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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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Sayfa 2 Outline Introduction Physics in ATLAS Experiment ATLAS B-Physics Programme Trigger Simulation of the Events Example Reconstruction
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Sayfa 3 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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Sayfa 4EP328 – Particle Physics LHC: Large Hadron Collider Circumference 27 km ~100 m underground Protons ve Pb nuclei will collide Cost: 3 billions € PHYSICS Higgs Boson(s) Supersymmetric particles furher quarks and/or hadrons Big-Bang and mini-black holes
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Sayfa 5 LHC About 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 = 10 11 Bunch diameter = 16 μm (hair 50 μm) Max Luminosity: L = 10 34 cm ‒ 2 s ‒ 1 Collision frequency f = 1/25 ns = 40,000,000 Hz = 40 MHz Debris of a collision E = m c 2
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Sayfa 6 LHC Detectors CMS
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Sayfa 7
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Sayfa 8 16/11/2007 YFD 22 m 44 m ATLAS Detector (http://atlas.ch)
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Sayfa 9 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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Sayfa 10 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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Sayfa 11 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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Sayfa 12 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 +, B d, B s, B c ) and B-baryons (Y, Λ b ) Precise measurements of weak B-hadrons decays Rare decays of B-hadrons
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Sayfa 13 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 = 10 33 / s.cm 2 ) 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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Sayfa 14 In ATLAS, B-Physics potential begins during early data taking at low luminosity (L = 10 31 / s.cm 2 ) Main B-Physics measurements will be made at the luminosity of L = 10 33 / s.cm 2. With the integrate luminosity of L int = 10 pb -1 ATLAS will be able to register about 1.3x10 5 events containing either directly produced from p-p collisions or indirectly from decays of B-hadrons.
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Sayfa 15 During the period of L int = 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 L int = 200 pb -1 – 1 fb -1 Statistics will be simalar to Tevatron SM rare decays will be studied (e.g. ) During the period of L int = 10 – 30 fb -1 (around 3 years) Luminosity will mostly be L = 10 33 / s.cm 2 Measuremnts of Λ b and osciallation pghenomena of Bs – Bs_bar
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Sayfa 16 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 p T > 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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Sayfa 17 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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Sayfa 18 Example Reconstruction
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