LHC Run 3
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| LHC Run 3 | |
|---|---|
| Name | LHC Run 3 |
| Start | 2022 |
| End | present |
| Location | CERN |
| Facility | Large Hadron Collider |
| Operator | European Organization for Nuclear Research |
| Beam | proton–proton; lead–lead; proton–lead |
| Energy | 13.6 TeV centre-of-mass (protons) |
| Previous | LHC Run 2 |
| Next | High-Luminosity Large Hadron Collider |
LHC Run 3 LHC Run 3 is the third major data-taking campaign at the Large Hadron Collider located at CERN, commencing in 2022 after a long shutdown and accelerator upgrade period. The campaign involves coordinated operations of experiments such as ATLAS, CMS, LHCb, and ALICE to pursue high-luminosity particle physics goals, extend searches initiated during LHC Run 1 and LHC Run 2, and prepare for the upgrade path toward the High-Luminosity Large Hadron Collider project. Run 3 combines upgraded accelerator systems, refurbished detectors, and enhanced computing and trigger infrastructure to increase integrated luminosity and explore rare processes.
Background and Goals
Run 3 followed an extended maintenance and consolidation phase after LHC Run 2; it built on milestones from the discovery of the Higgs boson by ATLAS and CMS in 2012 and precision measurements performed in subsequent years. Primary goals included increasing the integrated luminosity delivered to flagship experiments, enhancing sensitivity to phenomena predicted by theories such as supersymmetry, extra dimensions, and dark matter models, and improving measurements of the Higgs boson couplings and properties relevant to Standard Model tests. Run 3 also aimed to support heavy-ion physics programs linked to studies from RHIC and to refine detector technologies ahead of the High-Luminosity Large Hadron Collider upgrade overseen by CERN and partner institutions like European Strategy for Particle Physics contributors.
Machine Upgrades and Beam Parameters
The accelerator complex upgrades included consolidation of the RF systems, magnet maintenance for the main dipole magnets, and enhancements to the injector complex including Proton Synchrotron and Super Proton Synchrotron performance. Beam parameters were set to a nominal centre-of-mass energy of 13.6 TeV for proton–proton collisions with increased bunch intensity, reduced bunch spacing strategies, and higher pileup management. Upgrades to collimation systems, cryogenics, and power converters improved machine availability, while coordination with projects like HL-LHC informed hardware choices. Beam conditions also accommodated lead–lead and proton–lead collision modes to support heavy-ion campaigns echoing results from ALICE and comparisons to Quark–Gluon Plasma studies at BNL.
Detector Upgrades and Experiments
Major experiments implemented staged detector upgrades: ATLAS upgraded its inner tracker and trigger systems; CMS installed a new timing detector and improved its pixel tracker; LHCb deployed a full-software trigger and vertex detector improvements; ALICE upgraded tracking and readout for continuous readout modes. These detector changes were coordinated with computing and data-acquisition overhauls inspired by architectures used at facilities like Fermilab and SLAC National Accelerator Laboratory. Upgrades increased radiation hardness, timing resolution, and data throughput to handle the elevated instantaneous luminosity and pileup environment encountered during Run 3.
Physics Program and Key Measurements
The Run 3 physics program emphasized precision Higgs physics, searches for beyond-Standard Model signatures including supersymmetric particles and vector-like quarks, electroweak measurements, and rare decay searches such as flavor physics channels pursued by LHCb and Belle II. Heavy-ion physics targeted properties of the Quark–Gluon Plasma and collective phenomena, providing complementary insights to results from PHENIX and STAR. Measurements of the top quark mass and couplings, diboson production, and parton distribution functions were central, as were dedicated efforts to constrain dark matter mediator models and test predictions from effective field theory frameworks and lattice calculations.
Operations, Data Taking, and Performance
Operations during Run 3 balanced high-intensity filling schemes with detector protection and trigger rate control, relying on scheduling coordinated by CERN operations teams and collaborations with national laboratories and funding agencies. Data-taking strategies incorporated novel trigger menus, machine-learning based selection, and real-time calibration systems akin to methods used at ATLAS and CMS in previous runs. Performance metrics included delivered and recorded integrated luminosity, detector uptime, and data quality indicators, with luminosity milestones reported periodically by collaborations and cross-checked with luminosity monitors.
Results and Early Discoveries
Early Run 3 analyses produced refined measurements of Standard Model observables, improved constraints on rare decays from LHCb, and updated searches for new resonances and exotica by ATLAS and CMS. ALICE reported novel heavy-ion results on collective flow and strangeness enhancement, complementing past findings from CERN SPS programs. While definitive discoveries beyond the Standard Model remained elusive in initial Run 3 datasets, the campaign yielded important exclusions for parameter spaces in supersymmetry models and provided higher-precision inputs for global fits used by theory groups and phenomenologists.
Future Prospects and Legacy
Run 3 serves as a bridge to High-Luminosity Large Hadron Collider operations by demonstrating hardware, software, and operational concepts at increased luminosity and pileup, informing upgrade schedules and technologies. The legacy of Run 3 includes enhanced detector performance, datasets that enable long-term precision programs, and methodological advances in triggers and analysis pipelines leveraged by collaborations across particle physics institutions such as CERN, FNAL, and DESY. Results from Run 3 will feed into global efforts like the Particle Data Group compilations and influence future strategy reviews including updates to the European Strategy for Particle Physics.