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

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122 5. Correlated background tel-00821629, version 1 - 11 May 2013 Figure 5.10: ID energy as a function of the IV energy for IVT events. Since the IVT rely on the high multiplicity the FNs are created by their parent muon, the tagged FN is a separated event from the one interacting in the ID. An excess of events in E ID . 5 MeV and E IV . 1 MeV suggest some background contaminate the IVT sample. Prompt IV energy spectrum Entries/(25 keV) Entries/(0.25 MeV) 10 2 10 PMT Mult. ≥0 PMT Mult. ≥2 PMT Mult. ≥4 PMT Mult. ≥6 1 1 0 5 -1 10 15 20 25 30 10 1 Uncalibrated Energy (MeV) Figure 5.11: Prompt energy spectrum for di↵erent IVT multiplicity condition. The IVT based on the number of IV PMT hit allows then to tag FN events produced with high multiplicity by a muon interacting outside the detector. The tagging e ciency is measured between 33 % and 23 %, depending on the multiplicity condition. An excess of events in E ID . 5MeV suggest some background contaminate the IVT sample.
5.4 Fast Neutrons analysis 123 estimation of how many FN are in coincidence with an energy deposition in the IV, i.e. the IVT e ciency ✏ IV T . The tagging e ciency is measured between 33 % and 23 %, depending on the multiplicity condition. The prompt energy spectrum for the di↵erent IVT multiplicity condition is shown in Fig. 5.11. The minimal condition of 2 PMT hit is assumed as IVT condition in the following analysis. The systematic uncertainties introduced by such condition are discussed in Sec. 5.4.5. 5.4.2 IVT background tel-00821629, version 1 - 11 May 2013 The correlation between ID and IV energy shown in Fig. 5.10 presents an excess of events . 5 MeV in the ID and . 1 MeV in the IV. Such excess, also visible in the prompt energy spectrum of Fig. 5.11, is understood in term of backgrounds contaminating the IVT sample. Given the topology of the IVT events, which require a three-fold coincidence between IV energy deposition, ID prompt event and the following ID delayed, two categories of background, with similar topologies, have been identified: -events: generated by low energy from natural radioactivity. The undergoes Compton scattering in the IV and in the ID where, in accidental coincidence with a thermal neutron, it mimics the FN signature. As the accidental background discussed in Sec. 4.3.1, the energy distribution is expected to contaminate the IVT sample up to ⇠3 MeV in the ID. Due to the rather poor light collection e ciency and energy resolution of the IV, such background deposit energies . 1MeVinthe IV. The expected event topology is schematised in box 2 of Fig. 5.12. ¯⌫ e + IVT from /n: generated by an accidental coincidence between an ¯⌫ e interacting in the ID and an IV from natural radioactivity or thermal neutron capture on H. Since the ID energy deposition is produced by a true ¯⌫ e events, the ID energy distribution shown its spectrum, with a peak around ⇠3 MeV. As observed for the -background, the energy distribution in the IV is limited . 1 MeV. The expected event topology is schematised in box 3 of Fig. 5.12. As summarised in Tab. 5.3, tagged FN events are expected to show two kind of correlations, between prompt and delayed event in the ID but also between the ID and the IV energy deposition. The time and the spatial correlations between prompt and delayed events in the ID are the results of a single particle generating both prompt and delayed events, in a similar way as ¯⌫ e events. The correlation between IV and ID take place since both signals are generated by the same parent muon. The time correlation between ID and IV signals is expected in a short time window of few tens ns, dominated by the particles time of flight between IV and ID.
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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
Page 71 and 72: Regarding the pulse information, th
Page 73 and 74: 3.8 Data reconstruction 73 tel-0082
Page 75 and 76: 3.8 Data reconstruction 75 Gain (ch
Page 77 and 78: 3.9 Conclusions 77 tel-00821629, ve
Page 79 and 80: Chapter 4 Measurement of ✓ 13 wit
Page 81 and 82: 4.1 Data sample 81 create a signal
Page 83 and 84: 4.2 ¯⌫ e signal selection 83 Liv
Page 85 and 86: 4.2 ¯⌫ e signal selection 85 Pro
Page 87 and 88: 4.2 ¯⌫ e signal selection 87 Neu
Page 89 and 90: 4.3 Backgrounds 89 energy spectrum
Page 91 and 92: 4.3 Backgrounds 91 tel-00821629, ve
Page 93 and 94: 4.4 Selection e ciencies and system
Page 95 and 96: 4$&14+#':"'$"$468'#21%$;' ! $"$468'
Page 97 and 98: 4.4 Selection ! e ciencies and syst
Page 99 and 100: 4.5 Data analysis summary 99 4.4.3
Page 101 and 102: 4.6 Final fit and measurement of
Page 103 and 104: 4.6 Final fit and measurement of
Page 105 and 106: 4.7 Summary and Conclusions 105 tel
Page 107 and 108: Chapter 5 Correlated background tel
Page 109 and 110: 5.1 Measuring correlated background
Page 111 and 112: 5.2 High energy analysis 111 in a l
Page 113 and 114: 5.2 High energy analysis 113 tel-00
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
Page 119 and 120: 5.4 Fast Neutrons analysis 119 5.4.
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Page 125 and 126: 5.4 Fast Neutrons analysis 125 Corr
Page 127 and 128: 5.4 Fast Neutrons analysis 127 tel-
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
Page 139 and 140: 5.5 Stopping Muon analysis 139 5.5.
Page 141 and 142: 5.5 Stopping Muon analysis 141 tel-
Page 143 and 144: 5.5 Stopping Muon analysis 143 tel-
Page 145 and 146: 5.5 Stopping Muon analysis 145 Sour
Page 147 and 148: 5.5 Stopping Muon analysis 147 belo
Page 149 and 150: 5.5 Stopping Muon analysis 149 The
Page 151 and 152: 5.6 Estimation of correlated backgr
Page 157 and 158: 5.7 Conclusion 157 5.7 Conclusion t
Page 159 and 160: Chapter 6 Conclusions tel-00821629,
Page 161 and 162: 161 • The SM analysis could be im
Page 163 and 164: Chapter 7 Contributions to Double C
Page 165 and 166: 165 from this study and from [64] f
Page 167 and 168: List of Figures tel-00821629, versi
Page 169 and 170: LIST OF FIGURES 169 tel-00821629, v
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LIST OF FIGURES 173 tel-00821629, v
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List of Tables 3.1 Mean energy rele
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Bibliography [1] [2] tel-00821629,
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BIBLIOGRAPHY 183 [31] J.K. Ahn et a
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BIBLIOGRAPHY 185 [61] W. Hampel et
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BIBLIOGRAPHY 187 [92] A. Stueken et
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