XRISMは2016年に運用を終了した「ひとみ」衛星の背景や研究をもとに高温プラズマのX線精密分光撮像を通して,物質やエネルギーの流転を調べて天体の進化を解明していくミッションである.XRISMには,広視野撮像を目的としたCCDカメラ(Xtend)が搭載される.Xtendには,我々が独自に開発したASIC((Application-Specific Integrated Circuit)特定用途向け集積回路)を用いるが,このASICは,「ひとみ」衛星で未使用だった部品を使用する予定である.そこで,長期保管を経たこのASICがXRISMに使用しても問題ないか調べることが今回の研究の目的である.ASICにCCDの疑似信号を流す電気性能試験を行い,作成された当時の性能と比べた.結果,性能の劣化は見られなかった.また,ASICの入力信号の大きさと波高値の線形関係であるゲインについて,その温度依存性を調べる較正試験を行った.結果,20℃で変化率が0.1%となり,温度による影響は非常に小さいことが分かった.次に,CCDの較正試験を大阪大学で行った.CCDにASICを搭載したものに,数時間様々な線源を-100℃〜-130℃の範囲で一週間当て続けた.数種類の線源のデータを取得したが,本研究では〔55〕Feの-110℃の7時間分のデータを解析した.スペクトルの〔55〕Feの輝線から分解能が170eV @ 5.9keVとなり,これは「ひとみ」衛星の結果より良い性能を示した.これによりXtendのCCDカメラ部分のフライトモデル組み立てに移行する.

XRISM (X-ray Imaging and Spectroscopy Mission), a next X-ray astronomical satellite mission, will investigate the flow of matter and energy through X-ray high-resolution spectroscopic imaging of high temperature plasma and elucidate the evolution of celestial bodies based on the background and research of the ‟Hitomiˮ satellite, which was discontinued in 2016. XRISM is equipped with a CCD camera (Xtend) for wide-field imaging. For Xtend, we will use our proprietary ASIC (Application-Specific Integrated Circuit), for which we will use substitutes for the ‟Hitomiˮ satellite. Therefore, the purpose of this research is to investigate whether this ASIC, which has undergone long-term storage, can be used for XRISM. An electrical performance test was conducted in which a pseudo signal of CCD was passed through the ASIC, and the performance was compared with the performance at the time of Hitomi. As a result, no deterioration in performance was observed. In addition, a calibration test was conducted to investigate the temperature dependence of the gain, which is the linear relationship between the magnitude of the ASIC input signal and the peak value. The rate of change was 0.1% at ΔT of 20 °C, and it was found that the effect of temperature was very small. Next, a CCD calibration test was conducted at Osaka University. CCDs connected with the ASIC was exposed to various sources for several hours in the range of -100 °C to -130 °C for a week. We obtained data from several types of radiation sources. From the emission line of 〔55〕Fe in the spectrum, the resolution was derived to be 170eV @ 5.9keV, which was better than the result of the ‟Hitomiˮ satellite. With this results we will shift to the flight model assembly of the CCD camera part of Xtend.