Optical studies of scintillation detectors for precision beta-energy measurements

Abstract

This work presents optical calculations and simulations for scintillation detectors used in precision measurements of beta-particle energy spectra. Particular attention is given to Cherenkov photons and the impact of the light detection efficiency in the detector ensemble. We present an approach to estimate this light detection efficiency from the measured energy resolution of a detector. This is essential for the inclusion of scintillation photons in optical tracking Monte-Carlo simulations. A method to account for possible saturation and cross-talk of silicon photo-multipliers is also discussed. The impact of these effects is quantified in terms of systematic shifts in the extraction of the Fierz interference term from measurements of beta-energy spectra using scintillator detectors.