A5014180049- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Photocathodes and Microchannel Plates
- Electron and X-Ray Spectroscopy Techniques
- Particle physics theoretical and experimental studies
- Superconducting Materials and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum Chromodynamics and Particle Interactions
- Radiation Therapy and Dosimetry
- Gyrotron and Vacuum Electronics Research
- Advanced X-ray Imaging Techniques
- Plasma Diagnostics and Applications
- Particle Detector Development and Performance
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- Laser Design and Applications
- Dark Matter and Cosmic Phenomena
- Atomic and Molecular Physics
- Laser-Matter Interactions and Applications
- Advanced Fiber Laser Technologies
- Advanced Chemical Physics Studies
- Radiation Detection and Scintillator Technologies
- Laser-Plasma Interactions and Diagnostics
- Atomic and Subatomic Physics Research
Thomas Jefferson National Accelerator Facility
1997-2022
Stanford Synchrotron Radiation Lightsource
1977-2018
SLAC National Accelerator Laboratory
1978-2018
Tufts University
1968-2018
Cornell University
1967-2014
Lancaster University
2008
High Energy Accelerator Research Organization
2008
Arizona State University
2007
Continuous Electron Beam Accelerator Facility
1989-2002
EMI (United Kingdom)
2002
We report measurements of the asymmetry in deep inelastic scattering longitudinally polarized electrons by protons. The antiparallel-parallel asymmetries are positive and large agreement with predictions quark-parton models proton. A limit is obtained on parity nonconservation unpolarized nucleons.
We have conducted a multiobjective computational optimization of high brightness, average current photoinjector under development at Cornell University. This injector employs dc photoemission electron gun. Using evolutionary algorithms combined with parallel computing resources, the multivariate parameter space was explored for optimal values. powerful tool allows an extensive study complex and nonlinear systems such as space-charge dominated regions accelerator, has broad areas potential...
The $s$ and $t$ dependence of incoherent $\ensuremath{\psi}(3100)$ photoproduction from deuterium has been measured at the Stanford Linear Accelerator Center. $\ensuremath{\psi}(3700)$ hydrogen have also measured.
$\frac{J}{\ensuremath{\psi}}$ photoproduction has been measured from beryllium and tantalum targets by observing the yield of single muons at a transverse momentum 1.65 GeV/c with bremsstrahlung beam ${E}_{0}=20$ GeV. The results have interpreted in terms nuclearoptics model to $\ensuremath{\psi}$-nucleon total cross section. result is ${\ensuremath{\sigma}}_{\ensuremath{\psi}N}=3.5\ifmmode\pm\else\textpm\fi{}0.8$ mb.
An analysis was made of the decay angular distribution rho mesons produced via $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\rho}}^{0}$ by linearly polarized photons at 2.8 and 4.7 GeV. The reaction proceeds almost completely through natural-parity exchange, contribution from unnatural-parity exchange for momentum transfers $|t|<1$ Ge${\mathrm{V}}^{2}$ being (3.1\ifmmode\pm\else\textpm\fi{}2.2)% GeV (-1.1\ifmmode\pm\else\textpm\fi{}1.9)% behavior density-matrix elements...
Electron injectors delivering relativistic electron beams with very high brightness are essential for a number of current and proposed accelerator applications. These generally produced from photoemission cathodes. We formulate limit on the beam such cathodes set by transverse thermal energy electrons leaving photocathode accelerating field at cathode. Two specific examples--direct measurement phase space charge dominated high-voltage gun numerical optimization same higher...
Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in hydrogen bubble chamber. We discuss the experimental procedure, determination of channel cross sections, analysis $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. A model-independent ${\ensuremath{\rho}}^{0}$-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that reaction...
Substantially more than half of the electromagnetic nuclear physics experiments conducted at Continuous Electron Beam Accelerator Facility Thomas Jefferson National (Jefferson Laboratory) require highly polarized electron beams, often high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly laser light with photon energy slightly larger band gap. The photocathodes prepared activation clean surface to...
The thermal emittance and temporal response of a photocathode set an upper limit on the maximum achievable electron beam brightness from photoemission source, or photoinjector. We present measurements these parameters over broad range laser wavelength for two different negative affinity (NEA) photocathodes. NEA GaAs GaAsP has been measured by techniques—a measurement size downstream solenoid, whose strength was varied, double slit transmission measurement—for spot sizes shapes. effect space...
