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Title: Energy response study of thermoluminescent dosimeters to synchrotron radiation in the energy range 10-35 keV
Authors: Bakshi, A K
Dhabekar, B S
Chatterjee, S
Joshi, V J
Kher, R K
Keywords: Synchrotron radiation;energy response;TLDs
Issue Date: Jun-2009
Publisher: CSIR
Abstract:  LiF:Mg,Ti, LiF:Mg,Cu,P and CaSO4:Dy TLDs are worldwide used in the field of medical dosimetry, personnel monitoring and environmental monitoring. In view of the 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 CaSO4:Dy in the form of disc of thicknesses 0.8 mm and 0.4 mm made up of mixture of CaSO4:Dy phosphor and Teflon in the weight ratio 1:3 were used. The energy of the synchrotron radiation was calibrated using a Si (111) double crystal monochromator and several thin foils starting from Zn with Kedge 9.659 keV to KI compound with Kedge 33.169 keV. The energy response of the TLDs were normalized with respect its response to 60Co and corresponding relative response was evaluated. It was found that for CaSO4: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 CaSO4: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 on 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 in the present study, the relative response was always found to be less than 1 for LiF based TLDs. The relative response of the TLDs evaluated in the 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.
Page(s): 172-174
ISSN: 0975-1017 (Online); 0971-4588 (Print)
Appears in Collections:IJEMS Vol.16(3) [June 2009]

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