Measurement of Bs oscillations at CDF

The first precise measurement of the Bs0-B-bar s0 oscillation frequency Δms with the CDFII experiment is summarized in this talk. The measurement is performed with 1 fb-1 of data collected at the Fermilab Tevatron hadron collider. We find a signal consistent with flavour oscillations; the probability that such a signal is originated by random fluctuations is 0.2%. We measure Δms=17.31-0.18+0.33(stat.)±0.07(syst.)ps-1 [A. Abulencia et al. (CDF Collaboration), Phys. Rev. Lett. 97, 062003 (2006)]. After a brief theoretical overview, I will describe the experimental technique and show the results of the CDF analysis and the |Vtd/Vts| value we infer from this measurement