CERN The Worlds Largest Particle Physics Laboratory Stefan
CERN The World’s Largest Particle Physics Laboratory Stefan Ask, University of Cambridge - STFC
Outline of this Lecture CERN Particle Physics Accelerators / Colliders Co of ntain off icia ove l v rlap isit on with We intr dn odu es da ction y Experiments (more on Wednesday) Questions to be Answered. (more on Wednesday) Stefan Ask (Prince William School) 15 Dec 2010, CERN 2
CERN was founded in 1954 Stefan Ask (Prince William School) 15 Dec 2010, CERN 3
Initially 12 Member States Sweden! Stefan Ask (Prince William School) 15 Dec 2010, CERN 4
CERN has now 20 Member States OBSERVERS: • UNESCO • EU • Israel • Turkey SPECIAL OBS. (for LHC): • USA • Japan • Russia • India Stefan Ask (Prince William School) 15 Dec 2010, CERN 5
---- Particle Physics ---The Science Related to • The smallest constituents of matter • Their properties • And their interactions Stefan Ask (Prince William School) 15 Dec 2010, CERN 6
Natures Smallest Building Blocks ~1 m ~10 -10 m ~10 -14 m ~10 -18 m All known matter consists of Quarks and Leptons. Which both exist in Three Generations, only different by their rest mass. Stefan Ask (Prince William School) 15 Dec 2010, CERN 7
(FYI) The Number of Generations The number of generations was measured at CERN. The measurement was indirect evidence for the existence of 3 neutrinos. More about experiments and measurements tomorrow! Stefan Ask (Prince William School) 15 Dec 2010, CERN 8
The (Four) Forces in Nature Strong Force Weak Force carriers = gluons Force carriers = W and Z Binds together, protons and neutrons to form the nucleus, quarks to form protons and neutrons. Generates radioactive decays. Gravitational Force Electromagnetic Force carrier = graviton Keep us on the earth, earth around the sun… Force carrier = photon Keeps electron around nucleus, chemical reactions, electricity, light, radio… Stefan Ask (Prince William School) 15 Dec 2010, CERN 9
The W and Z Bosons W and Z discovered at CERN 1983. Carlo Rubbia and Simon van der Meer receives Noble price in 1984 Stefan Ask (Prince William School) 15 Dec 2010, CERN 10
Anti-Matter (1928) Like the equation, x 2=4, have two solutions (x=2 and x=-2), Dirac had two solutions to his equation. Both for an electron with positive as well as negative energy. … All particles have an anti-particle with opposite electric charge. (1932) Experiments confirm the anti-electron. Athena Alpha (1995) CERN produces anti-hydrogen, i. e. anti-matter (2002 and 2010) CERN produces larger quantities of anti-hydrogen. Stefan Ask (Prince William School) 15 Dec 2010, CERN 11
The Higgs? • The Higgs particle is a boson, but is not originating from a force like the other bosons, i. e. the force carries. • The Higgs boson is a consequence of how the particles are believed to acquire their mass (the so-called electroweak symmetry breaking). • The theory give very well defined properties of the Higgs boson. i. e. “one knows where to look and what to look for”. • But it will be difficult to spot it, i. e. “like a needle in a haystack”. Stefan Ask (Prince William School) 15 Dec 2010, CERN 12
The Standard Model Theoretical Description Small Fast Classical (Newton) Mechanics Theory of (Special) Relativity Quantum Mechanics Quantum Field Theory Leptons + Quarks + Force carriers + (Higgs) The Standard Model Describes with excellent precision (almost) all existing particle physics experiments. Stefan Ask (Prince William School) 15 Dec 2010, CERN 13
---- Particle Colliders ---Small Distance = Large Energy Accelerator provides, high energy particles and a well defined initial state. Experiment measure the final state. Stefan Ask (Prince William School) 15 Dec 2010, CERN 14
Basic Accelerator Components p+ Injection p+ Stefan Ask (Prince William School) 15 Dec 2010, CERN 15
