A5004070522- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Advanced NMR Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Laser Material Processing Techniques
- Radiation Therapy and Dosimetry
- Radiation Shielding Materials Analysis
- Algebraic and Geometric Analysis
- Magnetic confinement fusion research
- Advanced Thermodynamics and Statistical Mechanics
- Advanced MEMS and NEMS Technologies
- High-pressure geophysics and materials
- Transition Metal Oxide Nanomaterials
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Magnetic properties of thin films
- Semiconductor Lasers and Optical Devices
- Medical Imaging Techniques and Applications
- Aerospace Engineering and Energy Systems
Ohio University
1997-2012
Norfolk State University
2011
Rice University
2003
University of South Carolina
1995-2002
Campbell Collaboration
2001
Brookhaven National Laboratory
1997
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
1997
Istituto Nazionale di Fisica Nucleare, Sezione di Roma I
1997
University of Virginia
1997
Justus-Liebig-Universität Gießen
1997
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...
We have measured the Compton-scattering cross section on hydrogen at 60\ifmmode^\circ\else\textdegree\fi{} and 135\ifmmode^\circ\else\textdegree\fi{} using monochromatic tagged photons spanning energy between 32 72 MeV. These data, when analyzed with a low-energy expansion of scattering cross-section formula, provides determination values for electric magnetic polarizabilities proton. find, respectively,...
New high-precision measurements of $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},\ensuremath{\pi})$ and $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},\ensuremath{\gamma})$ cross sections beam asymmetries have been combined with other polarization ratios in a simultaneous analysis both reactions. Compton scattering has provided two important new constraints on the photopion amplitude. The $E2/M1$ mixing ratio for $N\ensuremath{\rightarrow}\ensuremath{\Delta}$...
The Compton scattering cross section on the proton has been measured at laboratory angles of 90\ifmmode^\circ\else\textdegree\fi{} and 135\ifmmode^\circ\else\textdegree\fi{} using tagged photons in energy range 70--100 MeV simultaneously untagged 100--148 MeV. With aid dispersion relations, these sections were used to extract electric magnetic polarizabilities, \ensuremath{\alpha}\ifmmode\bar\else\textasciimacron\fi{} \ensuremath{\beta}\ifmmode\bar\else\textasciimacron\fi{} respectively,...
New cross sections for the reaction e p-->e p eta are reported total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction important new information about response functions, photocouplings, N coupling strengths baryon resonances. Newly observed structure at approximately 1.65 is shown to come from interference between S P waves can be interpreted with known Improved values derived photon amplitude...
We report new high-precision measurements of $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},\ensuremath{\gamma}),$ $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},{\ensuremath{\pi}}^{0})$ and $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},{\ensuremath{\pi}}^{+})$ cross section beam asymmetry angular distributions for photon energies in the range from 213 MeV to 333 MeV. The sections all three channels are locked together with a small common systematic...
The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above resonance region was measured up to a momentum transfer -t = 5 GeV2 using CLAS detector at Thomas Jefferson National Accelerator Facility. channel extracted from two charged-pion sections by fitting pi(+)pi(-) and p pi(+) invariant masses. low shows typical diffractive pattern expected Reggeon exchange. flatter behavior large cannot be explained solely in terms of QCD-inspired two-gluon exchange...
We report new measurements of inclusive π production from frozen-spin HD for polarized photon beams covering the Δ(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions spin-difference cross sections entering Gerasimov-Drell-Hearn (GDH) sum rule. Recent results Mainz Bonn exceed GDH prediction proton by 22 μb, suggesting as yet unmeasured high-energy components. Our π0 reveal a different dependence than assumed in analyses integrate to...
A galvanometer laser beam scanning system is an essential element in many additive manufacturing (LAM) technologies including Stereolithography (SLA), Selective Laser Sintering (SLS) and Melting (SLM). Understanding the techniques recent innovations this field will greatly benefit 3D printing integration technology advance. One of challenges to achieve high quality printed parts due non-uniform power density delivered on materials caused by acceleration deceleration movements at ends...
