Positron annihilation in neutron-irradiated nickel single crystals

Abstract

Recently Mogensen et al¹ and Cotterill et al² have reported appreciable effects of voids on positron annihilation in polycrystalline molybdenum heavily irradiated by fast neutrons at elevated temperatures. These authors found that the voids cause change to the characteristics of annihilation process more severely than other lattice defects such as vacancies and dislocations. In order to study the annihilation behavior of positrons in fcc metals containing voids, it is aimed to investigate the effect of voids on the angular correlation curve and its recovery behavior by measuring positron annihilation in neutron-irradiated nickel single crystals. In the present study, a nickel in-situ activation method is used taking advantage of a nuclear reaction ⁵⁸Ni(n, p)⁵⁸ Co .