CERN Accelerator Complex Stefan Ask (Prince William School) 15 Dec 2010, CERN 16
The Large Hadron Collider Proton - proton collider Collisions Started: Nov 2009 Collision Energy: 7 (14) Te. V 1 e. V = energy of electron accelerated by 1 V. Collision Frequency: 1 GHz 350 MJ stored energy in beam. 350 MJ, approximately a train with velocity of 150 km/h. Stefan Ask (Prince William School) 15 Dec 2010, CERN 17
The LHC Experiments ATLAS p+ p+ General purpose CMS p+ p+ General purpose LHCb ALICE ATLAS ALICE Pb Pb Heavy Ions (Quark Gluon Pl. ) LHCb CERN Stefan Ask (Prince William School) 15 Dec 2010, CERN p+ p+ “Matter/Anti-Matter Asymmetry” 18
---- The (ATLAS) Experiment ---- Animation Stefan Ask (Prince William School) 15 Dec 2010, CERN 19
The (ATLAS) Experiment ATLAS Experimentet Lenght: 44 m Diameter: 22 m Weight: 6000 ton Collaboration: almost 3000 Physicists § Muon Chambers § Hadron Calorimeter § Electromagnetic Calorimeter § Tracking Chambers (174 Univ. , 38 Countiries) Stefan Ask (Prince William School) 15 Dec 2010, CERN 20
Particle Detection Stefan Ask (Prince William School) 15 Dec 2010, CERN 21
Particle Detection Animation Stefan Ask (Prince William School) 15 Dec 2010, CERN 22
What are the Problems? Dark Matter Experimentally Motivated • Gravitational lens effects. • Rotational velocity of galaxies. • Anisotropy of cosmic microwave background radiation. Could be explained by new particles that can be discovered at the LHC! Stefan Ask (Prince William School) 15 Dec 2010, CERN 23
What are the Problems? Unification of Forces Theoretically Motivated • The strength of a force vary with the energy where it is studied. • If the strength of several forces unify at some (larger) energy, they might be different shapes of the same thing. • Has happened before, Electro. Magnetic, Electro. Weak. • The strong, weak and electromagentic force almost unify at large energies. Could be explained by new particles that can be discovered at the LHC! Stefan Ask (Prince William School) 15 Dec 2010, CERN 24
What are the Problems? • What is Dark Matter? • What is Dark Energy? • What happened to all Anit-Matter? • Where do the particle mass come from? (Higgs? ) • Why is Gravity so extremely weak? (Extra Dimensions? ) • Could the different forces be the same thing? • … Could be explained by new particles that can be discovered at the LHC! Stefan Ask (Prince William School) 15 Dec 2010, CERN 25
---- Technological Spin-Offs ---Computing World Wide Web Communicating information over internet, invented by Tim Berners-Lee in 1989. The Computing Grid New way to share data storage and computing resources. Stefan Ask (Prince William School) 15 Dec 2010, CERN 26
Medical Applications Hadron Therapy Cancer treatment using different kind of particles. (Ugo Amaldi, DELPHI) Medical Imaging Improve ability to make images of tissue etc. inside the body, e. g. like from x-ray photos. (detector technology related) Stefan Ask (Prince William School) 15 Dec 2010, CERN 27
Transmutation (Energy) Particle accelerators could be used to produced nuclear energy in an even more controlled way than conventional reactors. Also, the so-called transmutation technique could be used to produce isotopes for medical use or to transmute long lived radioactive element (such from as nuclear waste) into stable, harmless, elements Stefan Ask (Prince William School) 15 Dec 2010, CERN 28
The CLOUD Experiment (Environment) Cosmic radiation is believed to affect the cloud formation in the atmosphere and there by also the climate. The CLOUD experiment at CERN will study this by radiating a so-called Cloud chamber, using the CERN accelerator facilities. Stefan Ask (Prince William School) 15 Dec 2010, CERN 29
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