Translator Disclaimer
11 March 2003 Radiation damage test of the x-ray CCDs for MAXI onboard the International Space Station
Author Affiliations +
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.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Emi Miyata, Hirohiko Kouno, Tomoyuki Kamazuka, Mitsunori Fukuda, Mototsugu Mihara, Kensaku Matsuta, Kanenobu Tanaka, Hiroshi Tsunemi, Tadanori Minamisono, Hiroshi Tomida, and Kazushisa Miyaguchi "Radiation damage test of the x-ray CCDs for MAXI onboard the International Space Station", Proc. SPIE 4851, X-Ray and Gamma-Ray Telescopes and Instruments for Astronomy, (11 March 2003);


Off-plane x-ray reflection grating fabrication
Proceedings of SPIE (September 20 2015)
Improving the high-energy sensitivity of x-ray CCDs
Proceedings of SPIE (October 21 1999)
Radiation damage test of the x ray CCDs with low...
Proceedings of SPIE (January 09 2003)
Radiation concerns for the Solar-A soft x-ray telescope
Proceedings of SPIE (June 30 1991)

Back to Top