Antiproton discovery team. Group portrait of the team that discovered the antiproton in 1955. Seen here from left to right are; Emilio Segre, Clyde Wiegand, Edward Lofgren (leader of another team searching for antiprotons), Owen Chamberlain and Tom Ypsilantis. All were conducting research at the Lawrence Berkeley Laboratory in California, USA. Antiprotons, a type of antimatter, were made by firing protons at a copper target. A few antiprotons were found amongst the various particles created by nuclear collisions. Segre and Chamberlain won the 1959 Nobel prize for physics for the discovery. Photographed in October 1955.