Elastic photon scattering cross sections have been measured on $^{4}\mathrm{He}$ in the region of giant dipole resonance (GDR) using tagged-photon technique. These data place stringent constraints total photoabsorption ${\mathrm{\ensuremath{\sigma}}}_{\ensuremath{\gamma}}$ at peak GDR, which to very good approximation is sum (\ensuremath{\gamma},p) and (\ensuremath{\gamma},n) sections. We find section be ${\mathrm{\ensuremath{\sigma}}}_{0}$=2.86\ifmmode\pm\else\textpm\fi{}0.12 mb. This...
The angular distributions for coherent photon scattering from $^{4}\mathrm{He}$ were measured at average laboratory bremsstrahlung energies of 187, 235, and 280 MeV. experiment was performed the Saskatchewan Accelerator Laboratory using new high duty factor electron beam. scattered photons observed with a high-resolution NaI(Tl) total absorption scintillation detector. These measurements are intended to investigate modification \ensuremath{\Delta} properties inside nuclear medium treatment...
Elastic photon scattering cross sections on $^{16}\mathrm{O}$ have been measured in the energy range 27-108 MeV. These data are inconsistent with a conventional interpretation which electric and magnetic polarizabilities of bound nucleon unchanged from free values meson-exchange seagull amplitude is taken zero-energy limit. Agreement can be achieved by invoking either strongly modified or substantial dependence to amplitude. It argued that these seemingly different explanations...
Spin asymmetries for the ${}^{16}\mathrm{O}(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},p{\ensuremath{\pi}}^{\ensuremath{-}})$ reaction are reported incident photon energies of 293 $\ifmmode\pm\else\textpm\fi{}$ 20 MeV, proton angles ranging from 28$\ifmmode^\circ\else\textdegree\fi{}$ to 140$\ifmmode^\circ\else\textdegree\fi{}$ (lab), and pion 35$\ifmmode^\circ\else\textdegree\fi{}$ 115$\ifmmode^\circ\else\textdegree\fi{}$. The data compared with calculations in a quasifree...
Compton backscattering gamma ray beams are characterized by a high degree of linear and circular polarization with low unpolarized backgrounds have proven to provide very precise measurements observables. Latest results from LEGS GRAAL experiments on proton deuteron targets presented. The Σ beam asymmetry for ω photoproduction has been measured the collaboration both ω→π0γ ω→π+π−π0 decay channels target; single double asymmetries provided also K channel. E G pion at using frozen spin HD target.
Angular distributions for photon scattering from $^{12}\mathrm{C}$ and $^{4}\mathrm{He}$ have been measured using continuous wave bremsstrahlung the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data carbon were taken at 158.8, 195.2, 197.2, 247.2, 290.2 MeV end-point energies, helium an energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect scattered photons laboratory angles ranging 20\ifmmode^\circ\else\textdegree\fi{}...
The first measurements of elastic photon scattering on complex nuclei from 150 MeV to the Δ(1232) (Eγ = 300 MeV) are compared with theoretical calculations. Data 4He at Δ peak in agreement a Δh calculation, but substantial disagreement occurs lower energies that is least partly due approximate treatment non-resonant parts elementary nucleon amplitude. An impulse approximation calculation which includes meson exchange provides an adequate description data 187 4He. Improved proton 20–30° and...
Cross sections are presented for the ${}^{16}\mathrm{O}(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},{\ensuremath{\pi}}^{\ensuremath{-}}p)$ reaction at incident photon energies between 290 and 325 MeV. The data specific proton pion angles as a function of energy, which compared with calculations in local distorted wave impulse approximation model. results agreement most kinematics, although some kinematics disagree by factor 2 or more. These do not support conclusion large...
A new polarized target using HD in the solid phase has been developed for studies of nucleon spin structure at Q(2) = 0 pion photo-production. In combination with high quality LEGS photon beam and a large angle spectrometer this allows practically background-free measurements on proton neutron. The first beam-target double-polarization data taken are reported here.
In laser via-drilling industry, improving the drill job throughput while maintaining high hole position accuracy has always been continuous drive. One push that direct impact on improvement is to speed up galvanometer based beam scan head used in drilling machine. The LightningTM II Plus from Cambridge Technology with newly engineered galvo design achieved step response time as fast 225µs for 300µm via-hole pitch a 100mm f-theta lens. This enables scanning frequency 4400 pps at this size....