Success!

That's it. Yesterday evening, around 22:30, the Large Hadron Collider at CERN, the LHC, produced its first collisions at an energy of 13 TeV, nearly twice the energy reached in 2012. The four LHC experiments all recorded collisions, providing evidence for a successful accelerator restart.

The man: Can you imagine? Collisions at 300 000 km/s!

The woman: There are really idiots everywhere!

Reproduced with the kind permission of the author, Gérald Herrmann ©Tribune de Genève, 3/13/2015

The good news could be seen on all faces as well as on the LHC information page, which is accessible to everyone at any time and gives details in real time on what's happening at the LHC, and is always broadcasted on numerous screens scattered all over the CERN site.

Below is a screen shot taken this morning while various tests continued. The two lines in red and blue correspond to the intensity of the two separate beams circulating in opposite directions around the accelerator. Every beam countained approximately 185 billion protons. The scale on the right gives the energy of these protons, such as indicated by the black line. The protons used for the LHC beams come from the Super Proton Synchroton, the SPS, the previous stage in the acceleration chain. They are injected in the LHC at an energy of 450 GeV (namely 0.450 TeV) before being accelerated to the final energy of 6.5 TeV by beam. The energy released during the collisions corresponds to twice that of each beam, that is, 13 TeV.

After being injected into the LHC, the protons are further accelerated, then adjusted (as it happened when this screen shot was taken) before being brought into collision. All these stages require a few hours. If everything goes well, that is, if none of the thousands of components forming the 27-km ring of the accelerator does not break down (pumps, magnets, transformers and others), the beams can be maintained in collisions for 3, 6, or even 12 hours or more. There are still several adjustments to be made before the machine can start producing regular and safe beams in June. In particular, countless collimators must be adjusted. Their role is to stop the particles that deviate from the beam, such that the detectors and the LHC magnets can operate without risk of being damaged. The beginning of the great adventure of the LHC second operation period is thus in sight. All hopes are allowed. For more details, visit CERN site.