Positron interactions in metals

Abstract

The thesis introduces positrons, their creation and annihilation, and describes how they can be used to demonstrate channelling. The design and construction of the electronic system used to investigate channelling is described and the system is also used in an experiment to find the stopping power of positrons in aluminium. Details are then given of various methods previously used to obtain the mono vacancy formation energies in metals together with a new method based on the phenomenon of Doppler Broadening of the positron annihilation radiation frequency. The relative merits of the different methods are discussed and values for the monovacancy formation energy in Copper, Aluminium and Zinc obtained from experimental data are presented and compared with previous values. A brief description is then given of an extension of the Doppler Broadening technique into the field of neutron irradiation damage together with some tentative conclusions.