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| ATLAS Luminosity Group | |
|---|---|
| Name | ATLAS Luminosity Group |
| Type | Scientific collaboration subgroup |
| Headquarters | CERN |
| Formation | 1990s |
| Region served | European Organization for Nuclear Research experiments |
| Parent organization | ATLAS experiment |
ATLAS Luminosity Group The ATLAS Luminosity Group is a specialized subgroup responsible for determining the integrated and instantaneous luminosity delivered to the ATLAS experiment at Large Hadron Collider. It provides precision luminosity measurements used across analyses by collaborations such as CMS experiment and external projects including LHCb and ALICE. The Group's work interfaces with institutions like CERN, Fermilab, and SLAC National Accelerator Laboratory and influences results cited in publications by collaborations such as ATLAS Collaboration and consortia referenced by Particle Data Group.
The Group coordinates luminosity determination for proton–proton collisions at Large Hadron Collider run periods including Run 1 (LHC), Run 2 (LHC), and Run 3 (LHC), and prepares strategies for High-Luminosity Large Hadron Collider upgrades. It integrates inputs from beam instrumentation teams at CERN Accelerator Complex, detector subsystems like ATLAS Inner Detector and ATLAS Calorimeter, and simulation groups using tools such as GEANT4 and PYTHIA. Outputs inform measurements of processes including Higgs boson production, top quark cross-sections, and searches for supersymmetry and dark matter candidates.
Membership spans universities and laboratories such as University of Oxford, University of California, Berkeley, University of Tokyo, Imperial College London, University of Melbourne, DESY, Brookhaven National Laboratory, and University of Chicago. Leadership typically comprises conveners from institutions with expertise in luminosity, beam instrumentation, and statistical analysis, drawn from groups involved in ATLAS Trigger and Data Acquisition and ATLAS Offline. The Group liaises with committees including the ATLAS Publication Committee, ATLAS Performance Coordination, and accelerator teams like Beam Instrumentation Group at CERN.
Instrumentation includes detectors and monitors such as ALFA (ATLAS) roman pots, LUCID Cherenkov detectors, BCM beam condition monitors, and dedicated calorimeter systems tied to Tile Calorimeter and Liquid Argon Calorimeter. Calibration campaigns use reference systems like Van der Meer scan techniques developed in collaboration with accelerator physicists at CERN and measurement comparisons with TOTEM and LHCf. Calibration relies on metrology standards from laboratories such as National Institute of Standards and Technology and comparisons to beam current transformers used by CERN Beam Instrumentation.
The Group employs van der Meer scans, event-counting algorithms, calorimeter-based methods, and track-based approaches using reconstructed vertices in ATLAS Inner Detector. Methods cross-validate using processes with well-predicted cross-sections such as Z boson production, W boson production, and elastic scattering channels measured by collaborations including TOTEM and CMS experiment. Techniques incorporate software frameworks like Athena (software) and statistical tools adopted from ROOT (software) and RooFit.
Analyses quantify uncertainties from sources such as beam-beam effects studied with MAD-X, detector stability monitored with Temperature control systems, and pile-up conditions modeled against PYTHIA8 tunes. Systematics include calibration drift, detector linearity, acceptance corrections, and model dependence of reference processes; these are evaluated with methods inspired by standards from Particle Data Group and statistical procedures using frequentist and Bayesian techniques described by scholars associated with Cowan (statistician). Results are subject to internal reviews by ATLAS Collaboration committees and external comparisons with CMS Collaboration luminosity determinations.
Luminosity results produced by the Group set the normalization for cross-section measurements of processes like Higgs boson decays measured by ATLAS Collaboration, precision determinations of the top quark pair-production rate, and limits in searches for supersymmetry and exotic resonances studied alongside CMS experiment results. Uncertainties in luminosity feed directly into global fits performed by groups such as CTEQ, NNPDF, and enter combined measurements reported to bodies like Particle Data Group and conferences including International Conference on High Energy Physics.
The Group coordinates with experiments and projects including CMS experiment, TOTEM, LHCb, ALICE, and accelerator teams at CERN for cross-calibration and common scans. It contributes to upgrade planning for High-Luminosity Large Hadron Collider detectors, interacts with engineering projects at European XFEL for sensor development, and collaborates with computing centers like CERN IT and WLCG for data processing. Joint publications and working groups involve stakeholders from Institute of High Energy Physics (IHEP), KEK, INFN, and agencies such as European Research Council.
Category:ATLAS experiment Category:Particle physics organizations