Muon location and mobility in high-purity metals

Positive muons are expected to be easily trapped by imperfections including impurities in metals (Seeger 1975). Therefore it is essential to study muon diffusion and localization on well-characterized high-purity materials. The sensitivity to impurities has been confirmed by recent ~SR studies on Nb (Birnbaum et al. 1978, Borghini et al. 1978). In this note we report results of DSR experiments on high-purity monocrystals of beryllium, tantalum, and niobium. Starting from high-purity material, the Be target was vacuum melted and zone-refined i0 times resulting in a residual resistivity ratio F ~ R2g3K/R4.2K = 400, corresponding to a purity of 99.993 wt% (Aldinger 197~).0f the remaining 70 wt.ppm impurities, the principal constituent was iron. The preparation of the Ta (F = 5000, interstitial C+O+N