Investigation of the Response of PAGAT Polymer Gel Dosimeter for Thermal Neutrons

Two major advantages of polymer gel dosimeters are their ability to determine the integrated 3D dose distribution as well as their ability to the formed in different shapes. In this research, PAGAT gel dosimeter was irradiated by moderated fission neutrons in the Tehran Research Reactor (TRR) thermal column, and the response of the gel was investigated as a change in the spin-spin relaxation rate of MR image of gel Phantoms. The linearity of the response (R2) versus the absorbed dose (D), sensitivity, dose resolution and minimum detectable dose (MDD) were investigated. For calibration of the gel response versus the dose rate, the foil activation analysis was made. In this method the flux map of the thermal column and by using flux to dose conversion factors, given by ANSI/ANS-6.1.1-1997, the flounce related to the absorbed dose map was obtained. To make sure that if there is any epithermal neutron in the thermal column a cadmium cover gold foil was set at the core nearest the thermal column. This study resulted in that PAGAT gel dosimeter can be used as a useful instrument for thermal neutron dosimetry. The sensitivity and MDD of the PAGAT gel dosimeter for thermal neutron was 0.01521±0.00552 Gy -1 s -1 and 1.8 Gy, respectively.