Proton Synchrotron

CERN Complex

Current particle and nuclear facilities
LHC	Accelerates protons and heavy ions
LEIR	Accelerates ions
SPS	Accelerates protons and ions
PSB	Accelerates protons
PS	Accelerates protons or ions
Linac 3	Injects heavy ions into LEIR
Linac4	Accelerates ions
AD	Decelerates antiprotons
ELENA	Decelerates antiprotons
ISOLDE	Produces radioactive ion beams
MEDICIS	Produces isotopes for medical purposes

The Proton Synchrotron (PS, sometimes also referred to as CPS^[1]) is a particle accelerator at CERN. It is CERN's first synchrotron, beginning its operation in 1959. For a brief period the PS was the world's highest energy particle accelerator. It has since served as a pre-accelerator for the Intersecting Storage Rings (ISR) and the Super Proton Synchrotron (SPS), and is currently part of the Large Hadron Collider (LHC) accelerator complex. In addition to protons, PS has accelerated alpha particles, oxygen and sulfur nuclei, electrons, positrons, and antiprotons.^[2]

Today, the PS is part of CERN's accelerator complex. It accelerates protons for the LHC as well as a number of other experimental facilities at CERN. Using a negative hydrogen ion source, the ions are first accelerated to the energy of 160 MeV in the linear accelerator Linac 4. The hydrogen ion is then stripped of both electrons, leaving only the nucleus containing one proton, which is injected into the Proton Synchrotron Booster (PSB), which accelerates the protons to 2 GeV, followed by the PS, which pushes the beam to 25 GeV.^[3] The protons are then sent to the Super Proton Synchrotron, and accelerated to 450 GeV before they are injected into the LHC. The PS also accelerates heavy ions from the Low Energy Ion Ring (LEIR) at an energy of 72 MeV, for collisions in the LHC.