Prospects for the measurement of B_s oscillations with the ATLAS detector at LHC

The prospects for the measurement of $B_s^0$ oscillations with the ATLAS detector at the Large Hadron Collider are presented. $B_s^0$ candidates in the $D_s^{-}{\pi }^{+}$ and $D_s^{-}{a}_1^{+}$ decay modes from semileptonic events were fully simulated and reconstructed, using a detailed detector description. The sensitivity and the expected accuracy for the measurement of the oscillation frequency were derived from unbinned maximum likelihood amplitude fits as functions of the integrated luminosity. A detailed treatment of the systematic uncertainties was performed. The dependence of the measurement sensitivity on various parameters was also evaluated.