An observation of the spin dependence of synchrotron radiation intensity

An experiment dealing with the observation of a change in the synchrotron radiation (SR) intensity during beam depolarization at the VEPP-4 storage ring is described. With a minute of measurement time, the magnitude of the effect exceeded ten statistical errors. The dependence of the sign of the effect on the sign of the magnetic field at the radiation point is demonstrated. The measured magnitude of the jump in the intensity is in agreement with the calculated spin-dependent contribution within a statistical error (equal to 7%). The suggested method is shown to be effectively applied to the observation of the transverse beam polarization in electron-positron storage rings.