Lattice steering (channelling) of relativistic positrons from positive muons implanted in crystals

We report on the first observation of the lattice steering (“channelling”) of relativistic positrons (e⁺) resulting from the decay of thermalized positive muons (μ⁺), implanted in an Au single crystal at 100 K. The steering effect manifests itself in a blocking pattern in the lang100rang crystal directions (relative depth at least 20%, FWHM about 0.1°) and supports the view that at low temperatures μ⁺ in Au are well localized in octahedral interstices. The potential of the new technique is briefly outlined.