1. 1 LHCb CMS ALICE ATLAS The ATLAS experiment at the LHC 27 km.

2. 2 …… 100 m.

3. The Large Hadron Collider 3..

4. µ µ n n p p   n n e e 30 million collisions per second Protons collide in ATLAS … ~ The energy of a single proton is equivalent to the energy of a mosquito (1 µJ) 2808 particle bunches per beam 100 billion (10 11 ) protons per bunch 11 245 turns per second The energy of the beam is equivalent to a train running at 160 km/h.

5. µ µ n n p p   n n e e The ATLAS experiment ~ 46 m 25 m a microscope for particles equivalent to the Eiffel Tower 7000 ton total weight 1992 Definition of the ATLAS project 1996 Start of civil engineering 1997 Start of construction of detector elements 2004 Start of detector installation 2008 Start of operation (will last > 15 years).

6. The questions …

7. 10 -15 m matter What are the components of matter? 10 -14 m 10 -10 m atom composed of a nucleus and electrons nucleus composed of protons and neutrons protons, neutrons composed of quarks 10 -9 m molecule <10 -18 m quark, electron electron, quark < 10 -18 m = 0,000´000´000´000´000´001 m.

8. The fundamental forces of Nature The aim is to describe everything by one single force Gravitation Weak force Strong force Electromagnetic force graviton ? gluons W, Z photon The forces act by exchanging particles.

9. The Higgs particle is very heavy one needs high energy to create it All ‘normal’ matter is made of electrons and ‘up’ et ‘down’ quarks Photon Gluon. W,Z The “Standard Model” But one piece is missing in the puzzle: the Higgs particle

10. Higgs mechanism in a nut shell Mass-less particles traverse with the speed of light. All particles are mass-less and hence move with same speed. Mass-less particles interact with a background “Higgs” field and slow down. Effectively they acquire a mass. The speed (=mass) of the particle depends on the interaction strength with the Higgs field. Higgs particle Quantum mechanical fluctuations of the background field: the Higgs particle. The syrup analogy 10.

11. (optical) Astromomy 1 TeV (0.16 µJ) 10 -12 sec. time - temperature - energy

12. 12 Our present view of the Universe Unknown form of dark matter Unknown form of dark energy 60% 40% 20% 0% 80% 100% Ordinary matter Neutrinos Stars / Galaxies No anti-matter.

13. The ATLAS experiment …

14. Collision of 2 bunches of protons ….

15. … one interesting event.