Experimentally determining the relative efficiency of spherically bent germanium and quartz crystals.

Rev Sci Instrum

Physics Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA.

Published: November 2016

We have used the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory and a duplicate Orion High Resolution X-ray Spectrometer (OHREX) to measure the relative efficiency of a spherically bent quartz (101̄1) crystal (2d = 6.687 Å) and a spherically bent germanium (111) crystal (2d = 6.532 Å). L-shell X-ray photons from highly charged molybdenum ions generated in EBIT-I were simultaneously focussed and Bragg reflected by each crystal, both housed in a single spectrometer, onto a single CCD X-ray detector. The flux from each crystal was then directly compared. Our results show that the germanium crystal has a reflection efficiency significantly better than the quartz crystal, however, the energy resolution is significantly worse. Moreover, we find that the spatial focussing properties of the germanium crystal are worse than those of the quartz crystal. Details of the experiment are presented, and we discuss the advantages of using either crystal on a streak-camera equipped OHREX spectrometer.

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http://dx.doi.org/10.1063/1.4962037DOI Listing

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Article Synopsis
  • - The study compares the effectiveness of two types of X-ray analyzers: the spherically bent Bragg analyzer and the cylindrically bent Laue analyzer, focusing on their reflectivity and energy resolution using a SiO glass sample.
  • - Bragg analyzers perform well at photon energies up to 10 keV but experience a decline in reflectivity and resolution as energy increases, particularly beyond 20 keV.
  • - In contrast, Laue analyzers show improved reflectivity and steady resolution at energies over 10 keV, making them ideal for high-energy-resolution fluorescence-detection and X-ray emission spectroscopy of certain materials, with both analyzers demonstrating similar performance in specific measurements.
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