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Proceedings Paper

Radiation damage test of the x-ray CCDs for MAXI onboard the International Space Station
Author(s): Emi Miyata; Hirohiko Kouno; Tomoyuki Kamazuka; Mitsunori Fukuda; Mototsugu Mihara; Kensaku Matsuta; Kanenobu Tanaka; Hiroshi Tsunemi; Tadanori Minamisono; Hiroshi Tomida; Kazushisa Miyaguchi
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Paper Abstract

We have investigated the radiation damage effects on a CCD to be employed in the Japanese X-ray astronomy mission including the Monitor of All-sky X-ray Image (MAXI) onboard the International Space Station (ISS). The X-ray CCD camera, ACIS, onboard Chandra have been seriously damaged by low energy protons having energy of ~150,keV since low energy protons release their energy mainly at the charge transfer channel, resulting a decrease of the charge transfer efficiency. We thus focused on the low energy protons in our experiments. A 171 keV to 3.91 MeV proton beam was irradiated to a given device. We measured the degradation of the charge transfer inefficiency (CTI) and dark current as a function of incremental fluence. A 292 keV proton beam degraded the CTI most seriously. Taking into account the proton energy dependence of the CTI, we confirmed that the transfer channel has a lowest radiation tolerance. On the other hand, dark current increased after proton irradiation for all energies except 171 keV. We have also developed the different device architectures to reduce the radiation damage in orbit. We then investigated the spatial distribution of the low energy protons in the orbit of the ISS. We found that their density has a peak around l ~20° and b ~-55° independent of the attitude. The peak value is roughly two orders of magnitude larger than that at the South Atlantic Anomaly. Taking into account the new anomaly and orbit of the ISS, we estimated the charge transfer inefficiency of MAXI CCDs to be 1.1 × 10-5 per each transfer after two years of mission life in the worse case analysis if the highest radiation-tolerant device is employed. This value is well within the requirement and we have confirmed the high radiation-tolerance of MAXI CCDs.

Paper Details

Date Published: 11 March 2003
PDF: 12 pages
Proc. SPIE 4851, X-Ray and Gamma-Ray Telescopes and Instruments for Astronomy, (11 March 2003); doi: 10.1117/12.461289
Show Author Affiliations
Emi Miyata, Osaka Univ. (Japan)
National Space Development Agency of Japan (Japan)
Hirohiko Kouno, Osaka Univ. (Japan)
Tomoyuki Kamazuka, Osaka Univ. (Japan)
Mitsunori Fukuda, Osaka Univ. (Japan)
Mototsugu Mihara, Osaka Univ. (Japan)
Kensaku Matsuta, Osaka Univ. (Japan)
Kanenobu Tanaka, Osaka Univ. (Japan)
Hiroshi Tsunemi, Osaka Univ. (Japan)
National Space Development Agency of Japan (Japan)
Tadanori Minamisono, Osaka Univ. (Japan)
Hiroshi Tomida, National Space Development Agency of Japan (Japan)
Kazushisa Miyaguchi, Hamamatsu Photonics KK (Japan)

Published in SPIE Proceedings Vol. 4851:
X-Ray and Gamma-Ray Telescopes and Instruments for Astronomy
Joachim E. Truemper; Harvey D. Tananbaum, Editor(s)

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