MoEDAL experiment

MoEDAL experiment
Name	MoEDAL experiment
Location	Large Hadron Collider, CERN
Established	2010
Field	Particle physics

MoEDAL experiment

The MoEDAL experiment is a dedicated detector facility at the Large Hadron Collider designed to search for highly ionizing, long-lived, exotic particles produced in high-energy proton–proton collisions. Conceived and installed within the CERN experimental complex near Geneva, the project complements general-purpose detectors such as ATLAS (experiment) and CMS (detector), while drawing on technologies related to nuclear track detectors, trapping detectors, and passive instrumentation used in past campaigns like SLAC studies. The collaboration brings together researchers from universities and laboratories that have participated in experiments associated with LEP, Tevatron, and LHCb.

Overview

MoEDAL originated as a targeted search initiative motivated by theoretical frameworks including supersymmetry, magnetic monopole models, and scenarios with stable massive charged particles inspired by extensions such as GUT-scale monopole proposals, extra dimensions (physics), and certain hidden sector constructions. Installed around the Intersection point 8 interaction region, the apparatus is optimized for signatures distinct from those of collider detectors like ALICE (A Large Ion Collider Experiment) and LHCb (experiment). The experiment employs passive arrays and active trapping systems to capture or record the passage of particles with anomalously high ionization or nonstandard time-of-flight properties, enabling searches complementary to analyses performed by collaborations including ATLAS (experiment), CMS (detector), and BaBar (experiment).

Detector and instrumentation

The MoEDAL facility uses an ensemble of detector types: arrays of plastic nuclear track detectors (NTDs) similar in spirit to materials used in CR-39 studies, arrays of ^{6}Li-doped scintillators analogous to detectors employed at Kamioka Observatory, and a Magnetic Monopole Trapper (MMT) system comprised of aluminum volumes designed for post-run analysis using superconducting magnetometers of the type deployed at Brookhaven National Laboratory and Fermilab. The experimental layout sits adjacent to the LHC beam pipe at Point 8 and interfaces with beamline elements developed during CERN upgrades. Instrumentation emphasizes passive recording and chemical etching methods, drawing methodological heritage from pattern recognition techniques used at CERN ISR and track analysis developed for NA48/NA62 experiments. The experiment’s material choices and geometrical configurations are informed by radiation hardness studies from CERN Radiation Protection efforts and detector simulation work performed with toolkits like GEANT4.

Physics goals and search strategies

Primary physics goals include direct searches for classical and quantum magnetic monopoles predicted by historical proposals such as Dirac monopoles and ’t Hooft–Polyakov configurations, as well as searches for massive stable or metastable charged states anticipated by supersymmetric models (e.g., long-lived gluino or stau (supersymmetric) scenarios), fractionally charged objects conjectured in some composite models, and highly ionizing remnants from black hole evaporation in certain extra dimensions (physics) frameworks. Search strategies combine passive track recording, trapping followed by magnetometer scans, and cross-calibration against active timing systems used by neighbouring experiments like LHCb (experiment); these approaches mirror historic strategies from MACRO (experiment) and SLIM (experiment) searches. Analyses are structured to discover particles with low velocity (beta), high charge-to-mass ratios, or unusual interaction cross sections relative to Standard Model expectations from Quantum Chromodynamics and Electroweak interaction processes.

Data collection and analysis

MoEDAL’s data collection is atypical: rather than continuous electronic readout, the NTD sheets undergo exposure during LHC runs and are then chemically etched and scanned in clean laboratories at institutions including University of Montreal, University of Oxford, and CERN. The MMT foils are retrieved and examined using superconducting magnetometers similar to those used in SQUID facilities at Brookhaven National Laboratory. Analysis pipelines integrate simulated production rates from event generators such as PYTHIA and detector-response modeling with GEANT4 to estimate acceptance for heavy slow-moving particles. Cross-checks leverage complementary datasets collected by ATLAS (experiment) and CMS (detector) and use statistical techniques developed in collaborations like LEP and Tevatron for limit setting. Quality assurance and background estimation involve calibration runs, cosmic-ray studies referencing work from Pierre Auger Observatory groups, and radiopurity assays akin to protocols at Gran Sasso National Laboratory.

Results and interpretations

Published results have set competitive constraints on magnetic monopole production cross sections and lower limits on masses for multiply charged or long-lived particles within specific theoretical scenarios, with comparisons drawn against searches from ATLAS (experiment), CMS (detector), and earlier efforts such as preliminary campaigns. Null results have been interpreted as exclusions in parameter spaces of Dirac monopole models, certain supersymmetry parameter sets involving long-lived charged sparticles, and models predicting fractionally charged relics. Occasional candidate signals are subjected to rigorous post-exposure studies including re-etching, magnetometer re-scans, and cross-collaboration vetting with teams from CERN and partner laboratories. Results continue to inform model-building in the communities connected to GUT phenomenology, dark matter model space, and nonperturbative solutions in field theory.

Collaborations and organization

The collaboration comprises institutes and universities across Europe, North America, and Asia, including groups from Imperial College London, University of Alberta, University of Manchester, University of Tokyo, and Instituto de Física Corpuscular. Governance follows structures similar to other LHC detectors with spokespersons, institutional boards, and technical coordination linked to CERN oversight and funding agencies such as European Research Council and national research councils. MoEDAL maintains close scientific ties with neighboring LHC experiments, theoretical groups at institutions like CERN Theory Division, and instrumentation partners at facilities including Brookhaven National Laboratory and Fermilab, facilitating data interpretation, hardware development, and outreach.

Category:Particle physics experiments