A5009625346- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Nuclear Physics and Applications
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Advanced Thermodynamic Systems and Engines
- Superconducting Materials and Applications
- Magnetic and Electromagnetic Effects
- High-pressure geophysics and materials
- Magnetic confinement fusion research
- Spacecraft and Cryogenic Technologies
- Earthquake Detection and Analysis
- Particle Detector Development and Performance
- Refrigeration and Air Conditioning Technologies
- Power Transformer Diagnostics and Insulation
- Electromagnetic Compatibility and Measurements
- Lightning and Electromagnetic Phenomena
- Seismic Waves and Analysis
- Neutrino Physics Research
- Energy Harvesting in Wireless Networks
- Microfluidic and Bio-sensing Technologies
- Advanced Frequency and Time Standards
- Advanced Thermodynamics and Statistical Mechanics
East Tennessee State University
2023
California Institute of Technology
2018-2022
Brown University
2007-2022
Los Alamos National Laboratory
2015-2021
Chinese Academy of Sciences
2021
Universidad Nacional Autónoma de México
2019
North Carolina State University
2016
John Brown University
2009-2014
Washington State University
2004
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$0.8 s). experiment described here...
The ultracold neutron (UCN) source at Los Alamos National Laboratory (LANL), which uses solid deuterium as the UCN converter and is driven by accelerator spallation neutrons, has been successfully operated for over 10 years, providing to various experiments, first production based on superthermal process. It recently undergone a major upgrade. This paper describes design performance of upgraded LANL source. Measurements cold spectrum density are presented compared Monte Carlo predictions....
A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with major improvement in sensitivity compared to the existing limit search for neutron Electric Dipole Moment (EDM). This uses superfluid 4He produce high density of Ultra-Cold Neutrons (UCN) which are contained suitably coated pair measurement cells. The be operated at Spallation Neutron Source Oak Ridge National Laboratory, polarized 3He from an Atomic Beam injected into and transported cells where it serves as...
It has been proposed recently that a previously unobserved neutron decay branch to dark matter particle ($\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 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...
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 <...
High spatial resolution of ultracold neutron (UCN) measurement is growing interest to UCN experiments such as spectrometers, polarimeters, quantum physics UCNs, and gravity. Here we utilize physics-informed deep learning enhance the experimental position demonstrate sub-micron resolutions for measurements obtained using a room-temperature CMOS sensor, extending our previous work (Kuk et al., 2021; Yue 2023[2]) that demonstrated uncertainty 1.5μm. We explore use open-source software Allpix...
We report results from a study on electrical breakdown in liquid helium using near-uniform-field stainless steel electrodes with stressed area of $\sim$0.725 cm$^2$. The distribution the field is obtained for temperatures between 1.7 K and 4.0 K, pressures saturated vapor pressure 626 Torr, different surface polishes. A data-based approach determining electrode-surface-area scaling presented. dependence probability strength as extracted data used to show that phenomenon closely correlated...
It has been shown that a bubble in liquid helium containing two electrons is unstable against fission. In this paper, we consider the stability of electron bubbles 4, 6, or 12 electrons. We find with four at zero pressure and presumably breaks up into single bubbles. Our calculation not accurate enough to determine whether six stable pressure. $^{4}\mathrm{He}$ over range from $\ensuremath{-}0.32$ 0.5 bar.
Lead magnesium niobate-lead titanate (PMN-xPT) single crystal plates were prepared close to the morphotropic phase boundary with PT compositions 27%−31%. The piezoelectric and dielectric properties of these at liquid-helium temperature (4.2 K) obtained by fitting measured impedance curves. In particular, strain constant e33 is found be in range 5.1−5.7 C m−2 4.2 K, which indicates an extraordinarily large effect compared other materials even such a low temperature. This result shows that...
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 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...