Radio Frequency Group

Why Radio Frequency?

Charged particles are accelerated by electric fields – the energy they can gain in the process is given by the product voltage times charge. To reach energies above some MeV, one needs fields varying in time at a high (radio) frequency and the particle beam in bunches rather than continuous. This is why Radio Frequency is the technique of choice for particle accelerators.

How does RF interact with the beam

The keyword here is “cavity”: a cavity (an evacuated metallic hollow) can support an electromagnetic field at a given (radio) frequency. An accelerating cavity is constructed such that beam can pass through it (beam pipes upstream and downstream) and that the electric field points in the direction of particle motion (beam axis). In this way, a passing particle beam bunch is accelerated and gains energy. This energy has to be resupplied to the cavity from a powerful RF amplifier via a power coupler. The phase of the cavity field has to be precisely controlled such that the accelerating voltage has the right direction when the bunch passes.



1) Operation of CERN's accelerator RF systems. This includes the design, construction or procurement, operation, consolidation and maintenance of RF cavities, RF power amplifiers, LLRF, and RF controls for all present and future accelerators at CERN. Manage and coordinate the manpower for this task, including a 24/7 piquet for the LHC accelerator chain during operation. Provide specialist manpower to support oprations and define/ maintain the longitudinal beam dynamics for all CERN accelerators.


2) Conception, setting up, operation and maintenance of test & repair facilities (amplifiers, normal- and superconducting cavities, electronics & measurement labs, HV test places, specialised mechanical workshops, assembly spaces, clean rooms, low/ high- pressure water rinsing, spare parts storage, coupler assembly & testing,...), including SPS SC test stand, X-Boxes, SM18, 112, 252,...


3) Conception and prototyping of RF systems for projects and studies (LIU, HL-LHC, FCC, AWAKE, CLEAR, CLIC, Muon-collider, Physics Beyond Colliders, medical studies,...) including longitudinal beam dynamics and calculation and measurement of impedances. Anticipate the technical progress of RF technologies and prepare a roadmap for their future deployment at CERN (e.g. replacement of tubes with solid state, VME -> uTCA, analog -> digital LLRF, etc.). Propose timelines and the resource needs of tailored R&D programs to the ATS management to achieve these goals.


4) Engage in and set up collaborations with partner labs, universities and industry to support above activities.