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

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Distance d between CMT and BX-GL TracksInumber of entries [per 0.2m]14121086hi_delta_glEntries 125Mean 2.603RMS 2.445χ2/ ndf 19.58 / 34Norm 9.807 ± 1.765Mean 0.5211 ± 0.0651σ 0.3288 ± 0.0684Offset 1.527 ± 0.2234200 1 2 3 4 5 6 7 8 9 10d I[m]Figure 5.25: Distances d I between the impact parameter as reconstructed by theCMT and the BX global tracking. A distinct peak can be seen around 0.5m. Thiscorresponds to the average distance of the tracks and gives a measure for the lateralresolution. Furthermore, a constant offset can be seen, which originates from falsereconstructed tracks randomly distributed. The distribution has been fitted with aGaussian plus a constant offset.interact with the surrounding rock of the Gran Sasso massive producing muons.Thus it can occur that such a rock muon is created in the rock in front of the Borexinodetector and then passes both Borexino and OPERA. OPERA reconstructs thesetracks with a high precision [58]. These tracks can also be used to test the Borexinomuon reconstruction.The OPERA PT 3 uses the drift tube technology described in Section 3.1. Dueto its setup it is only capable of reconstructing 2D tracks. However, the OPERAdetector is made out of more than just the PT. Together with information fromRPCs 4 and a target tracker based on plastic scintillator strips, a 3D track is reconstructed.For a detailed description of the OPERA detector and the 2D trackreconstruction see [58,79]. One major requirement to reduce background in OPERAis an exact time synchronization with the CNGS. CNGS neutrinos are not producedcontinuously, but rather in bunches at discrete times. By knowing the exact timinginformation it is possible to apply a cut on on-time events thus reducing mostbackground. Conveniently, the CNGS “OnTimeStamp” is also distributed to theBorexino DAQ.For a combined analysis all reconstructed on-time tracks that entered the OPERAdetector from either the front or side have been extracted from the OPERA data.This has been done for the 2008, 2009 and the beginning of the 2010 runs. A collectionof CNGS on-time events could be easily extracted also from the Borexinodata. Events from both detectors were then matched by the timestamp informationsimilar to the CMT events. Altogether 2291 common events were found.For the combined analysis all track information was transferred into the Borexino3 PT Precision Tracker4 RPC resistive plate chamber92
All tracks from OD fith5All tracks from OD fith6N [arbitrary units]605040Entries 2192Mean -0.4299RMS 3.716c 363.5 ± 9.5mean -0.2555 ± 0.0776σ 2.877 ± 0.082N [arbitrary units]4540353025Entries 2192Mean -0.7274RMS 4.585c 410.1 ± 10.2mean -0.9334 ± 0.1172σ 4.486 ± 0.10230202015101050-10 -5 0 5 10∆θ [°]0-10 -5 0 5 10∆ϕ [°]Figure 5.26: Polar and azimuth angle differences for muon tracks reconstructed inboth OPERA and BorexinoTable 5.7: Borexino muon tracking resolution determined by the comparison withOPERA rock muonsAngle σ [ ◦ ] (OD) σ [ ◦ ] (ID) σ [ ◦ ] (GL)θ 2.88 ± 0.08 4.86 ± 0.16 3.01 ± 0.12ϕ 4.49 ± 0.10 4.76 ± 0.14 4.11 ± 0.10α 3.75 ± 0.02 3.70 ± 0.04 2.63 ± 0.02coordinate system. For a detailed description of the coordinate transformation seeAppendix D.5.5.1 Direct Angular ComparisonFor a direct comparison of the tracks reconstructed by Borexino and OPERA for thesame muon, the azimuth and polar angles ϕ and θ are obtained for all trackings. Thedistribution of differences between the corresponding angles is shown in Fig. 5.26exemplarily for the OD tracking. Performing a Gaussian fit gives a measure forthe angular resolution of the Borexino reconstruction. The results are presented inTab. 5.7. This shows excellent values for θ, however, the resolution of ϕ is ratherpoor. This can be explained by the method how ϕ is determined in Borexino: muontracks are determined by their entry and exit points to the detector. Since thedetector is spherical, small uncertainties in the determination of these points leadto large uncertainties in ϕ around the poles. This could be accounted for e.g. bylooking at a θ-dependency of σ ϕ .However, another analysis is chosen; the absolute angle α between both tracks ⃗tis determined. This can be done as follows:⃗t bx ·⃗t op = |⃗t bx ||⃗t op |cos α⇔α = cos −1 (sin θ bx sin θ op (cos ϕ bx cos ϕ op + sin ϕ bx sin ϕ op ) + cos θ bx cos θ op )93
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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
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plastic scintillators. To avoid all
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N hitsHitmap Plane 06000h_hitmap0En
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Table 3.4: Data structure for calib
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TDC SpectrumN/[2 Channels]1000800H_
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Table 3.5: List of variables calcul
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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
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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 88 and 89: N/dayAll Triggers vs Time12000h_tim
Page 90 and 91: Reco Hits in Scintillatory [mm]1000
Page 92 and 93: PMTPMTScintillatorPMTPMTFigure 5.16
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Page 96 and 97: Zenith Angle CMT and BX-GL Tracks h
Page 98 and 99: Lateral x Resolution CMT - IDhlatx_
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
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Page 126: Jan Lenkeit und Björn Wonsak sowie
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