On Dec. 14, 2015, the Large Hadron Collider (LHC) shut down for maintenance (and also because the winter months are when the cost of electricity in France is at its most expensive). This enormous, complicated machine is one of the most complex devices humans have ever built. Its purpose is to smash together particle beams at unbelievable energy levels in an effort to discover what makes our universe tick.
And now it's coming back online.
Bringing the LHC back up to speed is no small task. At the end of the maintenance period, scientists conducted more than 8,500 tests on the collider's 1,600 circuits. And they did it in two weeks. By late March, the LHC was ready for some trial runs.
For the past several weeks, LHC scientists have been conducting tests with "quiet beams." These beams consist of small batches of particles, such as protons, moving in opposite directions around the 27-kilometer (nearly 17-mile) ring. The beams converge at different points around the circle, allowing for particle collisions and their detection. The purpose of the quiet beams is to make sure that the collisions are happening at the right locations when it's time to go into full operation.
When that happens, the LHC will blast out 2,808 bunches of protons to near the speed of light. Each bunch will have 25 feet (7.6 meters) of separation from the bunch ahead of and behind it. Experiment stations with names like ATLAS and ALICE will track the collisions (1 billion per second!) and search for secrets of the universe — from dark matter to how gravity fits into the Standard Model of physics.
Back in 2015, the LHC stepped up the power levels for its experiments. We won't see another boost in power in 2016, but we should see the LHC operate at full scale longer than ever before. That means we'll have more opportunities to discover things that could change our view of physics, including particles not predicted by the Standard Model.
It's time to get back to work!