Tau Neutrino Appearance via Neutrino Oscillations in Atmospheric ...

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5In the SM, neutrinos are considered to be massless. One implies that allneutrinos are left-handed and all anti-neutrinos are right-handed characterizedby the helicity. Neutrino’s helicity was measured by M. Goldhaber et al. [13].1.3 Neutrino Mass and Neutrino OscillationsDespite the masslessness of neutrinos in the SM, the mass of neutrinoshave been questioned since Fermi developed his theory of neutrinos. Severalexperiments have attempted to measure the mass of ν e , ν µ , and ν τ directly viaβ-decay, pion decay, and τ-lepton decay respectively, but were only successfulto set the upper limits to m νe < 2.2 eV [14, 15], m νµ < 170 keV [16], m ντ
6then, |ν α (t)〉 can be expressed in the basis of weak flavor |ν β 〉 :|ν α (t)〉 = ∑ β3∑U βi e −iEit Uαi ∗ |ν β〉 (1.6)i=1The amplitude of ν α → ν β transitions at time t is :3∑A να→ν β(t) = 〈ν β |ν α (t)〉 = U βi e −iEit Uαi ∗ (1.7)i=1The probability of ν α → ν β transition is given by :P να→ν β= |A να→ν β(t)| 2 3∑2=U∣ βi e −iEit Uαi∗ ∣i=1. (1.8)In the analysis presented in this thesis, the two flavor neutrino oscillationsare assumed, where there are two mass eigenstates and two flavor eigenstateswith a single mixing angle. In this assumption, the MNS matrix is written interms of a mixing angle θ :( )cos θ sin θU =(1.9)− sin θ cos θAnd, the flavor oscillation probability is given by :( 1.27∆mP (ν α → ν β ) = sin 2 2θ sin 2 2 (eV 2 ))L(km)E ν (GeV)(1.10)where θ is the neutrino mixing angle, ∆m 2 ≡ m 2 j − m2 i is the mass-squareddifference of neutrino mass eigenstates in eV 2 , L is the distance traveled byneutrinos in km, E ν is neutrino energy in GeV, and the factor 1.27 comesfrom 1/¯hc in the conversion of units to km and GeV. The survival oscillationprobability P (ν α → ν α ) is simply P (ν α → ν α ) = 1 − P (ν α → ν β ), that is :( 1.27∆mP (ν α → ν α ) = 1 − sin 2 2θ sin 2 2 (eV 2 ))L(km)E ν (GeV)(1.11)Figure 1.2 shows the survival probability and oscillation probability as a functionof L(km)/E(GeV).The neutrino oscillation discussed in this thesis concerns ν µ ↔ ν τ oscillations.Therefore, the flavor term is (α, β) = (µ, τ) and the mass term is(i, j) = (2, 3) throughout the thesis unless mentioned specifically otherwise.
Page 1 and 2: Tau Neutrino Appearance via Neutrin
Page 3 and 4: Abstract of the DissertationTau Neu
Page 5 and 6: ContentsList of FiguresList of Tabl
Page 7 and 8: 6 Event Reconstruction 966.1 Vertex
Page 9 and 10: List of Figures1.1 Feynman diagrams
Page 11 and 12: 6.7 PID likelihood distributions fo
Page 13 and 14: AcknowledgementsAfter spending six
Page 15 and 16: I would like to thank administrativ
Page 17 and 18: 2and obey the exclusion principle a
Page 19: 4Table 1.1: Table of elementary par
Page 23 and 24: 8As described in the next section,
Page 25 and 26: 10Table 1.2: List of the flavor rat
Page 27 and 28: 12much smaller than the unity with
Page 29 and 30: 14Data/Prediction (null oscillation
Page 31 and 32: Figure 2.1: The location of Super-K
Page 33 and 34: Figure 2.2: An overview of the Supe
Page 35 and 36: 202.1.1 Cherenkov RadiationThe prim
Page 37 and 38: 22Figure 2.5: The layout of the PMT
Page 39 and 40: 24< φ 520photosensitive area > φ
Page 41 and 42: 26Quantum efficiency0.20.10300 400
Page 43 and 44: 282.3.2 Outer Detector PMTThe OD ph
Page 45 and 46: 30CARTRIDGEPOLISHERUVSTERILIZERVACU
Page 47 and 48: 32system is shown in Figure 2.13. T
Page 49 and 50: 34A block diagram of the ATM board
Page 51 and 52: 3620-inch PMTSCHATMx 24020-inch PMT
Page 53 and 54: 38Super−Kamiokande Outer Detector
Page 55 and 56: 402.6.4 Flash ADCAs a part of the S
Page 57 and 58: 42UV filter ND filterXe Flash LampO
Page 59 and 60: 44Number of PMTs in Each Bin1400120
Page 61 and 62: 46ND filterTriggerPMTDyeN2 LaserDif
Page 63 and 64: 485432Timing Resolution (nsec)10543
Page 65 and 66: 50Optical FiberLASER337nmTop371nm40
Page 67 and 68: 52Light scattering measurementatten
Page 69 and 70: 54neutrino analyses, such an estima
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56Number of events14012010080604020
Page 73 and 74:
58momentum/range (MeV/cm)432DATAM.C
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60µ momentum/trackelectron momentu
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theoretical groups such as Honda fl
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640Zenith angle of arrival directio
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66Flux×E ν2(m -2 sec -1 sr -1 GeV
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684% [105]. The flux of atmospheric
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70where G E and G M are the electri
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72resonance), M j is the mass of th
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74σ (10 -38 cm 2 )0.25 (a) νp →
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761.5(a) ν µN → µ - XIHEP-JINR
Page 93 and 94:
7821.751.5ν 16 O → l ± 16 O π
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80ing experiments [158, 159, 160].
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82shown in Figure 3.5. The timing o
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8410.8ν τν µν eν - τν - µ
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86Chapter 5Data ReductionThe Super-
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88and exit the ID. The neutrino ene
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90• NHITA 800 ≤ 50The number of
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92• The distance between the cabl
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94Coincidence muonsThe remaining co
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96Chapter 6Event ReconstructionThe
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9842 deg. ring(possible center)hit
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100Number of events450400350Single-
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102by muons or charged pions and ha
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104Number of eventsNumber of events
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106the changes in the vertex positi
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108flux. This is because most of ν
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110NUM 14RUN 999999SUBRUN 99EVENT 2
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112expected to be upward-going.Base
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114150100500(a)10 2 (b)1013.5 4 4.5
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116SK-I Multi-GeV MCSK-II Multi-GeV
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118Number of Events9080706050403020
Page 135 and 136:
120Table 7.5: Fraction of neutrino
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122Number of Events604020TAU+BKGBKG
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124100SK-ITAU+BKGBKGDATA6050SK-IITA
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126• Up/down ratio : (For the obs
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128• Charge-current ν τ interac
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130• Tau likelihood selection eff
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132Table 7.8: (For only SK-I) Summa
Page 149 and 150:
134Table 7.10: (Common to SK-I and
Page 151 and 152:
136because for non-zero θ 13 , Mul
Page 153 and 154:
138Bay [184] reactor experiments, a
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140Table A.2: Summary of the damage
Page 157 and 158:
142Appendix BEnergy Flow AnalysisIn
Page 159 and 160:
Figure B.2: Example of subdivision
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146be handled by setting any negati
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148[16] K. Assamagan et al., Phys.
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150[48] H. Seo, A Measurement of ν
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152[84] T. H. Johnson et al., Phys.
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154[125] G. Radecky et al., Phys. R
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156[171] K. Hagiwara et al., Nucl.
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