Muon Diffusion and Trapping Studies in High Purity Vanadium

摘要

The first results of a study of the effects of varying impurity concentration on the temperature dependence of the depolarization rate of positive muons implanted into vanadium are presented. Data are reported for the most highly purified polycrystalline sample yet measured, and the same sample subsequently doped with about 500 ppM oxygen by weight. The data for the pure sample shows a low depolarization rate (< .15 mu sec exp -1 ) at all temperatures measured, showing a broad minimum centered at approx. 35 K, followed by a sharp peak near 90 K and a rapid drop to negligible values at 200 K. The data are contrasted with previously published data on less pure samples, and call into question previous interpretations of the behavior of the mu exp + at low temperatures in impure vanadium as one-phonon-assisted tunneling. 6 references. (ERA citation 04:035116)