J. Johnson
A5101843976- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Air Quality and Health Impacts
- Vehicle emissions and performance
- Atomic and Subatomic Physics Research
- Atmospheric chemistry and aerosols
- Neutrino Physics Research
- Particle Detector Development and Performance
- Lightning and Electromagnetic Phenomena
- Combustion and Detonation Processes
- Cosmology and Gravitation Theories
- Air Quality Monitoring and Forecasting
- Electrical Fault Detection and Protection
- Astrophysics and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Quantum Chromodynamics and Particle Interactions
- Fire effects on ecosystems
- Risk and Safety Analysis
- Nuclear reactor physics and engineering
- Graphite, nuclear technology, radiation studies
- Nuclear physics research studies
- Quantum, superfluid, helium dynamics
- Radioactive contamination and transfer
- Structural Response to Dynamic Loads
University of California, Davis
2020-2024
Lawrence Berkeley National Laboratory
2024
University of Wisconsin–Madison
2020
Brandeis University
2020
South Dakota Science and Technology Authority
2019
Washington University in St. Louis
2019
Corning (United States)
2008
Johnson Matthey (United States)
2008
Environmental Technologies (United States)
2008
University of Minnesota
2003-2008
The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and fiducial mass 5.5 t. data are found to be consistent with background-only hypothesis, limits set models including solar axion coupling, neutrino magnetic moment millicharge, couplings galactic axionlike particles hidden photons. Similar...
The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to $6.5\times10^{-48}$ cm$^2$ for the spin-independent interaction of a 30 GeV/c$^2$ WIMP at 90% confidence level. In this paper, we present comprehensive analysis backgrounds important result and other upcoming physics analyses, including neutrinoless double-beta decay searches effective field theory interpretations data. We confirm that in-situ determinations bulk fixed...
The continuously regenerating trap (CRT) is a diesel exhaust emission control that removes nearly all particulate matter on mass basis, but under some circumstances oxidation of sulfur leads to the formation nanoparticles. objective four year study was determine CRT performance controlled, real-world, on-road conditions, and develop quantitative relationships between fuel lubrication oil concentration particle number emissions. It shown nanoparticle emissions are minimized by use ultralow...
Searches for dark matter with liquid xenon time projection chamber experiments have traditionally focused on the region of parameter space that is characteristic weakly interacting massive particles, ranging from a few GeV/$c^2$ to TeV/$c^2$. Models mass much heavier than this are well motivated by early production mechanisms different standard thermal freeze-out, but they generally been less explored experimentally. In work, we present re-analysis first science run (SR1) LZ experiment, an...
On-road experiments were conducted to determine the sensitivities of rats real-world aerosol. This article summarizes on-road aerosol and gas measurements provides background information for companion paper on rat exposures. Measurements carried out over 10 days, 6 h/day, driving a route from Rochester Buffalo. Aerosol instrumentation used in this study included two scanning mobility particle sizers (SMPS) size distribution 300 nm, 2 stand-alone condensation counters total number...
The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double $\ensuremath{\beta}$ decay search in parallel to the main science goal of discovering dark matter particle interactions. We report expected LZ sensitivity $^{136}\mathrm{Xe}$ decay, taking advantage significant ($>600$ kg) mass contained within active volume without isotopic enrichment. After 1000 live-days, median exclusion half-life is projected be $1.06\ifmmode\times\else\texttimes\fi{}{10}^{26}$ years (90% confidence...
The detailed chemical composition of particulate matter emissions from four non-smoking gasoline powered motor vehicles were measured using three different driving conditions: a cold-cold start Unified Driving Cycle (UDC), hot UDC, and steady state cruise cycle. UDC tests performed with temperature 0°C, which is significantly lower than the 24°C cold widely used for vehicle testing. Each was operated over cycles, cycle comprised 2 hours at 100 kilometers per hour (kph) plus 1 50 kph....
LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity weakly-interacting massive particles interacting via nuclear recoils with $\ensuremath{\sim}7$-tonne xenon target mass. This paper presents projections several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) millicharge, both for $pp$-chain solar neutrinos, 3) axion flux generated by Sun, 4) axionlike forming Galactic matter, 5) hidden...
<div class="htmlview paragraph">It has been reported that particulate emissions from diesel vehicles could be associated with damaging human health, global warming and a reduction in air quality. These particles cover very large size range, typically 3 to 10 000 nm. Filters the vehicle exhaust systems can substantially reduce but until recently it was not possible directly characterise actual on-road vehicle. This paper presents first study of effect filter on heavy-duty during real-world...
We report results of a search for nuclear recoils induced by weakly interacting massive particle (WIMP) dark matter using the LUX-ZEPLIN (LZ) two-phase xenon time projection chamber. This analysis uses total exposure $4.2\pm0.1$ tonne-years from 280 live days LZ operation, which $3.3\pm0.1$ and 220 are new. A technique to actively tag background electronic $^{214}$Pb $\beta$ decays is featured first time. Enhanced electron-ion recombination observed in two-neutrino double electron capture...
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>...
Abstract LUX-ZEPLIN (LZ) is a tonne-scale experiment searching for direct dark matter interactions and other rare events. It located at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. The core of LZ detector dual-phase xenon time projection chamber (TPC), designed with primary goal detecting Weakly Interacting Massive Particles (WIMPs) via their induced low energy nuclear recoils. Surrounding TPC, two veto detectors immersed an ultra-pure water tank enable...
Abstract Weakly interacting massive particles (WIMPs) may interact with a virtual pion that is exchanged between nucleons. This interaction channel important to consider in models where the spin-independent isoscalar suppressed. Using data from first science run of LUX-ZEPLIN dark matter experiment, containing 60 live days 5.5 tonne fiducial mass liquid xenon, we report results on search for WIMP-pion interactions. We observe no significant excess and set an upper limit 1.5 × 10 −46 cm 2 at...
The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double $\ensuremath{\beta}$ decay $^{134}\mathrm{Xe}$ is presented. LZ a 10-tonne xenon time-projection chamber optimized for detection dark matter particles expected start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass natural provides an exceptional opportunity search $^{134}\mathrm{Xe}$, which detectors enriched $^{136}\mathrm{Xe}$ are less effective. For mode,...
Abstract The continued advancements of Silicon Photomultipliers (SiPMs) have made them viable photosensors for low recoil energy Pulse Shape Discrimination (PSD) between fast neutron and gamma interactions when coupled to an appropriate scintillator. At the same time, large number channels in a typical array calls development low-cost low-power electronics. A custom integrated circuit (ASIC) is ideal solution this purpose. To assess requirements such ASIC, studies were performed using two...
The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and fiducial mass 5.5t. data are found to be consistent with background-only hypothesis, limits set models including solar axion coupling, neutrino magnetic moment millicharge, couplings galactic axion-like particles hidden photons. Similar...