beamline dedicated to macromolecular crystallography experiments. Beamline ID23-2 makes use of well characterized optical elements: a single-bounce silicon (111) monochromator and two mirrors in Kirkpatrick,Baez geometry to focus the X-ray beam. A major design goal of the ID23-2 beamline is to provide a reliable, easy-to-use and routine microfocus beam. ID23-2 started operation in November 2005, as the first beamline dedicated to microfocus macromolecular crystallography. The beamline has taken the standard automated ESRF macromolecular crystallography environment (both hardware and software), allowing users of ID23-2 to be rapidly familiar with the microfocus environment. This paper describes the beamline design, the special considerations taken into account given the microfocus beam, and summarizes the results of the first years of the beamline operation. [source] Polycapillary-optics-based micro-XANES and micro-EXAFS at a third-generation bending-magnet beamlineJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2009Geert Silversmit A focusing system based on a polycapillary half-lens optic has been successfully tested for transmission and fluorescence µ-X-ray absorption spectroscopy at a third-generation bending-magnet beamline equipped with a non-fixed-exit Si(111) monochromator. The vertical positional variations of the X-ray beam owing to the use of a non-fixed-exit monochromator were shown to pose only a limited problem by using the polycapillary optic. The expected height variation for an EXAFS scan around the Fe K -edge is approximately 200,µm on the lens input side and this was reduced to ,1,µm for the focused beam. Beam sizes (FWHM) of 12,16,µm, transmission efficiencies of 25,45% and intensity gain factors, compared with the non-focused beam, of about 2000 were obtained in the 7,14,keV energy range for an incoming beam of 0.5 × 2,mm (vertical × horizontal). As a practical application, an As K -edge µ-XANES study of cucumber root and hypocotyl was performed to determine the As oxidation state in the different plant parts and to identify a possible metabolic conversion by the plant. [source] A dedicated small-angle X-ray scattering beamline with a superconducting wiggler source at the NSRRCJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2009Din-Goa Liu At the National Synchrotron Radiation Research Center (NSRRC), which operates a 1.5,GeV storage ring, a dedicated small-angle X-ray scattering (SAXS) beamline has been installed with an in-achromat superconducting wiggler insertion device of peak magnetic field 3.1,T. The vertical beam divergence from the X-ray source is reduced significantly by a collimating mirror. Subsequently the beam is selectively monochromated by a double Si(111) crystal monochromator with high energy resolution (,E/E, 2 × 10,4) in the energy range 5,23,keV, or by a double Mo/B4C multilayer monochromator for 10,30 times higher flux (,1011,photons,s,1) in the 6,15,keV range. These two monochromators are incorporated into one rotating cradle for fast exchange. The monochromated beam is focused by a toroidal mirror with 1:1 focusing for a small beam divergence and a beam size of ,0.9,mm × 0.3 mm (horizontal × vertical) at the focus point located 26.5,m from the radiation source. A plane mirror installed after the toroidal mirror is selectively used to deflect the beam downwards for grazing-incidence SAXS (GISAXS) from liquid surfaces. Two online beam-position monitors separated by 8,m provide an efficient feedback control for an overall beam-position stability in the 10,µm range. The beam features measured, including the flux density, energy resolution, size and divergence, are consistent with those calculated using the ray-tracing program SHADOW. With the deflectable beam of relatively high energy resolution and high flux, the new beamline meets the requirements for a wide range of SAXS applications, including anomalous SAXS for multiphase nanoparticles (e.g. semiconductor core-shell quantum dots) and GISAXS from liquid surfaces. [source] Internally cooled V-shape inclined monochromatorJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2008P. Oberta A simple variant of a Si internally cooled inclined X-ray monochromator of reasonable size is proposed. It has two inclined surfaces oriented into a V shape. This design substantially decreases the surface deformations introduced by radiation heat, and the size of the crystal is still feasible for a 50,mm broad impinging bending magnet or wiggler beam. The possibility of sagittal focusing of the diffracted beam is also discussed. [source] Design and performance of an ultra-high-vacuum-compatible artificial channel-cut monochromatorJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2008Suresh Narayanan The design and performance of a novel ultra-high-vacuum-compatible artificial channel-cut monochromator that has been commissioned at undulator beamline 8-ID-I at the Advanced Photon Source are presented. Details of the mechanical and optical design, control system implementation and performance of the new device are given. The monochromator was designed to meet the challenging stability and optical requirements of the X-ray photon correlation spectroscopy program hosted at this beamline. In particular, the device incorporates a novel in-vacuum sine-bar drive mechanism for the combined pitch motion of the two crystals and a flexure-based high-stiffness weak-link mechanism for fine-tuning the pitch and roll of the second crystal relative to the first crystal. The monochromator delivers an exceptionally uniform and stable beam and thereby improved brilliance preservation. [source] A sagittally focusing double-multilayer monochromator for ultrafast X-ray imaging applicationsJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2007Jinyuan Liu The development of a sagittally focusing double-multilayer monochromator is reported, which produces a spatially extended wide-bandpass X-ray beam from an intense synchrotron bending-magnet source at the Advanced Photon Source, for ultrafast X-ray radiography and tomography applications. This monochromator consists of two W/B4C multilayers with a 25,Å period coated on Si single-crystal substrates. The second multilayer is mounted on a sagittally focusing bender, which can dynamically change the bending radius of the multilayer in order to condense and focus the beam to various points along the beamline. With this new apparatus, it becomes possible to adjust the X-ray beam size to best match the area detector size and the object size to facilitate more efficient data collection using ultrafast X-ray radiography and tomography. [source] Performance of the atomic and molecular physics beamline at the National Synchrotron Radiation LaboratoryJOURNAL OF SYNCHROTRON RADIATION, Issue 6 2006Sisheng Wang At the National Synchrotron Radiation