The world's most powerful particle accelerator will shutter operations Monday for four years of renovations to dramatically boost its collision capacity and the potential for unlocking one of the greatest mysteries of the universe: dark matter.

The Large Hadron Collider (LHC)—a 27-kilometer (17-mile) proton-smashing circular tunnel at the heart of Europe's physics lab CERN near Geneva—has most famously been used to prove the existence of the Higgs boson, dubbed "the God particle."

In the tunnel, running about 100 meters (330 feet) below the French-Swiss border area, superconducting magnets and accelerating structures propel particles to extreme energies and then smash them together at phenomenal speeds.

But from Monday, activity will stop as the extraordinary device undergoes upgrades aimed at further increasing the precision and intensity of particle collisions.

Once completed, the enhanced particle smasher, bearing the new name High Luminosity LHC (HL-LHC), is scheduled to begin operations in June 2030 and to run for about a decade.

'Many discoveries' await
"This is a very important moment. From Monday, we will be entering a new phase," HL-LHC project chief Markus Zerlauth told reporters.

"We still have lots of physics questions without answers. There are still many discoveries to be made."

The goal is to increase the "luminosity"—that is, the total number of collisions produced over a given period—by a factor of 10 compared with the LHC.