Mohamad-Ziad Charif - Antares

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Chapter 5Dark Matter search in the directionof the SUN with 2007-2008 dataIn this chapter the analysis and the results obtained from looking at the 2007-2008data sample will be presented.5.1 Dark matter neutrino spectrumIn order to analyze the possibility of finding a dark matter neutrino signal, we mustfirst be able to estimate the (anti-)neutrino spectrum coming from WIMP annihilationin the Sun. The spectra were obtained using WIMPSIM[86]. WIMPSIM isdefined as:A WIMP (Weakly Interacting Massive Particle) Monte Carlo forneutrino telescopes. This code calculates the annihilation of WIMPsinside the Sun or the Earth, collects all the neutrinos that emerge andlet these propagate out of the Sun/Earth to the detector including neutrinointeractions and neutrino oscillations in a fully consistent threeflavorway. This is done in an event-based scenario which is particularlysuitable for interfacing to a neutrino telescope Monte Carlo.The neutrino spectrum coming from dark matter auto-annihilation is dependent onthe mass of the particle, and it changes between hard and soft spectrum dependingon which is the dominant annihilation channel. WIMPSIM offers range of DarkMatter masses such as:50GeV, 80.3GeV, 91.2GeV, 100GeV, 150GeV, 176GeV, 200GeV, 250GeV, 350GeV500GeV, 750GeV, 1000GeV, 2000GeV, 5000GeV76
Figure 5.1: Dark Matter neutrino differential flux showing the difference betweenW + W − and τ + τ − annihilation channels.The softest neutrino flux is due to χ ¯χ → b¯b. The hard flux has been studiedwith two different channels. In most general models the hardest flux is producedby χ ¯χ → τ + τ − (Figure 5.1). However assuming the SUSY models it is commonto use fluxes produced by χ ¯χ → W + W − since in such models the branching ratioto τ + τ − is usually suppressed in comparison with W + W − . However since allν µ + ¯ν µ spectrum are normalized to 1 we would expect to see small differencesbetween τ and W annihilation channels when calculating the limits to neutrinofluxes.It is interesting to note that by examining Figure 5.1 , and 5.3 we notice thatthe ¯ν flux is higher than the ν. This is due to the fact that ν have higher interactionprobability with the Sun’s matter than ¯ν, resulting in larger absorption of ν than¯ν inside the Sun. Another remark is that we can see the effect of the neutrinooscillations on the fluxes. Nevertheless there is no reason to assume that theseoscillations can be detected with the current detector.Another note to be taken into consideration is that the absorption for neutrinoswith energies above 1 TeV in the Sun is considerable, we would expect to seethat the neutrino spectrum from the annihilation of WIMPS with masses higherthan 1 TeV has some sort of high energy cutoff as see in figure 5.2, so we wouldexpect that the limits of Soft and Hard spectra converge at very high WIMP masses(above 5 TeV).77
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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
Page 28 and 29: 600km/s. If we assume the worst cas
Page 30 and 31: Figure 2.17: Conversion factor from
Page 32 and 33: The eigenstate mixing can be writte
Page 34 and 35: Figure 2.19: Flux of ν µ / ¯ν
Page 36 and 37: Figure 3.1: The neutral current (NC
Page 38 and 39: Muon Energy (GeV )1p| dEdx | (GeV.c
Page 40 and 41: Figure 3.4: Energy loss of per dist
Page 42 and 43: Figure 3.6: Effective muon range as
Page 44 and 45: Figure 3.8: Differential flux of at
Page 46 and 47: 3.2.1.1 Detector layoutOptical Modu
Page 48 and 49: • The LED (light emitting diode)
Page 50 and 51: Anchor & BuoyEach line is anchored
Page 52 and 53: Figure 3.17: Distribution of azimut
Page 54 and 55: Figure 3.20: Height and radial disp
Page 56 and 57: Figure 3.22: Distribution of sea cu
Page 58 and 59: 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 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 110 and 111: Chapter 6Dark Matter search in the
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
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Figure 6.17: Comparison of Nhit dis
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Figure 6.19: The estimation of the
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Figure 6.21: Comparison of the opti
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Figure 6.23: Comparison of sensitiv
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Figure 6.25: Estimation of our back
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Figure 6.28: Comparison of the mult
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Figure 6.29: Comparison of the Λ d
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Figure 6.31: Comparison of the cos(
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Figure 6.34: Comparison of the esti
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The optimal Λ cut for all dark mat
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Figure 6.40: Sensitivity to neutrin
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6.7 Comparison with 2007-2008 analy
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mass of 200 GeV and a cross-section
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Chapter 7ConclusionsThe limits pres
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Bibliography[1] Volders, L. M. J. S
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[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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