Abstract

Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in the design of an extremity dosemeter for mixed beta–photon radiation fields. Both detectors consist of an extremely thin layer of sensitive material with effective thicknesses of 5 and 8 mg cm−2, respectively, held in a 5 mg cm−2 PVC ring holder. Dosimetric performance was analysed according to the ISO 12794 standard and compared with 240 mg cm−2 TLD-100 measurements. In particular, the energy response was obtained for ISO narrow X-ray spectra, 137Cs, 60Co, 204Tl and 90Sr/90Y. From these measurements a mean calibration factor was calculated to estimate Hp(0.07). Subsequently, the performance of the dosemeters was checked for a set of 10 different mixed photon and beta–photon fields. The study shows that the proposed dosemeters can estimate Hp(0.07) in a wide range of mixed beta–photon fields with a maximum deviation from the given dose of 30% and an overall uncertainty of the order of 25% (k = 1). However, the results also highlight a large variability among the different thin detectors and, thus, the standard TLD-100 material is recommended whenever the workplace does not include low-energy beta radiation.

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