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  • 1
    Electronic Resource
    Electronic Resource
    Direct observation of TDS profiles from perfect silicon single crystals on a neutron diffractometer (1981)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 863-871 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: TDS profiles convoluted with the instrument resolution were obtained by forming differences between diffraction profiles measured with neutrons of wavelength 0.60 Å on three perfect Si crystals of different thickness. The profiles were measured with two detector apertures for the reflections 022, 004, 044, 026, 008 and 066. From these measurements TDS correction factors α and hence a correction term ΔB for the temperature parameter of Si were derived. The temperature parameter of Si was determined for two temperatures, 92 and 292 K, as B92 = 0.212 (3) Å2 and B292 = 0.422 (3) Å2, respectively, from the refinement of 100 symmetry-inequivalent reflections measured with neutrons of wavelength 0.53 Å on an imperfect Si crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739481001885
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  • 2
    Electronic Resource
    Electronic Resource
    Pendellösung suppression in the diffraction pattern of a set of thin perfect crystals in a Bonse–Hart camera : Proceedings of the 5th international conference on synchrotron radiation instrumentation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2206-2209 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In a Bonse–Hart camera, a set of two or more grooved (channel cut) perfect crystals are used to provide a very high angular resolution experiment. The resulting multireflection profiles can be calculated in a first approximation by the dynamical theory of diffraction, where usually only coherent scattering is considered. In addition, there is experimental evidence of incoherent Compton scattering (ICS) and thermal diffuse scattering (TDS) contributions. Such contributions are especially important when performing small angle scattering experiments where intensities in an interval of ten orders of magnitude are often recorded. We propose and analyze here the use of thin (a few micrometers) crystals for a Bonse–Hart camera in order to decrease the TDS and ICS components, thus to increase the performances of the device. However, using thin crystals causes the occurrence of interference (Pendellösung) fringes which degrades the instrument resolution. We study in this paper the possible elimination of Pendellösung fringes by angularly offsetting one or more crystals with respect to the others. Optimizing the offset value, the Pendellösung oscillations of the crystals interfere destructively, then significantly reducing their contribution to the total resolution function. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145707
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  • 3
    Electronic Resource
    Electronic Resource
    The Optics Laboratory of the ESRF (abstract) : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 450-450 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In parallel to the design and construction of new synchrotron radiation sources quite important efforts are required to upgrade existing and develop new x-ray optics that is capable of conditioning powerful x-ray beams with minimum losses of brilliance. In the context of these research and development activities a well equipped laboratory is absolutely vital. Such a laboratory must have capabilities to prepare, mount, transfer, align and test optical elements with the high precision that is typical for European Synchrotron Radiation Facility (ESRF) beamline instrumentation, for example, microroughness and slope error of mirrors down to 0.1 nm root mean square and μrad, respectively, and μm and μrad spatial and angular positioning. At ESRF the following facilities presently exist or are being installed: (i) a laboratory for single crystal orientation, cutting, grinding, polishing, and mounting, (ii) three interferometers for optical metrology of surfaces such as figure and finish, all in clean room and thermally stable environment, (iii) a three axis diffractometer for precise x-ray metrology of all kinds of optical elements up to 1-m long, also in clean room and stable environment, (iv) a multilayer fabrication facility featuring sputtering and plasma chemical vapor deposition with in situ x-ray diffraction and ellipsometry controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142728
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  • 4
    Electronic Resource
    Electronic Resource
    X-ray reflection properties of annealed silicon single crystals : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 907-910 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a series of x-ray reflectivity measurements performed on annealed Czochralski grown silicon (ACS) crystals in the energy range E〈50 keV using sealed tube sources. To analyze the origin of the enhanced reflectivity of this material compared to perfect, FZ-grown silicon, double and triple crystal diffractometer measurements were carried out. The results are discussed with regard to the application of ACS for monochromatization of synchrotron radiation in the mentioned energy range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143775
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  • 5
    Electronic Resource
    Electronic Resource
    Nondispersive Bragg diffraction in the general case of two cylindrically bent crystals : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 920-923 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The conventional double crystal setup, employing two flat crystals with equivalent reciprocal lattice vectors generalizes for two crystals with different lattice vectors if the crystals are bent to their appropriate radii. The conditions for nondispersivity are derived in the most general case for two cylindrically bent crystals in reflection geometry with asymmetric cuts using different reflections. The theoretical predictions are verified by experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143780
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  • 6
    Electronic Resource
    Electronic Resource
