CERN, the site of the world’s most powerful particle accelerator, is commemorating the 60th anniversary of its oldest particle accelerator, the Proton Synchrotron (PS), which is still operational. The PS accelerated its first protons on November 24, 1959, becoming the world’s highest-energy accelerator. Although it has been surpassed since then, it still provides protons and heavy ions to various particle physics experiments, including the Large Hadron Collider, which is currently the world’s largest and highest-energy accelerator.
Established in 1954 for the peaceful study of particle and nuclear physics, CERN launched the PS as one of its initial projects. Based on the alternating gradient principle, it was designed to be a higher-energy accelerator than the Synchrocyclotron, its predecessor, which was completed in 1957 and decommissioned in 1990. The alternating gradient principle focused the beam of particles using quadrupole magnets with alternating poles aligned in a plus-sign shape.
Getting the PS to function was a significant challenge, with scientists struggling to get the protons to orbit continuously for several weeks. Eventually, after many small adjustments, the accelerator ran at the planned energy, leading to a moment of celebration.
The PS’s 628-meter circumference sent protons around its circumference, reaching 25 giga electron-volts, a level sufficient to explore previously unattainable higher-energy physics. The PS was instrumental in discovering numerous new particles in the five years following its creation.
As time passed, scientists coupled larger accelerators and colliders with the PS, increasing the energy of the colliders in their quest for subatomic particles. The PS fed protons to the Large Electron-Positron Collider via the 400 GeV Super Proton Synchrotron and now feeds the Large Hadron Collider, the largest experiment in physics, with protons.
The PS is still being upgraded and maintained due to its importance. At present, the accelerator is undergoing a temporary shutdown to renovate 48 of its 100 magnets, clean it, and replace three kilometers of pipes in the cooling system.
In conclusion, happy 60th birthday to the Proton Synchrotron. Particle physics owes you a debt of gratitude!