A5034059623- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Particle Detector Development and Performance
- Cold Atom Physics and Bose-Einstein Condensates
- Magnetic confinement fusion research
- Planetary Science and Exploration
- Non-Destructive Testing Techniques
- Superconducting Materials and Applications
- Magnetic and Electromagnetic Effects
- Nuclear reactor physics and engineering
- Advanced NMR Techniques and Applications
- Fuel Cells and Related Materials
- Particle accelerators and beam dynamics
- Spacecraft and Cryogenic Technologies
- Astrophysics and Cosmic Phenomena
- Power Transformer Diagnostics and Insulation
- Muon and positron interactions and applications
- Advanced Sensor Technologies Research
- Graphite, nuclear technology, radiation studies
- Advanced Frequency and Time Standards
Los Alamos National Laboratory
2012-2023
Oak Ridge National Laboratory
2018-2022
Los Alamos Medical Center
2018
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...
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.
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....
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...
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...
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...
A precise value for the neutron lifetime (about 880 s) is needed nuclear astrophysics predictions of Big-Bang nucleosynthesis and solar neutrino production, as well in precision searches new physics beyond Standard Model. This work reports on a type magnetic trap that has potential to resolve present 4-sigma inconsistency measurements lifetime, suggests next generation with less than one second uncertainty possible.
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$%$...
A 1.2 × m2 muon tracker was moved from Los Alamos to the Toshiba facility at Kawasaki, Japan, where it used take ∼4 weeks of data radiographing Critical Assembly Reactor with cosmic ray muons. In this paper, we describe analysis procedure, show results experiment, and compare Monte Carlo predictions. The validate concept using rays image damaged cores Fukushima Daiichi reactors.
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,...
The Cryogenic Apparatus for Precision Tests of Argon Interactions with Neutrino (CAP- TAIN) program is designed to make measurements scientific importance long-baseline neutrino physics and topics that will be explored by large underground detectors. CAPTAIN detector a liquid argon TPC deployed in portable evacuable cryostat. Five tons are instrumented 2,000 channel photon detection system. Subsequent the commissioning phase, collect data high-energy neutron beamline part Los Alamos Neutron...
Precision measurements of free-neutron β decay have been used to precisely constrain our understanding the weak interaction. However, neutron Fierz interference term bn, which is particularly sensitive beyond-standard-model tensor currents at TeV scale, has thus far eluded measurement. Here we report first direct constraints on this term, finding bn=0.067±0.005stat+0.090−0.061sys, consistent with standard model. The uncertainty dominated by absolute energy reconstruction and linearity...
We have constructed an apparatus to study DC electrical breakdown in liquid helium at temperatures as low 0.4 K and pressures between the saturated vapor pressure ∼600 Torr. The can house a set of electrodes that are 12 cm diameter with gap 1–2 them, potential up ±50 kV be applied each electrode. Initial results demonstrated it is possible apply fields exceeding 100 kV/cm 1 two electropolished stainless steel for wide range K. also measured current electrodes. Our initial results, I <...
We report the first measurement of neutron cross section on argon in energy range 100-800 MeV. The was obtained with a 4.3-h exposure Mini-CAPTAIN detector to WNR/LANSCE beam at LANL. total is measured from attenuation coefficient flux as it traverses liquid volume. A set 2631 candidate interactions divided bins kinetic calculated time-of-flight measurements. These are reconstructed custom-made algorithms specifically designed for data time projection chamber size detector. averaged...
A technical demonstration of cosmic-ray muon radiography a UO2 fuel assembly was performed at Toshiba Nuclear Critical Assembly (NCA). The in the NCA imaged through obstacles such as steel and concrete. result suggested that method can be applicable to assess damage reactors Fukushima Daiichi nuclear power plant. Here, both scattering displacement methods are presented, results shown agree with Monte Carlo simulations. In addition, detailed simulations reactor were performed, which showed...