A5072282007- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Magnetic confinement fusion research
- Quantum Chromodynamics and Particle Interactions
- Particle Accelerators and Free-Electron Lasers
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Neutrino Physics Research
- Nuclear reactor physics and engineering
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Astrophysics and Cosmic Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Frequency and Time Standards
- Earthquake Detection and Analysis
- Atomic and Molecular Physics
- Non-Destructive Testing Techniques
- Magnetic and Electromagnetic Effects
- Radiation Therapy and Dosimetry
Los Alamos National Laboratory
2015-2024
California Institute of Technology
2001-2021
North Carolina State University
2020-2021
Tennessee Technological University
2020-2021
University of Kentucky
2020-2021
Indiana University Bloomington
2020-2021
East Tennessee State University
2020-2021
Utah State University
2020-2021
Kyushu University
2019
Osaka University
2012
We report an improved measurement of the free neutron lifetime τ_{n} using UCNτ apparatus at Los Alamos Neutron Science Center. count a total approximately 38×10^{6} surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns 2017 and 2018. extract from three blinded, independent analyses by both pairing long short storage time runs to find set replicate measurements performing global likelihood fit all while self-consistently...
We have measured the shift and width of kaonic hydrogen $1s$ state due to $\overline{K}N$ strong interaction. observed, for first time, distinct $K$-series x rays with good signal-to-noise ratio in energy spectrum. The were determined be $\ensuremath{\Delta}E(1s)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}323\ifmmode\pm\else\textpm\fi{}63(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}11(\mathrm{syst})\mathrm{eV}$ (repulsive)...
A neutron $\ensuremath{\beta}$-decay asymmetry measurement using polarized ultracold neutrons (UCN) determines the correlation between spin of and momentum decay electron. The authors extract ratio weak axial-vector to vector couplings with reduced uncertainties. This new result from first this UCN contributes a benchmark for lattice QCD calculations possibility improved precision on CKM matrix element ${V}_{u\phantom{\rule{0}{0ex}}d}$ $\ensuremath{\beta}$ decay.
The violation of Baryon Number, $\mathcal{B}$, is an essential ingredient for the preferential creation matter over antimatter needed to account observed baryon asymmetry in universe. However, such a process has yet be experimentally observed. HIBEAM/NNBAR %experiment program proposed two-stage experiment at European Spallation Source (ESS) search number violation. will include high-sensitivity searches processes that violate by one or two units: free neutron-antineutron oscillation...
We have measured the K-series x rays from kaonic hydrogen atoms and succeeded for first time in observing a distinct $K\ensuremath{\alpha}$ peak. The L x-ray peak has also been observed. strong-interaction shift width of atom $1s$ state were determined transition energy line rays. sign was confirmed to be repulsive, with results $\ensuremath{\Delta}{E}_{1s}=\ensuremath{-}323\ifmmode\pm\else\textpm\fi{}63 (\mathrm{statistical})\ifmmode\pm\else\textpm\fi{}11 (\mathrm{systematic}) \mathrm{eV}$...
A new measurement of the neutron $β$-decay asymmetry $A_0$ has been carried out by UCNA collaboration using polarized ultracold neutrons (UCN) from solid deuterium UCN source at Los Alamos Neutron Science Center (LANSCE). Improvements in experiment have led to reductions both statistical and systematic uncertainties leading $A_0 = -0.11954(55)_{\rm stat.}(98)_{\rm syst.}$, corresponding ratio axial-vector vector coupling $λ\equiv g_A/g_V -1.2756(30)$.
The ultracold neutron (UCN) source at Los Alamos National Laboratory (LANL), which uses solid deuterium as the UCN converter and is driven by accelerator spallation neutrons, has been successfully operated for over 10 years, providing to various experiments, first production based on superthermal process. It recently undergone a major upgrade. This paper describes design performance of upgraded LANL source. Measurements cold spectrum density are presented compared Monte Carlo predictions....
The violation of mirror symmetry in the weak force provides a powerful tool to study internal structure proton. Experimental results have been obtained that address role strange quarks generating nuclear magnetism. measurement reported here an unambiguous constraint on quark contributions proton's magnetic moment through electron-proton interaction. We also report evidence for existence parity-violating electromagnetic effect known as anapole is not yet well understood theoretically, but it...
We report a new measurement of the parity-violating asymmetry in elastic electron scattering from proton at backward angles. This is sensitive to strange magnetic form factor as well electroweak axial radiative corrections. The A = -4.92+/-0.61+/-0.73 ppm provides significant constraint on these quantities. implications for are discussed context theoretical estimates
Ultra-cold neutrons (UCN), with energies low enough to be confined by the Fermi potential in material bottles, are playing an increasing role measurements of fundamental properties neutron. The ability manipulate UCN guides and magnetic fields, gravity can lead experiments lower systematic errors than have been obtained cold neutron beams. densities provided existing reactor sources limit these experiments. promise much higher from solid deuterium has led proposed facilities coupled both...
