Repolarization of Negative Muons by Polarized $^{209}$Bi Nuclei

Abstract

A large µ − polarization was achieved in muonic Bi atoms with the help of the strong hyperfine field in a polarized nuclear target. Using 209 Bi nuclei polarized to (59 ± 9)% in ferromagnetic BiMn, we observed a µ-e decay asymmetry of (13.1 ± 3.9)%, which gives µ − polarization per nuclear polarization equal to −1.07 ± 0.35. This value is almost consistent with −0.792 calculated for nuclei with spin I = 9 2 and a positive magnetic moment under the assumption that the hyperfine interaction becomes effective in the lowest muonic states.