Why Large Hadron Collider's new boss is switching it off

Mark Thomson, a professor of experimental particle physics at the University of Cambridge, has landed one of the most coveted jobs in global science.

- Ian Sample

But it could appear at first glance that he has taken one for the team.

Today, Thomson takes over as the director general of Cern, the multi-Nobel prize-winning nuclear physics laboratory on the outskirts of Geneva. It is here, deep beneath the ground, that the Large Hadron Collider (LHC), the largest scientific instrument ever built, recreates conditions that existed microseconds after the big bang.

The machine won its place in history for discovering the mysterious Higgs boson, whose accompanying field turns space into a kind of cosmic glue. But one of the first things Thomson will do is turn the machine off for engineering work. It will not restart until his term is nearly over.

In an office on the first floor of the Cavendish laboratory, past a model of the DNA double helix discovered in Cambridge by James Watson and Francis Crick more than 70 years ago, Thomson is far from disconsolate about the shutdown. If anything, he is relishing the next five years.