We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from deuteron at backward angles Q2=0.038 (GeV/c)2. This quantity provides determination neutral weak axial vector form factor nucleon, which can potentially receive large electroweak corrections. The measured A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. also updated results previous experiment Q2=0.091 (GeV/c)2, are
In this paper, we describe the performance of Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements cold flux, very low energy production rate, and UCN rates density at exit from biological shield are presented compared to Monte Carlo predictions. The compare well with predictions code MCNPX agree our custom code. source is shown perform as modeled. maximum delivered 52(9) UCN/cc a solid deuterium volume ∼1500 cm3.
A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with major improvement in sensitivity compared to the existing limit search for neutron Electric Dipole Moment (EDM). This uses superfluid 4He produce high density of Ultra-Cold Neutrons (UCN) which are contained suitably coated pair measurement cells. The be operated at Spallation Neutron Source Oak Ridge National Laboratory, polarized 3He from an Atomic Beam injected into and transported cells where it serves as...
Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well those reached directly at high energy colliders. Discrimination between different models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss current status prospects near future a compelling suite such experiments, along with developments needed encompassing theoretical framework.
We report the first measurement of vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q2=0.1(GeV/c)2 and large angles. This quantity must vanish single virtual photon exchange, plane-wave impulse approximation for this reaction, can therefore provide information on two exchange amplitudes electromagnetic interactions with hadronic systems. The observable we have measured is driven by imaginary part amplitude, side which simply Compton amplitude...
A precise measurement of the neutron decay β asymmetry A₀ has been carried out using polarized ultracold neutrons from pulsed spallation source at Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, which determine ratio axial-vector to vector weak coupling nucleon g{A}/g{V}=-1.275 90{-0.004 45}{+0.004 09}.
We present a detailed report of measurement the neutron $\beta$-asymmetry parameter $A_0$, parity-violating angular correlation between spin and decay electron momentum, performed with polarized ultracold neutrons (UCN). UCN were extracted from pulsed spallation solid deuterium source via transport through 7-T magnetic field. The then transported an adiabatic-fast-passage spin-flipper field region, prior to storage in cylindrical volume situated within 1-T $2 \times 2\pi$ solenoidal...
It has been proposed recently that a previously unobserved neutron decay branch to dark matter particle ($\ensuremath{\chi}$) could account for the discrepancy in lifetime observed experiments use two different measurement techniques. One of possible final states discussed includes single $\ensuremath{\chi}$ along with an ${e}^{+}{e}^{\ensuremath{-}}$ pair. We data from UCNA (Ultracold Neutron Asymmetry) experiment set limits on this channel. Coincident electron-like events are detected...
The electric dipole moment of the neutron, leptons, and atoms provide a unique window to Physics Beyond Standard Model. We are currently developing new neutron EDM experiment (the nEDM Experiment) [4]. This experiment, which will be run at 8.9 Å Neutron Line Fundamental Beamline (FNPB) Spallation Source (SNS) Oak Ridge National Laboratory, search for with sensitivity two orders magnitude better than present limit. In this paper, motivation experimental method, status discussed.
The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the $\beta$-decay asymmetry parameter, $A_0$, for free neutron decay. In experiment, polarized ultracold neutrons are transported into a decay trap, and their electrons detected with $\approx 4\pi$ acceptance two detector packages which provide position energy reconstruction. also has sensitivity $b_{n}$, Fierz interference term in rate. this work, we determine $b_{n}$ from dependence of $A_0$ using data taken during...
We report the first measurement of an angular correlation parameter in neutron $\ensuremath{\beta}$ decay using polarized ultracold neutrons (UCN). utilize UCN with energies below about 200 neV, which we guide and store for $\ensuremath{\sim}30\text{ }\text{ }\mathrm{s}$ a Cu volume. The interaction magnetic dipole moment static 7 T field external to volume provides 420 neV potential energy barrier spin state parallel field, polarizing before they pass through adiabatic fast passage flipper...
We report a study of the intensity and time dependence scintillation produced by weak $\ensuremath{\alpha}$-particle sources in superfluid helium presence an electric field (0--45 kV/cm) temperature range 0.2 to 1.1 K at saturated vapor pressure. Both prompt delayed components exhibit reduction with application field. The component is well approximated linear on strength 15$%$ 45 kV/cm. When analyzed using Kramers theory columnar recombination, this leads conclusion that roughly 40$%$...
Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover details weak interaction. can evaluate ratio axial-vector vector coupling constants standard model, λ = g A / V , through multiple correlations. The Nab experiment will carry out measurements electron-neutrino correlation parameter a with precision δ 10 −3 Fierz interference term b 3 × unpolarized free neutron decay. These results, along more precise measurement lifetime,...