DEAP-3600

DEAP-3600
Name	DEAP-3600
Location	SNOLAB, Creighton Mine, Sudbury, Ontario, Canada
Type	Dark matter detector
Status	Completed data taking (2016–2019)
Target	Liquid argon (argon-40)
Mass	3,600 kg active target
Operator	DEAP Collaboration
Began	2014
Completed	2016

DEAP-3600 DEAP-3600 is a single-phase liquid argon detector designed to search for weakly interacting massive particles. The instrument operated at an underground laboratory in Ontario to minimize cosmogenic backgrounds and employed pulse-shape discrimination to separate nuclear recoils from electromagnetic backgrounds. The experiment integrated low-radioactivity materials, ultrapure cryogenics, and photomultiplier arrays to pursue sensitivity to rare-event signals.

Overview

The project combined expertise from institutions such as Queen's University at Kingston, Carleton University, University of Alberta, University of British Columbia, McGill University, University of Toronto, York University, TRIUMF, SNOLAB and international partners including Imperial College London, Royal Holloway, University of London, Stockholm University, Universiteit van Amsterdam, ETH Zurich, University of Zurich, University of Oxford, University of Cambridge, University of Sheffield, University of Liverpool, University College London, University of Manchester, University of Edinburgh, University of Glasgow, University of Warwick, University of Sussex, University of Nottingham, University of Southampton, University of Birmingham, University of Bristol, Rutherford Appleton Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, Fermi National Accelerator Laboratory, Brookhaven National Laboratory, Argonne National Laboratory, Stanford University, Massachusetts Institute of Technology, California Institute of Technology, Princeton University, Harvard University, Columbia University, Yale University, Cornell University, Brown University, University of Chicago, University of California, Berkeley, University of California, Davis, University of California, Santa Cruz, University of California, Los Angeles, University of Michigan, University of Wisconsin–Madison, University of Illinois at Urbana–Champaign, Ohio State University, University of Minnesota, Purdue University, Johns Hopkins University, National Research Council (Canada). The collaboration drew on techniques from predecessors like XENON, LUX-ZEPLIN, DEAP-1 and contemporaries such as DarkSide and PICO to refine low-background operations.

Detector Design and Instrumentation

The detector featured a spherical acrylic vessel instrumented with an array of 255 photomultiplier tubes from vendors and laboratories such as Hamamatsu, ET Enterprises, and test facilities at TRIUMF, SNOLAB surface facility, Queen's University. Scintillation in liquid argon produced vacuum ultraviolet photons shifted by wavelength shifters applied to the acrylic inner surface; engineering studies referenced methods used by MINOS, NOvA, MicroBooNE, ICARUS, ICARUS–WA104 and ProtoDUNE. The cryostat, cooling, and purification subsystems leveraged cryogenics expertise from CERN collaborators and cryostat fabrication practices comparable to ZEPLIN-III and XMASS. Passive shielding and active veto systems incorporated lessons from Sudbury Neutrino Observatory operations and shielding approaches used in Super-Kamiokande and SNO+ installations. Material assay campaigns relied on techniques and facilities at SNOLAB radiopurity facility, Pacific Northwest National Laboratory, Lawrence Livermore National Laboratory and NRC Canada.

Location and Infrastructure

Installed in the Creighton Mine complex at SNOLAB, the detector benefitted from a 2-km overburden similar to depths used by SNO, CLEAN and Borexino. The underground halls and cleanroom infrastructure shared logistical constraints with experiments such as CUORE, EXO, Majorana Demonstrator, GERDA, KamLAND-Zen and KAMLAND. Access tunnels and hoisting arranged operations akin to those at Homestake Mine deployments for LUX and DUNE prototypes. Site services, radon control, and radiopurity handling followed protocols developed in coordination with SNOLAB management, Ontario Ministry of Energy, Northern Development and Mines, INPO-style safety frameworks, and environmental standards applied at Canadian Nuclear Laboratories facilities.

Scientific Goals and Results

The principal objective was to detect nuclear recoils from dark matter candidates predicted in extensions to the Standard Model such as supersymmetric neutralinos and WIMPs envisioned by theories referenced at conferences like ICHEP and Lepton Photon Conference. The experiment set competitive limits on spin-independent WIMP-nucleon cross sections for argon-target detectors and produced exclusion curves compared with results from XENON1T, LUX, PandaX, DarkSide-50, CRESST, PICO-60, CDMS-II, SuperCDMS, SENSEI, DAMIC, EDELWEISS and MIMAC. DEAP-3600 demonstrated high pulse-shape discrimination power, influencing design choices for future detectors such as DarkSide-20k and informing proposals at SNOLAB expansions. Results were presented at venues including Moriond, Rencontres de Blois, Neutrino, TAUP and published in journals read across the communities at APS and European Physical Society meetings.

Data Processing and Analysis

Data acquisition systems used digitizers and trigger systems developed with input from CERN electronics groups, TRIUMF electronics, and firmware teams affiliated with Brookhaven National Laboratory and Fermilab. Signal processing pipelines employed pulse-shape discrimination algorithms, waveform calibration, and Monte Carlo simulations built on toolkits like GEANT4, ROOT, GEANT3 comparisons, and statistical frameworks analogous to those used in BAT and RooFit. Background models incorporated radiogenic neutron studies from LNGS programs, cosmogenic activation studies similar to EXO-200 and KamLAND analyses, and radon progeny surface contamination models informed by work at SURF. Blind-analysis procedures, data-quality monitoring, and systematic uncertainty treatments followed practices described by Particle Data Group reviews and technical coordination with analysts at SLAC and Lawrence Berkeley National Laboratory.

Collaboration and Project History

The collaboration formed from groups with histories in neutrino and dark matter research at institutions like SNO Collaboration, XENON Collaboration, LUX Collaboration, DarkSide Collaboration, CDMS Collaboration, COHERENT Collaboration as well as universities listed above. Project milestones included construction phases in coordination with Vale mine operations, cryostat commissioning influenced by CERN cryogenics tests, first fill and calibration campaigns using sources and deployable systems similar to those used by Borexino and SNO+, and final physics runs concluding prior to transitions to successor projects. Governance combined institutional boards and technical working groups following models from CERN experiments and inter-laboratory memoranda of understanding with agencies such as NSERC, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, UK Research and Innovation, Swedish Research Council, European Research Council, U.S. Department of Energy, and National Science Foundation.

Category:Particle detectors