1. 1 A collision in the CMS detector Particle trajectories are reconstructed with precision of few microns (1 μ = 10 -6 m)

2. 2 30 March 2010: first proton-proton collisions at an unprecedented energy  exploration of a new energy frontier starts

3. 3 An impressive start ! The accelerator, experiments and computing performed beyond expectations:   commissioning much faster than expected   year’s program completed ahead of time   the accelerator has achieved x2 the goal luminosity   GRID has allowed users from all over the world to analyse the data effectively   the experiments have already “rediscovered” the known (Standard Model) particles 2010 goal Beam intensity 1 M jobs/day Worldwide analysis

4. 4 e ν is invisible e In a few months we have “rediscovered” the (already-known) Standard Model particles e ν W Missing E W boson:  discovered at CERN in 1982  mass ~ 80 protons  as of today the experiments have ~ 500 000 W’s

5. 5 e - e - e+e+e+e+ Z Z boson:  discovered at CERN in 1983  mass ~ 90 protons  as of today the experiments have ~ 50 000 Z’s

6. 6 Quark top:   heaviest observed elementary particle ever: mass ~172 protons (~1 Gold atom)   discovered at the Tevatron in 1995   observed “for the first time in Europe” by ATLAS and CMS in July 2010   as of today the experiments have ~ 900 top events 344000 electrons1 top quark tt  be ν b μν event

7. 7 8 November: first collisions between lead ion beams (Pb nucleus: 82 protons + 126 neutrons)  Goal is to study the “primordial plasma” of quarks and gluons that (we think) permeated the Universe ~ 10 μ s after the Big Bang (we think) permeated the Universe ~ 10 μ s after the Big Bang

8. 8 ms) ATLAS Control Room on 20 November 2009 (the day of first LHC beams)

9. 9 ~ 3000 scientists from 38 countries from all over the world; 1000 PhD students

10. 10 Age distribution of ATLAS physicists All2690(< 35 y 47.2%) Male81.8%(< 35 y 44.0%) Female18.2%(< 35 y 61.3%) (Status 1.1.2010) ~ 1000 PhD students