The ZEUS Experiment

One of the more unique and powerful high-energy physics facilities available today is the HERA collider, operated by the Deutsches Elektronen-Synchrotron (DESY) laboratory in Hamburg, Germany. What makes HERA unique is that it collides a high-energy beam of electrons head on with a high-energy beam of protons. What makes HERA powerful is a 27.5 GeV electron accelerator and a 920 GeV proton accelerator, the latter of which is the second most energetic accelerator ever commissioned. Both accelerators reside in a 6.3 kilometer circular tunnel dug under the city of Hamburg and have been in operation since 1992.

The ZEUS experiment is one of four experiments conducted with the HERA collider. Designed to study deep-inelastic scattering of electrons on protons, the ZEUS experiment is run by a collaboration of 460 physicists from institutes in 12 different countries. It features a state-of-the-art Uranium-Scintillator calorimeter, wire drift chambers in a 1.4 Telsa magnetic field, and steel and stream-tube muon detectors. The dimensions of the main detector are 12 × 10 × 19 meters and its total weight is 3600 tons.

SCIPP's contribution to the ZEUS apparatus is the front-end electronics of the Leading Proton Spectrometer (LPS), a complex series of instruments placed within the HERA accelerater designed to detect those charged particles created during an electron-proton collision that are only slightly deflected out of the proton beam. The study of such semi-elastic collisions represent a unique approach to the study of quantum chromodynamics (QCD) and the structure of the proton.

In addition to measurements of the proton, the unique nature of the HERA accelerator provides a natural laboratory for the search of new and unexpected phenomena. Some of the searches SCIPP has been involved in include the search for quark compositeness and for interactions that violate lepton flavor. Both ZEUS and HERA will receive major upgrades in the year 2000, and the resulting increase in data will extend these searches even further.

SCIPP contact: Hartmut F.-W. Sadrozinski