Etude et impact du bruit de fond corrÃ©lÃ© pour la mesure de l'angle ...

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148 5. Correlated background Upon Digital Q max /Q tot cut, such events disappear. The HELN rejection e ciency (✏ HELN ) is estimated to be of 99.7 % by the fraction of events rejected by the cut. Prompt energy Delayed energy Entries 2 10 On Time coincidence On Time coincidence + HE LN Cut Entries/250keV 10 10 1 1 0 5 10 15 20 25 30 prompt E (MeV) 20 25 30 35 40 45 50 55 60 65 delayed E (MeV) tel-00821629, version 1 - 11 May 2013 PMT prompt number PMT with Qmax the Qmax (Prompt) Entries 45 40 35 30 25 20 15 10 5 0 0 50 100 150 200 250 300 350 400 PMTwithQmax PMT number with the Qmax PMT delayed number PMT with the Qmax Qmax (Delayed) Entries 40 35 30 25 20 15 10 5 0 0 50 100 150 200 250 300 350 400 PMTwithQmax PMT number with the Qmax Figure 5.28: SM selection with (yellow) and without (withe) Digital Q max /Q tot cut. SM events are expected below the detector chimney, so the PMT with Q max is expected at the top of the detector (PMT number < 50). After the Digital Q max /Q tot cut a reduction of such events is observed for the prompt event (bottom left), suggesting the rejection of some physics events. Assuming the events depositing the maximum charge on the PMTs whose number is < 50 are pure SM events, the physics selection e ciency is estimated to be 61.7 ± 12.1 %. Fig. 5.28 shows on-time selection with (yellow) and without (withe) Digital Q max /Q tot cut. SM events are expected below the detector chimney, so the PMT with Q max is expected at the top of the detector (PMT number < 50). After the Digital Q max /Q tot cut a reduction of such events is observed in Fig. 5.28 (bottom left), suggesting the rejection of some physics events. Assuming the events depositing the maximum charge on the PMTs whose number is < 50 are pure SM events, the physics selection e ciency is estimated to be 61.7 ± 12.1 %. The SM spectrum of Fig. 5.28 (top left) is then fitted with a flat and a sloped linear models. The SM rate is computed in agreement with Eq. 5.7, correcting for the Digital Q max /Q tot cut e ciency. Results are shown in Fig. 5.29 and summarised in Tab. 5.15.
5.5 Stopping Muon analysis 149 The shapes and the rates obtained by rejecting the HELN events with dedicated cut based on the Digital Q max /Q tot are well in agreement with the results of Sec. 5.5.2, obtained subtracting the HELN contribution selected o↵-time. Such results validate the o↵-time sample subtraction as valid LN reduction method. Fit const. slope 2 /dof R SM (R SM )/R SM model [1/(3 MeV)] [1/(3 MeV) 2 ] [cpd] [%] Flat 35.9 ± 7.7 – 7.9/9 0.57 ± 0.12 21 Slope 39.0 ± 20.1 -0.2 ± 1.1 8.4/8 0.60 ± 0.22 37 tel-00821629, version 1 - 11 May 2013 Table 5.15: Summary of SM spectral parameters and SM background rate for the flat and the sloped linear model. Figure 5.29: SM spectrum fit with flat model (left) and sloped linear model (right) upon Digital Q max /Q tot cut. The shapes and the rates are well in agreement with the results of Sec. 5.5.2. 5.5.4 Validating high energy delayed window The delayed event produced by the SM originates from the Michel electron, created by the muon decay ⇠ 2.2 µs after the muon has stopped, loosing all its energy by ionization. Since the muon energy losses and the muon decay are two independent processes, the prompt energy spectrum and the Michel electron spectrum are expected to be independent. The SM prompt spectrum obtained selecting the delayed events at high energy, [20, 60] MeV,
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UNIVERSITÉ DENANTES FACULTÉ DES S
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tel-00821629, version 1 - 11 May 20
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Abstract tel-00821629, version 1 -
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Acknowledgments Since so many peopl
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Contents 1 Introduction 13 tel-0082
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CONTENTS 11 tel-00821629, version 1
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Chapter 1 Introduction tel-00821629
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15 tel-00821629, version 1 - 11 May
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Chapter 2 Neutrino physics tel-0082
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2.2 Neutrino history in brief 19 ma
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2.3 Neutrino oscillation, the theor
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2.4 Measuring neutrino oscillation
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3-flavour oscillations The dominant
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After the Sun, the other main natur
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2.5 The problem with the neutrino m
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2.6 Summary and open questions 37 s
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In the next future, reactor experim
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Chapter 3 The Double Chooz experime
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3.1 The Double Chooz detector 43 to
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3.1 The Double Chooz detector 45 te
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3.1 The Double Chooz detector 47 it
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3.1 The Double Chooz detector 49 te
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3.2 The detector read-out 51 40 m o
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3.3 The online system 53 IV trigger
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3.3 The online system 55 tions as s
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3.3 The online system 57 tel-008216
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3.4 The calibration system 59 tel-0
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loosing their kinetic energy 3 and
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3.5 Reactor neutrino flux simulatio
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3.8 Data reconstruction 69 A dedica
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Regarding the pulse information, th
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3.8 Data reconstruction 73 tel-0082
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3.8 Data reconstruction 75 Gain (ch
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3.9 Conclusions 77 tel-00821629, ve
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Chapter 4 Measurement of ✓ 13 wit
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4.1 Data sample 81 create a signal
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4.2 ¯⌫ e signal selection 83 Liv
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4.2 ¯⌫ e signal selection 85 Pro
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4.2 ¯⌫ e signal selection 87 Neu
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4.3 Backgrounds 89 energy spectrum
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4.3 Backgrounds 91 tel-00821629, ve
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4.4 Selection e ciencies and system
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Page 107 and 108: Chapter 5 Correlated background tel
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Page 111 and 112: 5.2 High energy analysis 111 in a l
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Page 115 and 116: 5.3 OV Tag analysis 115 The t cut v
Page 117 and 118: 5.4 Fast Neutrons analysis 117 bigg
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Page 121 and 122: 5.4 Fast Neutrons analysis 121 tel-
Page 123 and 124: 5.4 Fast Neutrons analysis 123 esti
Page 125 and 126: 5.4 Fast Neutrons analysis 125 Corr
Page 129 and 130: 5.4 Fast Neutrons analysis 129 Prom
Page 131 and 132: 5.4 Fast Neutrons analysis 131 lect
Page 133 and 134: 5.4 Fast Neutrons analysis 133 mari
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Page 145 and 146: 5.5 Stopping Muon analysis 145 Sour
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Page 163 and 164: Chapter 7 Contributions to Double C
Page 165 and 166: 165 from this study and from [64] f
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Page 169 and 170: LIST OF FIGURES 169 tel-00821629, v
Page 179 and 180: List of Tables 3.1 Mean energy rele
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Page 183 and 184: BIBLIOGRAPHY 183 [31] J.K. Ahn et a
Page 185 and 186: BIBLIOGRAPHY 185 [61] W. Hampel et
Page 187: BIBLIOGRAPHY 187 [92] A. Stueken et
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