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Radiating top quarks
Gosselink, M.
Publication date 2010
Link to publication
Citation for published version (APA):
Gosselink, M. (2010). Radiating top quarks.
http://www.nikhef.nl/pub/services/biblio/theses_pdf/thesis_M_Gosselink.pdf
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Outlook
Since the first pp collissions at a centre-of-mass energy of 7 TeV on March 30th2010, three months ago from this writing, ATLAS has recorded data with an integrated luminosity of approximately 31 nb−1 (93% of the total amount of collision data provided by the LHC). The detector status, shown in Table 8.1, is excellent. More than 97% of all subdetector parts are operational and further improvement is foreseen after a future maintenance.
Subdetector Number of Operational Channels Fraction Pixels 80 M 97.4 % SCT Silicon Strips 6.3 M 99.2 % TRT Transition Radiation Tracker 350 k 98.0 % LAr EM Calorimeter 170 k 98.5 % Tile calorimeter 9800 97.3 % Hadronic endcap LAr calorimeter 5600 99.9 % Forward LAr calorimeter 3500 100.0 % LVL1 Calo trigger 7160 99.9 % LVL1 Muon RPC trigger 370 k 99.5 % LVL1 Muon TGC trigger 320 k 100.0 % MDT Muon Drift Tubes 350 k 99.7 % CSC Cathode Strip Chambers 31 k 98.5 % RPC Barrel Muon Chambers 370 k 97.0 % TGC Endcap Muon Chambers 320 k 98.6 %
Table 8.1: ATLAS detector status in June 2010. Numbers taken from [166].
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Chapter 8. Outlook
Observation of W± and Z boson events
The successful start of the first, long, data-taking period, has given the ATLAS collab-oration the opportunity to make the first observations of W± and Z bosons events in pp collisions at a centre-of-mass energy of 7 TeV [14]. Figure 8.1 shows an event display of a candidate W−→ µ−ν decay with three jets and Figure 8.2 shows an event display of a candidate Z → µ+µ− decay.
Figure 8.1: A candidate W−
→ µ−ν decay, collected on 16 May 2010. The left part of the figure is a three-dimensional cut-away view of the ATLAS detector and the right figure is a projection along the beam axis. The two thin red lines indicate two muon tracks, together with the locations of the the muon spectrometer hits. All other thin lines are tracks of other particles in the inner detector. The three red cones represent the three jets. The large yel-low arrow point in the direction of the missing transverse energy and the smaller yellow bars correspond to the amount of energy deposited in the calorimeters. Event properties: pµT− = 22 GeV, ηµ−
= 2.0, 6ET = 51 GeV, MT = 61 GeV. Three jets (anti-kT algorithm, R = 0.4) with jet ET above 15 GeV; the highest-ET jet contains a muon candidate. Figure taken from [167].
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Figure 8.2: Candidate Z → µ+µ−decay, collected on 10 May 2010. The left part of the figure is a projection along the beam axis and the right part of the figure is a three-dimensional cut-away view of the ATLAS detector. The two thin red lines in indicate the tracks together with the muon spectrometer hits of the two muons from the Z decay. All other thin lines are tracks of other particles in the inner detector. Event properties: pµT+ = 45 GeV, ηµ+
= 2.2, pµT− = 27 GeV, ηµ−
= 0.7, Mµ+µ− = 87 GeV. Figure taken from [167].
Finally...
The first observation of a t¯t event is expected any time soon now: top quark physics has started for the ATLAS experiment.
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