The official “start up” day of the Large Hadron Collider (LHC) has begun, with a low-energy beam of protons making it all the way round the 27 km-long ring.

At 9:30 am CET (8:30 am BST), control-centre scientists Stefano Radaelli and Rassano Giachino — given the go-ahead from project leader Lyn Evans — injected a proton beam with an energy of 450 GeV from the Super Proton Synchrotron into the LHC.

The beam travelled through one of the eight sectors and past the ATLAS experiment before being stopped by a purposefully inserted screen. At that moment the screen generated a flash — and an applause from all those in the control room.

After just a few minutes the operations team decided to remove the screen and take the beam through another sector. That, too, was successful.

At 9:44 am CET the team removed the screen preventing access to the third and fourth sector, and tried to get the beam to the halfway point where the CMS experiment is located. The first attempt failed, but the second produced the tell-tale flash, and even CMS saw some particle tracks.

Clearly on a lucky streak, Evans gave the order to allow the proton beam past the halfway point into sector four, where the “beam dump” point is located. At 9:54 am CET, the operations team cheered as their plasma monitors revealed the beam's successful progress. However, Evans decided — in French — that the beam was not “beautiful” enough and needed it to be “more corrected”.

“At this rate, we hope,” he said, “we should get a beam all the way around the LHC within an hour.” Minutes later at 10:06 am CET another ovation marked the successful passage of the proton beam through the 700 m-long beam-dump tube.

By 10:13 am CET the beam had made it round to the seventh sector past the LHCb experiment. Then, at 10:17 am, it reached ATLAS, the biggest of the four experiments at the LHC.

After several moments of tense silence, the home run came at 10:24 am and 30 s to a huge applause.

Robert Aymar, the director general of CERN, said he was “too happy to be on TV”.

The injection marks the beginning of a milestone day for CERN, the European lab hosting the €6.3 bn accelerator. Hundreds of journalists have packed into the lab’s science and innovation “globe” to report on the day’s events, while at least three international satellites are relaying a live video and data stream to institutions worldwide.