In-flight calibration of Hitomi Soft X-ray Spectrometer. (1) Background
Tsujimoto, Masahiro; Eckart, Megan E.; Kelley, Richard L.; Kilbourne, Caroline A.; Leutenegger, Maurice A.; Porter, Frederick S.; Tashiro, Makoto S.; Terada, Yukikatsu; Mitsuda, Kazuhisa; Fujimoto, Ryuichi; Yamasaki, Noriko Y.; Nakashima, Shinya; Ishisaki, Yoshitaka; Koyama, Shu; Loewenstein, Michael; McCammon, Dan; Sawada, Makoto; Seta, Hiromi; Takei, Yoh; Yamada, Shinya; Boyce, Kevin R.; Angellini, Lorella
United States, Japan
Abstract
The X-Ray Spectrometer (XRS) instrument of Suzaku provided the first measurement of the non-X-ray background (NXB) of an X-ray calorimeter spectrometer, but the data set was limited. The Soft X-ray Spectrometer (SXS) instrument of Hitomi was able to provide a more detailed picture of X-ray calorimeter background, with more than 360 ks of data while pointed at the Earth, and a comparable amount of blank-sky data. These data are important not only for analyzing SXS science data, but also for categorizing the contributions to the NXB in X-ray calorimeters as a class. In this paper, we present the contributions to the SXS NXB, the types and effectiveness of the screening, the interaction of the screening with the broad-band redistribution, and the residual background spectrum as a function of magnetic cut-off rigidity. The orbit-averaged SXS NXB in the range 0.3-12 keV was 4 × 10-2 counts s-1 cm-2. This very low background in combination with groundbreaking spectral resolution gave SXS unprecedented sensitivity to weak spectral lines.