A5048707523- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Nuclear physics research studies
- Advanced NMR Techniques and Applications
- Atomic and Molecular Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Superconducting Materials and Applications
- Nuclear reactor physics and engineering
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Non-Destructive Testing Techniques
- Particle Detector Development and Performance
- Advanced Frequency and Time Standards
- Physics of Superconductivity and Magnetism
- Particle accelerators and beam dynamics
- Radiation Detection and Scintillator Technologies
- Radioactive Decay and Measurement Techniques
- Welding Techniques and Residual Stresses
- Electron and X-Ray Spectroscopy Techniques
- Magneto-Optical Properties and Applications
- Advanced Chemical Physics Studies
University of Kentucky
2013-2024
Florida International University
2004-2023
William & Mary
2019-2020
Williams (United States)
2019-2020
North Carolina Agricultural and Technical State University
2009-2019
University of Ljubljana
2018
University of Virginia
2015
Thomas Jefferson National Accelerator Facility
2015
University of Houston
2015
AGH University of Krakow
2013-2014
Results are reported from the HERMES experiment at HERA on a measurement of neutron spin structure function $g_1^n(x,Q^2)$ in deep inelastic scattering using 27.5 GeV longitudinally polarized positrons incident $^3$He internal gas target. The data cover kinematic range $0.023
We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < or =Q2 =1.0 GeV2. These asymmetries, arising from interference electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions currents proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer detect recoiling protons liquid hydrogen target. results indicate nonzero, Q2 dependent, provide new information...
We report the first measurement of target single spin asymmetries in semi-inclusive $^3{He}(e,e'\pi^\pm)X$ reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using 5.9 GeV electron beam, covers range 0.14 $< x <$ 0.34 with 1.3 $<Q^2<$ 2.7 GeV$^2$. Collins and Sivers moments were extracted from azimuthal angular dependence measured asymmetries. $\pi^\pm$ for $^3$He are consistent zero, except $\pi^+$ moment $x=0.34$, which deviates zero by 2.3$\sigma$....
We report on measurements of the neutron spin asymmetries An1,2 and polarized structure functions gn1,2 at three kinematics in deep inelastic region, with x=0.33, 0.47, 0.60 Q2=2.7, 3.5, 4.8(GeV∕c)2, respectively. These were performed using a 5.7GeV longitudinally electron beam 3He target. The results for An1 gn1 x=0.33 are consistent previous world data and, two higher-x points, have improved precision by about an order magnitude. new show zero crossing around x=0.47 value x=0.60 is...
We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at ${Q}^{2}=0.22$ $0.63\text{ }\text{ }{\mathrm{GeV}}^{2}$. They are sensitive to strange quark contributions currents the nucleon axial-vector current. The results indicate of $\ensuremath{\lesssim}10%$ charge magnetic form factors these four-momentum transfers. also present first measurement anapole moment effects current
The radioactive radium-225 ((225)Ra) atom is a favorable case to search for permanent electric dipole moment. Because of its strong nuclear octupole deformation and large atomic mass, (225)Ra particularly sensitive interactions in the medium that violate both time-reversal symmetry parity. We have developed cold-atom technique study spin precession atoms held an optical trap, demonstrated principle this method by completing first measurement moment, reaching upper limit...
Background: Octupole-deformed nuclei, such as that of $^{225}\mathrm{Ra}$, are expected to amplify observable atomic electric dipole moments (EDMs) arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015 we reported first ``proof-of-principle'' measurement $^{225}\mathrm{Ra}$ EDM.Purpose: This work reports on several experimental upgrades improve statistical sensitivity our EDM measurements by orders magnitude evaluates systematic effects contribute current...
The flavor asymmetry of the light quark sea nucleon is determined in kinematic range $0.02<x<0.3$ and $1<{Q}^{2}<10{\mathrm{GeV}}^{2}$ for first time from semi-inclusive deep-inelastic scattering. quantity $[\overline{d}(x)\ensuremath{-}\overline{u}(x)]/[u(x)\ensuremath{-}d(x)]$ derived a relationship between yields positive negative pions unpolarized hydrogen deuterium targets. $\overline{d}\ensuremath{-}\overline{u}$ found to be nonzero $x$ dependent, showing an excess $\overline{d}$ over...
We determined the electric form factor GnE of neutron from quasielastic 2H(e→,e'n→)1H reaction at a central squared four-momentum transfer Q2=0.255 (GeV/c)2 with longitudinally polarized electron beam 868 MeV and low (∼0.8%) duty factor. A polarimeter designed constructed specifically for this experiment was used to measure sideways polarization recoil neutron, which detected in coincidence scattered electron. Theoretical calculations have established that polarization-transfer technique...
We report the first measurement of parity-violating asymmetry in elastic electron scattering from proton. The depends on neutral weak magnetic form factor proton which contains new information contribution strange quark-antiquark pairs to moment obtain value ${G}_{M}^{Z}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.34\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.05\mathrm{n}.\mathrm{m}.$ at...
