Muon detection

Cosmic rays were used to measure the detection efficiency and resolution of the super-layers. The momenta of cosmic muons were measured by CDC with the solenoid field of 1.5 T. Below 500 MeV/c, the muon does not reach KLM. A comparison of the measured range of a particle with the predicted range for a muon allows us to assign a likelihood of being a muon. In Fig. the muon detection efficiency versus momentum is shown for a likelihood cut of 0.66. Some fraction of charged pions and kaons will be misidentified as muons. A sample of $\pi^+$$\pi^-$ events in the $e^+e^-$ collision data was used to determine this fake rate. The fraction of pions which are misidentified as muons is shown in Fig. , again with a muon likelihood cut of 0.66. The solid points with error bars are the measured data and the histogram is the result of a Monte Carlo simulation. Above 1.5 GeV/c we have a muon identification efficiency of better than 90 % with a fake rate of less than 5 %.

Figure: Muon detection efficiency versus momentum in KLM.

Figure: Fake rate versus momentum in KLM.