A comparison of hypersensitive TL materials in card configurations

There has been great interest expressed in hypersensitive thermoluminescent (TL) phosphors and particularly the newly developed LiF:Mg,Cu,P. These materials exhibit sensitivities one to two orders of magnitude greater than the most commonly used phosphor, LiF:Mg,Ti (TLD-100). This greater sensitivity results in improved signal-to-noise ratios and consequently lower detection thresholds, making the material ideal for low-dose applications such as environmental monitoring. A series of tests has been conducted to characterize the performance of these materials in card format using a Harshaw Model 8800 Automatic TLD Card Reader. Because of temperature sensitivities above 240 degrees C, special precautions must be taken when mounting the material into a card in order to preserve the material trap structure and sensitivity. Accordingly, a process has been implemented whereby the various phosphors are affixed to a polyimide film, then mounted into cards. This paper describes the method used and presents the results from the tests. These test provided data on minimum detectibility, reproducibility, residual effects, sensitivity to ambient light, and linearity. A comparison of the various materials' sensitivity to ionizing radiation is also presented