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  • 1
    Electronic Resource
    Electronic Resource
    Tungsten-carbon multilayer composition and the effects of annealing: A glancing angle extended x-ray absorption fine structure study (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4250-4255 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are presented from a glancing angle extended x-ray absorption fine structure study to investigate the structure of W/C multilayers and the effects of moderate annealing. There is evidence of considerable interlayer mixing prior to any heat treatment. It is found that after annealing to 350 °C for several hours, drastic changes can occur in the structural environment of the W atoms, with minimal changes in the reflectivity of the sample. There is extensive formation of W2C depending on the W thickness and the W/C ratio. Identification of this carbide as the product of annealing is unambiguous. Above a critical thickness, W begins to grow in its bcc form within the W layer, as it is prepared. This bcc layer is unaffected by the annealing process. The presence of carbon is shown to stabilize the amorphous state of W and inhibits any formation of W2C when the W thickness and W/C ratio are small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343308
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  • 2
    Electronic Resource
    Electronic Resource
    Performance of multilayers in intense synchrotron x-ray beams : International conference on synchrotron radiation instrumentation (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1999-2002 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The use of multilayer reflectors under intense synchroton x-ray beams requires to develop a new generation of multilayered materials that can withstand a high-power load in excess of 100 W/mm2. Multilayers with the high-Z layer consisting either of a pure element or of compounds such as carbides, nitrides, or silicides have been produced. Because the fabrication conditions are not yet optimized, thin films with satisfactory layer were not obtained leading to poor reflectivities. Such multilayers have been both thermally annealed in a furnace and exposed to a synchrotron beam with a power density of about 1 W/mm2. The resulting damage ranges from the total destruction of the layering to a reduction of the reflectivity by typically 40%–60%. In some cases an only 1%–15% loss in reflectivity has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140859
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  • 3
    Electronic Resource
    Electronic Resource
    Performance of a hard x-ray undulator at CHESS (invited) : International conference on synchrotron radiation instrumentation (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1419-1425 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 3.3-cm period Nd-Fe-B hybrid undulator has been designed and successfully operated in the Cornell Electron Storage Ring (CESR). This 2-m-long, 123-pole insertion device is a prototype of one of the undulators planned for the Advanced Photon Source. In dedicated operation, the undulator produced the expected brightness at 5.437 GeV with the fundamental x-ray energy ranging from 4.3 to 7.9 keV corresponding to a change in gap from 1.5 to 2.8 cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140955
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  • 4
    Electronic Resource
    Electronic Resource
    Spectral properties of segmented undulators for the 7-GeV Advanced Photon Source : INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1820-1823 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The effect of nonzero particle beam emittance and magnetic field errors on the on-axis spectral brightness (BT0) of long undulators is discussed. It is shown that the quadratic dependence of BT0 on the number of undulator periods, N, is reduced by emittance to Nx with 1≤x〈2. Further reductions in the intensity result from random magnetic field errors present in the undulator. An approximate model for the intensity of the central core of radiation of the principle harmonics is discussed and the results compared to those from Monte Carlo-type calculations where emittance is explicitly accounted for. An estimation of the effects of random field errors on the on-axis brightness in the presence of nonzero particle emittance is made. For the particular case of undulators proposed for the 7-GeV Advanced Photon Source, the results indicate that 5-m-long devices segmented into two sections will provide the required spectral intensity of a single long undulator when both emittance and magnet errors are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140912
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  • 5
    Electronic Resource
    Electronic Resource
    Spectral properties of a tapered gap hard x-ray undulator (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 858-863 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A tapered undulator, in which the entrance and exit magnetic gaps are different, will show an increase in the energy width of the harmonics compared to the nontapered case. This increase can occur without substantial broadening in the collimation of the undulator radiation. We present the spectral properties measured for a tapered 3.3-cm period prototype undulator of the Advanced Photon Source at the Cornell High Energy Synchrotron Source. The width of the on-axis first harmonic at 6.9 keV increased from 0.32 to 0.66 keV for a gap tapering of 12%. Minimal angular broadening in the first harmonic x rays was detected and measurements of off-axis radiation were also performed. The results are found to be in good agreement with model calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144133
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  • 6
    Electronic Resource
    Electronic Resource
