Preliminary results of a dosimetric system for personal dose equivalent assessment

Full text: Thermoluminescence (TL) or thermally stimulated luminescence dosimetry has been actively developed in the past decades thanks to its successful applications. CaSO4:Dy is one of the most useful and sensitive thermoluminescence dosemeter material for radiation dosimetry. Because of its high sensitivity and stability of the response, it is often used in environmental and personal dosimetry. At IPEN, the Personal Monitoring against external radiation is provided using a TLD badge based on CaSO4:Dy Teflon TLD disc. The TLD discs are mounted in a plastic badge, under plastic filters (2.3 mm thick), lead filters and lead filters with a hole. In this work, the thermoluminescent phosphor CaSO4:Dy is used in the form of sintered discs with 6 mm in diameter and 1 mm in thickness mounted on a plastic badge under different metal filters, to determine the individual dose equivalent according to national and international recommendations. The TLD discs of CaSO4:Dy were placed between plastic filters, copper plus plastic filters and copper plus lead filters to assess the personal equivalent dose, in a new TL dosemeter developed at IPEN. The thermoluminescence dosimetry reader 3500 (Harshaw Model) was employed for the readout of the irradiated dosemeters. The TL detectors were irradiated with gamma rays using a 60Co source over the range from 1 to 100 mGy and always carried out at normal incidence. The photon energy dependence response was investigated using an X ray tube operated at a potential of 160 kV, with average energy ranging from 33 to 118 keV and normalized to 60Co. Preliminary results on reproducibility, radiation dose response and energy dependence show the possibility of their use for estimating the personal equivalent dose. (author)