W. M. Snow
A5054454838- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Advanced NMR Techniques and Applications
- Nuclear physics research studies
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- High-pressure geophysics and materials
- Nuclear reactor physics and engineering
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Chromodynamics and Particle Interactions
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- NMR spectroscopy and applications
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Advanced MRI Techniques and Applications
- Radiation Therapy and Dosimetry
- Particle accelerators and beam dynamics
- Methane Hydrates and Related Phenomena
- Computational Physics and Python Applications
Indiana University
2005-2025
Indiana University Bloomington
2015-2024
Institute of Astronomy and Astrophysics, Academia Sinica
2014-2023
University of Hawaii at Hilo
2023
Oak Ridge National Laboratory
2005-2018
NASA Astrobiology Institute
2016
Atacama Large Millimeter Submillimeter Array
2012
University of Manitoba
2008
Material (Belgium)
2005
Tulane University
2005
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest all low-energy neutrino couplings. This mode interaction offers new opportunities to study properties and leads a miniaturization detector size, with potential technological applications. We observed this process at 6.7σ confidence level, using low-background, 14.6-kilogram CsI[Na] scintillator exposed emissions from Spallation Neutron...
The most precise determination of the neutron lifetime using beam method was completed in 2005 and reported a result $\tau_n = (886.3 \pm 1.2 [\textrm{stat}] 3.2 [\textrm{syst}])$ s. dominant uncertainties were attributed to absolute fluence (2.7 s). measured with monitor that counted neutron-induced charged particles from absorption thin, well-characterized 6Li deposit. detection efficiency calculated areal density deposit, detector solid angle, evaluated nuclear data file, ENDF/B-VI...
We measured the cross section of coherent elastic neutrino-nucleus scattering (CEvNS) using a CsI[Na] scintillating crystal in high flux neutrinos produced at Spallation Neutron Source Oak Ridge National Laboratory. New data collected before detector decommissioning have more than doubled dataset since first observation CEvNS, achieved with this detector. Systematic uncertainties also been reduced an updated quenching model, allowing for improved precision. With these analysis improvements,...
Various theories beyond the standard model predict new particles with masses in sub-eV range very weak couplings to ordinary matter. A $P$-odd and $T$-odd interaction between polarized unpolarized nucleons proportional $\stackrel{\ensuremath{\rightarrow}}{K}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{r}$ is one such possibility, where $\stackrel{\ensuremath{\rightarrow}}{r}$ distance $\stackrel{\ensuremath{\rightarrow}}{K}$ spin of nucleon. Such an involving...
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...
The COHERENT Collaboration searched for scalar dark matter particles produced at the Spallation Neutron Source with masses between 1 and 220 MeV/c^{2} using a CsI[Na] scintillation detector sensitive to nuclear recoils above 9 keV_{nr}. No evidence is found we thus place limits on allowed parameter space. With this low-threshold detector, are coherent elastic scattering nuclei. cross section process orders of magnitude higher than other processes historically used accelerator-based...
A measurement of the neutron lifetime ${\ensuremath{\tau}}_{n}$ performed by absolute counting in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto silicon detector held at high potential counted with nearly unit efficiency. The device an efficiency inversely proportional to velocity, which cancels dwell time beam trap. result is...
We report the first experimental upper bound to our knowledge on possible in-matter torsion interactions of neutron from a recent search for parity violation in spin rotation liquid He-4. Our experiment constrains coefficient $ζ$ consisting linear combination parameters involving time components fields $T^μ$ and $A^μ$ nucleons electrons helium which violates parity. an $|ζ|<9.1x10^{-23}$ GeV at 68% confidence level indicate other physical processes that could be analyzed constrain torsion.
The physical origin of the dark energy that causes accelerated expansion rate universe is one major open questions cosmology. One set theories postulates existence a self-interacting scalar field for coupling to matter. In chameleon theory, this induces screening mechanism such amplitude nonzero in empty space but greatly suppressed regions terrestrial matter density. However measurements performed under appropriate vacuum conditions can enable appear apparatus, where it be subjected...
The possible existence of short-range forces between unpolarized and polarized spin-1/2 particles has attracted the attention physicists for decades. These are predicted in various theories provide a new source parity (P) time reversal (T) symmetry violation. We use an ensemble 3He gas cell with 250 um thickness glass window to search force from scalar boson exchange over sub-millimeter ranges. This interaction would produce NMR frequency shift as mass is moved near far ensemble. report...
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 coupling between Earth's rotation and orbital angular momentum (OAM), known as the Sagnac effect, is observed in entangled neutrons produced using a spin-echo interferometer. After correction for instrument systematics measured within 5% of theory, with an uncertainty 7.2%. The OAM our setup transverse to propagation direction scales linearly neutron wavelength (4–12.75 Å), so can be varied without mechanically rotating device, which avoids systematic errors present previous experiments....
Results of detailed structural studies, using elastic neutron scattering, the freezing liquid O2 and D2 in porous vycor glass are presented. The experimental studies have been complemented by computer simulations dynamics a Lennard-Jones narrow channels bounded molecular walls. Our results point to new simple physical interpretation confined geometries.
We have performed high-precision measurements of the coherent neutron scattering lengths gas phase molecular hydrogen and deuterium using interferometry. After correcting for binding multiple from molecule, we find ${b}_{\mathrm{np}}=(\ensuremath{-}3.7384\ifmmode\pm\else\textpm\fi{}0.0020)\mathrm{fm}$ ${b}_{\mathrm{nd}}=(6.6649\ifmmode\pm\else\textpm\fi{}0.0040)\mathrm{fm}.$ Our results are in agreement with world average previous measurements,...
Deep-inelastic neutron scattering measurements on liquid $^{4}\mathrm{He}$ have been carried out for temperatures from 0.35 to 4.2 K at a density of 0.147 g/${\mathrm{cm}}^{3}$. These relative resolution comparable previous reactor measurements, but momentum transfer 23 A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}1}$. This is sufficiently high that the differences between observed and predicted by impulse approximation are small well described recent theoretical treatment allowing direct...
Experiments using slow neutrons address a growing range of scientific issues spanning nuclear physics, particle astrophysics, and cosmology. The field fundamental physics has experienced significant increase in activity over the last two decades. This review summarizes some recent developments outlines prospects for future research.