EFFECTS OF LOW-LET RADIATIONS ON CR-39 TRACK DETECTOR

The effects of Co-60 gamma-rays and about 25-MeV pulsed electrons have been investigated on CR-39 plastic nuclear track detector. The bulk e tch rate was measured as a function of the absorbed dose under three d ifferent irradiation conditions; gamma-ray exposure in air at the dose rate of 6 kGy/h, that in vacuum and electron shower in air at 126 kGy /h on average. It was found that the bulk etch rate (V) increased near ly exponentially with the dose (D); V=V(o)exp(kD), and the characteris tic parameter (k) was 35, 9 and 12 MGy(-1), respectively. It is consid ered that a lack of oxygen in damage formation processes could occur m omentarily during a short electron pulse, just similarly to the vacuum effect of reduction in track etch rates in outgassed CR-39 plastic.