Copper Mosaic Crystals for Laue Lenses

Abstract

Large single crystals of copper with an uniform and very narrow mosaic spread between 25 seconds and 1 minute of arc are now available at I.L.L. This result is of great interest in the construction of a Laue lens for astrophysical applications for which such quality copper single crystals may be used. The X-ray diffraction properties of copper single crystals produced at I.L.L. were studied for x-ray energies ranging from 100 keV to 400 keV. Several monocrystalline plates with different thicknesses and mosaic distributions were then prepared from the as-grown crystals in order to measure their diffraction efficiency as a function of energy. As expected, the value of the peak reflectivity depends on the crystal thickness. Reflectivity measurements show the excellent properties of copper crystals for gamma-ray diffraction. A peak reflectivity of 24% was measured at 220 keV from a copper single crystal of 3.75 mm thickness having a mosaic spread of 1.5 minutes of arc. Some technical aspects on the preparation of copper single crystal plates are also discussed.

Laue Gamma-Ray Lenses for Space Astrophysics: Status and Prospects

“…From extended tests performed on Cu(111) supplied by ILL [32], it was found that the condition above is satisfied in single points [22], but not when the entire crystal cross section is irradiated (values even higher than 100 μm have been found [24]). In addition, in [24], it is found that t 0 is energy dependent, which is a surprising result that requires an interpretation (see discussion therein).…”

“…Mosaic crystals of Copper are developed and produced at ILL [32]; gradient composition crystals of Si 1−x Ge x alloy with x increasing along the crystal growth axis (curved crystal) are produced at IKZ [39]. Crystal developments for Laue lenses are being undertaken in Italy: mosaic crystals at the CNR-IMEM Institute and curved crystals at the Physics Department, University of Ferrara (see Figure 6).…”

R and D progress on second-generation crystals for Laue lens applications

“…Among them, low mosaicity copper 11 produced by the monochromator group of the Institute Laue-Langevin (ILL, Grenpble, France) and Si 1-x Ge x gradient crystals 12 grown in the Institute of Crystal Growth (IKZ, Berlin, Germany) have been the most extensively studied, but they are not the only option for Laue lens applications; Mosaic germanium crystals 13 , as used on the CLAIRE lens prototype 1,2 remain interesting.…”

“…This problem has been overcome in ILL by Courtois et al during summer 2005 when a refined growth process allowed large ingots (12 kg) of very high quality to be obtained 11 . The sample used here comes from one of these new ingot, number 805.…”

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

“…Abrosimov et al, 2006;Courtois et al, 2006;Smither et al, 2006). However, to achieve the best possible performance of MAX, it is also necessary to optimize the detector used to collect the source photons concentrated by the lens.…”