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H1 particle detector. Scientist using an oscillos- cope to test the trigger electronics of H1 particle detector at DESY (Deutsche Elektronen Synchrotron). An accelerator, known as HERA, accelerates protons and electrons to a combined energy of 850 GeV before they collide in the H1 detector. The trigger electronics review all the resulting collision events and discard those which do not fit specified criteria. A maximum of 5 events per second are recorded. It is hoped that data from this detector will provide more information about the quarks in protons and the gluon force moderators that bind them together. Photographed near Hamburg, Germany, in May 1999. (KEYSTONE/SCIENCE PHOTO LIBRARY/DAVID PARKER)