CERN shut down the Large Hadron Collider, launching a four-year, $1.5 billion upgrade to convert the instrument into the High-Luminosity LHC. The project will rebuild 1.2 kilometers of the tunnel to deliver ten times more collisions when operations restart in June 2030.
The Final Collision and the Transition to Long Shutdown 3
Operational loggers at the world’s largest particle accelerator recorded their final data point on a Saturday morning, logging a single word on the dashboard before technicians sealed down the facility (the Large Hadron Collider’s operational dashboard logged its last collision data point). Two days later, crews entered the 27-kilometer circular tunnel sitting roughly 100 meters below the border area of France and Switzerland (a 27-kilometer proton-smashing circular tunnel at the heart of Europe’s physics lab CERN near Geneva). This maintenance window represents the most extensive intervention on the CERN accelerator complex since its initial construction.
The machine first circulated beams in 2008 and achieved its most famous milestone in 2012, when researchers detected the Higgs boson (the LHC has been in operation since circulating its first particle beams in 2008). Across its operational history, the collider enabled discoveries including the Higgs boson. The most recent operational stretch, dubbed Run 3, recorded more than twice the collision data of the first two runs combined before halting.
“For nearly two decades, it has transformed our understanding of the Universe and inspired generations of scientists, engineers and citizens around the world. Today we say goodbye to the LHC as we have known it, while preparing to welcome its successor.”
Oliver Brüning, CERN’s Director for Accelerators and Technology
Engineering the High-Luminosity Upgrade and New Superconducting Magnets
The total cost of the transformation is projected at 1.2 billion Swiss francs, equivalent to $1.5 billion (The total cost of the upgrade is expected to tick in at 1.2 billion Swiss francs ($1.5 billion)). Funding comes primarily from CERN membership fees alongside in-kind contributions from international partners including the United States, Japan, Canada, and China. Engineers are focusing on luminosity.
Key components of this strategy include the installation of advanced inner triplet quadrupole magnets tested at CERN’s IT String facility. These new magnets achieved a major milestone by successfully reaching their nominal operating current of 16 230 amperes on July 8. Featuring a larger aperture expanded from 70 to 150 millimeters, the niobium–tin superconducting coils operate at magnetic fields of 11.3 teslas, which is roughly 35% higher than the previous generation of magnets.
Global Institutional Roles and Data Processing Challenges
Institutions worldwide are contributing specialized hardware and software to prepare for the massive influx of data expected when the upgraded facility goes live. At Indiana University, researchers involved in the ATLAS experiment are designing algorithms to run on specialized computer chips that sit on the detector itself. These systems will use machine learning to sort through data streams in billionths of a second.
Once operational, the upgraded detector will encounter data rates so high that storing every event becomes impossible. Between 140 and 200 collisions will occur simultaneously during packet intersections inside the detectors, raising the frequency to several billion events per second (Once operational, between 140 and 200 collisions will occur each time two packets of particles meet inside detectors in the tunnel, up from 60 currently).
Scientific Objectives and the Search for Dark Matter
The primary scientific driver for the High-Luminosity LHC is to increase the luminosity by a factor of 10 compared to the LHC, allowing scientists to collect up to 100 times more total data over its decade-long operational span. This statistical increase targets rare physical phenomena, such as the simultaneous production of two Higgs bosons, an event that could shed light on how the universe evolved shortly after the Big Bang.
While ordinary matter accounts for a small fraction of the universe, the remaining portion consists of dark matter and dark energy, which remain unobserved directly (Scientists believe that ordinary matter … accounts for just 5% of the universe. The rest is believed to consist of dark matter (27%) and dark energy (68%)). By expanding the total yield of Higgs bosons from roughly 55 million gathered since 2008 to an expected 380 million over the lifetime of the HL-LHC, researchers aim to test the limits of the Standard Model and search for physics beyond it.
CERN plans a second operational campaign in September to validate commissioning procedures and test integrated system performance under conditions matching the future collider (This second operational campaign in September will primarily focus on validating the commissioning procedures and analysis tools). Gradual restarts of the accelerator complex are scheduled to begin in 2028, leading up to full scientific operations in June 2030 (CERN expects the accelerator complex to begin restarting gradually from 2028, ahead of the High-Luminosity Large Hadron Collider entering full scientific operation in 2030).
Keep reading
