O. P. Dzyubak
A5081371543- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- Superconducting Materials and Applications
- Quantum, superfluid, helium dynamics
- Particle accelerators and beam dynamics
- Advanced X-ray and CT Imaging
- Advanced NMR Techniques and Applications
- Quantum chaos and dynamical systems
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Radiotherapy Techniques
- Microtubule and mitosis dynamics
- Mathematical Biology Tumor Growth
- Lanthanide and Transition Metal Complexes
- Radiation Dose and Imaging
- Gene Regulatory Network Analysis
- Nonlinear Dynamics and Pattern Formation
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Molecular Physics
Ascension
2019-2020
Inserm
2015
Memorial Sloan Kettering Cancer Center
2012-2015
Mayo Clinic in Florida
2011
University of South Carolina
2003-2010
WinnMed
2009
Mayo Clinic
2007-2008
Systems Planning and Analysis (United States)
2007
California State University, Dominguez Hills
2007
University of Connecticut
2007
In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to exotic baryon with strangeness S=+1 is seen in K(+)n invariant mass spectrum. The at 1.542+/-0.005 GeV/c(2) measured width 0.021 FWHM, which largely determined by experimental resolution. statistical significance (5.2+/-0.6)sigma. and observed are consistent recent reports other groups.
High-statistics cross sections for the reactions gamma + p --> K^+ Lambda and Sigma^0 have been measured using CLAS at Jefferson Lab center-of-mass energies W between 1.6 2.53 GeV, -0.85 < cos theta_{K^+}^{c.m.}< +0.95. In channel we confirm a resonance-like structure near W=1.9 GeV backward kaon angles. The position width of this change with angle, indicating that more than one resonance is likely playing role. forward angles all well described by t-channel scaling characteristic Regge...
The ratios of inclusive electron scattering cross sections 4He, 12C, and 56Fe to 3He have been measured at 1<xB<3. At Q2>1.4 GeV2, the exhibit two separate plateaus, 1.5<xB<2 xB>2.25. This pattern is predicted by models that include 2- 3-nucleon short-range correlations (SRC). Relative A=3, per-nucleon probabilities SRC are 2.3, 3.1, 4.4 times larger for A=4, 12, 56. first measurement in nuclei.Received 16 August 2005DOI:https://doi.org/10.1103/PhysRevLett.96.082501©2006 American Physical Society
The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state strangeness S=+1 and mass M=1555+/-10 MeV/c(2) observed in the nK(+) invariant spectrum. peak's width is consistent CLAS resolution (FWHM=26 MeV/c(2)), its statistical significance (7.8+/-1.0)sigma. positive has exotic structure cannot be described framework naive constituent quark model. predicted by chiral soliton model for Theta(+)...
The beam-spin asymmetries in the hard exclusive electroproduction of photons on proton ($\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}ep\ensuremath{\gamma}$) were measured over a wide kinematic range and with high statistical accuracy. These result from interference Bethe-Heitler process deeply virtual Compton scattering. Over whole (${x}_{B}$ 0.11 to 0.58, ${Q}^{2}$ 1 $4.8\text{ }\text{ }{\mathrm{GeV}}^{2}$, $\ensuremath{-}t$ 0.09 $1.8\text{ }{\mathrm{GeV}}^{2}$),...
Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}+p\ensuremath{\rightarrow}{K}^{+}+\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\Lambda}}$ and $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}+p\ensuremath{\rightarrow}{K}^{+}+{\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\Sigma}}}^{0}$. The data were obtained using CEBAF Large Acceptance Spectrometer (CLAS)...
The ratios of inclusive electron scattering cross sections $^4$He, $^{12}$C, and $^{56}$Fe to $^3$He have been measured for the first time. It is shown that these are independent $x_B$ at Q$^2>$1.4 (GeV/c)$^2$ $x_B>$ 1.5 where section depends primarily on high-momentum components nuclear wave function. observed scaling shows momentum distributions high-momenta same shape all nuclei differ only by a scale factor. onset $x_B >$1.5 consistent with kinematical expectation two nucleon short range...
Dual-Energy CT Iodine-Subtraction Virtual Unenhanced Technique to Detect Urinary Stones in an Iodine-Filled Collecting System: A Phantom StudyNaoki Takahashi1, Robert P. Hartman1, Terri J. Vrtiska1, Akira Kawashima1, Andrew N. Primak1, Oleksandr Dzyubak1, Jayawant Mandrekar2, Joel G. Fletcher1 and Cynthia H. McCollough1Audio Available | Share
We report the first evidence for a nonzero beam-spin azimuthal asymmetry in electroproduction of positive pions deep-inelastic kinematic region. Data reaction $e\stackrel{\ensuremath{\rightarrow}}{p}{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+}X$ have been obtained using polarized electron beam 4.3 GeV with CEBAF Large Acceptance Spectrometer at Thomas Jefferson National Accelerator Facility. The amplitude $\mathrm{sin}\ensuremath{\varphi}$ modulation increases momentum pion relative to virtual...
We report results for the virtual photon asymmetry $A_1$ on nucleon from new Jefferson Lab measurements. The experiment, which used CEBAF Large Acceptance Spectrometer and longitudinally polarized proton ($^{15}$NH$_3$) deuteron ($^{15}$ND$_3$) targets, collected data with a electron beam at energies between 1.6 GeV 5.7 GeV. In present paper, we concentrate our $A_1(x,Q^2)$ related ratio $g_1/F_1(x,Q^2)$ in resonance deep inelastic regions lowest highest energies, covering range momentum...
