Infrared and visible thermoluminescence signals of Tm-doped CaF2 measured by a semiconductor photodiode

This brief note presents preliminary results of tests using a semiconductor photodiode in a reader for thermoluminescent dosimetry. CaF2 TLD detectors doped with 0.35% Tm were used, annealed in the usual way as for clinical neutron dosimetry, and irradiated with a Co60 unit having a dose rate of 0.2387 Gy min-1. Correction for infra-red sensitivity of the photodiode is discussed and results of tests for dose dependence of glow peak amplitudes from 100 and 1500C peaks presented. For a signal to noise ratio of 10 from the 1500 peak there was a minimal detectable doe of 37 mGy for the visible and 2.4 mGy for the infrared glow curve of the TLD 300 detectors used in this study. (U.K.)