S. Kravitz
A5026988080- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Quantum, superfluid, helium dynamics
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Radiation Detection and Scintillator Technologies
- Big Data Technologies and Applications
- Quantum Chromodynamics and Particle Interactions
- Nuclear Physics and Applications
- Computational Physics and Python Applications
- Atmospheric Ozone and Climate
- Geophysical and Geoelectrical Methods
- Nuclear reactor physics and engineering
- Optical Polarization and Ellipsometry
- Solar and Space Plasma Dynamics
- Nuclear physics research studies
- Photochemistry and Electron Transfer Studies
- Advanced Optical Sensing Technologies
- Underwater Acoustics Research
- Chemical Thermodynamics and Molecular Structure
- Analytical Chemistry and Chromatography
- Random lasers and scattering media
The University of Texas at Austin
2024
Lawrence Berkeley National Laboratory
2018-2024
University of California, Berkeley
2021
Stanford University
2014-2018
Ford Motor Company (United States)
1971
We report on an improved measurement of the $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ half-life ${}^{136}$Xe performed by EXO-200. The use a large and homogeneous time-projection chamber allows for precise estimate fiducial mass used measurement, resulting in small systematic uncertainty. also discuss detail data-analysis methods double-$\ensuremath{\beta}$ decay searches with EXO-200, while emphasizing those directly related to present measurement. is found be...
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...
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...
We apply deep neural networks (DNN) to data from the EXO-200 experiment. In studied cases, DNN is able reconstruct relevant parameters—total energy and position—directly raw digitized waveforms, with minimal exceptions. For first time, developed algorithms are evaluated on real detector calibration data. The accuracy of reconstruction either reaches or exceeds what was achieved by conventional approaches over course Most existing event classification in particle physics trained Monte Carlo...
We report the first measurement of discrimination between low-energy helium recoils and electron in liquid xenon. This result is relevant to proposed low-mass dark matter searches which seek dissolve light target nuclei active volume liquid-xenon time projection chambers. Low-energy were produced by degrading <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>α</a:mi></a:math> particles from <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"...
Alpha decays in the EXO-200 detector are used to measure fraction of charged $^{218}\text{Po}$ and $^{214}\text{Bi}$ daughters created from $\ensuremath{\alpha}$ $\ensuremath{\beta}$ decays, respectively. $^{222}\text{Rn} \ensuremath{\alpha}$ liquid xenon (LXe) found produce $^{218}\text{Po}^{+}$ ions $50.3\ifmmode\pm\else\textpm\fi{}3.0%$ time, while remainder atoms neutral. The $^{214}\text{Bi}^{+}$ $^{214}\text{Pb} \ensuremath{\beta}$ LXe is be $76.4\ifmmode\pm\else\textpm\fi{}5.7%$,...
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...
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...
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...
This paper presents a novel technique for mitigating electrode backgrounds that limit the sensitivity of searches low-mass dark matter (DM) using xenon time projection chambers. In Large Underground Xenon (LUX) detector, signatures DM interactions would be very low-energy ($\ensuremath{\sim}\mathrm{keV}$) scatters in active target ionize only few atoms and seldom produce detectable scintillation signals. this regime, extra precaution is required to reject complex set electron have long been...
Superfluid $^{4}\mathrm{He}$ is a promising target material for direct detection of light ($<1\text{ }\text{ }\mathrm{GeV}$) dark matter. Possible signal channels available readout in this medium include prompt photons, triplet excimers, and roton phonon quasiparticles. The relative yield these signals has implications the sensitivity discrimination power superfluid matter detector. Using $16\text{ }{\mathrm{cm}}^{3}$ volume 1.75 K read out by six immersed photomultiplier tubes, we measured...
We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase double beta decay experiment, nEXO. The goal is Ba ion resulting from an extremely rare nuclear isotope 136Xe, hence providing confirmation occurrence decay. This achieved through Resonance Ionization Spectroscopy (RIS). In test setup described here, can be xenon or vacuum collected on clean substrate. substrate then removed analysis chamber under vacuum, where...
