  We present the atomic parity violation measurements made in Cs vapour using a
pump-probe scheme. After pulsed excitation of the 6S-7S forbidden transition in
the presence of a longitudinal electric field, a laser beam resonant with one
of the 7S-6P transitions stimulates the 7S atom emission for a duration of 20
ns. The polarisation of the amplified probe beam is analysed. A seven-fold
signature allows discrimination of the parity violating linear dichroism, and
real-time calibration by a similar, known, parity conserving linear dichroism.
The zero-field linear dichroism signal due to the magnetic dipole transition
moment is observed for the first time, and used for in-situ determination of
the electric field. The result, ImE1^{pv}= (-808+/- 21) 10^{-14} ea\_{0}, is in
perfect agreement with the corresponding, more precise measurement obtained by
the Boulder group. A transverse field configuration with large probe
amplification could bring atomic parity violation measurements to the 0.1%
accuracy level.
