High Frequency Compact Linear Proton Accelerator

In the frame of its programme for medical applications, and building on its experience with the LINAC4 injector (the first stage in the Large Hadron Collider accelerator chain), the High-Frequency Radio Frequency Quadrupole (HF-RFQ) was constructed with the goal of providing a compact, low-current injector for a proton therapy linear accelerator.

It is a suitable alternative to cyclotrons for use in medical applications, for example as a stand-alone accelerator or as an injector for larger high-energy accelerators, and adaptable to the power availability and portability needs of other applications such as medical isotope production and ion beam analysis  (a material analysis technique). 

The HF-RFQ can accelerate any charged particle with a mass to charge ratio up to 2, for example protons, deuterons, alpha parcles, fully stripped carbon ions.

Advantages & Applications


  • Compact - can be placed close to where it is needed.
  • Low beam-loss - no need for external shielding.
  • Modular - two or more HF-RFQs may be joined together in order to increase the energy output of the system (energies up to 10-15 MeV).
  • Particle compatibility - the particles provided by the source can be any charged particle with a mass to charge ratio up to 2. For example protons, deuterons, alpha particles, fully stripped carbon ions. 
  • Multi-user - as the HF-RFQ is capable of pulsed operation, redirecting the beam to multiple, individual targets is possible by triggering the re-direction in-between pulses.
    Low maintenance - one-piece device with a minimum number of parameters to adjust.


  • Linear accelerator (linac) based hadron / proton therapy facilities.
  • Medical isotope production - e.g. for use in PET (Positron Emission Tomography) and SPECT (Single Photon Emission Computed Tomography).
  • Material analysis (ion beam analysis).
  • Other applications requiring a low or medium output current beam.


Operating at a frequency of 750 MHz and having adapted beam optics, this RFQ can reach an energy of 5 MeV over a distance of 2 m.

Stage of Development:

For both of the above designs, CERN is seeking licensing and collaborative R&D opportunies. The HF-RFQ can also be re-designed for other applications.

US patent granted, July 2018
Chinese patent granted, September 2019
European patent granted, September 2021
Israel patent granted, October 2021
The IP is owned by CERN
Year Filed
Patented; available for licensing