First observation of magnetic moment precession of channeled particles in bent crystals

Spin precession of channeled particles in bent crystals has been observed for the first time. Polarized ${\mathrm{\ensuremath{\Sigma}}}^{+}$ were channeled using bent Si crystals. These crystals provided an effective magnetic field of 45 T which resulted in a measured spin precession of 60\ifmmode\pm\else\textpm\fi{}17\ifmmode^\circ\else\textdegree\fi{}. This agrees with the prediction of 62\ifmmode\pm\else\textpm\fi{}2\ifmmode^\circ\else\textdegree\fi{} using the world average of ${\mathrm{\ensuremath{\Sigma}}}^{+}$ magnetic moment measurements. This new technique gives a ${\mathrm{\ensuremath{\Sigma}}}^{+}$ magnetic moment of (2.40\ifmmode\pm\else\textpm\fi{}0.46\ifmmode\pm\else\textpm\fi{}0.40)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$, where the quoted uncertainties are statistical and systematic, respectively. We see no evidence of depolarization in the channeling process.