New parameters of annealing and re-use of TLDs based on CaSO4:Dy phosphor

A study on CaSO4:Dy TLDs was undertaken to confirm the validity of the annealing treatment (400 degrees C, 1 h) for its re-use. The temperature range of the study was from 230 degrees C to 700 degrees C. The effect of thermal treatments on the TL sensitivity and glow curve structure showed that the lattice of CaSO4:Dy is sensitive to thermal treatment in the temperature range from 350 degrees C to 425 degrees C. It is also seen that both TL sensitivity and peak height ratio (dosimetric peak at 240 degrees C to low temperature satellite peak at 140 degrees C) reduces with an increasing number of annealing cycles in the temperature range from 350 degrees C to 425 degrees C. No significant change was observed in TL emission and ESR spectrum of the phosphor. The study shows that the annealing treatment in the temperature range from 600 degrees C to 650 degrees C could be the best alternative for annealing and re-use of CaSO4:Dy phosphor or a temperature below 350 degrees C for Teflon embedded dosemeters.