DESY

byname of Deutsches Elektronen-synchrotron, English German Electron-synchrotron the largest centre for particle-physics research in Germany, located in Hamburg. DESY is funded jointly by the German federal government and the city of Hamburg; in addition, scientists from other countries who participate in the experiments there donate equipment. The laboratory was founded in 1959, when construction began on an electron synchrotron, which was completed in 1964 and eventually could generate an energy level of 7.4 billion electron-volts (GeV). The Double Ring Storage Facility (DORIS) was completed 10 years later and was capable of colliding beams of electrons and positrons at 3.5 GeV per beam; in 1978 its power was upgraded to 5 GeV per beam. DORIS is no longer used as a collider, but its electron beam provides synchrotron radiation (mainly at X-ray and ultraviolet wavelengths) for experiments on a variety of materials. A larger collider capable of reaching 19 GeV per beam, the Positron-Electron Tandem Ring Accelerator (PETRA), began operation in 1978. Experiments with PETRA the following year gave the first direct evidence of the existence of gluons, the particles that carry the strong force between quarks. The laboratory's newest facility, completed in 1992, is the Hadron-Electron Ring Accelerator (HERA), the first machine capable of colliding electrons and protons. HERA consists of two rings in a single tunnel with a circumference of 6.3 km (3.9 miles); one ring accelerates electrons to 30 GeV and the other protons to 820 GeV. It is being used to continue the study of quarks. Christine Sutton