Performance of the Cosmic Ray Veto Detector of the Mu2e Experiment

The Mu2e experiment at Fermilab will search for the charged-lepton flavor-violating process of a neutrino-less muon-to-electron conversion in the presence of a nucleus. The experiment's goal is a final sensitivity of four orders of magnitude below the current strongest limits on this process. This requires all backgrounds to sum to fewer than one event over the lifetime of the experiment. One major background is due to cosmic-ray muons producing electrons that fake a signal inside of the Mu2e apparatus. The Cosmic Ray Veto Detector was designed to veto these muon-induced events with an efficiency of 99.99%. The veto system was fabricated at the University of Virginia and is now stored at Fermi National Lab. Studies of the performance of the system are ongoing at Fermilab. Some preliminary results from that work are discussed in this presentation.