| Résumé | The radiation absorption characteristics of LiF thermoluminescence dosemeters (TLDs) are such that the TLD response per unit air kerma is expected to be almost the same for 137Cs and 60Co gamma rays. However, various reports in the literature suggest that the response per unit air kerma is several per cent greater for 137Cs than for 60Co. The response of LiF per unit air kerma has been measured under well defined conditions using 137Cs and 60Co gamma rays. Measurements were carried out with LiF chips mounted in Lucite and aluminium holders as well as in commercial holders. For the Lucite and aluminium holders, the effect on the TLD response of photon attenuation and scattering was estimated by varying the wall thickness of the holder. After correcting for the effect of the Lucite and aluminium holders, the response per unit air kerma was 2.5 ± 0.7% greater for 137Cs than for 60Co. For TLDs mounted in a commercial holder which uses aluminium for build-up, the response to 137Cs was 5.8 ± 0.6% greater than to 60Co. For a commercial holder made largely of plastic, the corresponding result was 2.2 ± 0.9%. Our results show that the holder can play an important role in enhancing the response per unit air kerma of LiF TLDs to 137Cs relative to 60Co gamma rays. However, part of the enhancement may be due to a change in the TLD response with LET. |
|---|
