  We have detected, by using stimulated emission, an Atomic Parity Violation
(APV) in the form of a chiral optical gain of a cesium vapor on the 7S -
6P$_{3/2}$ transition,consecutive to linearly polarized 6S-7S excitation. We
demonstrate the validity of this detection method of APV, by presenting a 9%
accurate measurement of expected sign and magnitude. We underline several
advantages of this entirely new approach in which the cylindrical symmetry of
the set-up can be fully exploited. Future measurements at the percent level
will provide an important cross-check of an existing more precise result
obtained by a different method.
