Thermoluminescence, electron paramagnetic resonance, and structural characterization of natural prehnite for high-dose radiation dosimetry

Abstract

Natural prehnite was evaluated as a thermoluminescence (TL) material for high-dose dosimetry. XRF identified SiO₂, Al₂O₃, and CaO as major constituents. Prehnite samples annealed between 200 and 800 °C (1 h) were examined by XRD and Rietveld analysis, confirming prehnite as the majority phase and revealing calcite and vaterite after heating. The 600 °C sample provided the highest TL yield and was selected for detailed study. Fading tests showed a ~40% loss in the 240 and 350 °C peaks over 5.42 days (130 h), followed by signal stability. Dose–response demonstrated, for the 245 °C peak and 325 °C peak, linear regions in the ranges of 0.1–2 kGy and 0.5–20 kGy, respectively, with saturation occurring between 30 and 100 kGy. Kinetic parameters were obtained using TM-Tstop, initial-rise, and variable-heating-rate methods; glow-curve deconvolution resolved five TL components. TL spectra displayed an intense band near 530 nm and a weak band at 550 nm, suggesting two main recombination centers.