Ray-tracing simulations of spherical Johann diffraction spectrometer for in-beam X-ray experiments

• DOI: 10.1016/j.nima.2014.04.004
• Publication Date: 2014-04-13T02:47:00Z
• Authors: P. Jagodziński; M. Pajek; D. Banaś; H.F. Beyer; M. Trassinelli; Th. Sto¨hlker
• Keywords: High-resolution X-ray spectroscopy; Spherical Johann spectrometer; 0103 physical sciences; Monte-Carlo simulations; [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]; Crystal rocking curve; 01 natural sciences; [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat]; Ray-tracing; X-ray diffraction

Abstract The results of the Monte-Carlo ray-tracing simulations for a Johann-type Bragg spectrometer with spherically curved-crystal designed to detect the X-rays from a fast-moving source are reported. These calculations were performed to optimize the X-ray spectrometer to be used at the gas-target installed at ion storage ring for high-resolution X-ray experiments. In particular, the two-dimensional distributions of detected photons were studied using the Monte-Carlo method both for the stationary and moving X-ray sources, taking into account a detailed description of X-ray source and X-ray diffraction on the crystal as well as a role of the Doppler effect for in-beam experiments. The origin of the asymmetry of observed X-ray profiles was discussed in detail and the procedure to derive a precise (sub-eV) X-ray transition energy for such asymmetric profiles was proposed. The results are important for the investigations of 1 s 2 p P 2 3 → 1 s 2 s S 1 3 intrashell transition in excited He-like uranium ions in in-beam X-ray experiments.