    On the phase-space description of synchrotron x-ray beams (abstract) : INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2126-2126 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Simple graphic methods for illustrating the transformation of x-ray beams by optical elements such as mirrors, monochromators, and slits are very helpful tools when optimizing synchrotron radiation experiments. They provide guidelines for matching the optical components to the source and to the experiment, and for checking the physical meaning of the more detailed results obtained by subsequent ray-tracing calculations. Phase-space diagrams have been used extensively to describe synchrotron radiation experiments by plotting an angular variable against a positional one with the possibility to add the energy in a third dimension. For neutron scattering, the traditional method consists in parallel representations, in reciprocal and in real space, that can also be considered as another kind of phase-space diagram. In this paper, we show the specific advantages and the complementary character of the above diagrams. The representation of several optical elements and their effect on beam transformation is given first individually and then for some arrangements of two or more beam-defining devices. Finally, a beamline is described and optimized as a demonstration of the usefulness and the limits of these graphic methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140844
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  • 7
    Electronic Resource
    Electronic Resource
    Performance of very thin silicon single-crystal foils under high x-ray power density : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 442-445 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this paper x-ray diffraction tests of very thin silicon single crystals exposed to a wiggler beam that can generate a power density up to 200 W/mm2 are reported on. This beam was provided by the beamline X25 at NSLS, where 75 W total power are focused into a spot of 0.8 mm(h)×0.45 mm(v). An 11 μm "thin'' Si foil glued at its periphery onto an aluminum ring at 30 °C was applied to a box that could be pressurized with He. The whole assembly was then mounted on an optically polished and watercooled Be support. By increasing the temperature of the water and thus of the Al ring above 30 °C it was possible to apply a stretching force to the Si membrane in order to keep it flat. Rocking curves 3.3 arcsec wide were obtained with a strongly attenuated beam. The rocking curve width increased to 3.9 arcsec when the power density was increased to 15 W/mm2. The crystal was destroyed at 125 W/mm2 because of the limited thermal conductivity across the small He gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142725
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  • 8
    Electronic Resource
    Electronic Resource
    On the phase-space description of synchrotron x-ray beams : International Conference on Synchrotron Radiation Instrumentation (SRI−88) (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2579-2585 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Simple graphic methods for illustrating the transformation of x-ray beams by optical elements such as mirrors, monochromators, and slits are very helpful tools when optimizing synchrotron radiation experiments. They provide guidelines for matching the optical components to the source and to the experiment, and for checking the physical meaning of the more detailed results obtained by subsequent ray-tracing calculations. Phase-space diagrams have been used extensively to describe synchrotron radiation experiments by plotting an angular variable against a positional one with the possibility to add the energy in a third dimension. For neutron scattering, the traditional method consists in parallel representations, in reciprocal and in real space, that can also be considered as another kind of phase-space diagram. In this paper, we show the specific advantages and the complementary character of the above diagrams. The representation of several optical elements and their effect on beam transformation is given first individually and then for some arrangements of two or more beam-defining devices. Finally, a beamline is described and optimized as a demonstration of the usefulness and the limits of these graphic methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140674
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  • 9
    Electronic Resource
    Electronic Resource
    Multilayer optics for intense synchrotron x-ray beams: Recent results on their performance : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 496-500 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Present-day synchrotron x-ray beams are very demanding in terms of thermal, mechanical, and radiation stability of any optical element to be inserted in the beam. A set of multilayers was recently exposed and could resist to an x-ray power density in excess of 7.5 W/mm2, which is comparable to the one expected for the multilayers to be used at ESRF. Such a power density was obtained by setting the multilayers at a grazing angle of about 2° in a focused wiggler beam of 4.6 keV critical energy. The specimen, W/B4C and W/Si multilayers, were cooled either at room temperature or down to liquid nitrogen temperature during an 8–16 h exposure time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142690
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  • 10
    Electronic Resource
    Electronic Resource
    Monochromator on a synchrotron undulator source for liquid surface studies : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1156-1159 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For liquid surface studies a monochromatic beam of relative bandwidth between 0.1% and 1% at a variable angle in the vertical plane between 0° and 10° is needed. The beam should be like a sheet some tens of μm thick and some mm wide, and as intense as possible. We discuss a monochromator made of a beryllium mosaic crystal using the (002) reflection in Laue geometry placed in undulator beams of DORIS III at the Hamburger Synchrotronstrahlungslabor and of the European Synchrotron Radiation Facility. An analysis of the diffraction properties in terms of mosaic spread, heat load, optical quality of the monochromatic beam, and, in particular, the expected flux, gives an optimum value of about 0.2 mrad for the mosaic spread. We show by experiments that presently available crystals a few hundred μm thick have the required quality and are capable of reflecting up to 45% of the useful x rays, in full agreement with diffraction theory including secondary extinction. Heat load experiments reported elsewhere in this conference prove that Be crystals can withstand high beam power density and that the thermal deformation is small compared to the mosaic spread. The results of the flux calculations are most encouraging: a gain of order 103 to 104 can be expected as compared to existing liquid surface spectrometers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143121
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