The ATLAS detector is composed of cylindrical layers

The ATLAS detector … … is composed of cylindrical layers: Tracking detector: Pixel, SCT, TRT (Solenoid magnetic field) Calorimeter: Liquid Argon, Tile Muon spectrometer: MDT, RPC, TGC, CSC (Toroid magnetic field) .

Particle detection in ATLAS We measure: time charge energy position .

Trigger and Data acquisition The particles create electric signals in the detector The signals are converted in digital data 1001010010100011110010 Out of 1 billion proton collisions per second 100 000 have an interesting particularity detected by the dedicated electronics of the Trigger Level 1 For 3000 of them this is confirmed by dedicated processors of the Trigger Level 2 In the end only 200 interesting events are filtered out by 2000 multi-core PCs of the Trigger Level 3 and are finally recorded ATLAS writes the equivalent of 1 CD every 3 seconds This is a CD tower of of 7 km height every year.

LHC Computing Grid Tier-0 (CERN) • Data recording • First-pass reconstruction • Data distribution Tier-1 (11 centres) • Permanent storage • Re-processing • Analysis Tier-2 (>50 ATLAS centres) • Simulation • End-user analysis 4.

The cavern …

Excavation of Cavern UX (10/99) ATLAS, H. Burckhart, CERN 6 .

… the ceiling … ATLAS, H. Burckhart, CERN 7 .

ATLAS, H. Burckhart, CERN 8.

The detector …

The Globe … .

… and ATLAS Helfried Burckhart Globe 27 m high, 40 m wide Atlas 25 m high, 46 m long .

12 .

The ATLAS members …

The ATLAS Collaboration 37 countries 169 institutions 2800 scientists (incl. 750 Ph. D students) The data are distributed all over the world .