  The CP violating phase $\phi_s$ can be measured in the interference between
mixing and decay of $B_s^0$ mesons decaying to CP eigenstates. The phase
$\phi_s$ the decay width difference $\Delta\Gamma_s$ and the average decay
width $\Gamma_s$ have been measured at LHCb, using the full 1 fb$^{-1}$ of $pp$
collisions data at a centre-of-mass energy $\sqrt{s} $ = 7 TeV collected during
the 2011 LHC run.
