UV-C radiation effect on nuclear tracks of different ions in polycarbonate

Abstract

The neutron autoradiography technique was developed in our laboratory using polycarbonate nuclear track detectors, to qualitatively and quantitatively analyze boron distribution and concentration in biological samples from experimental models coming from Boron Neutron Capture Therapy research. Spatial resolution was later improved by generating an imprint of the biological sample (e.g. cellular culture, tissue sections) on the detector surface, which can be microscopically observed together with nuclear tracks originated by 10B capture products. This methodology was developed for polycarbonate detectors and involves UV-C light irradiation of the sample-detector assembly. The chemical etching process of the detector, usually performed to enlarge the nuclear tracks, also “reveals” the imprint of the sample. In this work we report a fading effect in nuclear tracks due to UV-C exposure. Significant differences in track density produced by alpha ions and Li recoils coming from the neutron capture reaction, 10B(n,α)7Li, were found between exposed and unexposed to UV-C light (254 nm wavelength) polycarbonate foils. A decreasing relation between track density and exposure time to UV-C radiation could also be observed for these ions. To analyze the effect produced by UV-C radiation on nuclear tracks of different ions, polycarbonate detectors irradiated with 7Li, 12C, 16O, 32S, 127I, 197Au beams and air degraded alpha particles from a241Am source were also studied. A wavelength dependent photodegradation mechanism affecting the polycarbonate detector would be altering the nuclear tracks development in different ways, according to ion damage characteristics.