T. Oshima
Japan Aerospace Exploration Agency
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by T. Oshima.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1999
Kazuhisa Mitsuda; Ryuichi Fujimoto; Toshiyuki Miyazaki; K. Maegami; Y. Aruga; T. Oshima; Satoshi Nakayama; Shuichi Shoji; Hiroyuki Kudo; Yuichi Yokoyama; Tatehiro Mihara; H.M. Shimizu
Abstract We propose a new method to read out signals from a TES (superconducting Transition-Edge Sensor) calorimeter array with a single or a small number of SQUIDs. Since phonon noise and Johnson noise of a calorimeter can be made very small in these calorimeters, an increase in noise, thus a degradation of energy resolution by adding signals from plural pixels together at some stage of signal processing may be acceptable for some applications of TES calorimeters. We propose to use a SQUID with multi-input coils which will sense signals from different pixels. The input coils of a SQUID are electrically well-isolated from each other. The pixel that generates a signal can be identified by utilizing additional information, such as the pulse shape. We studied the feasibility of this method with analysis and simulations, and show for example, that a 16×16 pixel array can be read out with 16 SQUIDs.
LOW TEMPERATURE DETECTORS: Ninth International Workshop on Low Temperature Detectors | 2002
Toshiyuki Miyazaki; M. Yamazaki; K. Futamoto; Kazuhisa Mitsuda; Ryuichi Fujimoto; N. Iyomoto; T. Oshima; D. Audley; Yoshitaka Ishisaki; Tomohiro Kagei; Takaya Ohashi; Noriko Y. Yamasaki; S. Shoji; Hiroyuki Kudo; Yuichi Yokoyama
In order to realize a large format (e.g. ∼32×32) calorimeter array, it is essential to multiplex calorimeter signals at cryogenic temperatures without losing signal to noise ratio. For this purpose we propose a brand-new readout method, the CABBAGE (Cal¯orimeter B_ridge B_iased by an A_C Ge¯nerator) where an AC biased calorimeters are placed in resistance bridges. In this paper we first describe the principles of CABBAGE and investigate its response and noise. We propose the large format calorimeter array readout using CABBAGEs, and discuss the new TES microcalorimeter readout method without using SQUIDs.
LOW TEMPERATURE DETECTORS: Ninth International Workshop on Low Temperature Detectors | 2002
Ryuichi Fujimoto; Kazuhisa Mitsuda; N. Iyomoto; Michael D. Audley; Toshiyuki Miyazaki; T. Oshima; M. Yamazaki; K. Futamoto; Yoh Takei; Yoshitaka Ishisaki; Tomohiro Kagei; T. Hiroike; U. Morita; Takaya Ohashi; Noriko Y. Yamasaki; A. Kushino; Hiroyuki Kudo; Hironobu Sato; T. Nakamura; E. Goto; S. Shoji; Takayuki Homma; Tetsuya Osaka; Yoshikatsu Kuroda; Mitsunobu Onishi; M. Goto; Keiichi Tanaka; Toshimitsu Morooka; Satoshi Nakayama; Kazuo Chinone
A superconducting phase-transition microcalorimeter is a promising detector for high resolution X-ray spectroscopy. We are developing such a detector for future Japanese X-ray astronomy missions. In our design, a tin absorber is electrodeposited as a mushroom structure to achieve a high covering fraction. We have succeeded in detecting X-rays with the first model of our calorimeter with an electrodeposited absorber, though the energy resolution was limited due to residual resist. We are also developing a phase-transition microcalorimeter with a low transition temperature. We describe the results of these experiments, and discuss the limiting factors of their performance.
LOW TEMPERATURE DETECTORS: Ninth International Workshop on Low Temperature Detectors | 2002
Hiroyuki Kudo; Hironobu Sato; T. Nakamura; Takahiro Arakawa; E. Goto; Shuichi Shoji; Takayuki Homma; Tetsuya Osaka; Kazuhisa Mitsuda; Ryuichi Fujimoto; N. Iyomoto; M. D. Audley; Toshiyuki Miyazaki; T. Oshima; M. Yamazaki; K. Futamoto; Yoh Takei; Yoshitaka Ishisaki; Tomohiro Kagei; T. Hiroike; Takaya Ohashi; Noriko Y. Yamasaki; A. Kushino; Yoshikatsu Kuroda; Mitsunobu Onishi; M. Goto
For the next generation of astronomical X-ray imaging detectors, arrays with large numbers of microstructures (∼1000 pixels) will be required. To meet this requirement, a tin absorber for an X-ray microcalorimeter, which has a so-called “mushroom” shape, is fabricated by electrodeposition and polishing. This method enables the fabrication of a large number of arrayed microcalorimeters. Details of the fabrication process, the characteristics of the absorber and the fabricated microcalorimeters are reported.
