ALEPH - Apparatus for LEP PHysics at CERN

ALEPH was one of the four Experiments a the Large Electron Positron Collider (LEP) at CERN. It was taking data from 1989 until the year 2000. In total it recorded more than 4 million Z-decays. They were and are still used to do precision studies of the Standard Model. The most important results are:

  • The determination of the mass of the W-boson and Z-boson to within one part in a thousand.
  • The finding that the number of families of particles with light neutrinos is 2.982±.013, which is consistent with the standard model valueof 3.
  • By measuring the coupling alpha_s of quantum chromodynamics (QCD) at various energies it was found to vary in accordance with perturbative calculations in QCD.

At Innsbruck ALEPH data are still used to do phenomenology of the theory of strong interactions (Quantum Chromodynamics, QCD).

The ALEPH experiment