HL-LHC upgrade

HL-LHC upgrade
Name	HL-LHC upgrade
Location	CERN
Status	Active
Start	2015
Estimated completion	2027
Budget	Multi‑billion euro programme

HL-LHC upgrade

The High-Luminosity Large Hadron Collider upgrade is a major enhancement of the Large Hadron Collider facility at CERN intended to increase the collider's instantaneous luminosity and integrated dataset. The programme involves coordinated work across international laboratories including the CERN Laboratory, national laboratories such as Fermilab, KEK, INFN, and institutions like DESY, SLAC National Accelerator Laboratory, and numerous universities. It builds on prior projects and milestones such as the original Large Hadron Collider construction, the LHC Run 1, and the LHC Run 2 operation campaigns.

Overview and Objectives

The primary objective is to raise the instantaneous luminosity of the Large Hadron Collider by a factor of about five to seven, enabling a tenfold increase in integrated luminosity for the ATLAS experiment and the CMS experiment during the planned High Luminosity LHC running period. Goals include precision measurement programmes following the Higgs boson discovery by the ATLAS Collaboration and the CMS Collaboration, searches for physics beyond the Standard Model, and detailed studies relevant to projects like the proposed Future Circular Collider and the International Linear Collider. The upgrade aligns with strategic roadmaps from organizations such as the European Strategy for Particle Physics, the US Particle Physics Project Prioritization Panel, and national funding agencies including the European Commission funding frameworks.

Technical Upgrades

Key technical elements comprise new superconducting magnets, advanced radiofrequency systems, upgraded cryogenics, and novel beam instrumentation. Superconducting magnet technologies draw on progress from projects like the Superconducting Super Collider R&D legacy, applied research at ITER and developments at Brookhaven National Laboratory. Radiofrequency enhancements reference work from laboratories including CERN RF groups, DESY and KEK. Cryogenic systems are scaled using expertise from CERN Cryogenics, ESA collaborations, and industrial partners. Beam instrumentation and control integrate systems developed at Fermilab, SLAC, Diamond Light Source, and synchrotron facilities such as ESRF.

Accelerator and Injector Modifications

Upgrades span the injector chain including refurbishments to the Proton Synchrotron and Super Proton Synchrotron and enhancements to booster stages pioneered at CERN and partner labs. The insertion regions near the ATLAS experiment and CMS experiment host new high‑field quadrupole magnets based on niobium tin superconductors, leveraging industrialization efforts documented by CERN and INFN. Collimation systems are upgraded with concepts tested at LHC Run 2 and R&D at Fermilab and DESY, while beam dynamics studies reference theoretical work from research groups at MIT, Princeton University, and University of Oxford. Integration with the LHCb experiment and the ALICE experiment requires schedule coordination with the respective collaborations and institutions such as Nikhef and GSI Helmholtz Centre for Heavy Ion Research.

Detector Upgrades and Integration

Detector upgrades for ATLAS and CMS include new inner trackers using silicon pixel and strip technologies developed through collaborations with CERN EP‑CMM, RBRC, KEK, and manufacturers across Italy, Germany, and Japan. Calorimeter and muon system refurbishments draw on designs tested in prototypes at facilities like the CERN SPS test beams and beamlines at DESY and SLAC. Integration work involves software and computing contributions from the Worldwide LHC Computing Grid, the Open Science Grid, and major data centres such as CERN Data Centre and FNAL Tier‑1. Upgrades also coordinate with experiments like LHCb for trigger and data acquisition interoperability and with the ALICE Collaboration for heavy‑ion running optimisation.

Project Organization, Schedule, and Budget

The programme is coordinated by CERN in partnership with national laboratories and university consortia including INFN, CNRS, US Department of Energy, and agencies represented in the European Strategy Group. The schedule follows phased installation windows during long shutdowns, notably Long Shutdown 3, with milestone reviews informed by bodies such as the CERN Council and advisory panels including the Scientific Policy Committee (SPC). Budgetary oversight involves agencies like the European Commission and national funders; contributions resemble prior funding models used for the LHC and international projects like ITER and XFEL.

Physics Goals and Expected Performance

With the targeted integrated luminosity, precision measurements of the Higgs boson couplings, self‑coupling, and rare decays will improve constraints on models such as Supersymmetry, Composite Higgs models, and Extra Dimensions. The increased dataset enhances sensitivity to signatures predicted by frameworks including Dark Matter simplified models, Axion searches, and heavy resonance scenarios explored in Grand Unified Theory motivated models. Expected performance gains for ATLAS and CMS are quantified in projected limits and discovery reaches communicated through collaborations and review articles from institutions such as CERN, Fermilab, and leading universities.

Risks, Challenges, and Mitigation Strategies

Challenges include technical risks in niobium tin magnet production, supply chain constraints involving industrial partners across Europe, North America, and Asia, and integration risks during complex shutdown periods. Mitigation strategies draw on contingency planning used in projects like the LHC construction, risk registers maintained by CERN, redundancy in vendor qualification informed by European Commission procurement practices, and staged commissioning approaches adopted in collaborations such as ATLAS and CMS. Programmatic risks are managed via governance from the CERN Council and consultation with stakeholder groups including international funding agencies and scientific advisory boards.

Category:Particle accelerators