B. G. Lenardo
A5060603958- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Gyrotron and Vacuum Electronics Research
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Radioactive contamination and transfer
- Radiation Therapy and Dosimetry
- Non-Destructive Testing Techniques
- CCD and CMOS Imaging Sensors
- Functional Brain Connectivity Studies
- Nuclear reactor physics and engineering
- Geophysical Methods and Applications
- Graphite, nuclear technology, radiation studies
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- Atmospheric Ozone and Climate
- Radioactivity and Radon Measurements
- Photocathodes and Microchannel Plates
SLAC National Accelerator Laboratory
2023-2024
Stanford University
2018-2023
Menlo School
2023
University of California, Davis
2015-2022
Lawrence Livermore National Laboratory
2015-2022
Colorado School of Mines
2020
Moscow Engineering Physics Institute
2019
University of Edinburgh
2014-2016
University of Maryland, College Park
2012
We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35×104 kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 active mass is operated at Sanford Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence nuclear recoils. At 50 GeV c−2,...
We present constraints on weakly interacting massive particles (WIMP)-nucleus scattering from the 2013 data of Large Underground Xenon dark matter experiment, including 1.4×104 kg day search exposure. This new analysis incorporates several advances: single-photon calibration at scintillation wavelength, improved event-reconstruction algorithms, a revised background model events originating detector walls in an enlarged fiducial volume, and calibrations decays injected tritium β source...
LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using two-phase xenon detector with an active mass of 7 tonnes, LZ search primarily for low-energy interactions weakly interacting massive particles (WIMPs), which are hypothesized to make up our galactic halo. In this paper, projected WIMP sensitivity presented based on latest background estimates...
We present experimental constraints on the spin-dependent WIMP-nucleon elastic cross sections from total 129.5 kg-year exposure acquired by Large Underground Xenon experiment (LUX), operating at Sanford Research Facility in Lead, South Dakota (USA). A profile likelihood ratio analysis allows 90% CL upper limits to be set WIMP-neutron (WIMP-proton) section of $\sigma_n$ = 1.6$\times 10^{-41}$ cm$^{2}$ ($\sigma_p$ 5$\times 10^{-40}$ cm$^{2}$) 35 GeV$c^{-2}$, almost a sixfold improvement over...
A search for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{136}$Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between $0\nu\beta\beta$ and background events. Relative previous analyses, signal detection efficiency has been raised from 80.8% 96.4$\pm$3.0% energy resolution of detector at Q-value improved $\sigma/E=1.23\%$ $1.15\pm0.02\%$ upgraded detector. Accounting new data, median 90% confidence level half-life sensitivity this analysis...
We present experimental constraints on the spin-dependent WIMP (weakly interacting massive particle)-nucleon elastic cross sections from LUX data acquired in 2013. is a dual-phase xenon time projection chamber operating at Sanford Underground Research Facility (Lead, South Dakota), which designed to observe recoil signature of galactic WIMPs scattering nuclei. A profile likelihood ratio analysis 1.4×104 kg day fiducial exposure allows 90% C.L. upper limits be set WIMP-neutron (WIMP-proton)...
The scattering of dark matter (DM) particles with sub-GeV masses off nuclei is difficult to detect using liquid xenon-based DM search instruments because the energy transfer during nuclear recoils smaller than typical detector threshold. However, tree-level DM-nucleus diagram can be accompanied by simultaneous emission a bremsstrahlung photon or so-called "Migdal" electron. These provide an electron recoil component experimental signature at higher energies corresponding recoil. presence...
The first searches for axions and axionlike particles with the Large Underground Xenon experiment are presented. Under assumption of an axioelectric interaction in xenon, coupling constant between electrons ${g}_{\mathrm{Ae}}$ is tested using data collected 2013 exposure totaling 95 live days $\ifmmode\times\else\texttimes\fi{}118\text{ }\text{ }\mathrm{kg}$. A double-sided, profile likelihood ratio statistic test excludes larger than...
We present measurements of the electron-recoil (ER) response LUX dark matter detector based upon 170 000 highly pure and spatially uniform tritium decays. reconstruct energy spectrum using combined model find good agreement with expectations. report average charge light yields ER events in liquid xenon at 180 $105\text{ }\text{ }\mathrm{V}/\mathrm{cm}$ compare results to NEST model. also measure mean recombination fraction its fluctuations, we investigate location width band. These provide...
Abstract The nEXO neutrinoless double beta (0 νββ ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon search for the in 136 Xe. Progress detector design, paired with higher fidelity its simulation an advanced data analysis, based on one used final results EXO-200, produce sensitivity prediction that exceeds half-life 10 28 years. Specifically, improvements have been made understanding production scintillation photons charge as...
