Properties of NaI(Tl) scintillator at liquid nitrogen temperature

Since early 50´s NaI(Tl) scintillators have been commonly used in many branches of physics and industry and have dominated such areas as homeland security and nuclear medicine. Through this period of time, both spectroscopic and luminescence properties of NaI(Tl) were measured precisely at room temperature. However, until now its properties at liquid nitrogen temperature (LN₂) haven´t been well-known. In this work, the spectroscopy and the luminescence properties of the NaI(Tl) at LN₂ temperature were studied. It was observed that non-proportionality measured at LN₂ temperature is significantly improved in comparison with than at room temperature. The energy resolution of the NaI(Tl) at 662 keV measured at room and LN₂ temperature was estimated to be 7.5% and 6.6%, respectively. A decay time measurement of the NaI(Tl) at LN₂ showed that the slow component related to the emission through Thallium absorption lengthen significantly. Comparison of the following properties with the previously measured undoped NaI crystals was done as well.