A5038076817- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- Particle physics theoretical and experimental studies
- Quantum, superfluid, helium dynamics
- High-Energy Particle Collisions Research
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Advanced NMR Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Electromagnetic Compatibility and Measurements
- Superconducting Materials and Applications
- Electromagnetic Compatibility and Noise Suppression
- Radioactive Decay and Measurement Techniques
- Atomic and Molecular Physics
- Particle Detector Development and Performance
- Magnetic confinement fusion research
- Scientific Research and Discoveries
- Methane Hydrates and Related Phenomena
- Photocathodes and Microchannel Plates
- Advanced Frequency and Time Standards
University of California, Riverside
2024
University of Tennessee at Knoxville
2014-2023
Los Alamos National Laboratory
2012-2022
University of Virginia
2007-2021
University of Tennessee System
2015
California Institute of Technology
2008
Budker Institute of Nuclear Physics
2000-2001
New Jefferson Lab data are presented on the nuclear dependence of inclusive cross section from $^{2}\mathrm{H}$, $^{3}\mathrm{He}$, $^{4}\mathrm{He}$, $^{9}\mathrm{Be}$ and $^{12}\mathrm{C}$ for $0.3<x<0.9$, ${Q}^{2}\ensuremath{\approx}3--6\text{ }\text{ }{\mathrm{GeV}}^{2}$. These represent first measurement EMC effect $^{3}\mathrm{He}$ at large $x$ a significant improvement $^{4}\mathrm{He}$. The do not support previous $A$-dependent or density-dependent fits to suggest that quark...
We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination the strength two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, first time, be examined. The also include kinematic region three-nucleon are expected to dominate.
We studied simultaneously the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with or neutron recoiling almost back missing momentum, leaving residual A=2 system low excitation energy. These data were used identify two-nucleon short-range correlated pairs deduce their isospin structure as function momentum region where nucleon-nucleon force is expected...
High-energy electron scattering is a clean and precise probe for measurements of hadronic nuclear structure, with key role in understanding the high-momentum nucleons (and quarks) nuclei. Jefferson Lab has dramatically expanded our generated by short-range correlations, providing sufficient insight to model much their impact on structure neutron stars, low- medium-energy observables including neutrino oscillation measurements. These correlations also appear be related modification quark...
The 1H(e,e′π+)n cross section was measured for arange of four-momentum transfer up to Q2=3.91GeV2 at values the invariant mass W above resonance region. Q2 dependence longitudinal component found be consistent with Q2-scaling prediction hard exclusive processes. This suggests that QCD factorization theorem is applicable rather low Q2. transverse term falls off slower than naive Q−8 expectation and remains appreciable even Q2=3.91GeV2.Received 12 July...
Background: The density of the nucleus has been important in explaining nuclear dependence quark distributions, also known as EMC effect, well presence highmomentum nucleons arising from short-range correlations (SRCs). Recent measurements both these effects on light nuclei have shown a clear deviation simple density-dependent models. Purpose: A better understanding distributions and requires careful examination experimental data to constrain models that attempt describe phenomena. Methods:...
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...
Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well those reached directly at high energy colliders. Discrimination between different models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss current status prospects near future a compelling suite such experiments, along with developments needed encompassing theoretical framework.
We have measured the nuclear transparency of A(e,e′π+) process in H2, C12, Al27, Cu63, and Au197 targets. These measurements were performed at Jefferson Laboratory over a four momentum transfer squared range Q2=1.1 to 4.7 (GeV/c)2. The was extracted as super-ratio (σA/σH) from data model pion-electroproduction nuclei without π−N final-state interactions. Q2 atomic number dependence both show deviations traditional physics expectations are consistent with calculations that include quantum...
