The CERN Hadron Linacs are linear accelerators that accelerate beams of hadrons from a standstill to be used by the larger circular accelerators at the facility. Linac The Linac, some times referred to as the PS Linac and much later Linac 1, was CERN's first linear accelerator, built to inject 50 MeV protons into the Proton Synchrotron (PS). Conceived in the early 1950s, its principle design was based on a similar accelerator at AERE in England. The first beams were accelerated in 1958, at currents of 5 mA and a pulse length of 20 μs, which was the world record at that time. The accelerator was fully operational by September 1959, when the design energy of 50 MeV was first reached. From then on, the Linac experienced a phase of rapid development and constant improvement of the output parameters. This culminated in 1978, when a maximal proton current of 70 mA at pulse lengths of 100 μs could be reached. From 1972 on, the Linac didn't deliver the protons directly to the PS anymore, but to the Proton Synchrotron Booster (PSB). The PSB had been built to allow for higher energies of the protons beams already before they enter the PS. After Linac 2 had taken over the task of accelerating protons in 1978, the Linac continued to be used as a reliable testbed for new developments. This included the testing and implementation of a radio-frequency quadrupole as the initial accelerator, which replaced the original Cockcroft-Walton generator in 1984. Furthermore, ways to create and accelerate deuterons, α-particles and H− atoms were developed. The latter were used as test beams for LEAR. From late 1986 on, the Linac was also used to accelerate oxygen and sulphur ions. The Linac ceased to be used in experiments in summer of 1992. It was then decommissioned and removed from its tunnel to make room for Linac 3; the construction of which started October 1992 after the Linac had been removed from the tunnel. Parts of the Linac remain as museum pieces in the Microcosm exhibit. Linac 2 Linac 2, in the beginning simply referred to as the new Linac was announced in 1973. It was decided to build a new linear accelerator, since the old Linac was unable to keep up with the technical advances of the other machines within CERN's accelerator complex. Linac 2 replaced the Linac as CERN's primary source of proton