CR-39 plastic nuclear track detectors have been cast with no additive and with methyl methacrylate

diallyl phthalate

dibutyl phthalate and di-（2-ethylthexyl） phthalate. After irradiated with 5.15 MeV a particles

the responses of the detectors were found to be significantly different for each kind of additive. The performance was reported of a new CSR solid state nuclear track detector

the CR-39 （DPA）. The sheets with 1 % addition of DPA of CR-39 monomer were more sensitive than those of pure CR-39.