After 17-week-long extended technical stop, the world’s largest and most powerful particle smasher Large Hadron Collider (LHC) has restarted circulating beams of protons.
Last week, the detectors of the Large Hadron Collider (LHC) witnessed their first collisions of 2017. The first particles circulated on 29 April 2017 and, soon after, the operators started work on their long list of adjustments. They tested the radiofrequency system, which accelerates the particles.
Over the past month, after the completion of the maintenance work that began in December 2016, each of the machines in the accelerator chain have been switched on and checked until last week when the LHC, the final machine in the chain, could be restarted.
Each year, the machines shut down over the winter break to enable technicians and engineers to perform essential repairs and upgrades, but this year the stop was scheduled to run longer, allowing more complex work to take place.
Work this year included the replacement of a superconducting magnet in the LHC, the installation of a new beam dump in the Super Proton Synchrotron (SPS) and a massive cable removal campaign.
Among other things, these upgrades will allow the collider to reach a higher integrated luminosity — the higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.
Last year, the machine was able to run with stable beams — beams from which the researchers can collect data — for around 49% of the time, compared to just 35% the previous year.
The challenge the team faces this year is to maintain this or increase it further. The team will also be using the 2017 run to test new optics settings — which provide the potential for even higher luminosity and more collisions.
About Large Hadron Collider:
The Large Hadron Collider (LHC) is the world’s largest and most powerful particle collider, most complex experimental facility ever built, and the largest single machine in the world.
It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories.
It lies in a tunnel 27 kilometres (17 mi) in circumference, as deep as 175 metres (574 ft) beneath the France–Switzerland border near Geneva, Switzerland.
Its first research run took place from March 2010 to early 2013 at an energy of 3.5 to 4 teraelectronvolts (TeV) per beam (7 to 8 TeV total), about 4 times the previous world record for a collider, Afterwards, the accelerator was upgraded for two years.
It was restarted in early 2015 for its second research run, reaching 6.5 TeV per beam (13 TeV total, the current world record).
The aim of the LHC is to allow physicists to test the predictions of different theories of particle physics, including measuring the properties of the Higgs boson and searching for the large family of new particles predicted by supersymmetric theories, as well as other unsolved questions of physics.
