BGO readout with photodiodes as a soft gamma-ray detector at -30∘C

BGO is expected to be plausible devices for soft gamma-ray detectors, because of a high detection efficiency for soft gamma-rays. Here we report on the good performance of BGO readout with PIN-photodiode or avalanche photodiode as a soft gamma-ray detector. We confirmed that the signal output of BGO becomes comparable to that of GSO when it is readout with photodiodes due to better matching between emission wavelength of BGO and quantum efficiency of photodiode. The energy resolution of 6.2% and 3.4% for 662 and 1836 keV, respectively, gamma-rays at -30∘C is obtained with the combination of the 5×5×5mm3 cube BGO and the Hamamatsu avalanche photodiode (APD) S8664-55. In this combination, the lowest detectable energy is found to be ∼10keV. These performances are better than that obtained with Photomultiplier tube (PMT), and our results increase many possible applications of BGO readout with photodiodes as soft gamma-ray detectors.