A hadron/lepton collider with polarized beams has been under consideration
by the scientific community since some years, in the U.S. and Europe.
Among the various proposals, those by JLAB and BNL with polarized electron
and proton beams are currently under closer study in the U.S.
In the BNL Ring-Ring design electrons are stored at top energy
in a ring to be accommodated in the existing RHIC tunnel. The transversely
polarized electron beam is injected into the storage ring at variable top energy, between
5 and 18 GeV. Polarization is brought into the longitudinal direction at the
IP by a couple of spin rotators. In addition
experimenters call for the simultaneous storage of electron bunches
with both spin helicities.
In this paper studies of the attainable beam polarization level
and lifetime in the storage ring at 18 GeV are presented.