Design of a prototype system to measure the non-proportional response of scintillators using angular information

In this paper, a prototype system was designed to efficiently measure the non-proportional electron response of scintillation materials using only angular information. Similar to other measurement systems used in this type of research, our design relies on the fundamental principles of Compton scattering. All current designs measure coincident events that arise when Compton electrons are deposited in a test scintillator while the associated Compton gamma ray is detected by one or more secondary detectors. Nearly all current designs utilize the conservation of energy and a second high-resolution, linear detector in order to determine the energy of the Compton electron. In this work, we use only the angular information and the well known Compton formula which relates scattering angle and energy. By using a position sensitive BGO block detector as the secondary detector, it is possible to simultaneously collect data at multiple scattering angles. The results obtained were found to agree with both literature data and results obtained through a source library measurement. The bias introduced into the results by setup geometry deviations is also discussed.