Investigations of the use of electron spin resonance for nuclear track counting and gamma-ray dosimetry in CR-39

CR-39 plastic detectors were exposed to (i) alpha-particles from an Am-241 source with different fluences (up to similar to 8.1 x 10(6) cm(-2)), (ii) fast neutrons (similar to 6 MeV, with a fluence of similar to 7.6 x 10(11) cm(-2)) from an accelerator, and (iii) gamma-rays (up to similar to 1.3 x 10(4) Gy) from a Co-60 source. The alpha-particles and neutron-recoils produce "latent tracks" in the CR-39, which are thought to be accompanied by long-lived free radicals. After irradiation, all the samples were subjected to electron spin resonance (ESR) analysis. The neutron-and alpha-irradiated samples failed to yield an observable ESR signal, thus ruling out the possibility of using ESR in place of track counting for the measurement of moderate doses of alphas or fast neutrons in CR-39. The Co-60-irradiated samples produced an ESR signal at doses greater than or equal to 100 Gy and showed a good linear dose curve up to the maximum dose used of similar to 1.3 x 10(4) Gy. The decay rates of the ESR signal from these samples stored at room temperature and at similar to 4 degrees C have also been examined.