The target theory applied to the analysis of irradiation damages in organic detectors

The Target Theory was used to explain the radiation damage in samples containing 1% (g//L) of 2,5-diphenyl-oxazolyl (PPO) diluted in toluene and irradiated with 60Co (1.8 Gy/s). The survival molecules of irradiated PPO obeys the bi-exponential mathematical model [74.3 x exp(-D/104.3) + 25.7 x exp(-D/800,0)]. It indicates that 74.3% of the molecules decay with D37=104.3 kGy and 25.7% decay with D37=800 kGy. From the Target Theory it was inferred the energies involved in the irradiation damages which were 0.239 ± 0.031 eV (G=418.4 ± 54.1. damages/100 eV) and 1.83 ± 0.30 eV (54.5 ± 8.9 damages/100 eV). The diameter of PPO molecule estimated from the Target Theory is in the interval of 45.5 to 64.9 angstrom. (author)