Since this week, after the usual winter break, the LHC particle accelerator at CERN is back in business again for the experiments (among which three that Nikhef works on) at the lab. Monday afternoon officially begins the fourth and final year of the LHC Run-3.
In the 27-kilometre accelerator tube, protons in this run fly around at almost the speed of light, reaching a collision energy of 13.6 TeV. The goal is to deliver at least as many collisions this year, as last year 2024. With a higher beam intensity, this can be done in less time, leaving room for other experiments.
Run-3 will continue until mid-2026, after which the accelerator will close for four years for a major refurbishment for much more intense beams. This high-luminosity LHC (HL-LHC) should come online in 2030.
In October and November this year, the LHC will be used for collisions with lead ions. In July, a beam of oxygen ions will also be used for some time. The heavy ions provide insight into very different physics from the colliding protons.
Nikhef is involved in three of the four major detector experiments at CERN: ALICE, LHCb and ATLAS. During the past winter period, plenty of work was done on these. At the large ATLAS detector, several muon chambers were replaced. Cooling systems were also replaced or prepared for the arrival of the switch to much more intense beams in the HL-LHC.
This round of measurements saw the LHCb detector return to full operation for the first time, following an earlier incident in which the central Vertex Locator was damaged. That device near the point of contact of the proton beams determines exactly where collisions occur. Nikhef played a central role in the repairs of this VELO.
All three experiments report on their websites the first collisions of this physics run. On CERN’s website, the activities of the LHC accelerator can be followed live.
Read the news article on the CERN website: https://home.cern/news/news/accelerators/and-theyre-2025-lhc-physics-season-gets-underway