Laboratory, The University of Science and Technology of China, an atomic and molecular physics beamline with an energy range of 7.5,124,eV has been constructed for studying the spectroscopy and dynamics of atoms, molecules and clusters. The undulator-based beamline, with a high-resolution spherical-grating monochromator (SGM), is connected to the atomic and molecular physics end-station. This end-station includes a main experimental chamber for photoionization studies and an additional multi-stage photoionization chamber for photoabsorption spectroscopy. A mid-photon flux of 5 × 1012,photons,s,1 and a high resolving power is provided by this SGM beamline in the energy range 7.5,124,eV. The size of the synchrotron radiation beam spot at the sample is about 0.5,mm in the vertical direction and 1.0,mm in the horizontal direction. Some experimental results of photoionization efficiency spectroscopy and photoabsorption spectroscopy of atoms and molecules are also reported. [source] XAFS experiments at beamline I811, MAX-lab synchrotron source, SwedenJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2006Stefan Carlson A description of a new facility for X-ray absorption spectroscopy at the materials science beamline, I811, at MAX-lab synchrotron source, Lund, Sweden, is given. The beamline is based on a superconducting multipole wiggler source inserted in a straight section of the 1.5,GeV MAX-II ring. X-rays in the energy range 2.4,12,keV are extracted by a standard optical scheme consisting of a vertical collimating first mirror, double-crystal monochromator, and a second vertically focusing mirror. The second monochromator crystal provides sagittal focusing. The total flux impinging on the sample at 9,keV is 5 × 1011,photons,s,1, for a minimum beam spot of 0.5,mm × 0.5,mm. The beamline has facilities for experiments in transmission, fluorescence and total-electron-yield mode and experiments have been performed by international research groups on a wide range of materials, such as dilute systems with metal concentrations below 10,p.p.m. [source] The ID23-1 structural biology beamline at the ESRFJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2006Didier Nurizzo The demand for access to macromolecular crystallography synchrotron beam time continues to increase. To meet this demand the ESRF has constructed a dual station beamline using a canted undulator system as the X-ray source. The first phase of the beamline to be constructed is ID23-1, a tunable MAD-capable station with a mini-focus X-ray beam. The beamline makes use of well characterized optical elements: a channel-cut monochromator with a high-precision toroidal mirror to focus the X-ray beam. The beamline has been conceived with the aim of providing high levels of automation to create an industrial-like environment for protein crystallography. A new software suite has been developed to permit reliable easy operation for the beamline users and beamline staff. High levels of diagnostics are built in to allow rapid trouble-shooting. These developments are now being exported to the ESRF macromolecular crystallography beamline complex and have been made in a modular fashion to facilitate transportability to other synchrotrons. [source] Suite of three protein crystallography beamlines with single superconducting bend magnet as the sourceJOURNAL OF SYNCHROTRON RADIATION, Issue 6 2004Alastair A. MacDowell At the Advanced Light Source, three protein crystallography beamlines have been built that use as a source one of the three 6,T single-pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single-pole superconducting bend magnets enables the development of a hard X-ray program on a relatively low-energy 1.9,GeV ring without taking up insertion-device straight sections. The source is of relatively low power but, owing to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double-crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described. [source] Performance of a cryogenic silicon monochromator under extreme heat loadJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2004Aleksandr Chumakov The performance of an indirectly cooled cryogenic silicon monochromator under heat loads up to 870,W has been studied. The investigation was performed over numerous parameters and included measurements of total flux, spectral density, rocking curves, angular beam profiles and crystal slope errors. An almost ideal monochromator performance was observed in the 270,570,W range of the heating power. At a heat load of ,400,W and under standard operation conditions, the crystal distortions did not exceed 1,µrad. At the highest available heat load of 870,W, the crystal distortions were about 7,µrad. [source] X-ray diffraction topography using a diffractometer with a bendable monochromator at a synchrotron radiation sourceJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2002D. Altin The different properties of laboratory- and synchrotron-based double-crystal setups for X-ray topographic applications are discussed as a basis for the realization of a versatile instrument allowing the investigation of all kinds of crystals with high strain sensitivity and without any reduction in image size. It appears that the use of a bendable highly perfect monochromator (silicon) achieves this goal, through the local adaptation of Bragg angles, to compensate either dispersion or a bending of the sample. [source] A compact optical design for Bragg reflections near backscatteringJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2001Alfred Q. R. Baron A very compact in-line X-ray optical design is presented which is optimized for use with Bragg reflections close to backscattering (Bragg angles near 90°). The essential idea is to use a low-order Bragg reflection to couple the X-ray beam into a small channel-cut backscattering crystal. The design is demonstrated in an almost theoretically performing high-resolution monochromator providing 2 × 108 photons,s,1 in a 0.52,meV bandwidth at 25.65,keV. The monochromator is used to measure inelastic nuclear scattering from phonons in 161Dy-containing samples. [source] Calcium L -edge XANES study of some calcium compoundsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001S. J. Naftel The Ca L3,2 -edge XANES spectra of six calcium salts have been measured in both total electron and fluorescence yields using a high-resolution spherical grating monochromator. The compounds investigated were; CaF2, CaCO3, CaCl2,2H2O, calcium phosphate, calcium glycerophosphate and calcium gluconate. We find that the fine structure of the Ca L3,2 -edges for each compound is unique and relates to the local structure of the Ca atom. The implications of these results to the study of the structure of calcium binding sites in systems of biologically interest will be discussed. [source] | |||||||||||||