The ATLAS detector

ATLAS is the largest volume detector ever constructed for a particle collider. It is 46m long and 25m in diameter, and sits in a cavern almost 100m below ground.

The detector consists of six different subsystems wrapped concentrically in layers around the collision point to record the trajectory, momentum, and energy of particles, allowing them to be individually identified and measured. A huge magnet system bends the paths of the charged particles so that their momenta can be measured as precisely as possible.

Beams of particles travelling at energies up to 7 trillion electron-volts, or speeds up to 99.9999991% that of light, from the LHC collide at the centre of the ATLAS detector producing new particles, which fly out from the collision point in all directions.

Over a billion particle interactions take place in the ATLAS detector every second, a data rate equivalent to 20 simultaneous telephone conversations held by every person on the earth.

Only one in a million collisions are flagged as potentially interesting and recorded for further study.

The detector tracks and identifies particles to investigate a wide range of physics, from the study of the Higgs boson and top quark to the search for extra dimensions and particles that could make up dark matter. The four major components of the ATLAS detector are:

  • Inner Detector: measures the momentum of each charged particle;
  • Calorimeter: measures energies carried by neutral and charged particles;
  • Muon Spectrometer: identifies and measures the momenta of muons;
  • Magnet System: bends the trajectories of each charged particle to allow the measurement of its momentum.

Integrated with the detector components are: * Trigger and Data Acquisition System: specialized multi-level computing system, which selects physics events with distinguishing characteristics * Computing System: develops and improves computing software used to store, process and analyze vast amounts of collision data at 100 computing centres worldwide.

More details can be found on this page. The text of this page is taken from this brochure at CERN.