Calibration and modelling of the SODART-OXS Bragg spectrometer onboard the SRG satellite

Preprint of the full paper (788 kb gziped postscript)

I. Halm [1], H.-J. Wiebicke [1], F.E. Christensen [2], P. Frederiksen [2], I. Rasmussen [2]

1. Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
2. Danish Space Research Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark

Abstract

The SODART X-ray telescope includes an Objective Crystal Spectrometer (OXS) providing a high energy resolving power by Bragg reflection upon crystals. To cover a wide energy range, 3 types of natural crystals
(LiF, Si, RAP) and a Co/C multilayer structure upon Si are used in the ranges 5-11 keV, 2-5 keV, 0.5-1.2 keV, and 0.16-0.42 keV. All types of crystals besides Si being an ideal crystal (with parameters which were calculated) have been calibrated individually and after gluing onto the Bragg panel. The X-ray calibration procedures are described and results are discussed. A ray-tracing program using the OXS calibration data and simulating the X-ray photon reflection on the mentioned crystals and the multilayers has been developped and is described also.

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