e+ e- events at CERN, less than one event was retained out of every 109 interactions. This illustrates an important point about searching for new physics: until you know what you are looking for, you have little chance of finding it. The most systematic way to look for unexpected new effects is to measure very accurately pieces of standard physics that 32 Introduction can be precisely predicted; any significant discrepancy then points to something new.
Track curvatures then measure particle momenta. These coils usually form part of the calorimeter. Calorimeter: alternating layers of material and detectors in which particles make showers which deposit energy and are sampled via their ionization. Total energy deposition is inferred. The pattern of deposition versus depth shows whether the initiating particle is a hadron or electromagnetic (e, 'Y). Muon counters: muons are the only charged particles likely to penetrate the iron and other dense material in the calorimeter behind which these counters stand.