Experiments with longitudinally polarized electrons in a storage ring using a Siberian snake

We report on first measurements with polarized electrons stored in a medium -energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was emp loyed to preserve the polarization. Longitudinal polarization at the intera ction point and polarization lifetime of the stored electrons were determin ed with laser backscattering. Spin observables were measured for electrodis integration of polarized He-3, with simultaneous detection of scattered ele ctrons, protons, neutrons, deuterons, and He-3 nuclei, over a large phase s pace.