Scientists overseeing Earth’s largest particle accelerator turned it on for the first time in three years this weekend to solve some of physics’ biggest mysteries.
The Large Hadron Collider (LHC), the powerful particle accelerator located at CERN near Geneva, Switzerland, restarted on Friday (April 22) after a three-year shutdown for maintenance and upgrades. The reactivation kicked off what scientists are calling Run 3, the LHC’s third science run, which will run experiments until 2024.
“Machines and facilities underwent major upgrades during the second extended closure of CERN’s accelerator complex,” said Mike Lamont, Director of Accelerators and Technology at CERN, in a statement on Friday. “The LHC itself has undergone an extensive consolidation program and will now run at even higher power and, thanks to major improvements to the injector complex, will provide much more data to the upgraded LHC experiments.” Those experiments will build on the LHC’s discoveries during its Run 1 (2009-2013) and Run 2 (2015-2018).
Related: The Large Hadron Collider will explore the cutting edge of physics after a 3-year shutdown
For its reactivation, scientists switched on the LHC’s 16.7-mile-long (27-kilometre) ring to inject two beams of protons in opposite directions at an energy level of 450 billion electron volts. That’s just an appetizer for even higher energy levels the LHC will operate once it reaches its target of 13.6 trillion electron volts for run 3, the scientists said.
“These beams circulated with injection energy and contained a relatively small number of protons. High-intensity, high-energy collisions are a couple of months away,” said Rhodri Jones, who heads CERN’s beam department, at the release. “But first the beams represent the successful reset of the throttle after all the hard work of the long shutdown.”
The three-year shutdown of the LHC allowed scientists to make substantial improvements to four key experiments at the particle accelerator. Its ATLAS and CMS detectors alone will receive more particle collisions than the last two runs combined, according to CERN. ATLAS (short for A Toroidal LHC Apparatus) detects the tiny subatomic fragments of particle collisions and is used to search for the Higgs boson, dark matter and extra dimensions. CMS (short for Compact Muon Solenoid) is a general purpose detector that uses different systems for ATLAS-like observations.
In addition to ATLAS and CMS, the heavy ion collision particle accelerator ALICE experiment will be able to detect 50 times more collisions thanks to its upgrade, while another instrument, called LHCb, will see its detection capacity increase by a factor of three. , according to CERN.
“The unprecedented number of collisions will allow international teams of physicists at CERN and around the world to study the Higgs boson in great detail and subject the Standard Model of particle physics and its various extensions to the most stringent tests yet.” CERN officials wrote in the statement.
Two new experiments will be activated at the LHC for run 3. Called the Forward Search Experiment (FASER) and the LHC Neutrino and Scattering Detector (SND@LHC), they are expected to explore new physics beyond the standard model, measure with what frequency antimatter forms and explores the physics of cosmic rays and a strange state of matter called quark-gluon plasma.
It will take several weeks of commissioning work before the revamped LHC is ready for actual science measurements. Those science careers are expected to start in the summer, CERN officials said.
Once Run 3 wraps up in 2024, CERN scientists will shut it down for another planned review that will include more updates to the massive particle accelerator. Once complete, those upgrades will allow scientists to rename the LHC the “Large High-Luminity Hadron Collider” once it reopens in 2028.