Positron Annihilation Doppler Broadening Spectroscopy (PADBS) is a characterization technique that is sensitive to damage of radiation in polymers. A damage zone or defect will be created due to the irradiation of Polyallyl diglycol carbonate (CR-39) with α-particles. It is convenient to study this defect caused by α-particle energies using both PADBS and track diameter measurements. An abrupt change in the S and W line-shape parameters has been observed at 3.75 Mev of α- particle energy, while the track diameter shows a continuous decrease for samples irradiated at more than 2.5 MeV of the α- particle energies.