辻本 匡弘

one of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high-spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor (TES) and absorbers that consist of metal and semi-metal layers and a multiplexed SQUID readout. The array (32 x 32 pixels) provides an energy resolution of < 3 eV. Due to the large collection area of the Athena optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. Compared to the requirements for the same instrument on IXO, the performance requirements have been relaxed to fit into the much more restricted boundary conditions of Athena. In this paper we illustrate some of the science achievable with the instrument. We describe the results of design studies for the focal plane assembly and the cooling systems. Also, the system and its required spacecraft resources will be given. © 2012 SPIE.

We present the development status of the Pulse Shape Processor (PSP), which is the on-board digital electronics responsible for the signal processing of the X-ray microcalorimeter spectrometer instrument (the Soft X-ray Spectrometer; SXS) for the ASTRO-H satellite planned to be launched in 2014. We finished the design and fabrication for the engineering model, and are currently undertaking a series of performance verification and environmental tests. In this report, we summarize the results obtained in a part of the tests completed in the first half of this year. © 2012 SPIE.

資料番号: AA0064574158レポート番号: JAXA-SP-09-008E

著者人数: 25人(含チーム1)資料番号: AA0064574159レポート番号: JAXA-SP-09-008E

A digital signal processing system for the X-ray microcalorimeter array (SXS) is being developed for the next Japanese X-ray astronomy satellite, ASTRO-H. The SXS digital signal processing system evaluates each pulse by an optimal filtering process. For the ASTRO-H project, we decided to employ digital electronics hardware, which includes a digital I/O board based upon FPGAs, and a separate CPU board. It is crucially important for the FPGA to be able to detect the presence of an "secondary" pulses on the tail of an initial pulse. In order to detect the contaminating pulses, we have developed a new finite impulse response filter, to compensate for the undershoot in the derivative. By employing the filter it is possible for FPGA to detect the secondary pulse very close the first pulse, and to reduce the load of the CPU in the secondary pulse searching process. © 2009 American Institute of Physics.

原始星は低温ガスや塵が集合した極低温(約10K)の分子雲中で生まれる.こんな低温環境下で10^6-16^8Kに相当する現象,X線放射があるだろうか.自然は我々の想像力を凌駕していた.日本のX線天文衛星「あすか」は原始星からのX線放射を発見した.続く米国の衛星「チャンドラ」は,ほぼ全ての若い星からのX線放射を確立した.その多くはフレア的な強度変動を示し,太陽と同様,磁場を介した激しいエネルギー解放を示唆した.それらが意味するものは何か。X線による研究は星,惑星の形成過程の解明に迫る.本稿ではこのユニークで意外性に富む研究の一端を紹介する.研究は始まったばかりである.将来も展望する.

We study the relation between diffusion and loss of charge produced in X-ray CCDs with the fitting method. We obtain the extent and the pulse height of each X-ray event in a CCD by a two-dimensional image-fitting the charge distribution of the event. For the monochromatic X-rays, we find that the event with small extent keeps all the charge produced, while that with larger extent than a certain value loses some part of the produced charge as a function of extent. The result suggests that the event with a small extent is produced by an X-ray absorbed in the depletion layer. On the other hand, the event with large extent corresponds to an X-ray absorbed in the field-free region. We develop two new methods which enable us to derive the relation between the extent of an event and the absorption depth. One is performed by illuminating well calibrated monochromatic X-ray source. The other is realized by using with two monochromatic X-rays and enables us to measure the thickness of the CCD depletion layer without calibrating absolute flux of the monochromatic X-rays.

CCDs can function as the X-ray spectrometer by counting the number of electrons created by the ionization of semiconductor atoms following the photoelectric absorption of a X-ray photon. In order to measure the incident X-ray energy correctly, we have to sum up all the electrons split over several pixels, thus the grade method is conventionally used. We will discuss the possible alternative to this method the fitting method -, which has several advantages over the grade method. By applying this method to the data taken with our CCD chip, we will show that the fitting method can improve the quantum efficiency, is appliable to the analysis of polarized X-ray events, and gives us insights on the structure of CCDs.