Scintillation of bismuth germanate at liquid helium temperatures

The recent development of a solid-state photon counter with excellent sensitivity in the visible spectrum has made it possible to measure the scintillation properties of a bismuth germanate (BGO) scintillation crystal at liquid helium temperature (~6.5-8 K) activated by 511 keV photons. This measurement result is the first of its kind since the measurement of the scintillation properties of most of the scintillation crystals, including BGO at helium temperature was never before possible due to a lack of photon detectors in that temperature range. Although the experimental setup was not comprehensive enough to quantify the relative increase in scintillation light outputs in comparison to the room (300 K) or liquid nitrogen (77 K) temperature, the decay time was measured with good precision and found to be in the range of 150 μs, which tends to follow the trend of decay time increase observed in the temperature range between 300 and ~200 K