The polarization experiments, E154 and E155, in deep inelastic electron
scattering require the 50-GeV polarized beam and the polarized targets at
End Station A at SLAC. The polarized He target for E154 at SLAC is
based on spin-exchange optical pumping technique and represents a technical
break-through for our field. As a result of the successful use of a spin-
exchange polarized
He target in the electron beam at MIT/Bates, a
large-scale spin-exchange
He target was proposed and used for
experiment E142. Similar targets are now approved for experiments at
MIT/Bates and CEBAF. The E154 target is presently being constructed and
will be installed for the scheduled experiment during 1995. Experiment E155
will make use the polarized NH
and ND
targets as were used in
experiment E143. These targets are state-of-the-art, are highly polarized,
and can withstand relatively high beam currents (100 nA).
The SLAC experiments are approved and scheduled. However, the future program in ESA is uncertain after experiments E154-5 are completed in the next two-three years. There exist no plans for ESA after these experiments. The priority of SLAC is the completion of the B-Factory and initiation of a B-Factory physics program.
The HERMES experimental program very likely will require a laser-driven H and D target as well as a RICH detector for particle identification. The HERMES program will likely require dE/dx detectors, recoil detectors, a gas jet target and improved beam polarimetry.
The CEBAF experiments will require high current, high figure-of-merit 6-GeV polarized electron beams to make measurements of the spin structure function of the neutron as well as other experiments planned for tests of the Drell-Hearn-Gerasimov sum rule.