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

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N/dayAll Triggers vs Time12000h_timeEntries 371481Mean 1.272e+09RMS 5.801e+06100008000600040002000031.01. 02.03. 01.04. 01.05. 31.05. 30.06. 30.07. 29.08.DateFigure 5.12: Trigger rate per day for the period of data taking. The spike in thebeginning is correlated with events where almost all tubes of the detector showed anentry. Although still unexplained, the events are ignored by a noise cut of n hit < 48.the density of the drift gas has been used. In the latter case, a measurement withambient conditions similar to those at Gran Sasso has been performed. However,with this method, new systematic errors occur due to the different hardware used.Although it has been tried to account for different delays resulting from differentcabling and slow control settings, results were not completely satisfactory. In athird attempt, the actual data from Gran Sasso was taken for a calibration in spiteof the low statistics. In all three cases, the resolution and efficiency were well belowthe expected values from Hamburg conditions. Spatial resolutions around 360ñmwere obtained. A worse resolution also leads to a rather large amount of falselyreconstructed tracks, especially for events containing only three hits and additionalcross talk or δ electrons. Therefore it has been decided to apply a rather harsh cuton the reconstructed data. The total number of hits may not exceed the number ofhits used by the fit by more than one.5.2.2 PerformanceFig. 5.12 shows the number of triggers distributed by the trigger board each day.The rate started at a constant level of approximately 2000 triggers per day. It thenslowly reclined during the summer—an effect which is connected to instabilities ofthe trigger. However, it suddenly rises again to the prior value in the end of August.During this period, maintenance was done at the detector. It can thus be assumed,that this effect is correlated with the work on the detector. As will be shown in detaillater, the trigger system is not working properly and has to be replaced. Thus, thiseffect is not further studied.To check the performance of the underground operation the distribution of hitsin the single tubes and the number of events per day were investigated. Since thetrigger rate is dominated by far from random coincidences of the PMT’s dark noise(∼ 1 coincidence per minute), most of the events do not contain any hit tube.80
Hits per Event - Plane 0N1000h_hit0Entries 2789Mean 3.81RMS 3.407Hits per Event - Plane 1N1600h_hit1Entries 3919Mean 3.241RMS 3.05180014001200600100040080060020040020000 2 4 6 8 10 12 14 16 18 20N hit00 2 4 6 8 10 12 14 16 18 20N hitFigure 5.13: Number of hits per event for both 2D planes. Events with no hits werecut from the data. On can clearly identify a peak at four hits per event, which isexpected from the layout of the detector. However, the distribution shows also eventswith more than ten hits. These are caused mainly by noise or multiple muon events.Hitmap after noise cut - Plane 0N hits908070605040302010h_hitmapc0Entries 5794Mean 46.26RMS 27.6500 10 20 30 40 50 60 70 80 90TubeHitmap after noise cut - Plane 1N hits24022020018016014012010080604020h_hitmapc1Entries 7850Mean 38.1RMS 25.5700 10 20 30 40 50 60 70 80 90TubeFigure 5.14: Hit map of all tubes in the CMT. The peaks in the x − z-plane (plane1) can be explained by the poor trigger efficiency of trigger scintillators A and B.Therefore a cut of n hits > 0 is applied for each 2D plane.The number of hits per event is shown in Fig. 5.13. As expected, a peak atn hit = 4 is observed. However, the distributions show a rather long tail towardslarger values. A large number of hits can occur when a track with a steep inclinationcrosses the detector. However, this cannot explain the extent of the tail in thedistribution. By looking at single events, one finds that many of the events inquestion show fake hits probably occurring from cross talk and also δ electrons. Asecond cause for large values of n hit are multiple muon events, where there is anexpected average of eight hits per event (see also Fig.5.17).Fig. 5.14 shows the hit maps for both 2D planes. All tubes except tube 0 inmodule 1.0 seem to be working fine. However, instead of a homogeneous distribution,four distinct peaks can be seen for the same module. These are a hint for a systematicerror in the setup. The error source could be identified in a poor efficiency in someof the trigger scintillators, namely scintillators A and B (cf. Fig. 5.1). Due the thesegmentation of the trigger plane, the characteristic shapes occur. The (presumablywell working) trigger scintillators C and D are the small ones on the left facingthe x − z-plane. Hence, tubes located at small x show significantly more hits (cf.Fig. C.1 for a channel map of each tube). The peak maximum reduces slightlyfor each layer of tubes the further they are away from the scintillator, but it also81
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Setup of a Drift Tube Muon Trackera
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AbstractIn this work the setup and
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3.5.5 Pattern Recognition . . . . .
