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 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-degrees +/- 17-degrees. This agrees with the prediction of 62-degrees +/- 2-degrees using the world average of SIGMA+ magnetic moment measurements. This new technique gives a SIGMA+ magnetic moment of (2.40 +/- 0.46 +/- 0.40),mu(N), where the quoted uncertainties are statistical and systematic, respectively. We see no evidence of depolarization in the channeling process.