D. Doughty
A5090990270- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Atmospheric chemistry and aerosols
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Quantum, superfluid, helium dynamics
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Infection Control and Ventilation
- Glioma Diagnosis and Treatment
- Advanced NMR Techniques and Applications
- Nuclear Physics and Applications
- Indoor Air Quality and Microbial Exposure
- Medical Imaging Techniques and Applications
- Superconducting Materials and Applications
- Radiation Detection and Scintillator Technologies
- Meningioma and schwannoma management
- Vascular Malformations Diagnosis and Treatment
- Advanced Radiotherapy Techniques
DEVCOM Army Research Laboratory
2015-2024
United States Army Combat Capabilities Development Command
2020-2024
Janus University
2024
Christopher Newport University
2007-2020
Thomas Jefferson National Accelerator Facility
2006-2015
Associated Universities, Inc.
2015
Oak Ridge Associated Universities
2015
Campbell Collaboration
2004-2014
Institut de Physique
2014
Pennsylvania State University
2009-2013
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.
The atomic nucleus is composed of two different kinds fermions, protons and neutrons. If the neutrons did not interact, Pauli exclusion principle would force majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between form correlated high-momentum neutron-proton pairs. Thus, greater probability than momentum Fermi This...
Detection of bioaerosols, or primary biological aerosol particles (PBAPs), has become increasingly important for a wide variety research communities and scientific questions. In particular, real-time (RT) techniques autonomous, online detection characterization PBAP properties in both outdoor indoor environments are becoming more commonplace have opened avenues research. With advances technology, however, come challenges to standardize practices so that results reliable comparable across...
The use of the edible photosynthetic cyanobacterium Arthrospira platensis (spirulina) as a biomanufacturing platform has been limited by lack genetic tools. Here we report engineering methods for stable, high-level expression bioactive proteins in spirulina, including large-scale, indoor cultivation and downstream processing methods. Following targeted integration exogenous genes into spirulina chromosome (chr), encoded protein biopharmaceuticals can represent much 15% total biomass, require...
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...
We report the first results of beam-spin asymmetry measured in reaction $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}\mathrm{ep}\ensuremath{\gamma}$ at a beam energy 4.25 GeV. A large with $\mathrm{sin}\ensuremath{\varphi}$ modulation is observed, as predicted for interference term deeply virtual compton scattering (DVCS) and Bethe-Heitler process. The amplitude this...
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(+)...
We present results on the electroexcitation of low mass resonances Delta(1232)P33, N(1440)P11, N(1520)D13, and N(1535)S11 in a wide range Q2. The were obtained comprehensive analysis JLab-CLAS data differential cross sections, longitudinally polarized beam asymmetries, longitudinal target beam-target asymmetries for pion electroproduction off proton. analysed using two conceptually different approaches, fixed-t dispersion relations unitary isobar model, allowing us to draw conclusions model...
Models of baryon structure predict a small quadrupole deformation the nucleon due to residual tensor forces between quarks or distortions from pion cloud. Sensitivity quark versus degrees freedom occurs through Q2 dependence magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for ratios E(1+)/M(1+) S(1+)/M(1+) over range = 0.4-1.8 GeV2, extracted precision p(e,e(')p)pi(0) data using truncated multipole...
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 $1.8\text{ }{\mathrm{GeV}}^{2}$),...
Cross-sections and recoil polarizations for the reactions gamma + p --> K^+ Lambda Sigma^0 have been measured with high statistics good angular coverage center-of-mass energies between 1.6 2.3 GeV. In K^+Lambda channel we confirm a structure near W=1.9 GeV at backward kaon angles, but our data shows more complex s- u- resonance than previously seen. This is present forward angles not central its position width change angle, indicating that one playing role. Rising back-angle cross sections...
We present measurements of the differential cross section and $\ensuremath{\Lambda}$ recoil polarization for $\ensuremath{\gamma}p\ensuremath{\rightarrow}{K}^{+}\ensuremath{\Lambda}$ reaction made using CLAS detector at Jefferson Lab. These cover center-of-mass energy range from $1.62$ to $2.84$ GeV a wide ${K}^{+}$ production angles. Independent analyses were performed ${K}^{+}p{\ensuremath{\pi}}^{\ensuremath{-}}$ ${K}^{+}p$ (missing ${\ensuremath{\pi}}^{\ensuremath{-}}$) final-state...
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 transition helicity amplitudes from the proton ground state to $P_{11}(1440)$ and $D_{13}(1520)$ excited states ($\gamma_{v}pN^*$ electrocouplings) were determined analysis of nine independent one-fold differential $\pi^{+} \pi^{-} p$ electroproduction cross sections off a target, taken with CLAS at photon virtualities 0.25\enskip {\rm GeV$^{2}$} $<$ $Q^{2}$ 0.60 \enskip GeV$^{2}$}. phenomenological reaction model was employed for separation resonant non-resonant contributions final...
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...
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...
Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam energies from 0.725 to 2.875 GeV. Where available, results obtained here compare well previously published reaction. Agreement SAID MAID analyses is found below 1 The present set of has incorporated into database, exploratory fits made up 2.7 Resonance couplings extracted compared previous determinations. With addition these world...
High-statistics differential cross sections for the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\eta}$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\eta}}^{'}$ have been measured using CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab center-of-mass energies from near threshold up to 2.84 GeV. The ${\ensuremath{\eta}}^{'}$ results are most precise date provide largest energy angular coverage. $\ensuremath{\eta}$ measurements extend range of...
We report the first measurement of transverse momentum dependence double-spin asymmetries in semi-inclusive production pions deep-inelastic scattering off longitudinally polarized proton. Data have been obtained using a electron beam 5.7 GeV with CLAS detector at Jefferson Lab (JLab). Modulations single spin over azimuthal angle between lepton and hadron planes ϕ measured wide kinematic range Bjorken x virtual photon squared four-momentum Q2. A significant nonzero sin2ϕ asymmetry was...
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...