CERN LHC beams return after 3 years

The CERN complex – chain of accelerators and all experiments – went through major upgrades in the last three years. And finally, on October 19, 2021, counter-rotating protons were injected into the LHC

After two weeks of beam tests including low-energy collisions in the experiments, the accelerator complex will go into the maintenance mode until March 2022. Due to spiking electricity prices in winter months in Europe the CERN complex typically goes into hibernation during December, January, February. Run 3 (physics data taking) will start in May 2022 and continue for 3 years.

There is an excellent presentation by Andreas B. Meyer explaining the physics potential of Run 3 with many diagrams and graphs:

Physics with LHC Run-3 and HL-LHC

A quick summary of Run 3 characteristics from CERN Courier:

“When the LHC comes back online for physics in May 2022, it will not only be more luminous (with up to 1.8 × 1011 protons per bunch compared to 1.3–1.4 × 1011 during Run 2), but it will also operate at higher energies. This year, the majority of the LHC’s 1232 dipole magnets were trained to carry 6.8 TeV proton beams, compared to 6.5 TeV before, which involves operating with a current of 11.5 kA (with a margin of 0.1 kA). Following the beam tests this autumn, magnet training for the final two of the machine’s eight sectors will take place during a scheduled maintenance period from 1 November to 21 February. After that, the LHC tunnel and experiment areas will be closed for a two-week-long “cold checkout”, with beam commissioning commencing on 7 March and first stable beams expected during the first week of May.”

“Meanwhile, the LHC experiments are continuing to ready their detectors for the bumper Run-3 data harvest ahead: at least 160 fb–1 (as for Run 2) to ATLAS and CMS; 25 fb–1 to LHCb (compared to 6 fb–1 in Run 2); and 7.5 nb–1 of Pb–Pb collisions to ALICE (compared to 1.3 nb–1 in Run 2). ”

You can learn more about the operational characteristics of Run 3 from this paper.

The link showing the operational status of the LHC collider still works.

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