[en] The polarization mechanism of alpha peak which occurs at the higher temperature than the electret-forming temperature Tsub(f), as reported in a previous paper, was re-examined. a question whether this polarization relates to the interfaces of electrodes or exists in the volume of polyethylene was made clear. In addition, the relationship between the carrier source causing the polarization and the crystallization was investigated in view of the heat treatment effect and the comparison of thermally stimulated current between the polyethylene specimen of low density and that of high density. Some knowledge on beta-peak, obtained by this experiment, is included. The specimen films were prepared by inflation method. Gold was vacuum-evaporated on the films, and the films were irradiated with 4 Mrad gamma-ray from a Co-60 source in air at dose rate from 8x10⁴ to 6x10⁴ rad/hr. After that, the films were held at the temperature Tsub(f), and electric field Esub(f) was applied to them for 45 minutes. The value of Esub(f) was 190 kv/cm for the high density polyethylene, and 300 kv/cm for the low density one. The polarized conditions were frozen with liquefied nitrogen. The thermally stimulated current was obtained by raising the temperature up to the melting point at rate of 2⁰C per minute. The experiment revealed that the peak was caused by the polarization uniformly distributed within bulk. The carrier and recombination center produced by the ionization with gamma-ray took part in the polarization. The two site hopping model suggested that the skip distance of carrier was related to the lamella structure. (Iwakiri, K.)