Setup of a Drift Tube Muon Tracker and Calibration of Muon ...

yyxxα0: 3.439729, α1: 6.001542, θ: 0.399388, ϕ: 5.527881nhit0: 8/8, nhit1: 8/8Event: 52, Entry: 50, Time: Sun Oct 24 11:01:58 2083Figure 3.13: Left: quasi online display of a muon event (Event 52 from RUN 063 18-33-59). A hit tube is filled with a color indicating the signal width, yellow meaningwidth=3. The solid circles correspond to the drift times. Right: the same event afterreconstruction. Different colors indicate the different 2D-planes. The event time inthe display is not correct since the data was taken before the modification of the clockemulation data to UNIX time (cf. Section 3.3).3.8.1 Monte Carlo StudiesAt sea level, the angular distribution of muons is proportional to cos 2 θ, where θ is thepolar angle [33]. However, the muon tracker only has a limited angular acceptance.To be able to compare measurements to the expectations a Monte Carlo study hasbeen performed. Muons are generated at a fixed height z = 220 mm. This is wherethe top scintillators are located. For each event four values are randomly generated:x linear between -500 mm and 500 mmy linear between -500 mm and 500 mmϕ linear between 0 and 2πθ according to a cos 2 distribution between 0 and π 2 .The generation of θ is not straightforward since the random number generator onlyreturns homogeneously distributed values between 0 and 1. Therefore, θ has to bederived from this distribution. One also has to take into account that due to thesolid angle each value θ has to be weighted by sinθ. A random number r has to45