Energy response study of thermoluminescent dosimeters to synchrotron radiation in the energy range 10-35 keV

LiF:Mg,Ti, LiF:Mg,Cu,P and CaSO(4):Dy TLDs arc worldwide used ill the field of medical dosimetry, personnel monitoring and ell environmental monitoring. In view of file wide spread applications of synchrotron radiation for material research and diagnostic radiology in particular medical imaging, the present study of the energy response of some popular TLDs was undertaken. For the energy response study the most useful energy range 10-35 keV of synchrotron radiation was chosen and the present experimental work was carried out at SYRMEP beam line of Elettra Synchrotron Accelerator facility, Bassoviza, Trieste, Italy. The LiF based TLDs in the form of chips and disc, and CaSO(4):Dy in the form of disc of thicknesses 0.8 mm and 0.4 mm made up of mixture of CaSO(4):Dy phosphor and Teflon in the weight ratio 1:3 were Used. The energy of the synchrotron radiation was calibrated using a Si (1 1 1) double crystal monochromator and several thin foils starting from Zn with K(edge) 9.659 keV to KI compound with K(edge) 33.169 keV. The energy response of the TLDs were normalized with respect its response to (60)Co and corresponding relative response was evaluated. It was found that for CaSO(4):Dy discs the relative response is about 12 at 25 keV which is maximum and subsequently falls down on either side of energy for both 0.4 mm and 0.8 mm thick discs. The relative response at 10 keV Was found to be about 4.5 and 6 for 0.8 mm and 0.4 mm thick discs of CaSO(4):Dy respectively. Maximum relative response of LiF:Mg,Cu,P chip of thickness 0.4 mm Was found to be about 1.26 at 25 keV and it also exhibited lower response oil either side of energy. LiF:Mg,Ti chips and discs Show maximum response at the 30 keV which were 1.33 and 1.39, respectively. At 10 keV which was the lowest energy used ill the present Study, file relative response-was always found to be less than 1 for LiF based TLDs. The relative response of the TLDs evaluated ill file Present experiment was compared with the published value in the literature and also confirmed through theoretical calculation using ratio of mass absorption coefficient of these materials with respect to air.