Energy Resolution of Compton Electrons in LaBr$_{3}$:Ce Scintillator

A method based on the Compton coincidence technique was applied to study the energy resolution of Compton electrons in wide energy range. The experimental setup was comprised of a High Purity Germanium (HPGe) detector and a LaBr$_{3}$:Ce scintillator coupled to a photomultiplier. The detectors were set in a face-to-face geometry and the source was placed between them. Thus gating on events backscattered in the scintillator and detected in HPGe allowed one to measure the energy resolution of Compton scattered electrons at an energy corresponding to the Compton edge for a given source. This study confirms the importance of the electron scattering ($\delta$ -rays) as the main component of the intrinsic resolution in scintillators. The results are particularly important for discussion of the light yield non-proportionality contribution to the energy resolution of scintillators.