SPEAR
SPEAR was a particle physics collider at the SLAC National Accelerator Laboratory. It began running in 1972, colliding electrons and positrons with an energy of, and collecting data about the resulting particles with the Mark I detector. During the 1970s, experiments at the accelerator played a key role in particle physics research, including the discovery of the meson, many charmonium states, and the discovery of the lepton.
After its use as a particle collider had been superseded, the facility built for SPEAR was converted to a dedicated synchrotron radiation source for the Stanford Synchrotron Radiation Lightsource beamlines, known as SPEAR2.
A major upgrade of the ring completed in 2004 gave it the current name SPEAR3.