New CERN chief pledges to forge ahead with $17-billion supercollider

British particle physicist Mark Thomson has been named as the next leader of CERN, the European particle-physics laboratory outside Geneva, Switzerland.

As CERN’s director general, Thomson will face major challenges, including an uncertain political landscape amidst the war in Ukraine, which has led the lab to break government-level ties with Russia. He will also have to repair a faltering consensus around the Future Circular Collider (FCC), a new 90-kilometre tunnel to host the lab’s flagship experiments throughout the rest of the century. The German government, CERN’s largest contributor, expressed scepticism about the project earlier this year, and China could beat CERN to the punch with a similar project.

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Thomson is no stranger CERN: he worked at a major experiment there in the 1990s, and helped to discover the Higgs boson at the Large Hadron Collider (LHC) — the world’s most powerful particle accelerator — in 2012, together with the current director general Fabiola Gianotti. He is currently chair of the Science and Technology Facilities Council, a UK funding agency, and is a representative on the CERN Council, the board that oversees the laboratory on behalf of its member countries. He will take up the director general post at the end of 2025, when Gianotti’s second consecutive five-year term is due to end.

In a press conference on 7 November, both Gianotti and Thomson stressed the need for continuity, and the importance of the ongoing €1.5 billion upgrade to the 27-kilometre LHC. Thomson also reiterated Gianotti’s commitment to build the FCC. “I am very much aligned with the vision of the current DG,” he told reporters.

Former CERN council president Ursula Bassler is optimistic about Thomson’s appointment. “He is a person who values what the FCC can bring to CERN, but who is also aware of the reservations some people might have,” says Bassler, who is a particle physicist and scientific director at French National Institute of Nuclear and Particle Physics in Paris. “I think he will really act in a quite transparent way to come to a decision.”

Thomson will be the first UK physicist to lead the organization since the 1990s. As well as having worked at the LHC, he has been a co-leader and spokesperson of the Deep Underground Neutrino Experiment under construction in Illinois and South Dakota.