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 car ried out. The detection threshold of CaSO4:Dy powder is lower than tha t of Teflon discs because there is less spurious TL from powder and mo st of it is removable with nitrogen flow. Preliminary studies indicate that the spurious TL from CaSO4:Dy Teflon discs is higher and not ent irely removable with nitrogen flow, which results in the overestimatio n of radiation doses at low dose levels. Higher sensitivity and other desirable dosimetric properties of CaSO4:Tm made in Hungary, such as r educed intensity of the fast fading low temperature TL peak near 100-d egrees-C and reduced spurious TL, are confirmed. The ratio of TL sensi tivities of CaSO4:Tm (Hungary), CaSO4:Dy (Hungary) and CaSO4:Dy (India ) is 1.5:1.26:1.0.