There are several major new experimental initiatives at Bates that are user-driven, user-initiated projects. These projects significantly increase the physics ``reach'' of the facility. They also indicate the interest and committment of this community to enhancing the experimental facilities at Bates.
The OOPS collaboration is building a quartet of small magnetic
spectrometers that can detect protons out of the (e,e) plane. This allows
several additional electromagnetic response functions to be determined
including the electron asymmetry
. This observable will be
essential for constraining FSI in (e,e
p) reactions on nuclear targets and
the non-resonant components in the
excitation of the proton. The
basic spectrometer modules are complete as are the two satellite supports;
the gantry which supports the other two OOPS modules should be completed
this year.
The FPP collaboration has built a proton focal plane polarimeter for the
OHIPS spectrometer. This will allow (,e
) and (e,e
) reactions over the
full proton energy range available at Bates. As the spin transfer
coefficients typically result from interference between amplitudes, the FPP
will allow small, but interesting, reaction components, such as the
quadrupole amplitude of the
transition, to be studied.
The FPP has been calibrated at IUCF, installed in OHIPS and the first
experiments have begun.
The SAMPLE collaboration will measure parity violating electron scattering from the proton and, later, the deuteron. The primary goal is to determine the contribution of strange quarks to the magnetic moment of the proton. They build on the experience developed in the Bates carbon parity experiment where systematic effects were controlled at the level of 0.02 ppm [So90]. In SAMPLE, backward scattered electrons are detected in a large solid angle (2 sr) air Cherenkov detector constructed especially for this experiment. A state-of-the-art high power (600 W) cryogenic target is also utilized.