Prospects for Measuring Parity Nonconservation in AN Optically-Pumped Cesium Beam

An experiment to measure the parity non-conserving transition amplitude between the 6S and 7S states in atomic cesium is described. The value of this transition amplitude is predicted by the Weinberg-Salam model of electroweak interactions, and comparison of experiment and theory is a test of the electroweak theory which complements high -energy experiments. The experiment outlined here is very similar to previous experiments performed by this group but employs an optically-pumped cesium atomic beam and a higher 6S to 7S exciting laser power to increase the signal-to-noise ratio. The efforts to optically pump the atomic beam are described in some detail. 99.98% of the atoms in the beam were placed into a single hyperfine level, allowing a shelving approach to be used to detect 6S to 7S transitions. This shelving technique requires very low-noise excitation of 6S to 6P transitions, which is accomplished by a diode laser with optical feedback from a diffraction grating. The 6S to 6P excitation rate signal-to-noise ratio is greater than 3 times 10^5 in 1 second and approaches 2 times 10^6 at higher frequencies. Higher 6S to 7S exciting laser power is obtained by using improved mirrors in a power buildup cavity, yielding a one-way power buildup factor of 10^4. The new power buildup cavity's reduced resonance linewidth of 10 kHz required further frequency stabilization of the dye laser, described herein.