Operation of BGO with SiPM readout at dry ice and liquid nitrogen temperatures

The light yield and decay constant of BGO were measured at both dry ice and liquid nitrogen temperatures using two SiPMs directly coupled to a $6\times6\times6$ cm$^2$ cubic BGO crystal. With the measured light yield (5.2$\pm$0.3 PE/keV at dry ice temperature and 10.5$\pm$0.4 PE/keV at liquid nitrogen temperature) and decay constants, potential applications of BGO in ToF-PET and SPECT were discussed.