The Calibrations for the Chang’E-2 Solar X-Ray Monitor

Abstract

The calibrations of the Solar X-ray Monitor (SXM) on the Chinese lunar mission Chang’E-2 are presented. The SXM payload uses a solid-state silicon PIN photodiode (Si-PIN) whose detection energy ranges from 0.5 keV to 10 keV. The energy resolution of SXM is 0.3 keV (FWHM) at 5.9 keV. The solar soft X-rays are collected in 976 channels every 10 seconds. The purpose of the calibrations is to specify the performance of SXM, which enables a reliable spectral analysis of the observed solar X-ray data. The characteristic lines of Fe at ${\approx}\,6.7~\mbox{keV}$ and of the Fe/Ni complex at ${\approx}\,8.0~\mbox{keV}$ are clearly determined during a solar flare. We compare the flux measured by SXM and the Geostationary Operational Environmental Satellite (GOES) series and find consistent results. The preliminary results of the analysis of observed spectra are also presented. The spectra are measured with high energy and time resolutions, which provide additional information such as element abundances in the solar flare region. This information could be very valuable for studying the dynamic evolution of solar flares.