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  • 1
    Electronic Resource
    Electronic Resource
    Measurement and analysis of leaded glass polycapillary optic performance for hard x rays (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5363-5368 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of borosilicate glass polycapillary x-ray optics have been extensively studied. Small-area scatter rejection borosilicate glass polycapillary optics have been demonstrated with good results. Many medical imaging and industrial radiographic applications for x rays would require large-area optics with good scatter rejection. Since shorter optics are easier to manufacture, optics with a shorter length would provide a faster route to bringing the benefit of polycapillary x-ray optics to these applications. Leaded glass would allow the optic to be much shorter and still give good contrast enhancement, because of the superior absorption of lead glass. In order to investigate the feasibility of using leaded glass polycapillary x-ray optics for these applications, measurements and simulations have been performed on the behavior of leaded glass polycapillary fibers in the 9–80 keV energy range. The transmission efficiencies of these fibers of different types and lengths were measured as a function of source location and x-ray energy. The measurements were analyzed using a geometrical optics simulation program, which included roughness, waviness, bending effects, and a leaded glass filter layer. Despite low transmission at low energies, leaded glass polycapillary x-ray optics with a length of 30–60 mm seem promising for many high-energy (〉20 keV) x-ray applications. The longer fibers have transmission efficiency of up to 50% in the 35–40 keV, and very low scatter transmission of less than 0.06% up to 80 keV. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1408593
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  • 2
    Electronic Resource
    Electronic Resource
    Wavelength-dispersive x-ray fluorescence detector : 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. 1410-1412 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A wavelength-dispersive x-ray fluorescence detector system has been developed that can be used to discriminate fluorescent photon energies for practically any incident flux. The system uses a Kumakhov polycapillary lens to collimate fluorescent photons from a sample. The collimated photons are transmitted to a crystal-counter combination on a stepping motor driven θ–2θ stage. The stage diffracts the photon wavelength of interest and a photon-counting or current-mode counter is used to measure the photons. The system had a resolution of less than 150 eV at 8 keV using the (200) reflection from an abraded and etched LiF crystal, and was easily able to discriminate between Zn Kα (8.620 keV) and Cu Kβ (8.905 keV) x rays emitted from a brass sample. The LiF (400) reflection had a resolution of approximately 50 eV, but with ten times less intensity. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145924
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  • 3
    Electronic Resource
    Electronic Resource
    Performance study of polycapillary optics for hard x rays (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3628-3638 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to investigate the feasibility of using Kumakhov capillary x-ray optics for high energy x-ray applications, measurements have been performed on the behavior of capillary optics from 10 to 80 keV. Transmission efficiencies of straight polycapillary fibers of different types have been measured as a function of source location and x-ray energy. The measurements are analyzed using a geometrical optics simulation program, which includes roughness and waviness effects. Despite the low critical angle for total external reflection at high energies, capillary x-ray optics appear promising for many hard x-ray applications. Transmission measurements at high energies have also proven to be a very sensitive tool in capillary quality analysis. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363309
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of implanted iron in silicon by channeling and Rutherford backscattering (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1336-1341 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Different amounts of 100-keV iron ions have been implanted into high-resistivity p-type FZ-silicon samples. The implantation damage, recovery of damage during various annealing periods and temperatures, movement of iron atoms under annealing and oxidation, and the kinds of defects created after implantation, annealing, or oxidation are all investigated by channeling and backscattering measurements. We have found that the critical fluence of 100-keV iron implanted into silicon at room temperature is ∼2.5×1014 Fe/cm2, and that iron atoms are gettered by silicon oxidation. In this supersaturated region iron atoms diffuse slightly towards bulk silicon during high-temperature annealing (≥1100 °C) but not at all during low-temperature annealing (≤1000 °C) in dry nitrogen ambient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337306
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  • 5
    Electronic Resource
    Electronic Resource
    Monolithic polycapillary focusing optics and their applications in microbeam x-ray fluorescence (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1529-1531 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Monolithic polycapillary focusing optics can collect a large solid angle of x rays from a point source and form intense focused beams for microbeam x-ray fluorescence (MXRF) analysis. Such an optic was tested and characterized in a MXRF setup. For the Cu Kα line, the measured focal spot size of the optic was 43 μm full width at half-maximum (FWHM). With the 16 W microfocusing x-ray source (50 μm×10 μm), the average Cu Kα intensities over the focal spot was measured to be 8.9×104 photons/s/μm2. When compared to a straight single channel capillary optic with approximately the same output beam size, an intensity gain of 44 was obtained. The optic was applied to the MXRF setup to analyze trace elements in various samples and a minimum detection limit (MDL) of about 2 pg was achieved for the transition elements (V, Cr, Mn, and Fe). The optic was also used to map the distributions of trace elements in various samples. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117994
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  • 6
    Electronic Resource
    Electronic Resource
    Lattice location of Ca in GaN using ion channeling (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2355-2357 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Ca dopant site in the GaN lattice has been investigated using ion channeling. Metal organic chemical vapor deposition grown GaN on c-plane sapphire substrates implanted with 40Ca at a dose of 1×1015 cm−2 with postimplant annealing were studied. Our results indicate that more than 80% of Ca are near Ga sites even in as-implanted samples, however, they are displaced by ∼0.2 Å from the Ga sites and that the Ca goes to the exact Ga sites after annealing at 1100 °C while the annealing did not change the apparent fraction of substitutional Ca. We suggest that the displaced Ca in the as-implanted sample are electrically compensated due to formation of complex defects with donor-like point defects and that CaGa becomes electrically active when these complex defects are broken and the point defects diffuse away with annealing at 1100 °C. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123849
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  • 7
    Electronic Resource
    Electronic Resource
    Lattice location of Si in ion implanted GaN (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1406-1408 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lattice location of Si in GaN has been investigated by ion channeling in combination with Rutherford backscattering spectrometry, particle induced x-ray emission, and nuclear reaction analysis. Metalorganic chemical vapor deposition grown GaN on c-plane sapphire substrates and implanted with 28Si at a dose of 7×1014 cm−2 with postimplant annealing were investigated. It was found that almost 100% of Si goes into the Ga site at 1100 °C. Our results directly indicate that the electrical activation of Si implanted GaN with postimplant annealing is due to the formation of substitutional Si at this temperature. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121958
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  • 8
    Electronic Resource
    Electronic Resource
    Epitaxial growth and characterization of CaF2 on Si (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 302-308 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: CaF2 films have been grown epitaxially on (100) and (111) Si substrates by molecular beam epitaxy. These films have been characterized by electron microscopy, reflection high-energy electron diffraction, Rutherford backscattering ion channeling, and back-reflection Laue x-ray diffraction. In addition, chemical etching has been used to reveal dislocations and to delineate cracks. Film cracking appears to be related to crystalline perfection through misfit dislocation mobility. It is possible to grow high quality, (xmin=3.0%) single-crystal films on (111) Si which are free of cracks and atomically flat. However, the high free energy of the (100) surface in an ionic fluorite crystal prevents the growth of comparable CaF2 films on the (100) Si surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335676
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  • 9
    Electronic Resource
    Electronic Resource
    Personnel Selection and Placement (1988)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Psychology 39 (1988), S. 349-374 
    Details
    ISSN: 0066-4308
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Psychology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ps.39.020188.002025
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  • 10
    Electronic Resource
    Electronic Resource
    Blocking Measurements of Nuclear Decay Times (1975)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nuclear and Particle Science 25 (1975), S. 465-508 
    Details
    ISSN: 0066-4243
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ns.25.120175.002341
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