Estimation of dose and elapsed time after unrecognized high-dose radiation exposure using the continuous-wave optically stimulated luminescence from Mg2SiO4:Tb

Abstract For precisely estimating dose and elapsed time after an unrecognized high-dose radiation exposure in radiological emergency, applicability of the continuous-wave optically stimulated luminescence (CW-OSL) signals from Mg2SiO4:Tb (MSO) was investigated. Small disks of MSO were irradiated with β-rays from a Sr-90 source and their CW-OSL signals were analysed. The CW-OSL curves obtained by stimulation with a blue light (λ = 458 nm) at 5, 10, 20, 50 and 1,119 h after irradiation indicated that they have short- and long-life components; each component was empirically deconvoluted to the sum of two exponential functions. Through repetitive regression analyses on those curves, a practical method for estimating the dose and elapsed time after an unrecognized radiation exposure was proposed. Results of blind tests indicated that the accuracy of absorbed dose estimation using this method was satisfactory while the estimated elapsed times were accompanied with considerable uncertainties.