We have measured the transverse asymmetry ${A}_{{T}^{\ensuremath{'}}}$ in ${}^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{e}{,e}^{\ensuremath{'}})$ quasielastic scattering Hall A at Jefferson Laboratory with high precision for ${Q}^{2}$ values from 0.1 to $0.6(\mathrm{GeV}/c{)}^{2}$. The neutron magnetic form factor ${G}_{M}^{n}$ was extracted based on Faddeev calculations ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.1$ and...
The H2(e,e’n)1H quasielastic cross section was measured at Q2 values of 0.109, 0.176, and 0.255 (GeV/c)2. neutron detection efficiency determined by the associated particle technique with H2(γ,pn) reaction for each three kinetic energies. These H2(e,e’n) measurements coincidence sections are first low Q2. sensitive primarily to magnetic form factor GMn these kinematics. extracted have smaller uncertainties than previous data consistent dipole parametrization two higher momentum transfers;...
We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in deep inelastic region x=0.33, 0.47, and 0.60, Q(2)=2.7, 3.5, 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for first time, that crosses zero around x=0.47 becomes significantly positive x=0.60. Combined world proton data, polarized quark distributions were extracted. results, general, agree relativistic constituent models perturbative quantum chromodynamics (PQCD) analyses based on...
The electric form factor of the neutron was determined from studies reaction ${}^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{e},{e}^{\ensuremath{'}}n)pp$ in quasielastic kinematics Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a target which nuclear polarization oriented perpendicular to momentum transfer. detected magnetic spectrometer coincidence with neutrons that registered large-solid-angle detector. More than...
We present a first attempt to experimentally extract an effective strong coupling constant that we define be low Q2 extension of previous definition by S. Brodsky et al. following initial work G. Grunberg. Using Jefferson Lab data and sum rules, establish its Q2-behavior over the complete Q2-range. The result is compared constants inferred from different processes calculations based on Schwinger–Dyson equations, hadron spectroscopy or lattice QCD. Although connection between extracted not...
High precision measurements of the differential cross sections for π0 photoproduction at forward angles two nuclei, 12C and 208Pb, have been performed incident photon energies 4.9-5.5 GeV to extract π0→γγ decay width. The experiment was done Jefferson Lab using Hall B tagger a high-resolution multichannel calorimeter. width extracted by fitting measured recently updated theoretical models process. resulting value is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst) eV. With 2.8% total uncertainty, this...
We present a measurement of the longitudinal spin asymmetry A(||) in photoproduction pairs hadrons with high transverse momentum p(T). Data were accumulated by HERMES experiment using 27.5 GeV polarized positron beam and hydrogen target internal to HERA storage ring. For h(+)h(-) p(h(1))(T)>1.5 GeV/c p(h(2))(T)>1.0 GeV/c, measured is = -0. 28+/-0.12(stat)+/-0.02(syst). This negative value contrast positive asymmetries typically deep inelastic scattering from protons, interpreted arise gluon...
The violation of mirror symmetry in the weak force provides a powerful tool to study internal structure proton. Experimental results have been obtained that address role strange quarks generating nuclear magnetism. measurement reported here an unambiguous constraint on quark contributions proton's magnetic moment through electron-proton interaction. We also report evidence for existence parity-violating electromagnetic effect known as anapole is not yet well understood theoretically, but it...
We report a new measurement of the parity-violating asymmetry in elastic electron scattering from proton at backward angles. This is sensitive to strange magnetic form factor as well electroweak axial radiative corrections. The A = -4.92+/-0.61+/-0.73 ppm provides significant constraint on these quantities. implications for are discussed context theoretical estimates
We report a measurement of the asymmetry in spin-dependent quasielastic scattering longitudinally polarized electrons from He3 target. The neutron magnetic form factor GMn has been extracted measured based on recent PWIA calculations using spectral functions. Our determination at Q2=0.19 (GeV/c)2 agrees with dipole parametrization. This experiment represents first electron scattering.DOI:https://doi.org/10.1103/PhysRevC.50.R546©1994 American Physical Society
We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from deuteron at backward angles Q2=0.038 (GeV/c)2. This quantity provides determination neutral weak axial vector form factor nucleon, which can potentially receive large electroweak corrections. The measured A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. also updated results previous experiment Q2=0.091 (GeV/c)2, are
We present a new extraction of the effective strong coupling constant αs,g1(Q2). The result agrees with previous determination and extends measurement low high Q2 behavior αs,g1(Q2) that was previously deduced from sum rules. In particular, it experimentally verifies lack Q2-dependence in limit. This fact is necessary for application AdS/CFT correspondence to QCD calculations. provide parameterization can equivalently be used parameterize generalized Gerasimov–Drell–Hearn Bjorken sums.
We extract the Bjorken integral ${\ensuremath{\Gamma}}_{1}^{p\mathrm{\text{\ensuremath{-}}}n}$ in range $0.17<{Q}^{2}<1.10\text{ }\text{ }{\mathrm{G}\mathrm{e}\mathrm{V}}^{2}$ from inclusive scattering of polarized electrons by protons, deuterons, and $^{3}\mathrm{H}\mathrm{e}$, for region which is dominated nucleon resonances. These data bridge domains hadronic partonic descriptions nucleon. In combination with earlier measurements at higher ${Q}^{2}$, we nonsinglet twist-4 matrix element ${f}_{2}$.