Integrated X-ray Reflectivity Measurements for Elliptically Curved PET Crystals
The elliptically curved pentaerythritol (PET) crystals used in the Supersnout 2 X-ray spectrometer on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) have been calibrated photometrically in the range of 5.5 to 16 keV. The elliptical geometry provides broad spectral coverage and minimizes the degradation of spectral resolution due to the finite source size. Four pairs of elliptically curved PET crystals were examined in the reflection mode. Each pair of crystals has a unique elliptical curvature, a major radius of approximately 550 mm and a minor radius that is relatively 10 to 15 times smaller. The reflectivity curve of the crystals was measured using a X-ray line source. The integrated reflectivity (RI) and width of its curve (ΔΘ) were the measurements of major interest. The former gives the spectrometer throughput, and the latter gives the spectrometer resolving power. Both parameters are found to vary considerably with the radius of curvature of the crystal and with spectral energy. The results are attributed to an enhanced mosaic effect due to the increase in curvature. There are also contributions from the crystal cleaving and gluing processes.
- Research Organization:
- Nevada Test Site (NTS), Mercury, NV (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- DE-AC52-06NA25946
- OSTI ID:
- 1057198
- Report Number(s):
- DOE/NV/25946-1511
- Journal Information:
- Review of Scientific Instruments, Vol. 83, Issue 10; Conference: 19th Topical Conference: High-Temperature Plasma Diagnostics, May 2012
- Country of Publication:
- United States
- Language:
- English
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