engleski

Dose response of radiophotoluminescent glass detectors in 3 MeV and 5 MeV proton beam

Our aim was to study the dose response of radio- photoluminescent (RPL) glass dosimeters in low- energy proton beams. A 6 MV Tandem Van de Graaf accelerator connected to a vacuum chamber at the Ruđer Bošković Institute (RBI) was used to produce 3 MeV and 5 MeV proton beams with cross-sectional area 1x1 mm2. These beams were directed at RPL glasses (type FD-7) with dimensions 16x16x1.5 mm3 taken from environmental RPL dosimeters (type SC- 1). The sensitivity of the detectors in the batch was checked before and after the experiments in the 137Cs gamma field at the Secondary Standard Dosimetry Laboratory at the RBI. Standard annealing procedures were used and the dosimeters were preheated before dosimeter response values were measured with the FGD-202 reader. Detectors were exposed to protons fluence ranged from 3.3x106 to 3.3x107 p/mm2 and from 3.5x106 to 4.5x107 p/mm2 for 3 MeV and 5 MeV, respectively. RPL signals were normalised to the number of protons irradiating the detector. The linearity index was calculated as a ratio of normalised RPL signal and reference normalized RPL signal where reference signal originates from the linear dose response range. Linear dose response was confirmed for the whole investigated fluence range for 5 MeV and for the fluence range from 3.5x106 to 2.2x107 for 3 MeV. The corresponding dose linearity index was in the range of 0.95 – 1.05 whilst linearity slope is larger for 5 MeV compared to 3 MeV. For the fluence 4.5x107 p/mm2 of 3 MeV protons, linearity index of 0.59 was calculated suggesting sublinearity. Sensitivity of detectors was not changed after irradiations with proton beams and an average value ± standard deviation was 1.00 ± 0.02. The data collected in the linear dose response range was used to evaluate relative efficiency of RPL detectors to 3 and 5 MeV protons [1].

radiophotoluminescent glass detectors ; dose response ; proton beam

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