The Large Hadron Collider (LHC) has been given the go-ahead to begin its 2017 run. The incredible particle smasher, which is housed at CERN on the border of France and Switzerland, has been on a 17-week-long technical stop for regular maintenance checks.
Every year the entire machinery is shut down to provide repairs and upgrades to all its components. The 27-kilometer (17-mile) ring is the most complex experimental facility ever built and every part is switched off and on separately after the upgrades. The operation team has now confirmed that they are ready to go.
“It’s like an orchestra, everything has to be timed and working very nicely together. Once each of the parts is working properly, that’s when the beam goes in, in phases from one machine to the next all the way up to the LHC,” Operation team leader Rende Steerenberg, said in a statement.
The technical stop allowed for the replacement of a superconducting magnet, a cable removal campaign, and the new SPS beam dump. The upgrades will hopefully push the luminosity to beat the 2016’s record of 40 collisions per femtobarn (40 fb-1), a unit of area a trillion time smaller than the area of a proton.
“Our aim for 2017 is to reach an integrated luminosity of 45 fb-1 and preferably go beyond,” Steerenberg continued. “The big challenge is that, while you can increase luminosity in different ways – you can put more bunches in the machine, you can increase the intensity per bunch and you can also increase the density of the beam – the main factor is actually the amount of time you stay in stable beams.”
Researchers can collect data only through runs with stable beams. In 2015, they were able to collect data 35 percent of the time. In 2016, this value jumped to 49 percent. They hope to match and surpass that value in 2017.
The team has also made more changes to the optical system of the beams to increase the number of particles and make the beams smaller, again to increase the number of collisions.
“We’re changing how we squeeze the beam to its small size in the experiments, initially to the same value as last year, but with the possibility to go to even smaller sizes later, which means we can push the limits of the machine further. With the new SPS beam dump and the improvements to the LHC injector kickers, we can inject more particles per bunch and more bunches, hence more collisions,” Steerenberg added.
But there won’t be any collisions for a few weeks. The LHC always start slowly to make sure everything is working properly before particles can start smashing into each other.