RESPONSE COMPARISONS OF ELECTRET ION CHAMBERS, LIF TLD, AND HPIC

During each quarter of 1991 electret ion chambers, (LiF)-Li-mat, (LiF) -Li-6, and (LiF)-Li-7 thermoluminescence dosemeters, all integrating i onising radiation monitors, were placed at a location in the grounds o f the National Institute of Standards and Technology. One group was ex posed to the total ambient field, while a second group was sealed for testing a method of protection against radon gas intrusion. A high-pre ssure ion chamber at the same location provided another measure of the field. Simultaneously with the environmental response test, other sea led and unsealed groups of electret ion chambers and thermoluminescenc e dosemeters were exposed during each quarter to discrete exposures fr om calibrated sources of Co-60 and Cs-137. All responses were evaluate d at the end of each quarter. The results indicated that the electret ion chamber gave results comparable to thermoluminescence dosemeters f or routine environmental monitoring. No significant difference was fou nd for any monitor type when sealed results were compared with unseale d results. The electret devices gave results that were, on the average , closer to the pressurised ion chamber results than did the thermolum inescence devices for both the sealed and unsealed sets for the ambien t fields, and the electret devices also gave results closer to the del ivered air kerma values than did the thermoluminescence devices in the deliberate exposure test. The electret ion chambers' responses showed a somewhat greater variability than did the thermoluminescence doseme ters' responses.