Measurement of spin observables using a storage ring with polarized beam and polarized internal gas target

We report the first measurement of analyzing powers and spin correlation parameters using a storage ring with both beam and internal target polarized. Spin observables were measured for elastic scattering of 45 and 198 MeV protons from polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei in a new laser-pumped internal gas target at the Indiana University Cyclotron Facility Cooler Ring. Scattered protons and recoil ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei were detected in coincidence with large acceptance plastic scintillators and silicon detectors. The internal-target technique demonstrated in this experiment has broad applicability to the measurement of spin-dependent scattering in nuclear and particle physics.