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

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comparably small value, integrating this over the Earth’s surface leads to a valueof 30 to 45 TW, an equivalent of ten thousand nuclear reactors [51]. The sourceof this heat is still unknown. One hypothetical explanation was the existence ofa natural thermonuclear reactor in the Earth’s core. However, recent geo-neutrinomeasurements by the Borexino experiment disfavor this hypothesis [50].2.4.5 Nuclear ReactorsNuclear reactors produce electricity from the thermal power of nuclear fission. Nuclearpower plants are usually fueled with 235 U, 238 U, 239 Pu and 241 Pu. The daughtersof the fission process are mostly unstable nuclei thus emitting ¯ν e in β − decays.Altogether, an average of ∼ 6 ¯ν e per fission are produced. The energy spectrum ofthese neutrinos is still not known without uncertainties and covers a range up to12 MeV with a mean energy between 2 and 3 MeV. Fig. 2.4 shows the predicted neutrinofluxes of neutrinos from the main fuel components of typical nuclear reactorsas presented in [52].Reactor neutrinos can be used in various kinds of experiments. As mentionedbefore, the very first neutrinos were observed at the Savannah River reactor. Reactorneutrinos have been used in many short and intermediate baseline experimentsand the KamLAND detector investigates neutrino oscillations over long baselines inJapan [30]. Because of the different sign in Eq. 2.4 for neutrinos and anti neutrinos,a distortion between solar ν e and reactor ¯ν e oscillations is expected for matter enhancedoscillations. The sign of x in Eq. 2.7 depends on the squared mass splitting∆m 2 . In the case of ν 2 being heavier than ν 1 , x is positive for neutrinos and negativefor anti neutrinos. In the case of ν 2 being lighter than ν 1 it would be the other wayaround. Comparing solar and reactor oscillation data hence offers an opportunityof determining the sign of ∆m 2 ⊙ . Monitoring ¯ν e fluxes from nuclear sites might alsobe used as a tool for the verification of the Non-Proliferation Treaty of NuclearWeapons.Reactor neutrinos are not only a welcome source for neutrino experiments, theirflux also is a background for any ¯ν e search from other sources like geo-neutrinos.2.4.6 Neutrino BeamsThe second man made neutrino source are neutrino beams. Neutrino beams canbe produced at particle accelerators from the decay of π and K mesons. These aregenerated by shooting high energy protons on a target (e.g. graphite). The chargedmesons can be focused by magnetic lenses before they then decay mainly into muonsand their corresponding neutrinos. If energies are high enough, the decay particleswill fly straight in the forward direction, where the muon is then absorbed by amuon dump before it decays further. The neutrino however travels on in the beamdirection. The magnetic lensing system allows to focus the parent particles andhence the neutrino beam on any given experiment. It is also sensitive to the energyof the parent meson so that the mean energy of the neutrinos can be controlled.By selecting only parents of a distinct charge, either neutrinos or anti neutrinos arechosen for the beam. Beams produced this way thus consist either of ν µ or ¯ν µ andare used for various short and long baseline experiments.18
Nb neutrino/fission-11010-2Neutrino fluxes from main fuel components1 235U239Pu241Pu238U-310-410-510-6102 4 6 8 10 12Energy (MeV)Figure 2.4: Typical ¯ν e energy spectrum from neutrinos emitted by the decay of thedaughters of 235 U, 238 U, 239 Pu and 241 Pu after fission in a nuclear reactor. Figurefrom [52].Currently, three noteworthy neutrino beams are in operation: the CNGS 9 beamin Europe [53], the NuMI 10 beam in the USA [54] and the T2K 11 beam in Japan[55]. The CNGS beam is focused on the LNGS underground laboratory, where theOPERA experiment is looking for ν τ appearance in the ν µ beam.In the context of this thesis, neutrino beams are of interest mainly for two reasons.First of all, the CNGS beam mentioned above crosses the Borexino detector before ithits OPERA. It’s impact thus has to be taken into account when analyzing Borexinodata. As will be shown in Section 5.5 it can even be used for a calibration ofthe Borexino muon tracking. However, it should also be noted that one of theprimary goals of neutrino beam experiments will be the measurement of θ 13 andδ cp . To determine these parameters, a three flavor oscillation analysis is necessarywhich relies strongly of a precise knowledge of ∆m 12 and θ 12 . Whereas the mostprecise values of ∆m 12 come from reactor experiments, solar neutrino experimentslike Borexino will provide the measurements of the solar mixing angle with theneeded precision.9 CNGS CERN Neutrinos to Gran Sasso10 NuMI Neutrinos at Main Injector11 T2K Tokai to Kamioka19
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: Figure 2.3: Expected ¯ν e energy
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 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
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P C P DSCINT C SCINT DySCINT BSCINT
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Figure 5.2: The CMT setup on top of
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Angular AcceptanceAngular Acceptanc
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Comparison nhits=3 vs nhits=4N [a.u
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Table 5.3: Overview of all muon run
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N/dayAll Triggers vs Time12000h_tim
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Reco Hits in Scintillatory [mm]1000
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PMTPMTScintillatorPMTPMTFigure 5.16
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the CMT data file and the Borexino
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Zenith Angle CMT and BX-GL Tracks h
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Lateral x Resolution CMT - IDhlatx_
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Distance d between CMT and BX-GL Tr
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Angular difference αN [arbitrary u
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[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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116
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Jan Lenkeit und Björn Wonsak sowie
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