Meanwhile, above ground, the team will replace banks of computers charged with capturing and analyzing millions of events per second. The upgrades will help researchers to deal with the torrent of data expected when the machine roars to life. Similar work will be going on at ATLAS, says Charlton.
Other physicists will scrutinize the collisions that have already been detected. Last July, the teams working on ATLAS and another detector, the Compact Muon Solenoid (CMS), announced compelling evidence for the Higgs boson, a long-predicted particle and part of the proposed mechanism that endows other particles with mass (see Nature 487, 147–148; 2012). But the detectors have accumulated double the amount of data since then. “We’re past the discovery and now in the measurement phase,” Charlton says.
Teams will work into the summer to try to determine the ‘spin’ of the new particle (theory predicts 0). Researchers will also try to further nail down its mass and behavior to see whether it is really the long-sought particle, or something else masquerading as a Higgs boson. Such a particle or particles would look much like the Higgs predicted by theorists and could do the job of helping to endow other particles with mass, but might differ in important ways that would hint at new physics beyond the current set of predictions.
Theorists, too, will be taking a second look at the data gathered so far, says John Ellis, a theoretical physicist at King’s College London. In their rush to discover the Higgs, experimentalists conducted only the easiest analyses. “The experiments went for the low-hanging fruit,” he says. There may be signals of something new hidden in the data.
Ellis plans to continue hunting through the data for signs of physics beyond the standard model. In particular, he hopes to turn up some hint of supersymmetry — a theory to which he has devoted years. Supersymmetry predicts a zoo of new particles, but none has so far appeared inside the detectors.
The teams will also spend the break looking towards the future. CMS spokesman Joe Incandela says the group is thinking about ways to make the most of the LHC’s new potency. “We have to start thinking already about replacement detectors for the early 2020s,” he says. Although the CMS will keep its magnets and metal superstructure, the plan is to eventually replace almost all of its electronic innards with new, state-of-the-art gear.
With the onset of the shutdown, the rhythm of the lab will change. Twenty-four-hour running shifts will come to an end, as will the frantic late-night analyses of the Higgs. But nobody is planning lengthy holidays, Incandela says. “Believe it or not, there’s not a lot of time to do everything we need to do.”