We report here the results of an Effective Field Theory (EFT) WIMP search analysis using LUX data. build upon previous analyses by extending window to include nuclear recoil energies up $\sim$180 keV$_{nr}$, requiring a reassessment data quality cuts and background models. In order use binned Profile Likelihood statistical framework, development new techniques account for higher-energy backgrounds was required. With 3.14$\times10^4$ kg$\cdot$day exposure collected between 2014 2016, we set...
We present the results of a direct detection search for mirror dark matter interactions, using data collected from Large Underground Xenon experiment during 2013, with an exposure 95 live-days $\times$ 118 kg. Here, calculations electron scattering rate in liquid xenon take into account shielding effects captured within Earth. Annual and diurnal modulation flux atomic shell are also accounted for. Having found no evidence recoil signal induced by interactions we place upper limit on kinetic...
We report results from an extensive set of measurements the \b{eta}-decay response in liquid xenon.These are derived high-statistics calibration data injected sources both $^{3}$H and $^{14}$C LUX detector. The mean light-to-charge ratio is reported for 13 electric field values ranging 43 to 491 V/cm, energies 1.5 145 keV.
Experiments searching for weakly interacting massive particle dark matter are now detecting background events from solar neutrino-electron scattering. However, the dominant radioactive in state-of-the-art experiments such as LZ and XENONnT is beta decays radon contamination. In spite of careful detector material screening, progenitor atoms ubiquitous long-lived, extremely soluble liquid xenon. We propose a change phase demonstrate that crystalline xenon offers more than factor <a:math...
Abstract The broad physics reach of the LUX-ZEPLIN (LZ) experiment covers rare phenomena beyond direct detection dark matter. We report precise measurements extremely decay 124 Xe through process two-neutrino double electron capture, utilizing a 1.39 kg × yr isotopic exposure from first LZ science run. A half-life <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn>...
We report here methods and techniques for creating an improved model that reproduces the scintillation ionization response of a dual-phase liquid gaseous xenon time projection chamber. Starting with recent release Noble Element Simulation Technique (NEST v2.0), electronic recoil data from β decays 3H 14C in Large Underground Xenon (LUX) detector were used to tune model, addition external sets allow extrapolation beyond LUX data-taking conditions. This paper also presents modeling complicated...
The Large Underground Xenon (LUX) dark matter search was a 250-kg active mass dual-phase time projection chamber that operated by detecting light and ionization signals from particles incident on xenon target. In December 2015, LUX reported minimum 90% upper C.L. of 6×10−46 cm2 the spin-independent WIMP-nucleon elastic scattering cross section based 1.4×104 kg⋅day exposure in its first science run. Tension between experiments absence definitive positive detection suggest it would be prudent...
Abstract Liquid xenon particle detectors rely on excellent light collection efficiency for their performance. This depends the high reflectivity of polytetrafluoroethylene (PTFE) at scintillation wavelength 178 nm, but angular dependence this is not well-understood. IBEX designed to directly measure distribution reflected off PTFE in liquid xenon. These measurements are fully described by a microphysical model with few free parameters. Dependence type, surface finish, pressure, and incident...
We present the results from combining machine learning with profile likelihood fit procedure, using data Large Underground Xenon (LUX) dark matter experiment. This approach demonstrates reduction in computation time by a factor of 30 when compared previous approach, without loss performance on real data. establish its flexibility to capture nonlinear correlations between variables (such as smearing light and charge signals due position variation) achieving equal pulse areas...
We discuss a novel paradigm in the optical readout of scintillation radiation detectors. In one common configuration, such detectors are homogeneous and light is collected recorded by external photodetectors. It usually assumed that imaging photon-starved large-emittance regime not possible. Here we show appropriate optics, matched with highly segmented photodetector coverage dedicated reconstruction software, can be used to produce images radiation-induced events. particular, ``distributed...
As noble liquid time projection chambers grow in size their high voltage requirements increase, and detailed, reproducible studies of dielectric breakdown the onset electroluminescence are needed to inform design. The Xenon Breakdown Apparatus (XeBrA) is a 5-liter cryogenic chamber built characterize DC behavior xenon argon. Electrodes with areas up 33~cm$^2$ were tested while varying cathode-anode separation from 1 6~mm difference 75~kV. A power-law relationship between field electrode area...