Ultraviolet and laser irradiation effects on various batches of CR-39

Different batches of CR-39 were irradiated with various ultraviolet (UV) sources and an excimer laser (λ = 308). A visible change of color of detectors under heavy doses appeared in both cases. The exposure to ordinary (non-linear) UV light sources resulted in an increase of the track sizes, bulk and track etch rate in two different wavelengths 254 nm and 350 nm. While at 300 nm no increase was observed. On the other hand, the exposure to the laser resulted in hardening of the surfaces and therefore a decreasing of track sizes. The laser effect (hardening) was, however, found to saturate above a certain exposure dose. The observed hardening of laser irradiated detectors suggests their possible use in the detection and study of ultra energetic particles without unnecessarily increasing the thickness of the detectors.