Measurement of the spin dependence of Rayleigh scattering

The spin dependence of Rayleigh scattering has been measured by scattering 129-keV $\gamma$ rays of ${}_{}{}^{191}{}_{}{}^{}\mathrm{Os}$ on a magnetized iron-cobalt alloy. The circularly polarized $\gamma$ radiation was produced by nuclear polarization of ${}_{}{}^{191}{}_{}{}^{}\mathrm{Os}$ alloyed in iron at temperatures of 20-30 mK. For a mean scattering angle of 32° a spin dependence of $\Delta \sigma =(-0.216\mathrm{}\pm 0.033)\%$ has been found, which has the same sign as spin-dependent Compton scattering, the larger cross section appearing for the case where the photon and electron spins are antiparallel.