Development of microcalorimeter arrays for observing the missing baryon in the universe

为了实现能量分辨率为2 eV、16 x 16像素的TES （Transition-Edge Sensor）微热量计，我们进行了以下研究：(1)微热量计器件的评估和器件制造的反馈；(2)256像素微热量计信号读取系统的研究；(3)与小型科学卫星上绝热消磁制冷机（ADR）的接口研究。这些结果被总结为DIOS（漫射星系间氧探测器）任务的提案文件，该任务利用一颗小型卫星来绘制宇宙中被称为失踪重子的温热星系间介质（WHIM），探测电离氧线（OVII， OVIII）。我们利用TMU的溅射机制作了器件，并在ISAS和AIST进行了内部加工。导出的能量分辨率为4.8 eV (E/dE=1200)，这是日本的纪录（世界纪录是由NIST小组创造的2.4 eV）。我们还制作了256像素的器件，并成功地探测到了x射线。在读出系统方面，研究了8输入SQUID的信号读出。测试了连接锡吸收体的伽马射线TES量热计，在60 keV下实现了40 eV的能量分辨率。采用循环法制备了用于ADR的CPA（铬钾明矾）盐丸，并在美国威斯康星大学获得了60 mK的温度。与此同时，利用2005年7月发射的Suzaku卫星对星系团进行了研究。利用响应矩阵文件（RMF）对x射线望远镜的射线跟踪和x射线CCD相机的简化模拟进行了蒙特卡罗模拟器的开发，用于分析星系团等空间扩展天体目标。

Aiming to realize TES (Transition-Edge Sensor) microcalorimeter with energy resolution of 2 eV and 16 x 16 pixels, we conducted following studies: (1) evaluation of microcalorimeter device and feed-back to the device fabrication, (2) research for readout system of 256 pixel microcalorimeter signals, (3) investigation of the interface to the adiabatic demagnetization refrigerator (ADR) onboard small scientific satellites. These results are summarized as the proposal document of the DIOS (Diffuse Intergalactic Oxygen Surveyor) mission utilizing a small satellite for mapping the warm-hot intergalactic medium (WHIM) known as the missing baryon in the universe, probing the ionized oxygen lines (OVII, OVIII).We fabricated a device using the sputtering machine at TMU, and conducted in-house processing at ISAS and AIST. The derived energy resolution was 4.8 eV (E/dE=1200) which is the Japanese record (world record is 2.4 eV by NIST group). We also fabricated a 256 pixel devices and succeeded in detecting X-rays with them. As for the readout system, signal readout with 8-input SQUID was investigated. Gamma-ray TES calorimeter attached with a tin absorber was tested, and 40 eV energy resolution at 60 keV was demonstrated. CPA (Chromium Potassium Alum) saltpill for ADR was made by a circulation method, and achieved 60 mK temperature at University of Wisconsin.In parallel, study of clusters of galaxies was performed using the Suzaku satellite launched in July 2005. Monte-carlo simulator including a ray-tracing of the X-ray telescope and the simplified simulation of X-ray CCD camera with a response matrix file (RMF) was developed to analyze spatially extended celestial targets like clusters of galaxies.