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 apolarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full)Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interactionpoint and polarization lifetime of the stored electrons were determined with laser backscattering. Spinobservables were measured for electrodisintegration of polarized