Effect of positive muon trapping by dislocations

Aluminium was deformed at room temperature so that vacancies are annealed out and only dislocations remain. The muon spin depolarization rate was found to be decreased as the temperature is raised. This indicates that some trapping-detrapping occur. Fitting the spin relaxation to the calculated spin relaxation function for the trapping-detrapping model, the values of the activation energy for the trapping rate and detrapping rate and of the depolarization rate at the trapping are found to be 25 meV, 66 meV, and 0.24 μsec-1, respectively for the best fit. This indicates that positive muons diffuse to dislocations and diffuse along dislocation lines and are trapped at a jog of the dislocation, and detrap from the jog. (Auth.)