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

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510Counts/(10 keV x day x 100 tons)410310210101-110-210Fit: χ 2 /NDF = 185/1747Be: 49±3 cpd/100 tons210Bi+CNO: 23±2 cpd/100 tons85Kr: 25±3 cpd/100 tons11C: 25±1 cpd/100 tons14C10C-310200 400 600 800 1000 1200 1400 1600 1800 2000Energy [keV]Figure 4.6: Fitted Borexino Data taken from [69]. The black data points alreadyinclude all relevant cuts. The Figure does not include contributions from 214 PB, pp,and pep neutrinos which are almost negligible. Again, the Compton like edge for the7 Be neutrinos can be clearly seen (red line). The fit result gives a rate of 49 ±3 countsper day. For the 11 C background, a rate of 25 ± 1 is found.100 tons.For the analysis, events were chosen by a selection of cuts. A fiducial volumeof 78.5 tons was chosen to reject external gamma background. Furthermore, eventswithin 2 ms after a crossing muon were rejected to suppress events from the decay ofshort living cosmogenic induced radionuclides. Decays due to radon daughters couldbe removed by vetoing 214 Bi– 214 Po coincidences. Events from the α decay of 210 Pocould be identified through pulse shape discrimination and were subtracted fromthe spectrum. The raw photo electron spectrum after these basic cuts is shown inFig. 4.5. The Compton-like edge from the reaction of 7 Be neutrinos is clearly visiblearound 300 photo-electrons. Below 100 photo electrons, the spectrum is dominatedby the decay of 14 C. Furthermore, the impact of the β + decay of 11 C can be seen inthe region between 400 and 800 photo electrons (cf. Section. 4.3.3).Fig. 4.6 shows the spectral fit of the data. For the 7 Be neutrinos, a rate of 49 ±3events per day and 100 tons is found. The high metallicity SSM predicts a rateof 74 ± 4 counts per day and 100 tons for no oscillations whereas the MSW-LMAscenario (assuming ∆m 2 12 = 7.6−5 eV 2 and sin 2θ 12 = 0.87) reduces this expectationto 48±4 counts per day per 100 tons. Hence, the results confirm the matter enhancedoscillation hypothesis.To test solar models, the measured neutrino flux is compared to the predictionof the SSM. The measurements also give new constrains to the ratio f Be between the7 Be neutrinos flux predicted by the high metallicity SSM and the measured value,where f is defined as the true solar neutrino flux divided by the corresponding valueof the fluxes predicted by the according solar model. For the MSW-LMA oscillationscenario, a value of f Be = 1.02±0.10 is obtained. The analysis ales gives a constraintfor the ratio f CNO for CNO neutrinos of f CNO < 3.80 and a value f pp for pp neutrinosof f pp = 1.005 +0.008−0.020 . The constraint on f CNO translates into a CNO contribution of62
0.80.70.6Solar Neutrino Survival ProbabilityMSW-LMA PredictionMSW-LMA-NSI PredictionMaVaN PredictionSNO DataGa/Cl Data Before Borexino0.80.70.6Solar Neutrino Survival ProbabilityMSW-LMA PredictionMSW-LMA-NSI PredictionMaVaN PredictionSNO DataBorexino DataGa Data after BorexinoP ee0.5P ee0.50.40.40.30.30.2Before Borexino E [MeV]1 100.2After Borexino E [MeV]1 10Figure 4.7: Energy dependent survival probability of solar neutrinos for differentmatter effect mechanisms compared with solar oscillation data before and after theBorexino 7 Be measurements. Figures taken form [44]. The Borexino data stronglysupports the LMA solution of the MSW effect.less than 3.3% to the solar luminosity.Matter Enhanced OscillationsThe survival probability of mono-energetic solar 7 Be neutrinos can be used to testthe different models of matter enhanced oscillations. Fig. 4.7 shows the predictions ofthe MSW-LMA, MSW-LMA-NSI, and MaVaN models presented in Section 2.3.3 foroscillations of solar neutrinos. Solar neutrino oscillation experiments before Borexinocould not distinguish between the different models. Results from the 7 Be neutrinomeasurements, however now strongly support the LMA solution of the MSW effect.Day-Night AsymmetryThe 7 Be neutrino spectrum has been also investigated for a possible day-night asymmetry.Depending on the model, mass effects in Earth could lead to a regenerationof solar neutrinos oscillated into ν µ or ν τ back into ν e . The neutrino rate wouldthen depend also on the latitude of the detector as well as the time of the day. Atnight, the Sun would appear brighter in the neutrino light. A preliminary analysisis presented in [73]. Measurements from 422.12 days are presented in Fig. 4.8. Thedata splits up into 212.87 days and 209.25 nights. The day night asymmetry A dn isdefined asA dn = c n − c dc n + c d,where c n and c d are the number of counts during night and day respectively. Anaverage value of A dn = 0.011 ± 0.014 is found, showing no significant day nightasymmetry and thus confirming the expectation of the LMA-MSW scenario andexcluding the alternate oscillation scenario based on the mass varying model (cf.Section 2.3.3)63
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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
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 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 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
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
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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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