A nearly monochromatic high-energy photon beam produced by Compton backscattering of ruby laser light has been used to study photoproduction in a hydrogen bubble chamber. The total hadronic $\ensuremath{\gamma}p$ cross sections at 1.44, 2.8, and 4.7 GeV are found be 145.1 \ifmmode\pm\else\textpm\fi{} 5.7, 131.3 4.3, 124.2 3.9 \ensuremath{\mu}b, respectively. Partial presented also.
We report on a new type of high-energy electron-proton scattering experiment in which longitudinally polarized electrons are scattered from protons. The asymmetry elastic at ${Q}^{2}=0.765$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ was measured; our result agrees with the theoretical and determines sign $\frac{{G}_{E}}{{G}_{M}}$ to be positive.
Practically all synchrotron x-ray sources to data are based on the use of storage rings produce high current electron (or positron) beams needed for radiation (SR). The ultimate limitations quality beam, which directly reflected in many most important characteristics SR beams, arise from physics equilibrium processes fundamental operation rings. It is possible with superior via photoinjected and high-energy linacs; however, energy consumption such machines prohibitive. This limitation can be...
Rho photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized photon beam in hydrogen bubble chamber. The dependence of the ${\ensuremath{\rho}}^{0}$ mass shape on momentum transfer inconsistent with Ross-Stodolsky factor. production ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ pairs $s$-channel c.m. helicity-conserving $p$-wave state accounts for almost all events $\ensuremath{\rho}$ region. Evidence presented an interference background. data are compared...
We report on a simple and robust technique to temporally shape ultrashort pulses. A number of birefringent crystals with appropriate crystal length orientation form set. When short pulse propagates through the set, is divided into numerous pulses, producing desired temporal shape. Flexibility in final achieved varying initial duration, divided-pulse number, polarization-mode delay, energy distribution The efficiency near 100% for train alternating polarizations, 50% linearly polarized train.
The longitudinal polarization of the new Yale University-Stanford Linear Accelerator Center polarized-electron beam has been determined at laboratory energies between 6.47 and 19.40 GeV. Spin-dependent elastic electron-electron scattering (M\o{}ller scattering) found to be a practical technique for measurements high energies. results are consistent with energy angular dependence predicted by quantum electrodynamics an energy-independent 0.76\ifmmode\pm\else\textpm\fi{}0.03.
We study the inclusive spectra of ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons from events obtained in three exposures SLAC 82-in. hydrogen bubble chamber to a nearly monochromatic polarized photon beam mean energies 2.8, 4.7, and 9.3 GeV. The data are presented terms transverse momentum ${p}_{\ensuremath{\perp}}$ suggested choices for other independent variable, i.e., longitudinal ${p}_{\ensuremath{\parallel}}$ laboratory system, rapidity variable...
The reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\omega}$ was studied in a hydrogen bubble chamber using linearly polarized photon beam. total cross section found to be 5.8 \ifmmode\pm\else\textpm\fi{} 0.5 \ensuremath{\mu}b at 2.8 GeV and 3.2 0.3 4.7 GeV. From the decay angular distributions these sections have been separated into contributions from natural- unnatural-parity exchange ${\ensuremath{\sigma}}^{\mathrm{N}}$,...
Bunch lengths as short 84 fs (rms) have been measured at Jefferson Laboratory using a rf zero-phasing technique. To the best of our knowledge, this is first accurate measurement longitudinal distribution function in regime. In paper, an analytical approach for computing and bunch length described arbitrary transverse distributions case where intrinsic energy spread small compared to correlated imparted by cavities. The results are presented, which excellent agreement with numerical simulations.
To achieve the lowest emittance electron bunches from photoemission guns, it is essential to limit uncorrelated growth due space charge forces acting on bunch in vicinity of photocathode through appropriate temporal shaping optical pulses illuminating photocathode. We present measurements profile a bulk crystal GaAs illuminated with 520 nm wavelength frequency-doubled Yb-fiber laser. A transverse deflecting rf cavity was used make these measurements. The measured laser pulse and...
For the generation of intense single and multiple bunches electrons (>8 nc per bunch) for accelerator studies at SLAC, a high peak current photoemission electron gun has been developed. A gallium arsenide photocathode is illuminated by optical beam from frequency doubled, actively mode-locked Q-switched Nd:YAG laser. The pulses are variable, sub-nanosecond width occur with spacing 8.4 nsec, synchronized 2856 MHz rf. designed to be space charge limited 15 200 kV, although emission 60 was...