A5047042578- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Particle physics theoretical and experimental studies
- Space Technology and Applications
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Cold Atom Physics and Bose-Einstein Condensates
- High-Energy Particle Collisions Research
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- High-pressure geophysics and materials
- Magnetic confinement fusion research
- Astro and Planetary Science
- Planetary Science and Exploration
- Superconducting Materials and Applications
- Nuclear physics research studies
- Laser-Plasma Interactions and Diagnostics
- Scientific Research and Discoveries
- Nuclear reactor physics and engineering
- Astronomy and Astrophysical Research
- Neutrino Physics Research
- Electromagnetic Launch and Propulsion Technology
- Gamma-ray bursts and supernovae
- Inorganic Fluorides and Related Compounds
Los Alamos National Laboratory
2016-2025
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso
2023
University of L'Aquila
2023
Indiana University Bloomington
2015-2022
North Carolina State University
2020-2021
California Institute of Technology
2020-2021
Tennessee Technological University
2020-2021
University of Kentucky
2020-2021
East Tennessee State University
2020-2021
Utah State University
2020-2021
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...
Fornal and Grinstein recently proposed that the discrepancy between two different methods of neutron lifetime measurements, beam bottle methods, can be explained by a previously unobserved dark matter decay mode, $n\ensuremath{\rightarrow}X+\ensuremath{\gamma}$. We perform search for this mode over allowed range energies monoenergetic $\ensuremath{\gamma}$ ray $X$ to matter. A Compton-suppressed high-purity germanium detector is used identify rays from in nickel-phosphorous-coated...
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...
Color is an essential element of human visual perception, which exists in all aspects our daily lives and plays a key role scientific research technological applications. produced by various mechanisms, including absorption reflection chemical pigments, complex formation transition metal ions, micro- nanostructural modulation structural colors. This paper aims to comprehensively explore the principles color generation its applications different fields. The article first describes how ions...
When a moving high-speed train experiences sudden fire and is forced to stop in tunnel with shaft, the smoke transport characteristics become complex due coupled effects of train's piston effect natural extraction through posing significant risks personnel safety infrastructure. This study numerically reproduces above scenario analyze impact shaft on following fire-induced stoppage. The research utilizes renormalization group (RNG) k-ε turbulence model buoyancy correction volume heat source...
We report the first observation of parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_\gamma$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at Spallation Neutron Source Oak Ridge National Laboratory. isolates $\Delta I=1$, \mbox{$^{3}S_{1}\rightarrow {^{3}P_{1}}$} component weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to single coupling constant either DDH meson model or pionless EFT....
Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding wide range questions in many-body physics. Unfortunately, pair correlation function $g(r)$ inferred neutron scattering measurements differential cross section $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}$ different reported literature inconsistent. We have measured energy dependence total slow neutrons...
In this paper, we describe a new method for measuring surviving neutrons in neutron lifetime measurements using bottled ultracold (UCN), which provides better characterization of systematic uncertainties and enables higher precision than previous measurement techniques. An active detector that can be lowered into the trap has been used to measure distribution as function height influence marginally trapped UCN on measurement. addition, have demonstrated phase-space evolution its effect
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 <...
Protons from the Los Alamos Neutron Science Center have been used for pulsed radiography in dynamic experiments past 25 years. Pulses of protons are imaged on a scintillator, and light these images is captured by fast gated cameras. The need fast, bright scintillators has led to some compromises image quality due tiling backgrounds with totally internally reflected light. We show how large-grain scintillator screens, made using thin plastic binder, solve problems.
A study of the dead layer thickness and quenching factor a plastic scintillator for use in ultracold neutron (UCN) experiments is described. Alpha spectroscopy was used to determine thin surface be 630 ± 110 nm. The relative light outputs from decay 241Am Compton scattering electrons were extract Birks’ law coefficient, yielding kB value 0.087 0.003 mm/MeV, consistent with some previous reports other polystyrene-based scintillators. results these measurements are incorporated into simulation...