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viii
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essential for vetoing these events.
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Chapter 2NeutrinosThe standard mode
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However, it did not yet deliver an
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Table 2.1: Neutrino oscillation par
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this assumption, the Standard Solar
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Figure 2.1: Neutrino flux at Earth
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asymmetry between neutrino and anti
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Figure 2.3: Expected ¯ν e energy
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Nb neutrino/fission-11010-2Neutrino
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108−dE/dx (MeV g −1 cm 2 )65432
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Figure 3.3: Setup of the muon track
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zyxModule b.0Module a.0Module b.1Mo
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Figure 3.6: Display of the slow con
Page 38 and 39: plastic scintillators. To avoid all
Page 40 and 41: N hitsHitmap Plane 06000h_hitmap0En
Page 42 and 43: Table 3.4: Data structure for calib
Page 44 and 45: TDC SpectrumN/[2 Channels]1000800H_
Page 46 and 47: Table 3.5: List of variables calcul
Page 48 and 49: with ∆⃗q = ⃗q n − ⃗q n−
Page 50 and 51: N [a.u.]∆ α (x)2200020000da0Entr
Page 52 and 53: d[mm]Reco Drift Distances201816H_RE
Page 54 and 55: N [a.u.]Real DataReal data0.06MCh1E
Page 56 and 57: χ 2N [a.u.]Probability103×10hc2p0
Page 58 and 59: N [a.u]Residuals20001800h0Entries 3
Page 60 and 61: Counts/(10 keV × day × 100 tons)1
Page 62 and 63: 4.1.3 Čerenkov LightČerenkov dete
Page 64 and 65: 4.2 The Borexino DetectorThe Borexi
Page 66 and 67: muons, is reduced by going deep und
Page 68 and 69: (typically below 50 cm), the locati
Page 70 and 71: 510Counts/(10 keV x day x 100 tons)
Page 72 and 73: counts/days*4 hitsDay (Red) and Nig
Page 74 and 75: eeSurvival probability for ν e, P0
Page 76 and 77: the CMT to the Borexino tracking, t
Page 78 and 79: P C P DSCINT C SCINT DySCINT BSCINT
Page 80 and 81: Figure 5.2: The CMT setup on top of
Page 82 and 83: Angular AcceptanceAngular Acceptanc
Page 84 and 85: Comparison nhits=3 vs nhits=4N [a.u
Page 86 and 87: Table 5.3: Overview of all muon run
Page 90 and 91: Reco Hits in Scintillatory [mm]1000
Page 92 and 93: PMTPMTScintillatorPMTPMTFigure 5.16
Page 94 and 95: the CMT data file and the Borexino
Page 96 and 97: Zenith Angle CMT and BX-GL Tracks h
Page 98 and 99: Lateral x Resolution CMT - IDhlatx_
Page 100 and 101: Distance d between CMT and BX-GL Tr
Page 102 and 103: Angular difference αN [arbitrary u
Page 104 and 105: [m]z bxTrack Position in BX x=0 Pla
Page 106 and 107: N [arbitrary units]∆y all data200
Page 108 and 109: To determine the Borexino tracking
Page 110 and 111: Table A.1: Variables that can be se
Page 112 and 113: espectively. The channel numbers ar
Page 114 and 115: xyϕϕ ′βx ′µFigure C.2: Rela
Page 116 and 117: the z-coordinate z op,0 of the firs
Page 118 and 119: xyEvent: 470, Entry: 470, Time Tue
Page 120 and 121: [14] Ch. Kraus et al. Final Results
Page 122 and 123: [49] T. Araki et al. Experimental i
Page 124 and 125: 116
Page 126: Jan Lenkeit und Björn Wonsak sowie
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