LOW-DOSE MEASUREMENTS WITH CASO4DY, CASO4TM AND CASO4DY TEFLON DOSIMETERS - A COMPARATIVE-STUDY

A comparative study of the low dose measurement capabilities of CaSO4:Dy, CaSO4:Tm in powder form and CaSO4:Dv embedded Teflon discs was carried out. The detection threshold of CaSO4:Dy powder is lower than that of Teflon discs because there is less spurious TL from powder and most of it is removable with nitrogen flow. Preliminary studies indicate that the spurious TL from CaSO4:Dy Teflon discs is higher and not entirely removable with nitrogen flow, which results in the overestimation of radiation doses at low dose levels. Higher sensitivity and other desirable dosimetric properties of CaSO4:Tm made in Hungary, such as reduced intensity of the fast fading low temperature TL peak near 100-degrees-C and reduced spurious TL, are confirmed. The ratio of TL sensitivities of CaSO4:Tm (Hungary), CaSO4:Dy (Hungary) and CaSO4:Dy (India) is 1.5:1.26:1.0.