Proton Synchrotron

Proton Synchrotron
Landua, Fabienne · CC BY 4.0 · source
Name	Proton Synchrotron
Caption	The CERN Proton Synchrotron complex.
Type	Synchrotron
Location	Meyrin, Geneva, Switzerland
Institution	CERN
Energy	28 GeV
Circumference	628.3 m
Particles	Protons, lead ions, alpha particles
Commissioning	1959

Proton Synchrotron. The Proton Synchrotron is a major particle accelerator located at the CERN laboratory near Geneva. First operated in 1959, it was the world's first synchrotron to achieve an energy of 28 GeV, making it the highest-energy accelerator of its time. It has served as a crucial workhorse for high-energy physics, acting as both a research machine in its own right and a vital injector for CERN's larger colliders, including the Super Proton Synchrotron and the Large Hadron Collider.

History and development

The Proton Synchrotron was conceived in the early 1950s as part of CERN's founding mission to rebuild European science after World War II. Its design was heavily influenced by the pioneering work on strong focusing by Ernest Courant, M. Stanley Livingston, and Hartland Snyder at Brookhaven National Laboratory. A key figure in its construction was the project leader, John Adams, who oversaw a large international team of engineers and physicists. The machine achieved its first beam on November 24, 1959, a significant milestone celebrated across the scientific community. This success firmly established CERN as a leading center for particle physics and demonstrated the feasibility of large-scale international scientific collaboration.

Design and operation

The accelerator is a ring-shaped synchrotron with a circumference of 628.3 meters, installed in a tunnel approximately 12 meters underground. It operates on the principle of strong focusing, using a combination of dipole magnets to bend the beam and quadrupole magnets to keep it tightly focused. Protons are first accelerated to 50 MeV by a linear accelerator, the Linac 2, before being injected into the ring. Inside, radio frequency cavities increase the particles' energy to 28 GeV as the guiding magnetic field is synchronously ramped up. The Proton Synchrotron can accelerate not only protons but also heavier ions like lead from the Low Energy Ion Ring and has been configured to provide beams for a wide variety of fixed-target experiments.

Technical specifications

The machine accelerates protons to a maximum energy of 28 GeV, corresponding to a magnetic field strength of about 1.2 teslas at the beam's final orbit. Its ring consists of 100 combined-function magnet units, each providing both bending and focusing fields. The beam typically circulates in bunches with a revolution frequency of 2.1 MHz, and the acceleration cycle lasts approximately 1.2 seconds. The Proton Synchrotron can produce intense beams, with up to 3×10¹³ protons per pulse, and it serves as the first-stage booster for the Super Proton Synchrotron, which in turn feeds the Large Hadron Collider.

Scientific contributions and discoveries

Throughout the 1960s and 1970s, the Proton Synchrotron was at the forefront of particle physics research. It enabled the discovery of the strange-antistrange meson, the phi meson, in 1962. The Gargamelle bubble chamber, installed at the Proton Synchrotron, provided the first direct experimental evidence for the weak neutral current in 1973, a crucial discovery that validated the electroweak theory of Sheldon Glashow, Abdus Salam, and Steven Weinberg. Furthermore, experiments like the European Muon Collaboration used its beams to study the internal structure of the proton, contributing to the understanding of quantum chromodynamics.

Upgrades and future prospects

The Proton Synchrotron has undergone numerous upgrades to maintain its reliability and increase beam intensity for CERN's expanding accelerator complex. Major improvements included the installation of the Proton Synchrotron Booster in 1972 to increase injection energy and the implementation of digital control systems. It was converted primarily to an injector role with the commissioning of the Super Proton Synchrotron in 1976. Today, it remains an indispensable part of CERN's infrastructure, supplying beam to facilities like the ISOLDE radioactive ion beam facility and the Antiproton Decelerator. Its long-term future is secure as a key component in the injector chain for the High-Luminosity Large Hadron Collider project and other potential future machines like the Future Circular Collider.

Category:Particle accelerators Category:CERN Category:Buildings and structures in the canton of Geneva