CERN Accelerating science

LINAC4 reaches target energy of 160 MeV
by Jennifer Toes & Maurizio Vretenar (CERN)

Installation of the CCDTL structures of LINAC4, built and assembled in Russia (Image: CERN CDS)

CERN’s new linear accelerator (LINAC4) reached its final energy goal of 160 MeV in October 2016. The new LINAC4 will double the brightness of the beam in the PS Booster (PSB), by injecting H- beams at a higher energy than the present 50 MeV of LINAC2. This is the first step for the increase of the LHC luminosity that will be possible after completion of the LIU (LHC Injectors Upgrade) and HL-LHC (High-Luminosity LHC) projects.

Approved in 2007, LINAC4 is the realization of nearly 10 years of work. The project has involved almost all CERN Departments and services, and included substantial in-kind contributions from Russia, Poland, Spain, Italy and India.    

This ultimate achievement comes after reaching 107 MeV energy in July 2016. The commissioning with beam took place in stages of increasing energy; from 3MeV in October 2013, to 12 MeV in August 2014, 50 MeV in November 2015, 100 MeV in July 2016, before ultimately bringing it up to the final goal of 160 MeV in October with the commissioning of 11 new accelerating cavities.

After optimizing the beam parameters and testing with the new high-energy beam the H- stripping equipment for the PSB, LINAC4 will begin a yearlong testing period in spring 2017. This phase will help to improve the accelerator’s reliability in preparation for taking over from LINAC2 as the first element of the LHC injection chain.

The final phase will include connecting the linac to the PSB; requiring extensive modifications to both the beam lines and to the PSB itself. This will take place during the second Long Shutdown (LS2) of the CERN accelerator complex in 2019-20.

“This achievement is a great success for all the people that contributed to the project, at CERN and outside,” said Maurizio Vretenar, LINAC4 Project Leader.

He continued: “All accelerating sections and components of the new linac performed remarkably well from the very beginning, showing the quality of the design, of the realisation and of the installation.”

Although CERN was responsible for the construction of the LINAC4, the R&D phase which preceded it was performed in close collaboration with six other laboratories as part of the first Integrating Activity project for accelerators; CARE (Coordinated Accelerator Research in Europe), which operated from 2004 to 2008.

“The collaborative environment and the support provided by this European project allowed us to go through the critical R&D phase refining the project at the level where it can be approved for construction, and helped strengthen the collaborations that evolved into our crucial in-kind contributions,” said Vretenar.