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

Comparison nhits=3 vs nhits=4N [a.u.]300250hdaEntries 1420Mean -0.005414RMS 0.2299Constant 358.8 ± 17.9Mean -0.00383 ± 0.00097Sigma 0.02409 ± 0.00076200150100500-1.5 -1 -0.5 0 0.5 1 1.5∆ α [rad]Figure 5.8: Comparison of the angular Hesse parameter α from a track reconstructionwith four hits vs. a reconstruction of the same event using only three hits. The plotshows the difference ∆α. A distinct peak around zero is observed showing that areconstruction only with three hits works.it has also been investigated how many tracks are expected to cross the Borexinoinner detector and inner vessel.To test the functionality of the detector, the angular distribution of real reconstructedevents was compared to those of the Monte Carlo for both events with andwithout the Borexino flag. Fig. 5.9 shows the comparison for all events analyzed sofar by the CMT. Monte Carlo and real data are in good agreement confirming thefunctionality of the setup at Borexino. A comparable result is obtained using onlydata of common events with Borexino.Table 5.2: Expected event rates for the CMT from the Monte Carlo simulation. Thefirst row contains the results for all simulated muons whereas in the second row onlymuons passing Borexino and finally in the third and fourth row events crossing theinner detector (ID) and inner vessel (IV), respectively, are selected. n trigger is the totalnumber of expected muons per day, n events requires at least a hit in each 2D plane.For the following columns stronger cuts on the minimal number of hits were applied(4 and 3 respectively).n trigger /day n events /day n events,4 /day n events,3 /dayAll MC events 27.84 15.6094 5.98253 12.0029BX CMT flag 19.0998 12.375 4.53726 9.64201BX ID 11.0443 7.68136 2.7781 6.06117BX IV 4.33561 3.1374 1.13226 2.4872476