In April, scientists at the European Center for Nuclear Research, or CERN, outside Geneva, once again fired up their cosmic gun, the Large Hadron Collider. After a three-year shutdown for repairs and upgrades, the collider has resumed shooting protons — the naked guts of hydrogen atoms — around its 17-mile electromagnetic underground racetrack. In early July, the collider will begin crashing these particles together to create sparks of primordial energy.
And so the great game of hunting for the secret of the universe is about to be on again, amid new developments and the refreshed hopes of particle physicists. Even before its renovation, the collider had been producing hints that nature could be hiding something spectacular. Mitesh Patel, a particle physicist at Imperial College London who conducts an experiment at CERN, described data from his previous runs as “the most exciting set of results I’ve seen in my professional lifetime.”
A decade ago, CERN physicists made global headlines with the discovery of the Higgs boson, a long-sought particle, which imparts mass to all the other particles in the universe. What is left to find? Almost everything, optimistic physicists say.
When the CERN collider was first turned on in 2010, the universe was up for grabs. The machine, the biggest and most powerful ever built, was designed to find the Higgs boson. That particle is the keystone of the Standard Model, a set of equations that explains everything scientists have been able to measure about the subatomic world.
But there are deeper questions about the universe that the Standard Model does not explain: Where did the universe come from? Why is it made of matter rather than antimatter? What is the “dark matter” that suffuses the cosmos? How does the Higgs particle itself have mass?
Physicists hoped that some answers would materialize in 2010 when the large collider was first turned on. Nothing showed up except the Higgs — in particular, no new particle that might explain the nature of dark matter. Frustratingly, the Standard Model remained unshaken.
The collider was shut down at the end of 2018 for extensive upgrades and repairs. According to the current schedule, the collider will run until 2025 and then shut down for two more years for other extensive upgrades to be installed. Among this set of upgrades are improvements to the giant detectors that sit at the four points where the proton beams collide and analyze the collision debris. Starting in July, those detectors will have their work cut out for them. The proton beams have been squeezed to make them more intense, increasing the chances of protons colliding at the crossing points — but creating confusion for the detectors and computers in the form of multiple sprays of particles that need to be distinguished from one another.
“Data’s going to be coming in at a much faster rate than we’ve been used to,” Dr. Patel said. Where once only a couple of collisions occurred at each beam crossing, now there would be more like five.
“That makes our lives harder in some sense because we’ve got to be able to find the things we’re interested in amongst all those different…