CERN High-Luminosity LHC

CERN High-Luminosity LHC
Name	High-Luminosity Large Hadron Collider
Location	Geneva
Type	Particle accelerator
Built	2020s
Owner	European Organization for Nuclear Research
Operator	European Organization for Nuclear Research
Length	27 km
Status	Under upgrade

CERN High-Luminosity LHC

The High-Luminosity upgrade of the Large Hadron Collider is a major accelerator and detector enhancement project centered at CERN in Geneva near the France–Switzerland border, intended to extend and intensify the research program that produced the discovery of the Higgs boson, the precision studies that involve the Standard Model (physics), and searches that connect to experiments in astroparticle physics, neutrino physics, and dark matter research. The project coordinates institutions including Fermi National Accelerator Laboratory, DESY, KEK, INFN, and national agencies such as European Commission member states, and involves collaborations with experiments like ATLAS experiment, CMS experiment, LHCb experiment, and ALICE experiment. It builds on prior upgrades such as the Large Hadron Collider luminosity campaign, the LHC Run 2, and the LHC Run 3 preparations.

Overview and Objectives

The upgrade aims to substantially increase the collision rate at the Large Hadron Collider interaction points to enable high-precision measurements and rare-process searches by the ATLAS experiment and CMS experiment, improve flavor physics reach for LHCb experiment and heavy-ion capabilities for ALICE experiment, and support cross-cutting studies relevant to particle cosmology, quantum chromodynamics, and electroweak interaction. Key objectives include accumulating integrated luminosities that far exceed those collected during the Higgs boson discovery era, enabling precision tests comparable to programs at facilities like SLAC National Accelerator Laboratory, CERN Neutrinos to Gran Sasso, and future projects such as the Future Circular Collider and International Linear Collider.

Design and Technical Upgrades

The technical program introduces novel systems across accelerator, cryogenics, magnets, and beam instrumentation. Central hardware changes include installation of new superconducting magnet technology such as Nb3Sn quadrupoles developed with partners including Brookhaven National Laboratory and CEA Saclay, advanced crab cavity radiofrequency systems inspired by developments at KEK and Cornell University, and upgraded beam screen and collimation systems tied to studies at John Adams Institute and Institute for High Energy Physics (Russia). The upgrade integrates high-current injector complex improvements at CERN Proton Synchrotron and Super Proton Synchrotron interlocks coordinated with teams from European Space Agency-linked cryogenics groups and industrial suppliers such as Siemens and Air Liquide. Control and instrumentation enhancements leverage experience from ITER cryogenic control, Diamond Light Source beam diagnostics, and European XFEL timing distribution.

Accelerator Performance and Luminosity Goals

Performance targets aim to increase instantaneous luminosity by a factor of about five relative to the LHC Run 2 baseline and to deliver an integrated luminosity of order 3000 to 4000 fb−1 to the ATLAS experiment and CMS experiment over about a decade of operation, enabling statistical sensitivity surpassing that of prior facilities such as Tevatron and LEP. Machine studies reference beam dynamics phenomena observed at RHIC, space-charge limits characterized at GANIL, and collective effects modeled with codes validated by CERN Accelerator School collaborations. The project must manage pileup conditions far beyond earlier campaigns, requiring operational strategies akin to those developed for ISR (particle accelerator) and CERN SPS tests.

Detector Upgrades and Instrumentation

Detector collaborations have pursued comprehensive upgrades: ATLAS experiment and CMS experiment plan tracker replacements employing radiation-hard silicon sensors developed with contributions from Universidade de São Paulo, University of Oxford, University of California, Berkeley, and University of Tokyo; calorimeter and muon system enhancements drawing on experience from DZero, CDF, and Belle II; and trigger/DAQ overhauls incorporating technologies used at ALICE experiment and LHCb experiment. New timing detectors exploit low-gain avalanche diodes and technologies pioneered in collaborations with MIP Timing Detector consortia and institutions like ETH Zurich and CERN IT Department to mitigate pileup. Upgrades also integrate advances from Microelectronics Research Center groups and testing facilities at European Organization for Nuclear Research test beams and national labs including Argonne National Laboratory.

Schedule, Construction, and Commissioning

The construction and installation phases coordinate shut-down windows established by CERN Council approvals and timelines informed by the progress of international projects such as HL-LHC Technical Design Report milestones and procurement cycles with firms like Thales and ABB. Major installation tasks occur during long shutdowns (LS3) following LHC Run 3, with commissioning sequences that parallel procedures used during the original Large Hadron Collider commissioning and refurbishments executed after the LHC accident of 2008. Integration tests involve cryogenic cool-downs, string tests historically used in LEP operations, and beam commissioning stages drawing on expertise from PS Booster teams and the Injector upgrade programs.

Physics Program and Expected Discoveries

The physics reach encompasses precision Higgs boson coupling measurements, sensitivity to rare decays comparable to limits set by B factory experiments, and expanded searches for beyond-Standard-Model signatures such as supersymmetry scenarios long investigated at ATLAS experiment and CMS experiment, long-lived particle searches informed by studies at SHiP and FASER, and dark-sector probes complementary to results from XENON and Planck (spacecraft). Heavy-ion runs will extend quark–gluon plasma studies pioneered at RHIC and ALICE experiment, while flavor physics runs at LHCb experiment will refine constraints on CP violation previously reported by BaBar and Belle. The program will inform theoretical frameworks developed by groups around Institute for Advanced Study, CERN Theory Division, and university departments like Massachusetts Institute of Technology and University of Cambridge.

Safety, Environmental, and Infrastructure Impacts

Safety and environmental considerations build on standards set by International Atomic Energy Agency guidelines and environmental assessments aligned with Geneva Canton regulations, addressing radiological protection, cryogenics hazards, and electrical infrastructure demands similar to those assessed at ITER and large research campuses like Fermilab. Civil engineering interacts with local authorities such as Canton of Geneva and utilities including SIG (Services industriels de Genève), while decommissioning and waste planning reference practices used at CERN during earlier upgrades and at national labs like Oak Ridge National Laboratory. The project includes community engagement facilitated through European Commission frameworks and outreach via institutions like Science et Cité and international partner universities.

Category:Particle physics Category:Accelerators