The Antiproton Accumulator (AA) was part of the antiparticle factory at CERN designed to decelerate and store antimatter, to study the properties of antimatter and to create atoms of antihydrogen. It was built at the end of the 70's in order to produce and accumulate high energy antiprotons to feed into the SPS in order to transform it into a "proton-antiproton collider". In 1986 it was expanded by the Antiproton Collector to greatly increase the production of antiprotons. It was decommissioned along with the rest of the antiparticle factory in 1996.
Low energy antiproton research continues at CERN using the Antiproton Decelerator which started operation in 2000.