Preflight performance measurements of a monolithic Ge:Ga array detector for the Far-Infrared Surveyor onboard ASTRO-F

Abstract

We present pre-flight performance of a monolithic Ge:Ga array detector for Far-Infrared Surveyor (FIS) onboard the ASTRO-F satellite. The primary purpose of the ASTRO-F mission is to perform an all-sky survey in four photometric bands form 50-200 um. For shorter half of this spectral range, 50-110 um, we have developed the monolithic Ge:Ga array which is directly connected to a cryogenic readout electronics (CRE) with the indium-bump technology. In order to investigate the point-source detectability in the survey observation, we carry out a simulation experiment. The experiment was done by taking a image of moving pinholes located on the focal plane of the FIS optics. A clear image without any distortion was obtained, but the size of point source image is slightly larger than expected. We estimate the detection limit in the survey observation by taking account of all detector properties including the imaging performance. The results show that the detector sensitivity is sufficiently high to meet the requirement of the ASTRO-F mission.