The CMS RPC project, results from 2009 cosmic-ray data

Abstract

Abstract The Resistive Plate Chambers (RPCs) are used in the CMS experiment as dedicated muon triggers both in the barrel and the endcap system. About 3000 square meters of double-gap RPCs were produced and have been installed in the experiment since 2007. The full barrel system and part of the endcaps have been extensively commissioned with millions of cosmic rays collected by CMS. Making use of the redundant muon system composed by drift tubes in the barrel and cathode strip chambers (CSC) in the endcaps which provide independent tracking and trigger information, the performance of the RPCs has been studied in terms of efficiency, cluster size multiplicity, spatial resolution and trigger response. Moreover during this long period of detector operations the stability of the system has been monitored to study the dark current and noise behavior as a function of time. First results obtained using the cosmic ray data taken during 2009 will be reported.