MEASUREMENT OF PARITY NONCONSERVATION AND AN ANAPOLE MOMENT IN CESIUM

The amplitude of the parity-nonconserving transition between the 6S an d 7S states of cesium was precisely measured with the use of a spin-po larized atomic beam. This measurement gives Im(E1(pnc))/beta = -1.5935 (56) millivolts per centimeter and provides an improved test of the st andard model at low energy, including a value for the S parameter of - 1.3(3)(exp)(11)(theory). The nuclear spin-dependent contribution was 0 .077(11) millivolts per centimeter; this contribution is a manifestati on of parity violation in atomic nuclei and is a measurement of the lo ng-sought anapole moment.