The Large Hadron Collider is back in business! On Friday, March 30th at 1
Restarting an accelerator involves much more than just flipping a switch, especially as the LHC is the last link in an accelerator chain that includes five separate machines. After the winter break, during which the teams were able to carry out a whole series of maintenance work, the machine operators gradually put the infrastructures and accelerators back into operation. In early March, the first protons were extracted from their hydrogen cylinder and injected into the Linac2 and then into the PS booster. On March 8, it was the turn of the proton synchrotron (PS) to receive rays and, a week later, the super proton synchrotron (SPS).
In parallel, the teams reviewed the entire LHC hardware. such as the cryogenic cooling systems, the high frequency chambers (which accelerate the particles), the power supplies, the magnets, the vacuum system and the safety devices. For example, no fewer than 1,560 circuits had to be powered and approximately 10,000 tests performed. Only after all these tests were completed could particles be injected into the LHC.
Nevertheless, commissioning is far from complete. The first rays that circulate have only one particle bundle that contains 20 times less protons than in normal operation. And their energy is limited to the injection energy of 450 GeV. Further adjustments and tests will be needed in the coming days before the energy and number of bundles in each beam can be increased and the bundles compressed to create initial collisions. The physics business is scheduled to start in May
The goal for 2018 is to accumulate more data than in 2017: the target is 60 inverse femtobars (fb -1 ) of integrated luminosity (around 50 fb -1 in 2017). Luminosity is a measure of the number of possible collisions per surface unit over a given period of time.
While we are waiting for collisions in the LHC, data acquisition is already starting elsewhere. CERN accelerators provide particles for a variety of experiments. The PS has already started delivering blasting to the nuclear physics facility n_TOF and to the experiments in the East Hall. The nuclear physics program at ISOLDE was due to start on April 9, while the antiproton retarder should restart in the second half of April.
2018 is an important year for collaboration with CERN accelerators, as it will be the last year of Run 2. In December, the accelerator complex will be decommissioned for two years with retrofit work aimed at further improving performance and performance to prepare for the LHC with high luminosity.
LHC reaches record brightness