DIPOLAR MAGNETIC-FIELD AND FERMI CONTACT FIELD AT THE MU-FE AT VERY-LOW TEMPERATURES( SITE IN ALPHA)

In a longitudinal mu+SR experiment on a high-purity alpha-Fe single cr ystal sphere magnetically saturated in a [ 111 ] direction damped osci llations (wiggles) were observed in a temperature range 30 mK to 600 m K and in a certain regime of applied magnetic fields B(appl). Meassure ments of the wiggle frequency as a function of B(appl) give us directl y the Fermi field B(Fermi) = (-1.13 +/- 0.02)T and the dipolar magneti c field \B(dip)parallel-to\ = (0.66 +/- 0.03)T. B(dip)parallel-to was used to determine the prefactor in the Arrhenius law obeyed by the mu hopping rate between 100 K and 1000 K. A comparision with the corresp onding values for protons and deuterons suggests diffusion via the adi abatic mechanism.