48 research outputs found
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X-Ray Diffraction Project Final Report, Fiscal Year 2006
An x-ray diffraction diagnostic system was developed for determining real-time shock-driven lattice parameter shifts in single crystals at the gas gun at TA-IV at Sandia National Laboratories (SNL). The signal-to-noise ratio and resolution of the system were measured using imaging plates as the detector and by varying the slit width. This report includes tests of the x-ray diffraction system using a phosphor coupled to a charge-coupled device (CCD) camera by a coherent fiber-optic bundle. The system timing delay was measured with a newly installed transistor-transistor logic (TTL) bypass designed to reduce the x-ray delay time. The axial misalignment of the Bragg planes was determined with respect to the optical axis for a set of eight LiF [lithium fluoride] crystals provided by SNL to determine their suitability for gas gun experiments
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Flash X-Ray Diffraction System for Fast, Single-PulseTemperature and Phase Transition Measurements (Pre-print)
A new, fast, single-pulse diagnostic for determining phase transitions and measuring the bulk temperature of polycrystalline metal objects has been developed. The diagnostic consists of a 37-stage Marx bank with a cable-coupled X-ray diode that produces a 35-ns pulse of mostly 0.71-{angstrom} monochromatic X rays and a P-43 fluor coupled to a cooled, charge-coupled device camera by a coherent fiber-optic bundle for detection of scattered X rays. The X-ray beam is collimated to a 1{sup o} divergence in the scattering plane with the combination of a 1.5-mm tungsten pinhole and a 1.5-mm-diameter molybdenum anode. X rays are produced by a high-energy electron beam transiting inward from the cathode to the anode in a needle-and-washer configuration. The anode's characteristic K-{alpha} X-ray emission lines are utilized for this diffraction system. The X-ray anode is heavily shielded in all directions other than the collimated beam. The X-ray diode has a sealed reentrant system, allowing X rays to be produced inside a vacuum containment vessel, close to the sample under study
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Real-time X-ray Diffraction Measurements of Shocked Polycrystalline Tin and Aluminum
A new, fast, single-pulse x-ray diffraction (XRD) diagnostic for determining phase transitions in shocked polycrystalline materials has been developed. The diagnostic consists of a 37-stage Marx bank high-voltage pulse generator coupled to a needle-and-washer electron beam diode via coaxial cable, producing line and bremsstrahlung x-ray emission in a 35-ns pulse. The characteristic Kα lines from the selected anodes of silver and molybdenum are used to produce the diffraction patterns, with thin foil filters employed to remove the characteristic Kβ line emission. The x-ray beam passes through a pinhole collimator and is incident on the sample with an approximately 3-mm by 6-mm spot and 1° full-width-half-maximum (FWHM) angular divergence in a Bragg-reflecting geometry. For the experiments described in this report, the angle between the incident beam and the sample surface was 8.5°. A Debye-Scherrer diffraction image was produced on a phosphor located 76 mm from the polycrystalline sample surface. The phosphor image was coupled to a charge-coupled device (CCD) camera through a coherent fiberoptic bundle. Dynamic single-pulse XRD experiments were conducted with thin foil samples of tin, shock loaded with a 1-mm vitreous carbon back window. Detasheet high explosive with a 2-mm-thick aluminum buffer was used to shock the sample. Analysis of the dynamic shock-loaded tin XRD images revealed a phase transformation of the tin beta phase into an amorphous or liquid state. Identical experiments with shock-loaded aluminum indicated compression of the face-centered-cubic (fcc) aluminum lattice with no phase transformation
Monte Carlo simulations of microchannel plate detectors. I. Steady-state voltage bias results
Mu2e Technical Design Report
The Mu2e experiment at Fermilab will search for charged lepton flavor
violation via the coherent conversion process mu- N --> e- N with a sensitivity
approximately four orders of magnitude better than the current world's best
limits for this process. The experiment's sensitivity offers discovery
potential over a wide array of new physics models and probes mass scales well
beyond the reach of the LHC. We describe herein the preliminary design of the
proposed Mu2e experiment. This document was created in partial fulfillment of
the requirements necessary to obtain DOE CD-2 approval.Comment: compressed file, 888 pages, 621 figures, 126 tables; full resolution
available at http://mu2e.fnal.gov; corrected typo in background summary,
Table 3.
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Real-time Studies of Shocked Polycrystalline Materials with Single-Pulse X-ray Diffraction
Characteristic K-α x-rays used for single-pulse XRD are conventionally produced by a 37-stage high-voltage Marx pulse generator coupled to a vacuum needle-and-washer x-ray diode via coaxial transmission line. A large field-of-view x-ray image plate detection system typically enables observation of several Debye-Scherrer rings. Recently, we have developed a fiber-optic reducer, coupled to a CCD camera, to obtain low-noise, large field-of-view images. The direct beam spot is produced by bremsstrahlung radiation attenuated by a twomillimeter tungsten beam stop. Determination of the direct beam position is necessary to perform the ring integration