The variation of the cascade localization induced bias effect with material parameters and irradiation conditions

The distribution of vacancies and interstitials produced by collision cascades is expected to be highly condensed with vacancies surrounded by interstitials. The effect, which comes from the imbalance of reactions between vacancies and interstitials originating from the difference of the initial distribution of point defects (cascade localization induced bias, CLISB), is examined with a method based on the solution of the diffusion equations of cascade dissipation with a variety of initial conditions. The strength of CLIB is defined as the difference of jumps between interstitials and vacancies before their annihilation. The variation of the strength with material parameters and irradiation conditions is estimated. The strength is higher in larger cascades than in smalles oner if the difference of the distributions is the same. It is also higher in compact cascades such as in Au and Ag than in dilute cascades such as Al and Fe because of the difference of the initial distributions. In subcascade structures, as in Cu and Ni, CLIB occurs in each subcascade and the effect per damage energy is not changed by PKA energy. (orig.)