SPEAR

{{About|the particle accelerator|other uses|spear (disambiguation)}}

{{No footnotes|date=December 2013}}

SPEAR (originally Stanford Positron Electron Accelerating Ring, now simply a name){{Cite web |title=S {{!}} SLAC Archives, History & Records Office |url=https://ahro.slac.stanford.edu/slacspeak/s |access-date=2024-04-24 |website=ahro.slac.stanford.edu}}{{ref label |notea|a}} was a collider at the SLAC National Accelerator Laboratory.{{cite web |last1=Williams |first1=Shawna |title=The Ring on the Parking Lot |url=https://cerncourier.com/a/the-ring-on-the-parking-lot/ |website=CERN Courier |date=31 May 2003 |access-date=29 March 2022}} It began running in 1972, colliding electrons and positrons with an energy of {{val|3|ul=GeV}}. During the 1970s, experiments at the accelerator played a key role in particle physics research, including the discovery of the {{SubatomicParticle|link=yes|J/Psi}} meson (awarded the 1976 Nobel Prize in Physics), many charmonium states, and the discovery of the tau (awarded the 1995 Nobel Prize in Physics).

Today, SPEAR is used as a synchrotron radiation source for the Stanford Synchrotron Radiation Lightsource (SSRL). The latest major upgrade of the ring in that finished in 2004 rendered it the current name SPEAR3.