Presentation 宇宙硬X線精密撮像分光観測に向けたCCD素子・ASIC素子の放射線耐性の実証

中嶋, 大  ,  井上, 翔太  ,  今谷, 律子  ,  薙野, 綾  ,  穴吹, 直久  ,  上田, 周太朗  ,  尾崎, 正伸  ,  北村, 尚

We have been developing a hard X-ray camera onboard the future astronomical satellite FFAST (Formation Flight Astronomical Survey Telescope). The focal place sensor is Scintillator -Deposited CCD (SDCCD) that has high detection effeciency for hard X-ray (10-80keV). The analog signals from SDCCDs are processed with low-noise analog ASICs (application-specific integrated circuits). Since the background rejection capability of the camera determines the sensitivity limit of the survey, we need to reproduce the detector responce against the backgrounds particles and electromagnetic waves. Especially the charged particles also damage the ICs inside the instruments. Therefore, we performed the particle irradiation test both for the SDCCD and ASIC. As a result, the charge transfer inefficiency (CTI) of the SDCCD was lower with a factor of 4 compared with that of the conventional CCD sensors after the absorbed dose corresponding to those during three years in alow earth orbit (LEO). This ensures the better spectroscopic performance compared with the conventional X-ray CCD cameras. The ASIC also showed the sufficient tolerance against radiation damage; the latch-up rate is expected to be below one events per 48 years and the noise performance is stable after the dose corresponding to those in about 590 years in the LEO.

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