Mohamad-Ziad Charif - Antares

More documents

Recommendations

Info

Livetime(days) 5 Lines 9 Lines 10 Lines 12 Lines3HT 96.2 36.5 38.4 52.210HT 37.8 1.7 0.1 30.5Table 5.1: List of different periods with the corresponding livetime.5.4 Monte Carlo selectionAs previously mentioned between 2007 and 2008 the detector went through thelast phases of construction. The effect of this is that the behavior of the detectordiffers during these periods, for this reason we have more than one set of MonteCarlo, and in fact the set includes 8 different Monte Carlo each with a differentlivetime (Table 5.1).Atmospheric neutrinos Monte Carlo for each period consists of two files, onefor neutrinos and one for anti-neutrinos.The simulation had the simulation parameters: Neutrino flux Γ = −1.4 ; Energyrange: 10 GeV - 10 8 GeV ; Isotropic simulation ;Atmospheric muons Monte Carlo each period consists of only one file.5.4.1 Dark matter Monte CarloThe neutrino Monte Carlo generator GENHEN, has two modes for generatingneutrinos. The point source mode, which just takes the source’s declination andgenerates the signal neutrinos, and an isotropic mode which generates atmosphericneutrinos. Since the Sun has a variable declination [−23 ◦ 26 ′ ,23 ◦ 26 ′ ] there is noway to directly use GENHEN to simulate neutrinos coming from the Sun. So inorder to create a Dark Matter neutrino MC we will use the atmospheric neutrinoMonte Carlo files to select from them neutrinos coming from the Sun’s direction.For the 2007-2008 analysis the following neutralino masses were chosen:50 GeV, 80.3 GeV, 100 GeV, 150 GeV, 200 GeV, 350 GeV, 500 GeV,1000 GeVAnd for the annihilation channels:Soft channel: b + b −Hard channel: W + W −Hard channel: τ + τ −The process goes as following:• For each period of 5, 9, 10, 12 lines detector, 3pe, 10pe threshold we selectthe appropriate atmospheric (anti)-neutrino files.80
• Take the start date of the first run in that period, and follow the Sun’s skyposition in Zenith Vs Azimuth for the first 24 hours after that date.• Take the end date of the last run in that period, and follow the Sun’s skyposition in Zenith Vs Azimuth for the last 24 hours preceding that date.• If the period includes a solstice, then the period is divided for two periodsfrom the start date to the solstice and from the solstice to the end date.• Any events found between these two boundaries are events that correspondsto positions that the Sun takes during that period (Figure 5.4). Events outsidethat region will be removed.• If the period include a solstice as indicated before, any event that is foundin the overlapping regions gets selected twice or more depending on howmany regions overlap at that position.• For different M χ we remove events that have E ν > M χ . To make sure themost energetic neutrinos in our sample can actually be a product of WIMPannihilation.• We apply for each spectrum the corresponding dNdE(Figure 5.3) to the remainingevents by re-weighting the MC events via a convolution with theeffective area of the detector.• We end up with dark matter (anti)-neutrinos for each specific period (Figures5.5& 5.6).It is interesting to note that the resulting MC file has a different livetime from theone used to generate it. The area selected by this method does not represent a fullyear but only an area with the livetime of that period.In Figure 5.5 we notice an effect where instead of having a smooth 1 eventdistribution, we find more events concentrated near the middle of the event distribution.This is due to the fact that during Autumn and Spring the Sun is found atexactly the same region of the sky. However what we see in Figure 5.6 is a slightvariation of this effect, where the geometry of the detector creates privileged 2 directionsin Azimuth (φ) where more events are reconstructed in these directionsthan others. No selection criteria were applied to Figures 5.5 and 5.6.1 Small variations are expected due to different number of reconstructed events betweenSummer-Autumn-Winter-Spring periods.2 These directions slightly changes whether there is 5, 9, 10, or 12 lines in the detector.81
Page 2 and 3:
"The most exciting phrase to hear i
Page 4 and 5:
3.2.1.4 Performance and characteris
Page 6 and 7:
Chapter 1IntroductionThe early hist
Page 8 and 9:
Chapter 2Dark MatterIn this chapter
Page 10 and 11:
Figure 2.2: Comparison of the measu
Page 12 and 13:
Figure 2.4: CMB anisotropy observed
Page 14 and 15:
Figure 2.5: Combination of the WMAP
Page 17:
Figure 2.6: Temporal evolution of t
Page 20 and 21:
Figure 2.9: Parameter space of m 1/
Page 22 and 23:
Figure 2.10: Limits on spin-indepen
Page 26 and 27:
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 78 and 79: Chapter 5Dark Matter search in the
Page 80 and 81: Figure 5.2: Annihilation spectrum f
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
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
Page 160 and 161:
[46] G. Debrassi, S. Heinemeyer, W.
Page 162 and 163:
[74] C. Hettlage, K. Mannheim, and
Page 164:
[102] D. Heck and J. Knapp, “Fors
show all

Mohamad-Ziad Charif - Antares

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?