LHC Report: CERN accelerators back in business
For the accelerator complex, 2018 started with the year-end technical stop (YETS), during which a very dense programme of maintenance and upgrade activities took place. Despite the tight schedules, all machines were closed in time and first beams will be injected as scheduled, signalling the start of an intense final straight before the second long shutdown (LS2).
Beam commissioning in the injectors started with Linac2, followed by the Proton Synchrotron Booster (PSB), which injected the first protons of 2018 on 2 March. This was followed by the injection of a beam into the Proton Synchrotron (PS) on 8 March, one day ahead of schedule. At present, protons are also circulating in the Super Proton Synchrotron (SPS), following the first injection on 16 March. Various types of beam are now being prepared and adjusted, among which is the beam required for the re-commissioning of the LHC. The first experiments in the PS East Area and n_ToF will start receiving beam on Good Friday. The other facilities in ISOLDE and the SPS North Area will follow after Easter.
In the run up to LHC beam commissioning, the operations team, in close collaboration with equipment experts, steered the LHC through an intense period of hardware re-commissioning. During that period, all electrical circuits were powered and many pre-defined tests (around 10 000) were performed and analysed in order to ensure correct functioning with the aim of identifying and solving any issues before injecting the low-intensity beam. This is expected to happen just after the Easter weekend or, if everything progresses faster than initially thought, even during the Easter weekend, but not before the so-called cold check-out is completed. During this phase, the full machine, including the experiments, should be in such a state as if it is ready to receive beam. All individual systems will then be run precisely at once, like an orchestra, as if the beam were in the machine. Only when all instruments are well tuned and play in synchronisation, music will sound and the LHC will be ready to receive beam.