Measurement of the cosmic muon charge asymmetry

In late 2008, CMS collected 300 million events from atmospheric cosmic ray muons in a dedicated long run, with the full detector operational assembled in its definitive place along the LHC ring. Using these data, CMS aims to measure the charge asymmetry of cosmic muons, as a function of the muon momentum, from approximately 100~GeV/c up to the TeV/c scale. While the analysis of cosmic muons is not part of the physics program of CMS, it requires high quality measurements that demand good performance of the CMS detector, from the data taking to the reconstruction and analysis software.