J. Phys. IV France 03 (1993) C4-283-C4-285
Positron irradiation effects on polypropyleneT. SUZUKI1, T. MIURA1, Y. OKI1, M. NUMAJIRI1, K. KONDO1 and Y. ITO2
1 National Laboratory for High Energy Physics, Radiation Control Center, Oho, Tsukuba, Ibaraki 305, Japan
2 Research Center for Nuclear Science and Technology, The University of Tokyo, Tokai, Ibaraki 319-11, Japan
Positron irradiation effects on polypropylene (PP) and polyethylene during the positron lifetime measurements have been studied in detail. The effect, which was to decrease I3, has been found to be larger in air than in vacuum. For PP, when the lifetime measurements were performed at temperatures above 348K, the radiation effect was scarcely observable. However at low temperature the radiation effect was accumulated and I3 was decreased during the measurements. Irradiation of Co-60 \Upsilon-ray up to the dose of 300 MRad also lead to similar decrease in I3, but the decrease due to \Upsilon-irradiation was not as large as that due to the positron irradiation. Irradiation effect of positrons appears to be different from that of \Upsilon-rays.
© EDP Sciences 1993