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

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χ 2N [a.u.]Probability103×10hc2p0Entries 242297Mean 0.4942RMS 0.3255χ 2N [a.u.]per d.o.f.22203×10hc2ndf0Entries 242297Mean 1.134RMS 1.02481816614121048624200 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1P(χ 2 )00 2 4 6 8 10 12χ 2 /dofFigure 3.16: The fit quality is checked by a look at the χ 2 distributions. Left: theχ 2 -probability shows a flat distribution as expected, with only a slight rise in the sideregions. Right: the χ 2 per degrees of freedom has a mean value close to 1.calibration was performed. Altogether 182728 events could be reconstructed. Theangular distributions of reconstructed tracks were already presented in Fig. 3.14.They show the expected behavior. The quality of the reconstruction was checked aspresented in the following section.3.8.3 Fit QualityAs described in Section 3.5.6, the track fit is done using a χ 2 -minimization. Thequality of the fit can be controlled by inspecting the distribution of χ 2 per degrees offreedom. The mean value of this χ 2 -distribution should be close to 1. Also, the χ 2 -probability can be used to investigate the fit quality. For a given number of degreesof freedom and a given χ 2 , the probability can be calculated, their distributionshould be homogeneous between 0 and 1. Fig. 3.16 shows the χ 2 -distribution andthe χ 2 /dof for real data. The χ 2 -distribution shows the desired behavior exceptfor the side regions. The excesses at zero and one can be explained by tracks thatwere reconstructed wrongly. This can be either due to a wrong pattern recognition(excess at zero) or a too good fit on fake drift circles, e.g. from δ electrons or crosstalk (excess at one). However, the mean value of χ 2 /dof shows the expected meanvalue around 1.If statistics are high enough, the calculated drift distances to the fitted trackshould be distributed homogeneously between 0 and the tube radius (18.15 mm).Fig. 3.17 shows this distribution. Besides a small discrepancy for very small driftcircles it is in good agreement with the expectation. This can be easily understoodby looking again at the TDC count to distance relation. For small drift distances,the TDC count to distance relation rises very steeply, meaning that a small deviationin the drift time has a large effect on the drift radius. Hence, small uncertaintiesoccur in this region. Since no negative drift distance can occur, the drift distanceis much likely to be overestimated in this region. This can be recognized by the48
N [a.u]Reconstructed Drift Circles1000h1Entries 34970Mean 9.153RMS 5.1880060040020000 2 4 6 8 10 12 14 16 18 20r [mm]Figure 3.17: Distribution of radii r from reconstructed drift distances. The radii aredistributed homogeneously except for the region around the center. This is due to thelarge uncertainties of the TDC count to distance relation in this region.small peak in the second bin of the distribution. However, the overall performanceis satisfactory.3.8.4 Spatial and Angular ResolutionBoth the spatial and angular resolutions can be determined from the reconstructeddata. Fig. 3.18 shows the distribution of residuals from all fitted tracks. The RMSvalue gives a measure for the lateral resolution σ r of the detector. It has been foundto be σ r = 270ñm. The angular resolution can be determined by comparing tracksreconstructed in each single module. For a perfect reconstruction, the fitted anglesα should be identical for all modules. However, comparing the angles for tracksof the same event reconstructed in two modules of the same 2D plane separatelyshows slight differences. The distribution of ∆α for real data is shown in Fig. 3.19.A sharp peak around zero is observed. To obtain a measure for the resolution, aVoigtian was fitted to the distribution. A Voigtian is a convolution of a Gaussianand a Breit-Wigner distribution. The σ of the fit is then obtained from the FWHMdivided by 2.35. For the CMT, a value of σ fit = 6.98 mrad has been found. Since twomodules are taken into account, the error of the reconstructed angle is taken intoaccount twice. It is therefore overestimated in the direct comparison. This effectcan be compensated for, by dividing σ by √ 2. Consequently the angular resolutionσ α is given by:σ α = σ fit√2= 4.65mrad.49
Page 1 and 2:
Setup of a Drift Tube Muon Trackera
Page 3:
AbstractIn this work the setup and
Page 6 and 7: 3.5.5 Pattern Recognition . . . . .
Page 8 and 9: viii
Page 10 and 11: essential for vetoing these events.
Page 13 and 14: Chapter 2NeutrinosThe standard mode
Page 15 and 16: However, it did not yet deliver an
Page 17 and 18: Table 2.1: Neutrino oscillation par
Page 19 and 20: this assumption, the Standard Solar
Page 21 and 22: Figure 2.1: Neutrino flux at Earth
Page 23 and 24: asymmetry between neutrino and anti
Page 25 and 26: Figure 2.3: Expected ¯ν e energy
Page 27: Nb neutrino/fission-11010-2Neutrino
Page 30 and 31: 108−dE/dx (MeV g −1 cm 2 )65432
Page 32 and 33: Figure 3.3: Setup of the muon track
Page 34 and 35: zyxModule b.0Module a.0Module b.1Mo
Page 36 and 37: 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 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 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
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
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N [arbitrary units]∆y all data200
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To determine the Borexino tracking
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Table A.1: Variables that can be se
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espectively. The channel numbers ar
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xyϕϕ ′βx ′µFigure C.2: Rela
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the z-coordinate z op,0 of the firs
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xyEvent: 470, Entry: 470, Time Tue
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[14] Ch. Kraus et al. Final Results
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[49] T. Araki et al. Experimental i
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Jan Lenkeit und Björn Wonsak sowie
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