The NPDGamma collaboration reports results from the first phase of a measurement parity violating up-down asymmetry Aγ with respect to neutron spin direction γ rays emitted in reaction n⃗+p→d+γ using capture polarized cold neutrons on protons liquid parahydrogen target. One expects parity-odd effects hadronic weak interaction between nucleons be induced by quarks. is dominated ΔI=1, 3S1-3P1 transition amplitude n-p system. was completed at Los Alamos Neutron Science Center spallation 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....
The fundamental theory of the strong interaction-quantum chromodynamics (QCD)—provides foundational framework with which to describe and understand key properties atomic nuclei. A deep understanding explicit role quarks gluons in nuclei remains elusive however, as these effects have thus far been well-disguised by confinement QCD are encapsulated a successful description terms effective hadronic degrees freedom. observation EMC effect has provided an enduring indication for nuclei, points...
Quasielastic $^{12}$C$(e,e'p)$ scattering was measured at space-like 4-momentum transfer squared $Q^2$~=~8, 9.4, 11.4, and 14.2 (GeV/c)$^2$, the highest ever achieved to date. Nuclear transparency for this reaction extracted by comparing yield that expected from a plane-wave impulse approximation calculation without any final state interactions. The consistent with no $Q^2$ dependence, up proton momenta of 8.5~GeV/c, ruling out quantum chromodynamics effect color scales in exclusive...
Inclusive electron scattering from nuclear targets has been measured to extract the dependence of inelastic cross section in Hall C at Thomas Jefferson National Accelerator facility. Results are presented for 2H, 3He, 4He, 9B, 12C, 63Cu and 197Au an incident beam energy 5.77 GeV a range momentum transfer Q^2 = 2 7 (GeV/c)^2. These data improve precision existing measurements EMC effect large x, allow more detailed examinations A effect.
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...
The observed correlation between the EMC effect and contribution of short-range correlations (SRCs) in nuclei suggests that modification quark distributions bound protons neutrons might occur within SRCs. This raises possibility may have an isospin dependence arising from np dominance We discuss previous attempts to test this perform a new analysis existing data. find no experimental support for observation effect.
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,...
Cross sections for the $^{1}\mathrm{H}$($e,{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+})n$ process on $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, $^{12}\mathrm{C}$, $^{27}\mathrm{Al}$, $^{63}\mathrm{Cu}$, and $^{197}\mathrm{Au}$ targets were measured at Thomas Jefferson National Accelerator Facility (Jefferson Lab) to extract nuclear transparencies. Data taken from ${Q}^{2}=1.1$--4.7 GeV${}^{2}$ a fixed center-of-mass energy of $W=2.14$ GeV. The ratio ${\ensuremath{\sigma}}_{L}$...
We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe rapid falloff the cross section for x>1, which is sensitive to short-range contributions nuclear wave function, and deep inelastic corresponds probing extremely high momentum quarks. This result agrees with higher energy muon measurements, but sharp contrast neutrino measurements suggested dramatic enhancement distribution "superfast" quarks probed x>1. The x>1...
Nuclear dynamics at short distances is one of the most fascinating topics strong interaction physics. The physics it closely related to understanding role QCD in generating nuclear forces as well super-dense cold matter relevant interior neutron stars. With an emergence high energy electron and proton beams there a significant recent progress scattering experiments aimed studies short-range structure nuclei. This turn stimulated new theoretical resulting observation several phenomena...
We report on new p(e,e′p)π∘ measurements at the Δ+(1232) resonance low momentum transfer region, where mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The data explore Q2 dependence of resonant quadrupole amplitudes first time indicate that Electric Coulomb converge as Q2→0. amplitude have been extended lowest ever reached, suggest more than half its magnitude attributed in this region. disagree with...
A precise value of the neutron lifetime is important in several areas physics, including determinations quark-mixing matrix element │Vud│, related tests Standard Model, and predictions light abundances Big Bang Nucleosynthesis models. We report progress on a new measurement utilizing cold beam technique. Several experimental improvements both proton counting that have been developed over last decade are presented. This effort should yield final uncertainty 1 s with an improved understanding...