Large Underground Xenon experiment

Large Underground Xenon experiment
Name	Large Underground Xenon experiment
Abbreviation	LUX
Location	Sanford Underground Research Facility, Homestake Mine
Status	Completed (2016), succeeded by LZ
Detector	Dual-phase liquid xenon time projection chamber
Target	WIMP dark matter
Published	2013–2016

Large Underground Xenon experiment The Large Underground Xenon experiment was a deep-underground particle physics detector searching for dark matter using a dual-phase xenon time projection chamber. Situated in the Homestake Mine at the Sanford Underground Research Facility, LUX operated as part of a broader international effort including groups from the United States Department of Energy, Lawrence Berkeley National Laboratory, Imperial College London, and the South Dakota School of Mines and Technology. The collaboration reported world-leading limits on WIMP interactions before transitioning to successor projects such as LZ (experiment).

Overview

LUX was designed to detect weakly interacting massive particles through nuclear recoils in liquid xenon and was built by an international team including scientists affiliated with Fermilab, University of California, Berkeley, Brown University, Case Western Reserve University, and University of Wisconsin–Madison. The experiment operated at a depth provided by the Homestake Mine infrastructure and coordinated closely with the Sanford Underground Research Facility management and oversight by agencies like the National Science Foundation and Department of Energy. Results were published in peer-reviewed journals and presented at conferences such as the American Physical Society meetings and workshops at CERN.

Detector Design and Technology

The LUX detector used a dual-phase liquid-gas time projection chamber with photomultiplier tubes sourced from vendors and characterized at facilities including Lawrence Livermore National Laboratory and SLAC National Accelerator Laboratory. The detector measured primary scintillation (S1) and electroluminescence (S2) signals to reconstruct event position and discriminate between electronic recoils and nuclear recoils, techniques developed alongside work at XENON (experiment), ZEPLIN, and PandaX. Materials screening and low-background construction involved collaborations with Oak Ridge National Laboratory and the Pacific Northwest National Laboratory, and the cryogenics design drew on expertise from Brookhaven National Laboratory.

Location and Infrastructure

LUX was installed on the 4850-foot level of the Homestake Mine within the Sanford Underground Research Facility near Lead, South Dakota. The underground laboratory provided shielding from cosmic rays comparable to other deep sites such as Gran Sasso National Laboratory, SNOLAB, and the Boulby Mine. Surface support infrastructure included cleanrooms modeled after those at Fermilab and Los Alamos National Laboratory, and the experiment relied on logistics coordinated with the South Dakota Science and Technology Authority and regional partners including Black Hills State University.

Science Goals and Results

The primary science goal was to set limits on spin-independent and spin-dependent interactions of hypothetical WIMP candidates predicted by extensions of the Standard Model such as supersymmetry and extra dimension scenarios formulated in frameworks discussed at CERN and by groups at Harvard University and Massachusetts Institute of Technology. LUX produced leading upper limits on WIMP-nucleon cross sections, reported null detection results with exclusion plots compared against results from DAMA/LIBRA, CoGeNT, CDMS-II, and XENON100. Data releases and analyses were coordinated with theoretical groups at Princeton University and California Institute of Technology and informed design choices for successor detectors including LZ (experiment) and DARWIN studies.

Backgrounds and Calibration

Control of radiogenic and cosmogenic backgrounds required extensive materials assay performed at facilities such as Lawrence Berkeley National Laboratory and University of Alabama assay labs, and cosmogenic activation studies in coordination with NASA and NOAA archives. Calibration campaigns used internal sources like tritiated methane and external neutron generators similar to devices developed at Pacific Northwest National Laboratory and gamma sources characterized by NIST. Background models incorporated contributions from radioactive isotopes found in detector components screened at Brookhaven National Laboratory and cosmogenic muon veto strategies informed by muon flux measurements from SNOLAB and Gran Sasso National Laboratory.

Data Analysis and Collaboration

The LUX collaboration developed blind analysis frameworks and event selection criteria using software tools and statistical methods similar to those employed at CERN experiments and in analyses from ATLAS and CMS teams, while engaging statisticians at institutions like University of Chicago and Carnegie Mellon University. Collaboration governance included spokespersons and working groups drawn from Imperial College London, University of Edinburgh, University of Maryland, and Texas A&M University, with data preservation and open-data policies coordinated with national laboratories including Fermilab and SLAC National Accelerator Laboratory.

Upgrades and Successor Experiments

Following LUX operations, the community consolidated efforts into the LUX-ZEPLIN (LZ (experiment)) project, a larger multi-tonne liquid xenon detector built with funding and technical contributions from Department of Energy, STFC, National Science Foundation, and international partners from Portugal, South Korea, and Russia. Parallel R&D and proposed future facilities include the multi-tonne DARWIN observatory concept and detector concepts at Gran Sasso National Laboratory and SNOLAB aimed at probing lower cross sections and diverse dark matter models explored at CERN and in theoretical groups at Institute for Advanced Study.

Category:Dark matter experiments