The leaders of the team which discovered the J/psi particle in November 1974 at the Stanford Linear Accelerator Center (SLAC), California. Left to right are Martin Perl, Burton Richter & Gerson Goldhaber. They are seen perusing the logbook of their Mark I detector, which operated at the SPEAR electron-positron collider at SLAC. Richter shared the 1976 Nobel prize for physics for this work with Sam Ting, leader of the team which discovered the particle at the Brookhaven National Laboratory, Long Island, at the same time. Perl discovered the tau particle in 1975. Richter became director of SLAC in 1984.