Linear accelerator 1 (Linac 1) was designed in the early 1950s to serve as an injector for the Proton Synchrotron (PS). It accelerated its first beam in 1958 and was fully commissioned in 1959 when one turn of 50 MeV protons went round the PS. Linac 1 was the only supplier of protons to the CERN synchrotrons until Linac 2 took over in 1978. Linac 1 accelerated light ions – such as deuterons and alpha particles, as well as oxygen and sulphur ions – for 33 years until its retirement in 1992. Linac 3 took over ion production in 1994.