Measurement of parity violation in the 6S-7S transition of cesium using stimulated emission

This document describes the design and implementation of a pump-probe polarimetry experiment in a cesium vapor, aiming at a 1% precision measurement of atomic parity violation (APV) induced by Z0 boson exchange. The experimental scheme, relying on induced emission by a probe laser, allows a detection efficiency close to unity, and the left-right asymmetry to be measured is amplified during the propagation of the probe beam in the excited vapour. The interest of the result presented here is to cross-check the unique previous result by an experiment with a completely different design, and hence with completely different systematics, that also allows measurements on long-lived isotopes especially 135Cs (nuclear spin 7/2 like 133Cs, half-life 3 million years). We have demonstrated improvements in polarimetry techniques (rejection of instrumental errors, implementation of a polarization magnifier), especially in pulsed polarimetry (doubly-differential, balanced-mode polarization analysis). But most importantly, the expected pump-probe chiral optical gain has been observed in a Cs vapor. The precision on the θpv measurement has been improved to 2.6%, and the achieved signal/noise ratio allows measurements at the 1% precision level. The achieved precision on lm E1pv is 2 x 10-13 ea0, 15 times better than the measurements obtained with the lead and thallium atoms. Our result is in agreement with the more precise Boulder result. The required amount of cesium is small enough to allow a measurement with 135Cs provided one takes reasonable radioprotection measures. (author)