Etude de bruit de fond induit par les muons dans l'expérience ...

tel-00724955, version 1 - 23 Aug 2012
x LIST OF FIGURES
3.8 Examples of plots from the online monitoring of bolometers . . . . . 65
3.9 Pictures of the cryostat of the EDELWEISS-II experiment . . . . . . 67
3.10 Schematic view of the passive shielding, the mechanical construction
and the muon veto detector of EDELWEISS-II . . . . . . . . . . . . . 69
3.11 Muon veto system of EDELWEISS-II . . . . . . . . . . . . . . . . . . 69
3.12 Electronic chain of the muon veto system . . . . . . . . . . . . . . . . 71
3.13 Muon veto monitoring wesite . . . . . . . . . . . . . . . . . . . . . . 73
3.14 Schematic of the side view of the muon-induced neutron counter . . . 75
3.15 EDELWEISS-I results . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.16 Current and expected limits from various direct Dark Matter search
experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.1 Energy deposit in the North side of the Top module #4 . . . . . . . . 83
4.2 Life time of the muon veto during three years of data acquisition . . . 84
4.3 Muon candidate rates of the Top and North side in coincidence with
the lower level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.4 Simulated total energy deposit and relative contribution of gammas,
electrons and muons . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.5 Time difference of the TDCs from both ends of a module in coincidence
with the other level per sets of modules per size . . . . . . . . . 91
4.6 Time difference within the neighboring module n + 1 versus the time
difference within module n of a level, further in coincidence with the
other level of the veto system . . . . . . . . . . . . . . . . . . . . . . 92
4.7 Time difference of through going muon candidates . . . . . . . . . . . 93
5.1 Run 8 - Electronic chain of the bolometers and distribution of the
time over the EDELWEISS-II experiment . . . . . . . . . . . . . . . . 96
5.2 Run 8 - Rate of the muon veto per 8-hour file . . . . . . . . . . . . . 98
5.3 Run 8 - Timeline of the veto events . . . . . . . . . . . . . . . . . . . 98
5.4 Run 8 - Time difference of consecutive muon veto events . . . . . . . 99
5.5 Run 8 - 3-D visualization of the selected bolometers for the muon
veto-bolometer coincidence analysis . . . . . . . . . . . . . . . . . . . 100
5.6 Run 8 - Shift applied to reconstruct the time stamp of s1 and of s3
to correspond to this of s2 . . . . . . . . . . . . . . . . . . . . . . . . 102
5.7 Run 8 - Time difference of the events which are in coincidence between
the three sets of bolometers . . . . . . . . . . . . . . . . . . . . . . . 102
5.8 Run 8 - Quality of the bolometer system events . . . . . . . . . . . . 104
5.9 Run 8 - Muon veto-bolometer events in coincidence . . . . . . . . . . 106
5.10 Run 8 - Muon veto-bolometer events in coincidence at high heat energy
EH > 6.5 MeV . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.11 Run 8 - Muon veto-bolometer events in coincidence with multiveto > 3 107
5.12 Run 8 - Geant-4 simulation of muon-induced Germanium hits . . . . 109
5.13 Run 8 - Q-plot of events in coincidence with ER < 250 keV inside and
outside the coincidence time interval ∆tcoinc ∈ (+15, +35) ms . . . . . 111
5.14 Run 8 - 3-D visualization of the four coincidence events in the region
ER < 250 keV in the nuclear recoil band in ∆tcoinc ∈ (+15, +35) ms . 112
5.15 Run 8 - Examples of coincidence events in the region ER ≥ 250 keV
in ∆tcoinc ∈ (+15, +35) ms in 3-D visualization . . . . . . . . . . . . . 113