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Hermes detector. Technician working on the Hermes detector of the HERA accelerator at DESY (Deutsche Elektronen Synchrotron). HERA consists of a pair of accelerator rings mounted in a 6.3km circumference tunnel. The Hermes detector is placed at one crossing point of the rings. In the centre of the detector, protons from one ring will collide with electrons from the other at extremely high energy. Hermes uses polarised electrons from HERA to investigate the property of spin of protons and neutrons. This involves exploring the quarks and gluons that make up protons and neutro- ns, and the strong force that binds them together. Photographed near Hamburg, Germany, in May 1999. (KEYSTONE/SCIENCE PHOTO LIBRARY/DAVID PARKER)