CO 2 diffusion from X-ray and γ-ray irradiated CR-39 plastic

Abstract

The CO 2 gas produced inside CR-39 plastic track detectors irradiated by both X-rays and γ-rays is found to diffuse out with time. The diffusion half-time of the gas was measured for both the irradiation cases. For X-rays, the irradiation doses ranged from 220 to 500 kGy and the half-time was found to decrease with increase in irradiation dose from 7.7 to 6.0 days. For γ-rays, the irradiation doses ranged from 130 to 950 kGy and the half-time of the gas diffusion was also found to decrease with increase in irradiation dose from 9.0 to 4.0 days. The results can be attributed to the degradation action of the energetic photons on the plastic with increase in dose, the CO 2 diffused out more readily at a higher rate through the more degraded plastic. No significant difference in the diffusion half-time as a function of dose between X-ray and γ-ray irradiation was found.