the quest for certainty LHC project Why an entity like CERN exists? To produce certainty, to provide solid and «undoubtable», i.e. «scientific», answers to some fundamental questions
Particle physics looks at matter in its smallest dimensions Why accelerators? To investigate Particle Physics Accelerators Microscopes Binoculars Optical, radio télescopes Accelerators are the finest microscopes: acto-scope or zepto-scope = h/p ; @LHC: T = 1 TeV 10-18 m Lucio Rossi Milano 24 01 15March2014 2008 3 L.Rossi@RheinMeeting
To understand where we come from 13.85 billion years 10 26 m 15March2014 L.Rossi@RheinMeeting 4
Opposite extremes in the space scale converge in time! Big Bang Protone Atomo Raggio della Terra Distanze Terra Sole Radius of galaxies LHC Universe Actoscope We were sure that the atom was something solid, then the nucleous came, then Hubble WMAP 15March2014 L.Rossi@RheinMeeting 5 VLT ALMA
The SM: the superb construction of the last 40 years Particles Leptons Quarks upu d down e electron e e neutrino c charm s strange muon neutrino t top b bottom tau neutrino g gluon photon W W boson Z Z boson and Forces Each with its own antiparticle 15March2014 Brian Foster L.Rossi@RheinMeeting Higgs Boson?
What remains to be done? Understanding the mass The Standard Model is a very good description of the Universe at the particle scale (~2M W ) But does not explain many things Why so many particles? Why so many forces? What is mass? Why do particles have the masses they have? How do neutrinos get mass? Are neutrinos different? How do they fit in? What is Dark Matter? Dark Energy? Why is matter different from antimatter? (Where did all the antimatter go?) LHC started in 1984; it took 25 years because 15March2014 we had to develop new technology L.Rossi@RheinMeeting
The surprise : mass energy of the universe is more 15March2014 L.Rossi@RheinMeeting 8
CERN was founded 1954: 12 European States LHC project Science for Peace Today: 21 Member States ~ 2300 staff ~ 1600 other paid personnel ~ 10500 users Budget (2014) ~1000 MCHF Member States: Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom Candidate for Accession: Romania Associate Member in Pre Stage to Membership: Serbia Applicant States for Membership or Associate Membership: Brazil, Cyprus, Pakistan, Russia, Slovenia, Turkey, Ukraine Observers to Council: India, Japan, Russia, Turkey, United States of America; European Commission and UNESCO 15March2014 L.Rossi@RheinMeeting 9 9
From Europe to the world 15March2014 L.Rossi@RheinMeeting 10
CERN accelerator chain Tradition is important From LINAC, through synchrotrons, to the LHC H?? Lucio Rossi Milan 24 Jan 15March2014 2008 11 L.Rossi@RheinMeeting 2004: The 20 member states
LHC: the giant and its large «eyes» LHC project LHCb CMS ATLAS Exploration of a new energy frontier in p-p and Pb-Pb collisions ALICE LHC ring: 27 km circumference Largest magnetic system (15 GJ) Four gigantic underground caverns to host huge detectors The highest energy accelearator At a temperature colder than 15March2014 outer space L.Rossi@RheinMeeting 12
LHC tunnel 2002
LHC tunnel 2006
The LHC Superconducting Dipole 15March2014 L.Rossi@RheinMeeting
Construction of 400 Magnets in troisdorf Lucio Rossi ASC 2006 16
Barrel Toroid magnet system LHC project Lucio 15March2014 Rossi ASC 2006 17 L.Rossi@RheinMeeting
Higgs signature at LHC (computer simulation, ca. 2006) Proton beams cross each other 100 millions time per second! Lucio Rossi Milan 24 Jan 15March2014 2008 18 We expect only 1 Higgs in 1,000,000,000,000 events L.Rossi@RheinMeeting
10 settember 2008:The success! 15March2014 L.Rossi@RheinMeeting 19
13 dicember 2009 : record 2 1.18 TeV 16 bunches Lucio Rossi Milan 24 Jan 15March2014 2008 20 L.Rossi@RheinMeeting
Building LHC is like directing a concert: each one counts 15March2014 L.Rossi@RheinMeeting 21
First hints of the Higgs Slide August 2011 15March2014 L.Rossi@RheinMeeting 22
Hints indicating a possibility December 2011: 99% probability Higgs 2 Z 4 15March2014 L.Rossi@RheinMeeting 23
The Higgs: the needle in a haystack Z μμ Z μμ event from 2012 data with 25 reconstructed vertices
4 July 2012 : Boson got! 15March2014 25 L.Rossi@RheinMeeting
Brout Englert Higgs mechanism 2013 Nobel Prize for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider 15March2014 26 L.Rossi@RheinMeeting