Milli-electronvolt monochromatization of hard X-rays with a sapphire backscattering monochromator

Abstract

Monochromatization of hard X-rays in the 20–40 keV energy range to ∼1 meV bandwidth using a sapphire backscattering monochromator is demonstrated.

Abstract

A sapphire backscattering monochromator with 1.1 (1) meV bandwidth for hard X-rays (20–40 keV) is reported. The optical quality of several sapphire crystals has been studied and the best crystal was chosen to work as the monochromator. The small energy bandwidth has been obtained by decreasing the crystal volume impinged upon by the beam and by choosing the crystal part with the best quality. The monochromator was tested at the energies of the nuclear resonances of ¹²¹Sb at 37.13 keV, ¹²⁵Te at 35.49 keV, ¹¹⁹Sn at 23.88 keV, ¹⁴⁹Sm at 22.50 keV and ¹⁵¹Eu at 21.54 keV. For each energy, specific reflections with sapphire temperatures in the 150–300 K region were chosen. Applications to nuclear inelastic scattering with these isotopes are demonstrated.