The Super Proton Synchrotron (SPS). (Image: CERN)
At CERN, beams of particles are accelerated faster and faster, just like a relay race (where each runner is faster than the previous one). The LHC's relay team has five runners, in order of appearance: Linear Accelerator 4 (Linac4), the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the Large Hadron Collider (LHC).
At the end of each year, the whole complex comes to a halt for the traditional "year-end technical stop". And every February, as the first green shoots of spring start to appear, the hustle and bustle begins again as CERN recommissions its accelerators.
This year, the wheels were set back in motion on 19 February, when the first particle beam of 2025 circulated in Linac4. The second link in the chain, the PS Booster, received its first particles on 26 February, the PS on 4 March and, today, the SPS accelerated its first proton beams of the year.
Of course, the recommissioning of the CERN accelerator complex is no walk in the park. The machines are restarted according to a meticulously planned process, combining sequential and parallel workflows. Nonetheless, things are progressing in leaps and bounds and, from next week, CERN's various experimental areas will gradually start receiving their first particles, until the LHC titan awakens on 4 April.
If you want to find out more about the 2025 physics programme at the LHC, in the injectors and in the various experimental areas, check out this article. Put the date of 4 April in your diaries, as well as the beginning of July for a special physics run: the acceleration and collision of oxygen ions (a first at the LHC!). Watch this space.
