title: Radiation effect on positronium formation in solid state nuclear track detector.
abstract: The effect of alpha-particles on CR-39, a material used in solid state nuclear track detectors (SSNTDs), has been investigated using the positron annihilation lifetime (PAL) technique. The samples were irradiated using a (238)Pu alpha-source of energy ranging from 1 to 5 MeV and with different doses ranging from 0 to 57.87 mGy. The ortho-positronium (o-Ps) lifetime, tau(3), shows a slight increase as the irradiation dose increases, while a rapid change in the o-Ps intensity, I(3) at 10 mGy was found. In addition, the PAL parameters (tau(3), I(3)) have been studied as a function of the energy of alpha-particles. The obtained results indicate that the o-Ps lifetime increases slightly with increasing energy of the alpha-particle. On the other hand, the o-Ps intensity decreases exponentially with increasing alpha-particle energy, plateaus, and finally increases. The data show that the track diameter increases with decreasing energy of the alpha-particle, while the track density increases with increasing the irradiation dose. A correlation between the track diameter and the o-Ps hole diameter was observed.
authors.affiliation: Physics Department, Faculty of Science, El-Minia University, B.O. 61519 El-Minia, Egypt. hamdyfm@link.net <hamdyfm@link.net>
authors.forename: Hamdy F M
authors.initials: HF
authors.lastname: Mohamed
authors.forename: M
authors.initials: M
authors.lastname: Abd El-Hady
authors.forename: E E
authors.initials: EE
authors.lastname: Abdel-Hady