Use of CaF2:Dy (TLD-200) in beta dosimetry

Preliminary data using CaF2:Dy (TLD-200) detectors have been obtained using a technique similar to that suggested by Koczynski et al. The CaF2:Dy chips used in this study were the large (1/4'' x 1/4'' x 0.035'') hot-pressed chips available commercially from the Harshaw Chemical Co. These detectors provided a higher sensitivity than the smaller, more conventional TLD chips. In this initial study, no attempt was made to modify the response by introducing other materials into the TLD chips. Front-to-back TL emission ratios were investigated for exposures in gamma, beta, and mixed beta-gamma radiation fields. In addition, the influence of selected shielding materials on the front-to-back ratio was investigated in these same radiation fields. Preliminary results indicate the ability to measure accurately the absorbed dose due to beta radiation in an exposure situation in which the gamma to beta ratio was about 10:1. These results will be presented, their implications for further research, and their influence on personnel dosimeter design will be discussed