Anti-proton experiment. Blackboard showing the provisional results and calculations for a series of experiments carried out in 1955 at the Berkeley Radiation Laboratory to discover the antiproton. Antiprotons were made by firing protons at a copper target in an early particle accelerator. This discovery of the antiproton by physicists Emilio Segre and Owen Chamberlain (together with a separate set of experiments by another group in 1956), confirmed Dirac's prediction of antimatter. Segre and Chamberlain were awarded the 1959 Nobel Prize in Physics for the discovery. Photographed on 6 October 1955, at the University of California, Berkeley, USA.