CMS detector performance

The performance of the CMS detector will be presented with special attention for B physics. The reconstruction of charged particles heavily depends on the tracker detector, and are the key elements to the reconstruction of primary and secondary vertices that are used for the identification of the weak decay of B-hadrons. The distribution of the track impact parameters and vertex properties are compared with the prediction of Monte Carlo simulation. Finally the performance of vertex reconstruction and B identification algorithms as directly derived from data are shown. Special attention will also go to the reconstruction and identification of muons as they are crucial in the reconstruction of the golden B decay modes and the beyond-the- Standard-Model searches. The muon detection and reconstruction efficiency determined with the pp collisions are described. The performance of the trigger, necessary to identify the events of interest, will be discussed.