APPEAL 10 Future Accelerator Projects

Big Science at the High Energy Frontier

6th July 2019: Organized by CERN, JAI, STFC & University of Oxford

Professor Emmanuel Tsesmelis CERN & John Adams Institute for Accelerator Science


The European Strategy for Particle Physics is the cornerstone of Europe’s decision-making process for the long-term future of the field.

The European Strategy process was initiated by the CERN Council in 2005.

1st Update – European Strategy for Particle Physics 2013

Scale of facilities required by particle physics is resulting in globalisation of the field.

Europe’s top priority should be exploitation of full potential of the LHC, including the HL-LHC machine and detectors with view to collecting 10x more data than in initial design, by around 2030.

The High Luminosity Large Hadron Collider (HL-LHC; formerly SLHC, Super Large Hadron Collider) is an upgrade to the Large Hadron Collider started in June 2018 that will boost the accelerator’s potential for new discoveries in physics, starting in 2026. The upgrade aims at increasing the luminosity of the machine by a factor of 10, up to 1035 cm−2s−1, providing a better chance to see rare processes and improving statistically marginal measurements.


The diagram above shows the location of the work required for the HL-LHC project.

CERN should undertake design studies for accelerator projects in a global context, with emphasis on proton-proton and electron-positron HE frontier machines.

These design studies should be coupled to vigorous accelerator R&D programme, including high-field magnets and high-gradient accelerating structures, in collaboration with national institutes, laboratories and universities worldwide.

The initiative from the Japanese particle physics community to host the ILC in Japan is most welcome, and European groups are eager to participate.

The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500 GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early proposed locations for the ILC were Japan, Europe (CERN) and the USA (Fermilab), the Kitakami highland, in the Iwate prefecture of northern Japan, has been the focus of ILC design efforts since 2013. The Japanese government is willing to contribute half of the costs, according to the coordinator of study for detectors at the ILC.


An overview graphic of the planned ILC based on the accelerator design of the Technical Design Report

Europe looks forward to a proposal from Japan to discuss a possible participation.

CERN should develop a neutrino programme to pave way for substantial European role in future long-baseline experiments.

The CERN Neutrino Platform is CERN’s undertaking to foster and contribute to fundamental research in neutrino physics at particle accelerators worldwide, as recommended by the 2013 European Strategy for Particle Physics. It includes the provision of a facility at CERN to allow the global community of neutrino experts to develop and prototype the next generation of neutrino detectors. The CERN Neutrino Platform is CERN’s main contribution to a globally coordinated programme of neutrino research.

Europe should explore possibility of major participation in leading long-baseline neutrino projects in US & Japan.

2nd Update – European Strategy for Particle Physics 2020

Europe, in collaboration with partners from around the world, is engaged in R&D projects for a range of ambitious post-LHC facilities under the CLIC and FCC umbrellas.

The Compact Linear Collider (CLIC) is a concept for a future linear particle accelerator that aims to explore the next energy frontier. CLIC would collide electrons with positrons and is currently the only mature option for a multi-TeV linear collider.

The Future Circular Collider (FCC) is a conceptual study that aims to develop designs for a post-LHC particle accelerator with an energy significantly above that of previous circular colliders (SPS, Tevatron, LHC).

It is time to check progress on these, matching their expected performance to physics needs. The discussions will be based on scientific evidence gleaned from the impressive results coming in from the LHC, as well as from technological and resourcing considerations.

Other areas of particle physics:

CERN, is now contributing fully to a globally-coordinated neutrino programme with experiments to be carried out in the USA and Japan.

The International Linear Collider, which would be complementary to the LHC, remains on the table with a site having been identified in Japan and a decision on whether to go forward expected soon.

There are ambitious plans to build a large collider in China. And at CERN, a study to investigate the potential for physics beyond colliders.

The Circular Electron Positron Collider is a proposed electron positron collider by the Chinese high energy physics community in 2012. This machine could be later upgraded to a high energy proton-proton collider with physics potential far beyond the Higgs factory.

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