Benchmarking the Compton coincidence technique for measuring electron response nonproportionality in inorganic scintillators

To study the light yield nonproportionality of inorganic scintillation materials, a Compton coincidence experiment has been designed and implemented. The coincidence technique is used to measure the nearly mono-energetic scintillators electron response by recording events only when energetic electrons are produced by gamma rays that are Compton scattered through a specific angle. This technique provides the ability to accurately determine the light yield nonproportionality of scintillation materials as a function of electron energy while minimizing the potential complicating effects of surface interactions and X-ray escape. To benchmark the Compton coincidence technique (CCT), the electron response for NaI(Tl) has been measured for electron energies from 2 keV to 450 keV and compared to previously-published analytical and measured light yield electron responses. These CCT results are believed to be the most accurate NaI(Tl) electron response measurements to date for energies below 20 keV where the light yield non-proportionality is most pronounced