  isabelle was a 200+200 gev proton-proton colliding beam particle accelerator partially built by the united states government at brookhaven national laboratory in upton, new york, before it was cancelled in july, 1983. ==colliding beam accelerators== 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 ada accelerator, an electron-positron system, stored its first beam in 1961 at frascati national laboratories, italy and was later moved to orsay laboratory, france, where in 1964 it recorded first e+e- collisions. adapted from physics in perspective (springer) 2:135-140 (2000). at the same time, two colliding-beam experiments were conceived and built by budker and his group at the institute of nuclear physics in novosibirsk, russia, soviet union: electron-electron vep-1 (first collisions in 1964) and electron-positron vepp-2 (first collisions in 1965). the idea of using alternating gradient synchrotron (ags) technology  to build storage rings for a proton-proton colliding beam accelerator was considered at a summer study held at brookhaven in 1963. the intersecting storage rings (isr) facility at cern, a 30+30 gev proton-proton system, opened in 1971 and became the first high energy hadron collider. 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 [[j/Ï particle|
Brookhaven_National_Laboratory Particle_physics_facilities United_States_Department_of_Energy_national_laboratories