A5075553435- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Nuclear physics research studies
- Quantum, superfluid, helium dynamics
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Space Technology and Applications
- Dark Matter and Cosmic Phenomena
- High-pressure geophysics and materials
- Laser-Plasma Interactions and Diagnostics
- Advanced NMR Techniques and Applications
- Atomic and Molecular Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Nuclear reactor physics and engineering
- Medical Imaging Techniques and Applications
- Gamma-ray bursts and supernovae
- Muon and positron interactions and applications
- CCD and CMOS Imaging Sensors
- X-ray Spectroscopy and Fluorescence Analysis
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Advanced X-ray and CT Imaging
- Superconducting Materials and Applications
Los Alamos National Laboratory
2016-2025
University of North Dakota
2023
North Carolina State University
2020-2021
California Institute of Technology
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
SLAC National Accelerator Laboratory
2020
Abstract We present experimental results supporting physics-based ejecta model development, where our main assumption is that form as a special limiting case of Richtmyer–Meshkov (RM) instability at metal–vacuum interface. From this assumption, we test established theory unstable spike and bubble growth rates, rates link to the wavelength amplitudes surface perturbations. evaluate rate through novel application modern laser Doppler velocimetry (LDV) techniques, coincidentally measure...
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...
Scintillators are important materials for radiographic imaging and tomography (RadIT), when ionizing radiations used to reveal internal structures of materials. Since its invention by R\"ontgen, RadIT now come in many modalities such as absorption-based X-ray radiography, phase contrast imaging, coherent diffractive high-energy X- $\gamma-$ray radiography at above 1 MeV, computed (CT), proton (IT), neutron IT, positron emission (PET), electron muon tomography, etc. Spatial, temporal...
Highly penetrating cosmic ray muons constantly shower the earth at a rate of about 1 muon per cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> minute. We have developed technique which exploits multiple Coulomb scattering these particles to perform nondestructive inspection without use artificial radiation. In prior work , we described heuristic methods for processing data create reconstructed images. this paper, present maximum...
The precise value of the mean neutron lifetime, $\tau_n$, plays an important role in nuclear and particle physics cosmology. It is a key input for predicting ratio protons to helium atoms primordial universe used search new beyond Standard Model physics. There 3.9 standard deviation discrepancy between $\tau_n$ measured by counting decay rate free neutrons beam (887.7 $\pm$ 2.2 s) surviving ultracold stored different storage times material trap (878.5$\pm$0.8 s). experiment described here...
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.
We use the Richtmyer-Meshkov instability (RMI) at a metal-gas interface to infer metal's yield stress ($Y$) under shock loading and release. first model how $Y$ stabilizes RMI using hydrodynamics simulations with perfectly plastic constitutive relation for copper (Cu). The is then tested molecular dynamics (MD) of crystalline Cu by comparing inferred from direct stress-strain calculations, both MD same conditions. Finally, new experiments solid validate our simulation-based...
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....
We demonstrate that high-Z material can be detected and located in three dimensions using radiographs formed by cosmic-ray muons. Detection of hidden inside large volume ordinary cargo is an important timely task given the danger associated with illegal transport uranium heavier elements. Existing radiography techniques are inefficient for shielded material, often expensive involve radiation hazards, real perceived. recently demonstrated muons [K. N. Borozdin et al., Nature (London) 422, 277...
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...
Over 120 million vehicles enter the United States each year. Many are capable of transporting hidden nuclear weapons or material. Currently deployed X-ray radiography systems limited because they cannot be used on occupied and energy dose too low to penetrate many cargos. We present a new technique that overcomes these limitations by obtaining tomographic images using multiple scattering cosmic radiation as it transits vehicle. When coupled with passive detection, muon interrogation could...
Double differential cross sections between 0°–12° were measured for the 90Zr(n, p) reaction at 293 MeV over a wide excitation energy range of 0–70 MeV. A multipole decomposition technique was applied to present data as well previously obtained 90Zr(p, n) extract Gamow–Teller (GT) component from continuum. The GT quenching factor Q derived by using total strengths. result is Q=0.88±0.06, not including an overall normalization uncertainty in unit section 16%.
We have determined a value for the ${}^{1}{S}_{0}$ neutron-neutron scattering length (${a}_{\mathit{nn}}$) from high-precision measurements of time-of-flight spectra neutrons $^{2}\mathrm{H}$$({\ensuremath{\pi}}^{\ensuremath{-}},n \ensuremath{\gamma}) n$ capture reaction. The were done at Los Alamos Meson Physics Facility by E1286 Collaboration. high spatial resolution our \ensuremath{\gamma}-ray detector enabled us to make detailed assessment systematic uncertainties in techniques. obtained...
Differential cross sections for elastic scattering of 0.8-GeV protons from $^{12}\mathrm{C}$, $^{58}\mathrm{Ni}$, and $^{208}\mathrm{Pb}$ have been measured. Preliminary analysis the data in terms Kerman-McManus-Thaler formalism with spin-dependent nucleon-nucleon amplitudes shows sensitivity to details proton neutron matter distributions.
The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei. leads to continuous energy loss stopping muons. nuclei angle "diffusion." Two muon-imaging methods that use flux attenuation multiple scattering cosmic-ray are being studied as tools for diagnosing damaged cores Fukushima reactors. Here, we compare these two methods. We conclude method can provide detailed information about core. Attenuation has low contrast little sensitivity
A study of imaging the Fukushima Daiichi reactors with cosmic-ray muons to assess damage is presented. Muon scattering has high sensitivity for detecting uranium fuel and debris even through thick concrete walls a reactor pressure vessel. Technical demonstrations using mockup, detector radiation test at Daiichi, simulation studies have been carried out. These establish feasibility imaging. few months measurement will reveal spatial distribution fuel. The muon technique would be best probably...
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 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}.