Thallium activated sodium iodide (NaI:Tl) is one of the most widely used gamma-ray scintillators. Commercially available NaI:Tl scintillators are typically characterized by a gamma-ray energy resolution of 6.5% at 662 keV and a scintillation decay time constant of 230 ns. Energy resolution, non-proportionality and scintillation decay time are improved when the crystal is co-doped with alkaline earth metals. The energy resolution of NaI:Tl+ is improved to 5.3% and the decay time is simultaneously reduced to 170 ns with Sr or Ca co-doping. The improvement in energy resolution, non-proportionality and decay time is likely due to the suppression of slow scintillation processes in NaI:Tl. We also demonstrated that Li+ can be substantially incorporated into the matrix of NaI under an optimized crystal growth process. The incorporation of Li+ introduces efficient neutron detection capability into an already successful gamma scintillator. Single crystals of Li co-doped NaI show similar gamma performance as standard NaI:Tl. Exceptional gamma-neutron pulse shape discrimination (PSD) has been demonstrated in all Li co-doped NaI crystals with up to 8% Li concentration. PSD Figure-of-Merits are up to 4.4 depending on Li content.
Conference Committee Involvement (1)
Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XIX
7 August 2017 | San Diego, California, United States