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Particle Physics and LHC Physics David Krofcheck Canterbury Teachers Workshop July 18th D. Krofcheck Canterbury Teachers Workshop 1 The place to be for high energy physicists Lac Léman Jura CMS experiment CERN (FR) Geneva airport CERN (CH) Thanks to Lucas Taylor, 2012 Large Hadron Collider CMS experiment • 27 km (17 miles) circumference Large Hadron Collider • 1600 superconducting magnets at 1.9° K (271.3° C or – 459.7° F) • 120 tonnes of liquid helium • Accelerates beams of protons to 99.9999991% the speed of light Thanks to Lucas Taylor, 2012 3 The CMS detector at the Large Hadron Collider Hadron Calorimeter EM Calorimeter New Zealand Beam Scintillator Counters Forward Calorimeter CASTOR Tracker (Pixels and Strips) ZDC Muon Endcaps Muon Barrel D. Krofcheck Pitt/CMU July 2011 4 The really important CMS detectors D. Krofcheck Pitt/CMU July 2011 5 What is matter? Aristotle : all matter is made up of various combinations of Earth, air, fire and water solids gases liquids change D. Krofcheck Canterbury Teachers Workshop This belief about the nature of matter lasted for 2000 years 6 Development of the Atomic Theory Aristotle Democritus John Dalton D. Krofcheck Canterbury Teachers Workshop Lucretius 7 Ideas about Atoms 1800’s John Dalton – meteorologist and teacher - successfully explained chemical reactions by proposing all matter is made up of atoms. - BUT they had no direct evidence! D. Krofcheck Canterbury Teachers Workshop 8 Dmitri Mendeleev Russian 1834-1907 Periodic Table Similar chemical properties D. Krofcheck Canterbury Teachers Workshop 9 ? Periodic Table Atoms D. Krofcheck Rutherford Canterbury Teachers Workshop (1909) Bohr (1913) 10 ... proton neutron electron • Are these the elementary particles, ? • Are they composed of even more elementary particles?? • D. Krofcheck Particle and Nuclear Physics are the studies to answer this question Canterbury Teachers Workshop 11 Matter Particles 1932 p, n, e 1937 μ 1940s mesons π, K 1950s particles Λ, Δ, Σ, ... ν …hundreds of new particles were discovered! D. Krofcheck Canterbury Teachers Workshop 12 In 1964 the idea of quarks was proposed… quarks These were elementary particle of, fractional electric charge, different flavours Zweig Gell-Mann D. Krofcheck u u d d d u proton neutron Canterbury Teachers Workshop 13 What is the composition of the proton d u u q(u) = +2/3 q(d) = -1/3 q(p) = +1 ...and of the neutron d u d D. Krofcheck Canterbury Teachers Workshop q(n) = -1/3 - 1/3 + 2/3= 0 14 What glues the quarks together? u u Gluons, of course D. Krofcheck d proton Canterbury Teachers Workshop 15 Elementary particles of matter 1897 1st family: u, d, e- , e 2nd family: c, s, - , leptons 3rd family: D. Krofcheck t, b, - , 1995 Canterbury Teachers Workshop 4 July, 2012 Higgs16 Antimatter Every particle has its antiparticle, of the same mass but opposite quantum numbers eg. electron, e- : q(e-) =-1 , spin = -1/2 , m(e-) = 9.110-28 gr. positron, e+ : q(e+) =+1 , spin = +1/2 , m(e+) = 9.110-28 gr. D. Krofcheck Canterbury Teachers Workshop 17 All these interactions are manifestations of only .. .10-2. . . 