The scheduled four-week lead-ion physics run began at the SPS North Area on 4 November and has since been progressing smoothly, with outstanding machine availability.
That same morning, the LHC successfully completed its proton–proton (p–p) reference run, colliding protons at 2.68 TeV to calibrate the machine ahead of the lead-ion run. Despite an electrical disturbance that caused an early beam dump at 9.51 a.m., all objectives for the p–p reference run were achieved.
Following this special run, LHC experts made some final adjustments to prepare for lead-ion operations. Among many other steps, loss maps were produced to ensure the integrity and alignment of the collimator hierarchy, confirming the machine’s readiness for lead-ion collisions.
On 6 November, the LHC was filled with 119 lead-ion bunches per beam, which were then brought into collision, marking the official start of the lead-ion physics run. This initial 119-bunch configuration was the first step in a five-phase intensity ramp-up, with the aim of reaching a full machine with 1240 bunches per beam by 10 November. At each stage of this intensity ramp-up, equipment experts validated the process using detailed checklists. Each phase required at least two injections and five hours of stable beam operation. During the intensity ramp-up, all four LHC experiments conducted Van der Meer scans to calibrate their luminosity measurements, ensuring accurate data for this lead-ion run, which is scheduled to end on 25 November.
On 13 November, the third and final facility started its lead-ion physics run. For the next two and a half weeks, the HEARTS experiments, located in the PS East Area, will receive lead ions for their tests. HEARTS@CERN is part of the EU-funded HEARTS (High-Energy Accelerators for Radiation Testing and Shielding) project, which aims to provide access to high-energy heavy-ion radiation testing facilities for space exploitation and space exploration. This project addresses the growing need to test commercial electronic components and modules for use in space. By adjusting the energy levels, scientists and engineers can study the effects of different ion interaction depths and ionisation levels on electronic devices.
To meet the rigorous beam requirements of the HEARTS experiments, several lead-ion cycles have been carefully developed and optimised in recent weeks at the PS. The lead-ion beams produced using these cycles are slow-extracted from the PS in one-second-long spills and delivered to the T8 beam line in the East Area. With optimised transfer line optics, these beams provide uniform irradiation across sample areas of a few square centimetres. For each experiment, researchers and radiation effects engineers can choose from six different energy levels (by varying the PS energy and local degradation) and can adjust the spill intensity within three orders of magnitude, which is necessary to successfully test the large range of electronics sensitivity.
HEARTS, like the experiments in the SPS North Area, will end its physics run on 2 December.