First study of the performance of the LHCb muon system with cosmic rays

In this note we report the results of performance obtained for the muon detector during this first year of cosmic rays acquisition of the LHCb experiment. Procedures for optimization of time alignment, threshold setting and noise response have been carried out. Then, the main detector’s characteristics have been tested and studied by means of cosmic rays acquisition in order to achieve a better understanding of its performance and to be prepared for the first pp collisions of the LHC.