4 basic interactions -40 10 Gravitational Force 1 Electromagnetic Force -5 10 nuclei Strong Colour Force átomo Weak Force n p + e- + e d u + e- + e Interaction Type Mediating Particle Electromagnetic γ (photon) Strong g (gluon) Weak bosons W, Z Gravitational G (graviton) Still not detected experimentally Example: Electromagnetic interaction p + + e- p + + e- http://www.cerimes.education.fr/ The Fundamental Interactions are produced by the exchange of a particle mediator http://www.cerimes.education.fr/ The particles of matter interact across a distance by exchanging a “messenger” particle The interaction range decreases as the mass of the messenger particle increases. Standard Model of Particle Physics • Messengers • interactions leptons In a quantum description of matter and the laws of interaction between them still do not know how to incorporate gravitation, but the rest of interactions are well described by a mathematical theory, the Standard Model, able to make predictions that have been confirmed in experiments. Standard Model (~1980) Symmetry Components of matter Interactions This model requires that the particle messengers are massless, But the W and Z are very heavy!! problem of the origin of mass Higgs Boson The British physicist Dr. Peter Higgs proposed (1964) the so-called Higgs mechanism: All the particles would be generated in the Big Bang without mass, but by interacting with the field created by the Higgs particle, the particles would acquire mass, the greater, the greater the interaction. This field would fill the whole universe. Interaction with the Higgs field ≡ Friction with a viscous liquid Higgs Boson The British physicist Dr. Peter Higgs proposed (1964) the so-called Higgs mechanism: All the particles would be generated in the Big Bang without mass, but by interacting with the field created by the Higgs particle, the particles would acquire mass, the greater, the greater the interaction. This field would fill the whole universe. Interaction with the Higgs field ≡ Friction with a viscous liquid Unico “Higgs” observado hasta ahora en un experimento…el propio Dr. Higgs!! Higgs Boson This particle predicted has not yet been unambiguously . detected in experiments, hopefully we are hot on the trail! ≡ A recent view of a Higgs at the CMS experiment !!?? H Z0 Z0 μ+ μ- μ+ μ- Gauge Bosons – Z0 First detection in HI collisions! First step is to find Z0 bosons in PbPb collisions Z0 → μ+μ - observed for the first time in HI collisions! Z0 → e+e- event candidate Z0 → e+e- observed for the first time in HI collisions! 29 lead + lead collisions may liberate quarks Jet production in pp collisions jet-jet correlation in QCD “vacuum” Jet Jet D. Krofcheck Dijet Probes of Hot Nuclear Matter at the LHC 31 Jet production in PbPb collisions jet-jet correlation in QCD “medium” γ – jet correlation to probe the medium? D. Krofcheck Dijet Probes of Hot Nuclear Matter at the LHC 32 E-ΔΕ1 Δφ Dijet imbalance in PbPb collisions E-ΔΕ2 Phys. Rev. C 84, 024906 (2011) D. Krofcheck Dijet Probes of Hot Nuclear Matter at the LHC 33 Jet production in PbPb collisions gamma-jet correlation in QCD “medium” Gamma Nuclear remnant D. Krofcheck Nuclear remnant Dijet Probes of Hot Nuclear Matter at the LHC 34 Observed momentum imbalance in γ – jet correlation Submitted to PLB, arXiv:1205.0206 • Momentum ratio shifts/decreases with centrality – jets shifting below the 30 GeV pT threshold not included D. Krofcheck Dijet Probes of Hot Nuclear Matter at the LHC 35 Energy Units! Electron Volt – Energy gained by an electron when accelerated in an electric field through a potential difference of 1 volt. 1 eV = 1 electron Volt Energy to ionise hydrogen = 13.6 eV 1 keV(kilo) = 1,000 eV = 103 eV Medical X-ray ~ 200 keV 1 MeV(Mega) = 1,000,000 eV = 106 eV Alpha particle decay of uranium 4.2 MeV 1 GeV(Giga) = 1,000,000,000 eV = 109 eV LEP collider beam (1989-2000) = 45 GeV 1 TeV(Tera) = 1,000,000,000,000 eV = 1012 eV Highest energy accelerator in world = 1 TeV (Tevatron) Highest energies found in cosmic rays (>1020 eV) Interactions between matter particles Why are there so many different substances in the world? D. Krofcheck Canterbury Teachers Workshop 40