  MOLLER is a future experiment designed to measure parity violation in Moller
scattering to extremely high precision. MOLLER will measure the right-left
scattering differential cross-section parity-violating asymmetry APV , in the
elastic scattering of polarized electrons off an unpolarized LH2 target to
extreme ppb precision. To make this measurement, the polarized electron source,
generated with a circularly polarized laser beam, must have the ability to
switch quickly between right and left helicity polarization states. The
polarized source must also maintain minimal right-left helicity correlated beam
asymmetries, including energy changes, position changes, intensity changes, or
spot-size changes. These requirements can be met with appropriate choice and
design of the Pockels cell used to generate the circularly polarized light.
Rubidium Titanyl Phosphate (RTP) has been used in recent years for ultra-fast
Pockels cell switches due to its lack of piezo-electric resonances at
frequencies up to several hundred MHz. However, crystal non-uniformity in this
material leads to poorer extinction ratios than in commonly used KD*P Pockels
cells when used in hald-wave configuration. It leads to voltage dependent beam
steering when used in quarter-wave configuration. Here we present an innovative
RTP Pockels cell design which uses electric field gradients to counteract
crystal non-uniformities and control beam steering down to the nm-level. We
demonstrate this RTP Pockels cell design is capable of producing precisely
controlled polarized electron beam at Jefferson Laboratory, a national
accelerator facility, for current experiments, including the recent PREX II
measurement, as well as the future MOLLER experiment.
