A colliding beam, storage ring accelerator was first proposed by Gerard O'Neill of Princeton in 1956, who built an electron-electron system beginning in 1957 (operational in 1962, first collisions in 1964) with assistance from Burton Richter, William C. Barber and Bernard Gittelman.
The idea of using alternating gradient synchrotron (AGS) technology [3] to build storage rings for a proton-proton colliding beam accelerator was considered at a summer study held at Brookhaven in 1963.
The SPEAR collider at the Stanford Linear Accelerator Center, a 3+3 GeV electron-positron system, was completed in 1972 and soon contributed to discoveries of the ψ meson and τ lepton, both recognized in Nobel Prizes.
[6][7] Delays in the project led to competitive evaluation against a proposal for a much larger machine, eventually called the Superconducting Supercollider, a proton-proton system aimed at 20,000+20,000 GeV; while developments in Europe at CERN, including discovery of the W and Z bosons, appeared to make ISABELLE redundant.
[10] After years of planning and development, parts of the tunnel, experimental hall and magnet infrastructure built for ISABELLE were salvaged and reused by the Relativistic Heavy Ion Collider (RHIC), a US$617 million joint project of the U.S. Department of Energy and National Science Foundation which was approved in 1991 and began operation in 2000.