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Introduction to B Physics in ATLAS Detector at LHC. Ahmet BİNGÜL Department of Engineering Physics University of Gaziantep. Feb 2010. Outline. Introduction Physics in ATLAS Experiment ATLAS B-Physics Programme Trigger Simulation of the Events Example Reconstruction. Introduction. - PowerPoint PPT Presentation
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Sayfa 1
Introduction to B Physics in ATLAS Detector at LHC
Ahmet BİNGÜL
Department of Engineering Physics
University of Gaziantep
Feb 2010
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Outline
Introduction
Physics in ATLAS Experiment
ATLAS B-Physics Programme
Trigger
Simulation of the Events
Example Reconstruction
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Introduction
This is a short introduction to some current topics in B-Physics in ATLAS Detector at LHC.
We will look at briefly
the LHC the ATLAS detector
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LHC: Large Hadron Collider
Circumference 27 km ~100 m underground Protons ve Pb nuclei will collideCost: 3 billions €
PHYSICS Higgs Boson(s) Supersymmetric particles furher quarks and/or hadronsBig-Bang and mini-black holes
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LHCAbout p-p collisions
Max proton energy: E = 7 TeV
Velocity: v = 0.999999991 c ~ 300,000 km/s
2808 x 2808 bunches of protons
# of p / bunch = 1011
Bunch diameter = 16 μm (hair 50 μm)
Max Luminosity: L = 1034 cm‒2s‒1
Collision frequency f = 1/25 ns = 40,000,000 Hz = 40 MHzDebris
of a collis
ion
E = m c2
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LHC Detectors
CMS
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Sayfa 816/11/2007 YFD
22 m
44 m
ATLAS Detector (http://atlas.ch)
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Physics Groups in ATLAS
https://twiki.cern.ch/twiki/bin/view/Atlas/AtlasResults
Standard Model (SM) QCD W/Z and jets Electroweak measurements
Higgs Discovery of SM Higgs Boson (for several decay channels) Charged Higgs Boson searces
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Physics in ATLAS
B-Physics Heavy quarkonium physics with early ATLAS data Production cross-sections measurements Study of B-hadrons Rare B-dacays
Top Physics t-tbar pair cross-section Top mass, charge, spin measurements Rare top decays
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Physics in ATLAS
SUSY Discovery of SUSY particles Test of SUSY models
Exotics Black hole Production New quarks and leptons
Heavy Ion Results of Pb-Pb collisions Heavy quark production Jet studies Quarkonia Reconstruction
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ATLAS B-Physics Programme
B-Physics programme covers many aspects of
beauty flavour physics.
by measuring production cross-sections of beauty and charm hadrons and of heavy-flavour quarkonia (J/ψ and Y (upsilon)),ATLAS will provide sensitive tests of QCD predictions.
ATLAS will study the properties of entire family of B-mesons (B+, Bd, Bs, Bc) and B-baryons (Y, Λb )
Precise measurements of weak B-hadrons decays
Rare decays of B-hadrons
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The rate of B-hadron production at the LHC is enormous thanks to the large hadronic cross-section for b-quark production and the high luminosity of the machine (L = 1033 / s.cm2)
About one collision in every hundred will produce a b-quark pair. (better S:N ratio wrt Tevatron)
At the LHC, ATLAS and CMS will face stiff competition from LHCb, which is a dedicated B-physics experiment.ATLAS and CMS will improve the combined precision of B-physics measurements from the LHC.
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In ATLAS, B-Physics potential begins during early data taking at low luminosity (L = 1031/ s.cm2)
Main B-Physics measurements will be made at the luminosity of L = 1033/ s.cm2.
With the integrate luminosity of Lint = 10 pb-1 ATLAS will be able to register about 1.3x105 events containing
either directly produced from p-p collisions or indirectly from decays of B-hadrons.
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During the period of Lint = 10 – 100 pb-1 B-physics and heavy quarkiona signatures will help
understand the detector performance and muon trigger promt J/ψ and Y events and
B-hadron decays to muon pairs via J/ψ will be analysed followind exclusive decays will be stuied
During the period of Lint = 200 pb-1 – 1 fb-1 Statistics will be simalar to Tevatron SM rare decays will be studied (e.g. )
During the period of Lint = 10 – 30 fb-1 (around 3 years) Luminosity will mostly be L = 1033/ s.cm2
Measuremnts of Λb and osciallation pghenomena of Bs – Bs_bar
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Trigger
All B-Physics studies include trigger reconstruction
ATLAS have three levels of trigger L1 – Hardware trigger L2 - L3 – Software trigger
B-Physics events is initiated by a L1 di-muon trigger by a L1 single-muon trigger L2 is used to combine ID tracks with L1 muon each muon has to have pT > 4 GeV (later rising to 6-8 GeV)
After getting L1 muon(s), cuts on invariant mass and secondary vertex reconstruction of B decay products are used.
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Simulation of Events
Some 1 million B-hadron events, along with 4x105 prompt J/ψ and Y as well as c-cbar events were produced using PYHTIA 6.4.
The events were passed trough detector simulation based on GEANT4.
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Example Reconstruction