The neutron elastic magnetic form factor GMn has been extracted from quasielastic electron scattering data on deuterium with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. kinematic coverage of measurement is continuous Q2=1 GeV2 to 4.8 GeV2. High precision was achieved by employing a ratio technique in which many uncertainties cancel, and simultaneous in-situ calibration detection efficiency, largest correction data. Neutrons were detected using CLAS electromagnetic...
The longitudinal target-spin asymmetry ${A}_{\mathrm{UL}}$ for the exclusive electroproduction of high-energy photons was measured first time in $e\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\rightarrow}{e}^{\ensuremath{'}}p\ensuremath{\gamma}$. data have been accumulated at JLab with CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized ${\mathrm{NH}}_{3}$ target. A significant azimuthal angular dependence observed, resulting from interference deeply virtual Compton...
We report a new measurement of the exclusive electroproduction reaction ${\ensuremath{\gamma}}^{*}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}p$ to explore evolution from soft nonperturbative physics hard processes via ${Q}^{2}$ dependence magnetic (${M}_{1+}$), electric (${E}_{1+}$), and scalar (${S}_{1+}$) multipoles in $N\ensuremath{\rightarrow}\ensuremath{\Delta}$ transition. 9000 differential cross section data points cover $W$ threshold $1.4\text{ }\text{ }\mathrm{GeV}/{c}^{2}$,...
A search for the Θ+ in reaction γd→pK−K+n was completed using CLAS detector at Jefferson Lab. study of same reaction, published earlier, reported observation a narrow resonance. The present experiment, with more than 30 times integrated luminosity our earlier measurement, does not show any evidence pentaquark angle-integrated upper limit on production mass range 1.52–1.56 GeV/c2 γd→pK−Θ+ is 0.3 nb (95% C.L.). This depends assumptions made and angular distribution production. Using Λ(1520) as...
New cross sections for the reaction $ep \to e'\eta p$ are reported total center of mass energy $W$=1.5--2.3 GeV and invariant squared momentum transfer $Q^2$=0.13--3.3 GeV$^2$. This large kinematic range allows extraction new information about response functions, photocouplings, $\eta N$ coupling strengths baryon resonances. A sharp structure is seen at $W\sim$ 1.7 GeV. The shape differential section indicative presence a $P$-wave resonance that persists to high $Q^2$. Improved values...
Differential cross sections for the reaction $\gamma p \to \pi^0$ have been measured with CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam energies from 0.675 to 2.875 GeV. The results reported here possess greater accuracy in absolute normalization than previous measurements. They disagree recent CB-ELSA measurements process at forward scattering angles. Agreement SAID MAID fits is found below 1 present set of has incorporated into database, exploratory extended 3...
The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. mesons, ρ, ω, and ϕ, are observed via their decay to e+e−, in order reduce effects final-state interactions nucleus. Of particular interest possible in-medium properties ρ meson. mass spectrum is extracted from data nuclei, 2H, C, Fe, Ti. We observe no significant shift some broadening consistent with expected collisional for meson.Received 20 July...
The exclusive reaction gammap-->K0K+n was studied in the photon energy range between 1.6 and 3.8 GeV searching for evidence of exotic baryon Theta+ (1540)-->nK+. decay to nK+requires assignment strangeness S=+1 any observed resonance. Data were collected with CLAS detector at Thomas Jefferson National Accelerator Facility corresponding an integrated luminosity 70 pb-1. No pentaquark found. Upper limits set on production cross section as function center-of-mass angle nK+ mass. 95% C.L. upper...
The helicity amplitudes of the electroexcitation Roper resonance are extracted for 1.7 < Q2 4.5 GeV2 from recent high precision JLab-CLAS cross section and longitudinally polarized beam asymmetry data pi+ electroproduction on protons at W=1.15-1.69 GeV. analysis is made using two approaches, dispersion relations a unitary isobar model, which give consistent results. It found that transverse amplitude A_{1/2} gamma* p -> N(1440)P11 transition, large negative Q2=0, becomes positive ~ 2 GeV2,...
The light vector mesons ($\rho$, $\omega$, and $\phi$) were produced in deuterium, carbon, titanium, iron targets a search for possible in-medium modifications to the properties of $\rho$ meson at normal nuclear densities zero temperature. detected with CEBAF Large Acceptance Spectrometer (CLAS) via their decays $e^{+}e^{-}$. rare leptonic decay was chosen reduce final-state interactions. A combinatorial background subtracted from invariant mass spectra using well-established event-mixing...
Semi-inclusive pi+ electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed a liquid-hydrogen target using 5.75 GeV electron beam. complete five-fold differential cross sections were over wide kinematic range including of azimuthal angles between hadronic and leptonic planes, phi, enabling us to separate phi-dependent terms. Our measurements phi-independent term section low Bjorken x found be in fairly good agreement pQCD...
The exclusive electroproduction process $\vec{e}p \to e^\prime n \pi^+$ was measured in the range of photon virtuality $Q^2 = 1.7 - 4.5 \rm{GeV^2}$, and invariant mass for $n\pi^+$ system $W 1.15 \rm{GeV}$ using CEBAF Large Acceptance Spectrometer. For first time, these kinematics are probed $\pi^+$ production from protons with nearly full coverage azimuthal polar angles center-of-mass system. channel has particular sensitivity to isospin 1/2 excited nucleon states, together $p\pi^0$ final...
Received 21 January 2004DOI:https://doi.org/10.1103/PhysRevLett.92.049902©2004 American Physical Society