Mohamad-Ziad Charif - Antares

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Chapter 6Dark Matter search in the directionof the SUN with 2007-2010 dataIn this chapter we will present the analysis with the 2007-2010 data.6.1 Data selection and new background Monte CarloA recent development in the generation of the MC allows us to use more data.Instead of having one MC file for each period (ex: 9 Lines 3 pe) now each run hasits own MC[110] that is generated according to the detector efficiency (workingOMs) and averaged optical background of that run. The benefit of this methodis the opportunity to include previously excluded data runs with lower quality inthe analysis. Each run now has 5 main MC files (plus an additional 12 for theν e neutrino and for NC interaction events), 1 for atmospheric muons and 4 foratmospheric (anti-)neutrinos (2 low energy simulation and 2 with normal energyranges). Data selection is now done for runs with QB ≥ 1 (section 4.1.3). Inaddition between 2007 and 2010 we have over 8000 runs. However, we excludefrom the data sample runs where the Sun is above the horizon. With this criteriawe find 2882 runs (314.6 days livetime) where the Sun is below the horizon forthe entire run-time, and an additional 1756 runs (226.3 days of livetime) wherethe Sun changes between below and above the horizon during run-time. We endup with 4638 runs with a total livetime of 541 days and 427.7 days of effectivelivetime with the Sun below the horizon. The simulation parameters of the MCis essentially the same as in the 2007-2008 analysis with small differences, weinclude some of them:• Atmospheric muons were generated with 1/3 of the livetime of the run.• Low energy atmospheric neutrinos are generated between 5 GeV and 3 TeV108
with 2.10 8 neutrinos per run.• Standard atmospheric neutrinos are generated between 100 GeV and 10 8GeV with 10 9 neutrinos per run.6.1.1 Dark Matter Monte CarloIn the section 5.4.1 we presented a way to simulate the dark matter neutrino signal.However, this method will not be used for this analysis because of the shortlivetime for each MC which is few hours, while it was few months in the previouschapter. So in this section we will present the new method that is based as well oneach run having its own dark matter neutrino MC.The Sun does indeed have a variable declination [−23 ◦ 26 ′ , 23 ◦ 26 ′ ] with a periodof 6 month (46 ◦ 52 ′ ), but during one run (typically 2 hours) the declination varieson average by 0.021 ◦ , so for all that matters during one run the Sun can be consideredstationary in equatorial (declination [δ] , right-ascension [RA]) coordinates.So it might be possible to use the neutrino MC generator in its point source modeto simulate a neutrinos coming from the Sun. However, we must first verify thatit works.In GENHEN, the point source mode is a mode where the source is fixed in δ butduring simulation RA is randomly generated in [0 ,2π] interval, so it is importantto verify that this will not affect the calculation of the position of the Sun with afixed δ. For this we pick a random run and calculate the position of the Sun inlocal coordinates [ Elevation, Azimuth ] via three different methods:1. True position of the Sun.2. Position of the Sun with both δ and RA fixed. Both values are calculated atmid-run time.3. Position of the Sun with δ fixed and RA randomized as in GENHEN. Theused δ is calculated at mid-run time.Figure 6.1 shows the true position of the Sun taken from the previously selectedrun. It is obvious that the position taken in the sky by the Sun is quite limitedin the coordinates space. Now if we take a look at figure 6.2, we can clearly seethat using methods (2) and (3) produce exactly the same Sun position in the localcoordinates but nevertheless they don’t look exactly like in 6.1. However, if welook at the distributions only in the region where the Sun should only be duringthe time of the run(taken from figure 6.1) we can see that the agreement is perfect(Figure 6.3).So the method for creating our signal MC is the following:109
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"The most exciting phrase to hear i
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3.2.1.4 Performance and characteris
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Chapter 1IntroductionThe early hist
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Chapter 2Dark MatterIn this chapter
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Figure 2.2: Comparison of the measu
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Figure 2.4: CMB anisotropy observed
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Figure 2.5: Combination of the WMAP