Proceedings of SPIE | 2000
Yuichi Yokoyama; Shuichi Shoji; Kazuhisa Mitsuda; Ryuichi Fujimoto; Toshiyuki Miyazaki; T. Oshima; M. Yamazaki; Naoko Iyomoto; K. Futamoto; Yoshinao Ishizaki; Tomohiro Kagei
An X-ray microcalorimeter that consists of an x-ray absorber to transfer the incident photon energy to the temperature rise, a temperature sensor to detect the temperature change and suspending beams for thermal isolation from the substrate have been fabricated. Titanium/Gold thin film transition edge sensor (TES) is used as the temperature sensor. We fabricated and tested the first prototype in the previous study and obtained the transition temperature of 0.52 K, energy resolution of 550 eV (FWHM) for 6 keV radiation. These values were smaller than that of expected. We applied a Sn absorber and redesigned the microstructure of the x-ray microcalorimeter. Consequently, we have obtained 158 eV at 5.9 keV radiation of the energy resolution, which is about 4 times higher than that of the first prototype. This value is nearly equal to the conventional X-ray CCD. The highest energy resolution of the x-ray microcalorimeter of our design is estimated to approximately 5 eV at the operating point of 0.2 K. To realize such a good energy resolution calorimeter array, we are going to improve the sensitivity of the TES by optimizing the process condition. A Sn absorber formed by electroplating is also under evaluating simultaneously. It is necessary to fabricate uniform array structures.
Proceedings of the 1999 Design, Characterization, and Packaging for MEMS and Microelectronics | 1999
Hiroyuki Kudo; Yuichi Yokoyama; Shuichi Shoji; T. Oshima; Youichi Aruga; Kana Maegami; Ryuichi Fujimoto; Toshiyuki Miyazaki; Kazuhisa Mitsuda
A prototype of an x-ray microcalorimeter using Titanium/Gold transition edge sensor (TES) for detecting cosmic rays is fabricated and tested. This paper reports first experimental result of the prototype. By using silicon bulk micromachining, freestanding microstructure suspended with fine beams are obtained to achieve thermal isolation from the substrate. A superconductor, Ti in this case, can be used as a very sensitive temperature sensor at the narrow temperature range around its transition temperature. At the low temperatures below 1K, the microstructure with very small heat capacity is expected to be thermally detecting single photons. Design consideration to realize radiation detection with extremely good energy resolution has been taken place. Our tentative goal is to obtain the energy resolution of 20eV for 10keV radiation at 0.5K. We have fabricated a test device of the TES. The sensitivity of it is larger than 1000, which is enough for this purpose. The energy resolution of the prototype of the x-ray microcalorimeter was 550eV for 6keV radiation at approximately 0.5K. This value is smaller than that expected. An optimization of the TES features is still necessary for a good energy resolution.
THE THIRTEENTH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS—LTD13 | 2009
H. Akamatsu; Yoshitaka Ishisaki; Akio Hoshino; Yuichiro Ezoe; Takaya Ohashi; Yoh Takei; Noriko Y. Yamasaki; Kazuhisa Mitsuda; T. Oshima; Keiichi Tanaka
We performed complex impedance measurements with a Ti/Au‐based gamma‐ray TES calorimeter with a bulk Sn absorber. Excellent energy resolution of 38.4±0.9eV at 60 keV was observed. The impedance of the calorimeter can be well explained by a two‐body thermal model. We investigated the behavior of the parameters of the calorimeter during the superconducting‐to‐normal transition. We confirmed that C and Ga are in good agreement with the predicted values. We performed a noise analysis and found several excess noise components, as well as internal thermal fluctuation noise (ITFN) term due to the thermal conductance between the Sn absorber and the Ti/Au TES. Dominanting the noise is an excess noise having a similar frequency dependence to the phonon noise and the ITFN noise.
international microprocesses and nanotechnology conference | 2003
Hiroyuki Kudo; S. Ohtsuka; Takahiro Arakawa; T. Izumi; Shuichi Shoji; Hironobu Sato; H. Kobayashi; Kentaro Mori; Takayuki Homma; Tetsuya Osaka; Kazuhisa Mitsuda; Noriko Y. Yamasaki; Ryuichi Fujimoto; N. Iyomoto; T. Oshima; K. Futamoto; Yoh Takei; T. Ichitsubo; T. Fujimori; Yoshitaka Ishisaki; U. Morita; T. Koga; K. Sato; Takaya Ohashi; Yoshikatsu Kuroda; Mitsunobu Onishi; K. Otake
In this paper we developed through-wafer interconnections using only a simple fabrication process. The interconnection was successfully transformed into the superconducting state. A current density of 13 cm/sup 2//mA was obtained in the superconducting state. We realize high energy-resolution X-ray imaging using the superconducting through-wafer interconnections.
Physica B-condensed Matter | 2003
Keiichi Tanaka; Toshimitsu Morooka; Ryuichi Fujimoto; Yoshitaka Ishisaki; Yoh Takei; U. Morita; N. Iyomoto; T. Oshima; Satoshi Nakayama; Noriko Y. Yamasaki; Masao Koyanagi; Kazuhisa Mitsuda; Takaya Ohashi; Kazuo Chinone
Abstract We present the performance of transition edge sensors (TES) using Au/Ti bilayer (operating temperature 113 mK ) with fast decay time for industrial applications. The energy resolution was 9.2 eV for Mn Kα1 (designed value 3.5 eV ) and the decay time 71 μs , yielding the count rate 2.3 kcps (count per sec). We found that the energy resolution was limited by excess noise. The excess noise increased in proportion to the inverse of TES resistance as decreasing the TES resistance from normal resistance. The source of excess noise might exist in the TES.
Journal of Low Temperature Physics | 2008
T. Oshima; Y. Yamakawa; H. Kurabayashi; Akio Hoshino; Yoshitaka Ishisaki; Takaya Ohashi; Kazuhisa Mitsuda; Keiichi Tanaka