Bubble chamber event: elastic antiproton-proton scatter near 180 degrees in center of mass with antiproton stopping and annihilating. Photograph taken December 2, 1960. Bubble Chamber-981. The antiproton is the antiparticle of the proton. An antiproton consists of two up antiquarks and one down antiquark. The properties of the antiproton that have been measured all match the corresponding properties of the proton, with the exception that the antiproton has electric charge and magnetic moment that are the opposites of those in the proton. The antiproton was experimentally confirmed in 1955 by University of California, Berkeley physicists Emilio Segr癡 and Owen Chamberlain, for which they were awarded the 1959 Nobel Prize in Physics. A bubble chamber is a vessel filled with a superheated transparent liquid (most often liquid hydrogen) used to detect electrically charged particles moving through it.