Long Shutdown 1 officially came to an end on 5 April 2015, when a beam of protons circulated the LHC for the first time after two years. Following this long period of upgrades, repairs, and consolidation, the LHC is now ready to restart at 13 TeV, almost double its previous energy. In the early morning, a team of technicians and engineers gathered at the CERN Control Centre to make the final preparations for the big day. "
Today, CERN’s heart beats once more to the rhythm of the LHC,” said CERN Director General, Rolf Heuer, who arrived at ten o'clock to watch the day's action. A sense of anticipation filled the air as the first beam was injected with an energy of 450 GeV at point 8, home of the LHCb, and circulated the LHC guided by the 15m-long dipole magnets. It passed through CMS, ALICE, and ATLAS, whose teams were in the control rooms, carefully monitoring the detectors to ensure that everything was running smoothly. At eleven o'clock the beam had completed more than 25 circuits. Then, a second beam was injected and also circulated successfully all sectors of the LHC. Now, the technicians and engineers of the LHC have to check the machine's hardware and software systems in detail before increasing the beam energy and restarting the physics programme.
The first particle collisions at the unprecedented energy of 13 TeV will probably take place in June, allowing the LHC experiments to further extend the frontiers of scientific knowledge and tackle the unsolved mysteries of the Universe. Of course, measuring the properties of the Higgs will be a priority in Run2, but other topics will also be explored, such as dark matter, antimatter, quark-gluon plasma, and supersymmetry. There are definitely exciting times ahead for particle physics.