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 t o 7.6 x 10(11) cm(-2)) from an accelerator, and (iii) gamma-rays (up t o 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 irradiati on, all the samples were subjected to electron spin resonance (ESR) an alysis. The neutron-and alpha-irradiated samples failed to yield an ob servable ESR signal, thus ruling out the possibility of using ESR in p lace of track counting for the measurement of moderate doses of alphas or fast neutrons in CR-39. The Co-60-irradiated samples produced an E SR signal at doses greater than or equal to 100 Gy and showed a good l inear 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 ro om temperature and at similar to 4 degrees C have also been examined.