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Figure 2.6: Temporal evolution of t
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Figure 2.9: Parameter space of m 1/
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Figure 2.10: Limits on spin-indepen
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Figure 2.14: Detected gamma ray flu
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600km/s. If we assume the worst cas
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Figure 2.17: Conversion factor from
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The eigenstate mixing can be writte
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Figure 2.19: Flux of ν µ / ¯ν
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Figure 3.1: The neutral current (NC
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Muon Energy (GeV )1p| dEdx | (GeV.c
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Figure 3.4: Energy loss of per dist
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Figure 3.6: Effective muon range as
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Figure 3.8: Differential flux of at
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3.2.1.1 Detector layoutOptical Modu
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• The LED (light emitting diode)
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Anchor & BuoyEach line is anchored
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Figure 3.17: Distribution of azimut
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Figure 3.20: Height and radial disp
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Figure 3.22: Distribution of sea cu
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Figure 3.24: Time offset among OMs
Page 60 and 61: Figure 3.26: Distribution of time d
Page 62 and 63: Line number Connection Date Mainten
Page 64 and 65: Figure 3.29: Comparison between sky
Page 66 and 67: Figure 3.31: The effective area for
Page 68 and 69: Figure 4.1: Median counting rate of
Page 70 and 71: Figure 4.4: Average neutrino events
Page 72 and 73: 2. All hits on the same floor are m
Page 74 and 75: 4.2.1 Neutrino simulationFigure 4.6
Page 76 and 77: • Multiplicity range of the muon
Page 78 and 79: Chapter 5Dark Matter search in the
Page 80 and 81: Figure 5.2: Annihilation spectrum f
Page 82 and 83: Livetime(days) 5 Lines 9 Lines 10 L
Page 84 and 85: Figure 5.4: Monte Carlo Truth distr
Page 86 and 87: Figure 5.7: Tchi2 distribution for
Page 88 and 89: Figure 5.9: Tchi2 distribution for
Page 90 and 91: Figure 5.11: Sun’s position taken
Page 92 and 93: Figure 5.13: Comparison between the
Page 94 and 95: Figure 5.15: Estimation of the back
Page 96 and 97: Figure 5.16: Mean angle between the
Page 98 and 99: Figure 5.18: A comparison of the di
Page 100 and 101: a look at figure 5.22 we find a cle
Page 102 and 103: The resulting optimized sensitiviti
Page 104 and 105: Figure 5.26: A comparison plot of t
Page 106 and 107: dΦ µdE ν= dΦ νdE νP earth ρN
Page 108 and 109: Figure 5.31: Limits on the muon flu
Page 112 and 113: Figure 6.1: . True Position of the
Page 114 and 115: Figure 6.3: Comparison of the three
Page 116 and 117: For BBFit all variables mentioned i
Page 118 and 119: Figure 6.6: The distribution of χ
Page 120 and 121: annihilation channel W + W − the
Page 122 and 123: lowering the total contribution of
Page 124 and 125: 6.4.2 BBFit Single-line analysisThe
Page 126 and 127: Figure 6.15: Comparison between the
Page 128 and 129: Figure 6.17: Comparison of Nhit dis
Page 130 and 131: Figure 6.19: The estimation of the
Page 132 and 133: Figure 6.21: Comparison of the opti
Page 134 and 135: Figure 6.23: Comparison of sensitiv
Page 136 and 137: Figure 6.25: Estimation of our back
Page 138 and 139: Figure 6.28: Comparison of the mult
Page 140 and 141: Figure 6.29: Comparison of the Λ d
Page 142 and 143: Figure 6.31: Comparison of the cos(
Page 144 and 145: Figure 6.34: Comparison of the esti
Page 146 and 147: The optimal Λ cut for all dark mat
Page 148 and 149: Figure 6.40: Sensitivity to neutrin
Page 150 and 151: 6.7 Comparison with 2007-2008 analy
Page 152 and 153: mass of 200 GeV and a cross-section
Page 154 and 155: Chapter 7ConclusionsThe limits pres
Page 156 and 157: Bibliography[1] Volders, L. M. J. S
Page 158 and 159: [22] S. Burles et al., “Big bang
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[46] G. Debrassi, S. Heinemeyer, W.
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[74] C. Hettlage, K. Mannheim, and
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[102] D. Heck and J. Knapp, “Fors
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Mohamad-Ziad Charif - Antares

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