Energy resolution and light yield non-proportionality of pure NaI scintillator studied with large area avalanche photodiodes at liquid nitrogen temperatures

The pure NaI crystal has been studied using a Large Area Avalanche Photodiode (LAAPD) at near liquid nitrogen (LN2) temperatures. The study showed a high light output of 44 000±4000 photons/MeV (ph/MeV), the energy resolution of 5.9±0.2% for 661.6 keV γ-rays from a 137Cs source and a good proportionality of the light yield versus γ-ray energy. It has been shown also that a cooled LAAPD is an excellent photodetector to study scintillators at near LN2 temperatures.