The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs

Abstract

LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above $1.4\times 10^{-48}$ cm${}^2$ for a WIMP mass of 40 GeV/c${}^2$ and a 1000 d exposure. LZ achieves this sensitivity through a combination of a large 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented.

arXiv comment45 pages (79 inc. tables), 7 figures, 9 tables

References in corpus (25)

• First results from the LUX dark matter experiment at the Sanford Underground Research Facility
• Results from a search for dark matter in the complete LUX exposure
• The Sudbury Neutrino Observatory
• The Large Underground Xenon (LUX) Experiment
• Projected WIMP sensitivity of the LUX-ZEPLIN (LZ) dark matter experiment
• The LUX-ZEPLIN (LZ) Experiment
• First limits on WIMP nuclear recoil signals in ZEPLIN-II: a two phase xenon detector for dark matter detection
• WIMP-nucleon cross-section results from the second science run of ZEPLIN-III
• Systematic study of trace radioactive impurities in candidate construction materials for EXO-200
• Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment
• Radiogenic and Muon-Induced Backgrounds in the LUX Dark Matter Detector
• Investigation of radioactivity-induced backgrounds in EXO-200
• Low Background Gamma Spectroscopy at the Boulby Underground Laboratory
• Study of radon reduction in gases for rare event search experiments
• Identification of Radiopure Titanium for the LZ Dark Matter Experiment and Future Rare Event Searches
• Position Reconstruction in LUX
• Trace radioactive impurities in final construction materials for EXO-200
• Radioactivity Backgrounds in ZEPLIN-III
• Measurement of the Gamma Ray Background in the Davis Cavern at the Sanford Underground Research Facility
• Ultra-low background mass spectrometry for rare-event searches
• A Liquid Scintillation Detector for Radioassay of Gadolinium-Loaded Liquid Scintillator for the LZ Outer Detector
• GEANT4 models of HPGe detectors for radioassay
• A New Method for Evaluating the Effectiveness of Plastic Packaging Against Radon Penetration
• Constraining Radon Backgrounds in LZ
• Radon Daughter Plate-out onto Teflon

Cited by in corpus (36)

• First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment
• NEXO: Neutrinoless double beta decay search beyond $10^{28}$ year half-life sensitivity
• A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics
• A search for new physics in low-energy electron recoils from the first LZ exposure
• Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment
• Low Radioactive Material Screening and Background Control for the PandaX-4T Experiment
• Trapped electrons and ions as particle detectors
• Projected sensitivities of the LUX-ZEPLIN (LZ) experiment to new physics via low-energy electron recoils
• Kiloton-scale xenon detectors for neutrinoless double beta decay and other new physics searches
• The XLZD Design Book: Towards the Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics
• First Constraints on WIMP-Nucleon Effective Field Theory Couplings in an Extended Energy Region From LUX-ZEPLIN
• Large Low Background kTon-Scale Liquid Argon Time Projection Chambers
• Projected sensitivity of the LUX-ZEPLIN (LZ) experiment to the two-neutrino and neutrinoless double beta decays of ${}^{134}$Xe
• Measurement of ambient radon progeny decay rates and energy spectra in liquid argon using the MicroBooNE detector
• Neutrinoless Double Beta Decay Sensitivity of the XLZD Rare Event Observatory
• The upgraded low-background germanium counting facility Gator for high-sensitivity $\gamma$-ray spectrometry
• Fast and Flexible Analysis of Direct Dark Matter Search Data with Machine Learning
• Two-neutrino double electron capture of ${}^{124}$Xe in the first LUX-ZEPLIN exposure
• Reduction of ${}^{222}$Rn-induced Backgrounds in a Hermetic Dual-Phase Xenon Time Projection Chamber
• Design, characterization and installation of the NEXT-100 cathode and electroluminescence regions
• Ultra-Low Background Germanium Assay at the Boulby Underground Laboratory
• Production and characterization of a ${}^{222}$Rn-emanating stainless steel source
• Development of a low-background HPGe detector at Kamioka Observatory
• A Novel Low-Background Photomultiplier Tube Developed for Xenon Based Detectors
• Probing the Scalar WIMP-Pion Coupling with the first LUX-ZEPLIN data
• Ultra-sensitive radon assay using an electrostatic chamber in a recirculating system
• AlphaCAMM, a Micromegas-based camera for high-sensitivity screening of alpha surface contamination
• An integrated online radioassay data storage and analytics tool for nEXO
• Design and production of the high voltage electrode grids and electron extraction region for the LZ dual-phase xenon time projection chamber
• Optical Calibration System for the LUX-ZEPLIN (LZ) Outer Detector
• HydroX, a light dark matter search with hydrogen-doped liquid xenon time projection chambers
• Radon emanation rate measurements using liquid scintillation counting
• Characterization of the Hamamatsu 8-inch R14688-100 PMT
• Exploration of Methods to Remove Implanted ${}^{210}$Pb and ${}^{210}$Po Contamination from Silicon Surfaces
• Monte Carlo Simulation Variance Reduction Techniques for Photon Transport in Liquid Xenon Detectors
• Study on cosmogenic activation in copper for rare event search experiments