Section of rectangular vacuum chamber with integral sputter ion vacuum pump. Since the complete vacuum chamber makes up a closed circular apparatus (SPEAR), object 1980.0177.03 has an arc-shaped length. Section cut away to reveal titanium sputter in vacuum pump.
SPEAR (Stanford Positron Electron Accelerating Ring) at SLAC was completed in 1972. SPEAR consists of a single ring some 80 meters in diameter, in which counter-rotating beams of electrons and positrons were circulated at energies up to 4 GeV. SPEAR was the first storage ring/colliding beam facility (collider) to provide important new discoveries in elementary particle physics, e.g., the J/psi meson that is made up of a combination of a quark and an antiquark of an entirely new kind (charm quark) and a third lepton in addition to the electron and the muon (tau lepton). Subsequently, the SPEAR facility has served as an intense x-ray source for research in physics, chemistry and biology. For detailed information, see:
http://www-ssrl.slac.stanford.edu/content/spear3/spear-history
https://www6.slac.stanford.edu/news/2011-06-02-shedding-light.aspx
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