The Migdal effect predicts that a nuclear recoil interaction can be accompanied by atomic ionization, allowing many dark matter direct detection experiments to gain sensitivity sub-GeV masses. We report the first search for M- and L-shell electrons in liquid xenon using recoils produced tagged neutron scatters. Despite an observed background rate lower than of expected signals region interest, we do not observe signal consistent with predictions. discuss possible explanations, including...
We present an updated model of light and charge yields from nuclear recoils in liquid xenon with a simultaneously constrained parameter set. A global analysis is performed using measurements electron photon compiled all available historical data, as well the ratio two. These data sweep over energies 1 - 300 keV external applied electric fields 0 4060 V/cm. The by constructing cost functions gradient descent minimizer, simulated annealing algorithm, Markov Chain Monte Carlo approach to...
Dual-phase xenon detectors, as currently used in direct detection dark matter experiments, have observed elevated rates of background electron events the low energy region. While this negatively impacts detector performance various ways, its origins only been partially studied. In paper we report a systematic investigation pathologies LUX experiment. We characterize different populations based on their emission intensities and correlations with preceding depositions detector. By studying...
The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon time projection chamber (TPC) operating at the Sanford Research Facility in Lead, South Dakota. A calibration of nuclear recoils was performed $\textit{in situ}$ LUX detector using collimated beam mono-energetic 2.45 MeV neutrons produced by deuterium-deuterium (D-D) fusion source. recoil energy from first neutron scatter TPC reconstructed measured scattering angle defined double-scatter events within active volume. We...
This work presents an analysis of monoenergetic electronic recoil peaks in the dark-matter-search and calibration data from first underground science run Large Underground Xenon (LUX) detector. Liquid xenon charge light yields for energies between 5.2 661.7 keV are measured, as well energy resolution LUX detector at those same energies. Additionally, there is interpretation existing measurements descriptions electron-ion recombination fluctuations liquid limiting cases a more general re-...
Various dark matter models predict annual and diurnal modulations of interaction rates in Earth-based experiments as a result the Earth's motion halo. Observation such features can provide generic evidence for detection interactions. This paper reports search both rate LUX experiment using over 20 calendar months data acquired between 2013 2016. focuses on electron recoil events at low energies, where leptophilic interactions are expected to occur DAMA has observed strong modulation two...
The LUX experiment has performed searches for dark-matter particles scattering elastically on xenon nuclei, leading to stringent upper limits the nuclear cross sections dark matter. Here, results derived from $1.4\ifmmode\times\else\texttimes\fi{}{10}^{4}\text{ }\text{ }\mathrm{kg}$ days of target exposure in 2013, details calibration, event-reconstruction, modeling, and statistical tests that underlie are presented. Detector performance is characterized, including measured efficiencies,...
We report an absolute calibration of the ionization yields($\textit{Q$_y$})$ and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV 33.2 keV. The average electric field applied across target is 180 V/cm. data are obtained using low energy $^{127}$Xe electron capture decay from 95.0-day first run LUX (WS2013) search Weakly Interacting Massive Particles (WIMPs). sequence gamma-ray X-ray cascades associated with $^{127}$I de-excitations produces...
We present a comprehensive analysis of electronic recoil vs nuclear discrimination in liquid/gas xenon time projection chambers, using calibration data from the 2013 and 2014--2016 runs Large Underground Xenon experiment. observe strong charge-to-light enhancement with increased event energy. For events $\mathrm{S}1=120$ detected photons, i.e., equivalent to energy $\ensuremath{\sim}100\text{ }\mathrm{keV}$, we an background acceptance $<{10}^{\ensuremath{-}5}$ at signal 50%. also modest...
Dual-phase xenon detectors are widely used in dark matter direct detection experiments, and have demonstrated the highest sensitivities to a variety of interactions. However, key component dual-phase detector technology--the efficiency charge extraction from liquid into gas--has not been well characterized. In this paper, we report new measurement electron (EEE) small using two mono-energetic decay features $^{37}$Ar. By achieving stable operation at very high voltages, measured EEE values...
We present a novel analysis technique for liquid xenon time projection chambers that allows lower threshold by relying on events with prompt scintillation signal consisting of single detected photons. The energy the LUX dark matter experiment is primarily determined smallest response detectable, which previously required twofold coincidence in its photomultiplier arrays, enforced data analysis. presented here exploits double photoelectron emission effect observed some models at vacuum...