Officials at the CERN particle-physics lab near Geneva have turned off the Large Hadron Collider (LHC) for the last time. Over the coming four years, the accelerator complex will be upgraded to prepare for the High-Luminosity LHC (HiLumi LHC) that is set to start operations in 2030.
Taking decades to plan and construct, the LHC began circulating its first proton beams in September 2008 garnering attention from the world’s media. Yet days later the accelerator suffered an electrical fault that delayed first proton collisions for a year.
On 4 July 2012 the ATLAS and CMS collaborations announced the discovery of the Higgs boson, which led to the Nobel Prize in Physics for Peter Higgs and François Englert a year later.
In the past decade, the LHC has also discovered more than 85 hadrons, put limits on the discovery of new particles, examined the imbalance between matter and antimatter and explored the nature of the quark–gluon plasma.
A new adventure
The LHC will now make way for HiLumi LHC that will increase the collider’s luminosity by a factor of up to ten. This will enable precision studies of the Higgs boson and enhance the potential to uncover phenomena beyond the Standard Model.
The shutdown will involve upgrading about 1.2 km of the 27 km ring by including 11-12 T superconducting magnets and superconducting “crab” cavities — that reduce the angle at which the bunches cross — to increase the number of collisions at the two detectors. Angels & Demons, Tom Hanks and Peter Higgs: how CERN sold its story to the world
The ATLAS and CMS detectors will also be upgraded to cope with between 140 and 200 proton–proton collisions in every “bunch crossing”, compared to around 60 during the last LHC run.
German accelerator physicist Oliver Brüning, who is director for accelerators and technology at CERN, says that the LHC has “exceeded every expectation”.
“For nearly two decades, it has transformed our understanding of the universe and inspired generations of scientists, engineers and citizens around the world,” adds Brüning. “We say goodbye to the LHC as we have known it, while preparing to welcome its successor: the HiLumi LHC, which will extend this scientific adventure far into the future.”
