Benchmarking the Compton coincidence technique for measuring electron response non-proportionality in inorganic scintillators

To study the light yield non-proportionality of inorganic scintillation materials, a Compton coincidence experiment has been designed and implemented. The coincidence technique is used to measure the nearly mono-energetic 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 non-proportionality of scintillation materials as a function electron energy while minimizing the potential effects of surface interaction 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 response data for electrons. The CCT data represent the most accurate electron response measurement to date on NaI(Tl) for energies below 20 keV. With the CCT benchmarked, the electron response non-proportionality of other scintillators can be analyzed.