Geant4 Monte Carlo simulation for beta ray spectra in liquid scintillation counter for estimating detection efficiency

摘要

Liquid scintillation counter (LSC) has been the most powerful tool in the fields of low-level and low-energy beta ray detection of radioactivity. Due to quench phenomena and loss of scintillation photons during the optical trace, the observed count rate becomes less than that of actual radioactivity. Therefore the compensation of count rate loss is essential to determine the radioactivity. In order to investigate influences of quench phenomena and the efficiency in LSC, a Geant4 based Monte Carlo simulation has been developed. The simulation takes into account radioactive decay, electromagnetic interaction, scintillation photons, and transportation of optical photons with reflection and refraction characteristics at material boundaries. The spectra in LSC were validated with the measurements for carbon-14 beta decay nuclide. The calculated efficiencies showed good agreement with the measurements.