Voir en


A busy Sunday for the LHC

The LHC started up again on Sunday for the first time in two years. LHC operators celebrated the smooth restart with champagne and chocolate eggs

A busy Sunday for the LHC

LHC operators smile as the Beam 2 (anticlockwise) makes it around the accelerator sector by sector (Image: Maximilien Brice/CERN)

It was a busy Easter Sunday for the LHC operators.

After two years of maintenance and months of preparation for restart, the world's most powerful particle accelerator is back in operation. At 10.41am on Sunday, a proton beam (Beam 2 – circulating anticlockwise) was back in the 27-kilometer ring, followed at 12.27pm by a Beam 1 rotating in the opposite direction. These beams circulated at their injection energy of 450 GeV. Over the coming days, operators will check all systems before increasing the energy of the beams.

“Operating accelerators for the benefit of the physics community is what CERN’s here for,” said Director-General Rolf Heuer. “Today, CERN’s heart beats once more to the rhythm of the LHC.” 

A packed CERN Control Centre on the day of the restart (Image: Maximilien Brice/CERN)

There were cheers from the LHC hub as the beams made around the accelerator sector by sector, and champagne was popping the LHCb and CMS control rooms as they received their first splash events. Shift engineer Laurette Ponce was presented with a giant chocolate Easter egg for her team's efforts.

Members of the CERN Communications group live-blogged the day's events – you can catch up with a blow-by-blow account of the restart here.

The Easter bunny found time to visit the Control Centre on Sunday (Image: Maximilien Brice/CERN)

“The return of beams to the LHC rewards a lot of intense, hard work from many teams of people," said Paul Collier of the Beams department. “It’s very satisfying for our operators to be back in the driver’s seat, with what’s effectively a new accelerator to bring on-stream, carefully, step by step.”

“After two years of effort, the LHC is in great shape," said Director for Accelerators and Technology, Frédérick Bordry. “But the most important step is still to come when we increase the energy of the beams to new record levels.”

LHC operators Giulia Papotti and Ronaldus SuykerBuyk describe a typical day running the accelerator from the CERN Control Centre (Video: Noemi Caraban Gonzalez)