Real time dose rate meter for gamma radiation using LDPE and PMMA in presence of 1-5 kV/mm electric field

Since polymers possess equivalent atomic number and mass density similar to soft tissue and are easily available material, the feasibility of their application in environmental dosimetry is worth investigating. The concept of radiation-induced conductivity in polymer dielectrics is utilized to develop an environmental dose rate meter for gamma radiation in real time. For this purpose, layers of PMMA (polymethylmethacrylate) and LDPE (low density polyethylene) polymers as two tissue equivalent samples were radiated with a 137Cs source of 0.2 mC activity. The dielectric sample received dose rate of 0.12-24.50 mSv/h at various distances from the source. The dielectric was sandwiched between two copper electrodes of 1 mm thickness and thus electrons liberated in the dielectric by gamma ray photons produce electric current proportional to number and energy of impinging photons. In this experimental work, LDPE and PMMA samples were constantly exposed to gamma radiation and the changes in the current were monitored online. Dosimetry characteristics namely dose rate response, linearity, bias polarity, angular dependence and reproducibility for such tissue-equivalent dose rate meter for environmental applications were investigated. The results show that the 5 mm LDPE can be considered as a real-time environmental dose rate meter and can easily be used for radiation dosimetry purposes while requiring calibration.