Sona Transition Studies in the RHIC OPPIS

In Optically Pumped Polarized Ion Sources (OPPIS), the atomic beam is first electron polarized, and then this polarization is transferred to the nucleus by a suitable perturbing magnetic field. In the BNL OPPIS, the electron polarized atomic beam experiences the perturbing field when it traverses a region where the axial magnetic field reverses direction in a controlled manner--strength and gradient. This is the so-called Sona Transition region, named after P. G. Sona, who first suggested the technique. We have extensively studied how the magnetic field profile in the Sona region affects beam polarization. In these studies, we have observed oscillations in polarization for certain field profiles, and tried explain them. We report on these studies