Proton Synchrotron Booster

Proton Synchrotron Booster
Landua, Fabienne · CC BY 4.0 · source
Name	Proton Synchrotron Booster
Location	CERN
Type	Synchrotron
Established	1972
Operator	European Organization for Nuclear Research
Energy	1.4 GeV (planned), 800 MeV (original)
Circumference	157 m
Status	Operational

Proton Synchrotron Booster is a fast-cycling synchrotron accelerator located at CERN that provides high-intensity proton beams for a wide range of experiments and downstream accelerators. Commissioned in the early 1970s, it serves as an intermediate injector between the Linear Accelerator 2 and the Proton Synchrotron, supporting physics programs at facilities such as Super Proton Synchrotron, Large Hadron Collider, and various fixed-target experiments. The Booster has undergone multiple upgrade campaigns to increase intensity, reliability, and energy, enabling contributions to projects including ISOLDE, n_TOF, and neutrino R&D.

History

The Booster was proposed in the late 1960s during planning at CERN to augment the Proton Synchrotron injector chain and to supply higher proton intensities for emerging experiments. Construction and installation coincided with developments at Linac facilities and international collaborations with laboratories such as Fermilab and DESY for technology exchange. Commissioning began in 1972, with early operation feeding the Proton Synchrotron and supporting extraction for fixed-target programs like NA experiments and radioactive beam initiatives at ISOLDE. During the 1990s and 2000s, the Booster adapted to evolving requirements from projects including the Large Hadron Collider upgrade planning and the Antiproton Decelerator era, prompting staged upgrades to magnets, radiofrequency systems, and beam instrumentation.

Design and Technical Specifications

The Booster is a fourfold-symmetric, fast-cycling synchrotron with a circumference of approximately 157 metres housed in the Meyrin site complex. Its lattice uses combined-function magnets arranged in repeating cells derived from designs contemporaneous with the Proton Synchrotron and influenced by magnet technology from CERN and partners. Radiofrequency acceleration is provided by cavities designed to cope with rapid ramping and high beam loading; these systems trace heritage to developments at Instituto Nazionale di Fisica Nucleare and other European institutes. Injection is from Linear Accelerator 2 at an energy originally 50 MeV, with extraction matched to the Proton Synchrotron at energies historically up to 800 MeV and subject to proposed increases. Key subsystems include vacuum chambers with low-impedance profiles, beam diagnostics inherited and improved in collaboration with Brookhaven National Laboratory expertise, and power converters compatible with pulse-to-pulse control strategies used at SLAC and KEK.

Operation and Beam Parameters

Operational cycles of the Booster are synchronized with the Proton Synchrotron timetable and downstream facilities such as the Super Proton Synchrotron and the Large Hadron Collider. Typical beam parameters have evolved: bunch intensity, repetition rate, transverse emittance, and longitudinal bunching are tuned for transfer efficiency to the Proton Synchrotron and for direct extraction to experiments like ISOLDE and n_TOF. The Booster supports multi-turn injection, RF capture, and fast extraction modes analogous to those practiced at CERN’s sister facilities. Beam instrumentation provides diagnostics including beam current transformers, position monitors, and loss monitors developed in cooperation with research groups from University of Oxford, CERN, and EPFL. Operational constraints such as space-charge limits, tune shifts, and collective effects are mitigated through operational settings informed by studies from GSI Helmholtz Centre and theoretical modeling groups.

Upgrades and Modernization

The Booster has been subject to iterative upgrade programs addressing performance, availability, and compatibility with high-intensity front ends. Major modernization efforts have targeted magnet power converters, RF systems, vacuum improvements, and active beam scraping and collimation systems influenced by upgrade pathways at DESY and Fermilab. The ongoing and planned energy upgrade initiatives aim to raise extraction energy closer to 1.4 GeV to reduce space-charge effects at injection into the Proton Synchrotron and to serve future projects such as high-intensity neutrino R&D and isotope production consortia. Upgrades also incorporate digital control systems, timing infrastructure interoperable with the Large Hadron Collider complex, and enhanced diagnostics developed in collaboration with CERN experimental groups and partner universities including University of Manchester and Université Paris-Saclay.

Role within CERN Accelerator Complex

Within the CERN accelerator chain, the Booster occupies the critical injector role between Linear Accelerator 2 and the Proton Synchrotron, shaping beam quality and intensity for downstream machines such as the Super Proton Synchrotron and the Large Hadron Collider. It provides extracted beams for fixed-target facilities including ISOLDE, n_TOF, and test-beam areas supporting detector R&D for collaborations like ATLAS and CMS. The Booster’s performance directly impacts cycle time, luminosity potential, and secondary-beam production for international experiments hosted at CERN, influencing programmatic decisions coordinated with partner institutions like European Spallation Source stakeholders and research consortia across Europe.

Safety and Radiation Protection

Operation of the Booster adheres to radiological protection standards established by CERN safety services and national regulatory bodies including Swiss authorities at Meyrin. Shielding, active collimation, and beam loss monitoring systems were progressively enhanced in partnership with safety engineering groups from University of Geneva and TU Darmstadt to limit activation of components and minimize personnel exposure. Machine maintenance procedures, hot-cell handling for activated equipment, and access controls follow protocols comparable to those employed at Fermilab and DESY, integrating lessons from incident analyses and international best practices. Environmental monitoring and waste management are coordinated with CERN’s radiation protection unit to ensure compliance with institutional and host-state regulations.

Category:CERN accelerators Category:Particle physics