Gamma and positron irradiation effects on polypropylene studied by coincidence Doppler broadening spectroscopy

The coincidence Doppler broadening (CDB) technique was applied to study the positron source irradiation effect on γ-irradiated and unirradiated polypropylene. CDB results showed presence of carbonyl groups (CG) whose concentration increase with the γ-irradiation dose. Positron annihilation lifetime (PAL) spectroscopy was used to monitor the positronium (Ps) formation. The γ-irradiation effect on Ps inhibition was significantly weaker than the positron irradiation effect. The joined examination of CDB and PAL data showed that the annihilation on CGs oxygen was not the main reason for the detected Ps inhibition during the positron-irradiation.