Design of a radioluminescence dosimetry system with photon energy discrimination capability for area monitoring

Area monitoring, including environmental and workplace radiation surveillance, is essential in settings with significant radiation exposure such as nuclear reactors, accelerator facilities, contaminated waste sites, and NORM-affected zones in the oil and gas industry. Photon energies in these environments typically range from 20 to 30 keV to several MeV, requiring dosimetry systems whose response accounts for energy dependence. This study explores the feasibility of using a real-time radioluminescence (RL) fiber dosimetry system designed to correct for energy-dependent detector response via photon energy discrimination. The system comprises multiple RL sensors with varying filtration layers, each coupled to transmission fibers. The primary scintillator is a 2 cm long, 1 mm diameter cerium-doped silica fiber, selected for its high sensitivity and well-characterized energy-dependent behavior. Monte Carlo simulations using the TOPAS/Geant4 tool were conducted to model the RL sensors and design filter combinations for energy correction, following ISO 4037 recommendations. The Low Air Kerma Rate Series was used as the reference photon spectra, and dosimeter responses were evaluated relative to the ¹³⁷Cs reference energy. Simulation results indicate that an optimized combination of filtered RL elements achieves reliable energy discrimination over the range of 10 keV to 1.5 MeV, with effective response correction for photon energies above 80 keV, thereby improving the accuracy of the calculation of ambient dose equivalent, H∗(10). These findings highlight the system's potential to provide accurate real-time dose assessment in workplace and environmental monitoring applications.