The dependence on applied electric field ($0 - 40$ kV/cm) of the scintillation light produced by fast electrons and $\alpha$ particles stopped in liquid helium temperature range 0.44 K to 3.12 is reported. For both types particles, reduction intensity signal due exhibits an apparent dependence. Using approximate solution Debye-Smoluchowski equation, we show that for can be explained time required geminate pairs recombine relative detector integration time. This finding indicates spatial...
Exploding bridgewire detonators are an industry standard technology used for over 75 years and valued their precise timing safety characteristics. Despite widespread use, functional mechanism remains controversial with both shock non-shock mechanisms attributed. In this work, we reexamine the detonator function a suite of modern diagnostics compare these observations existing literature. Traditional consisted voltage applied to time dependent current, integral response measurements such as...
A new boron-coated CCD camera is described for direct detection of ultracold neutrons (UCN) through the capture reactions $^{10}$B (n,$\alpha$0$\gamma$)$^7$Li (6%) and $^{10}$B(n,$\alpha$1$\gamma$)$^7$Li (94%). The experiments, which extend earlier works using a ZnS:Ag scintillator, are based on detections neutron-capture byproducts in silicon. high position resolution, energy resolution particle ID performance scientific allows observation identification all $\alpha$, $^7$Li $\gamma$...
In the $\mathrm{UCN}\ensuremath{\tau}$ experiment, ultracold neutrons (UCN) are confined by magnetic fields and Earth's gravitational field. Field-trapping mitigates problem of UCN loss on material surfaces, which caused largest correction in prior neutron experiments using bottles. However, dynamics field traps differ qualitatively from those latter case, bounce off surfaces with significant diffusivity population quickly reaches a static spatial distribution density gradient induced...
The LANL PHELIX pulsed-power driven liner implosion apparatus is fielded to measure the growth of Richtmyer-Meshkov instabilities (RMIs) in a cylindrical geometry under conditions liquid (Cren-1), mixed-state (Cren-2), and solid (Cren-3) release. 2D Lagrangian hydrocode simulations this imploding are compared against 800-MeV proton radiography data RMI growth. release (>35 GPa) was achieved with velocity 3 km s−1, demonstrates linear, continuous spike that agrees model. mixed (20 - 35 1.4...
The past two decades have yielded several new measurements and reanalyses of older the neutron lifetime. These led to a 4.4 standard deviation discrepancy between most precise decay rate producing protons in cold beams lifetime measured storage experiments. Measurements using different techniques are important for investigating whether there unidentified systematic effects any measurements. In this paper we report measurement Los Alamos asymmetric magneto-gravitational trap where surviving...
A pre- and post-collimation scheme has been applied to high energy proton radiography establish a dark field condition, which defaults state of no transmission until scatterer is placed at the object plane. This technique, radiography, provides two additional capabilities standard setup. First, protons with degree angular dispersion are removed from beam, reducing effects chromatic aberrations decreasing noise. Second, below same threshold beam downstream objects, effectively making highly...
Novel experimental techniques are required to make the next big leap in neutron electric dipole moment sensitivity, both terms of statistics and systematic error control. The nEDM experiment at Spallation Neutron Source (nEDM@SNS) will implement scheme Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. unique properties combining polarized ultracold neutrons, 3 He, superfluid 4 He be exploited provide a sensitivity ∼ 10 −28 e · cm. Our cryogenic apparatus deploy two small (3 L) measurement...
There is a growing realization that neutrinos can be used as diagnostic tool to better understand the inner workings of nuclear weapon. Robust estimates demonstrate an Inverse Beta Decay (IBD) neutrino scintillation detector built at Nevada Test Site 1000-ton active target mass standoff distance 500 m would detect thousands events per kTe yield. This provide less than 4% statistical error on measured rate and 5% energy. Extrapolating this test device explosive yield requires knowledge from...