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

为了实现能量分辨率为2 eV、16×16像素的TES(过渡边缘传感器)微量热计，我们开展了以下工作：(1)对微热量计器件的评价和对器件制作的反馈；(2)256像素微热量计信号读出系统的研究；(3)小型科学卫星上绝热退磁制冷机的接口研究。这些结果被总结为DIOS(漫射星际氧气测量者)任务的建议文件，利用一颗小卫星绘制宇宙中被称为缺失重子的温热星际介质(WHIM)的地图，探测电离氧线(Ovii，Oviii)。我们在TMU使用溅射机制造了一个装置，并在IAS和AIST进行了内部处理。得到的能量分辨率为4.8 eV(E/de=1200)，这是日本的记录(NIST小组的世界纪录是2.4 eV)。我们还制作了一个256像素的器件，并成功地用它们来探测X射线。在读出系统中，研究了8输入SQUID信号的读出。对装有TiN吸收体的伽马射线TES量热计进行了测试，在60keV的能量分辨率为40 eV。美国威斯康星大学用循环法制备了用于ADR的CPA盐丸，温度达到60MK。同时，利用2005年7月发射的Suzaku卫星进行了星系团的研究。为了分析星系团等空间扩展的天体目标，开发了蒙特卡罗模拟器，包括X射线望远镜的光线跟踪和利用响应矩阵文件(RMF)简化的X射线CCD相机模拟。

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.