    The combined effect of random magnetic field errors and nonzero particle beam emittance on undulator spectral properties (abstract) : INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1873-1873 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The very desirable spectral properties of transverse undulators as x-ray sources are very sensitive to both random magnetic field errors in the device and to nonzero particle beam emittance. Each of these factors can degrade the undulator performance and their effects must be realistically evaluated in order to accurately estimate the spectral characteristics of a given device. While both sources of degradation on undulator performance have been analyzed independently, no attempt has been made to investigate their combined effect. We have developed a code for calculating undulator-spectral properties which include both these effects. Results are given for typical undulators proposed for the 7-GeV Advanced Photon Source to be built at Argonne. The calculations indicate that present-day construction tolerances achieved for existing undulators will be more than adequate to achieve the desired spectral output of undulators proposed for the APS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140876
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of x-ray spatial coherence and its propagation : The 9th National conference on synchrotron radiation instrumentation (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3363-3363 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: X-ray beams of varying degrees of partial spatial coherence have been prepared and characterized, and the diffraction of these beams from patterned surfaces measured. The experiments were carried out at a bending magnet source at the NSLS (X-19C). The resulting diffraction patterns for a pair of slits and an optical grating are analyzed in terms of an x-ray mutual coherence function used to describe the propagation of the coherent wave front in the visible light regime. The diffraction and speckle pattern from the surface are the result of the mutual coherence function convoluted with the interference function of the grating. Forming diffraction patterns, or x-ray speckles, with partially coherent x-rays relaxes the requirement for the interference, thereby increasing the "effective'' coherent flux. This detailed knowledge of the propagation of the x-ray spatial coherence aids in defining the physical characteristics of beamline optical elements that must preserve the coherent x-ray wave front. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147470
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  • 8
    Electronic Resource
    Electronic Resource
    Coherent hard x-ray focusing optics and applications : 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. 582-585 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Coherent hard x-ray beams with a flux exceeding 109 photons/sec with a bandwidth of 0.1% will be provided by undulators at the third-generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic spectrum to the hard x-ray region. These x-ray techniques (e.g., diffraction-limited microfocusing, holography, interferometry, phase contrast imaging, and signal enhancement) may offer substantial advantages over noncoherence-based x-ray techniques currently used. For example, the signal-enhancement technique may be used to enhance an anomalous x-ray or magnetic x-ray scattering signal by several orders of magnitude. Coherent x rays can be focused to a very small (diffraction-limited) spot size, thus allowing construction of high spatial resolution microprobes. This paper will discuss the feasibility of extending some coherence-based techniques to the hard x-ray range and the significant progress that has been made in the development of diffraction-limited focusing optics. Specific experimental results for a transmission Fresnel phase zone plate that can focus 8.2 keV x rays to a spot size of about 2 microns will be briefly discussed. The comparison of measured focusing efficiency of the zone plate with that calculated will be made. Some specific applications of zone plates as coherent x-ray optics will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142711
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Soft x-ray undulator for the U5 beamline at NSLS : International conference on synchrotron radiation instrumentation (SRI−88) (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1813-1815 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The magnetic structure and spectral properties of a 7.5-cm, 30-period hybrid undulator are described. The device will be installed at the U5 port of the VUV storge ring at Brookhaven National Laboratory and will be a tunable source of very high brillance soft x-ray radiation over the range of 13 to approximately 150 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140910
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  • 10
    Electronic Resource
    Electronic Resource
    Hard x-ray phase zone plate fabricated by lithographic techniques (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1877-1879 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Fresnel phase zone plate with an unprecedented focusing efficiency of 33% was fabricated using an x-ray lithographic technique and was tested using synchrotron x rays. Contributions by the zeroth-order x ray to the focus were minimal. Spatial resolution in the micrometer range was achieved. The measured spot size was dominated by geometric demagnification of the source. It should be possible to obtain submicrometer resolution by aperturing the source. Experimental results of focusing efficiency measurements, intensity distribution at the focal plane, and spatial resolution tests are reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108400
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