R. P. Johnson
A5023969387- Particle physics theoretical and experimental studies
- Particle accelerators and beam dynamics
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Muon and positron interactions and applications
- Laser-Plasma Interactions and Diagnostics
- Neutrino Physics Research
- Particle Detector Development and Performance
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Dark Matter and Cosmic Phenomena
- Laser-Matter Interactions and Applications
- Nuclear Physics and Applications
- Plasma Diagnostics and Applications
- Structural Load-Bearing Analysis
- Magnetic confinement fusion research
- Structural Behavior of Reinforced Concrete
- Structural Engineering and Vibration Analysis
- Atomic and Molecular Physics
- Laser Design and Applications
- Radiation Detection and Scintillator Technologies
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
Muons (United States)
2015-2024
Thomas Jefferson National Accelerator Facility
1994-2024
Newport News Public Library System
2016-2024
Fermi National Accelerator Laboratory
1994-2022
Fermi Research Alliance
2006-2022
Los Alamos National Laboratory
2011-2021
Mentor
2018
University of California, Riverside
2017
University of California, Santa Cruz
1997-2015
Oak Ridge National Laboratory
2015
Neutrons are unique particles to probe samples in many fields of research ranging from biology material sciences engineering and security applications. Access bright, pulsed sources is currently limited large accelerator facilities there has been a growing need for compact over the recent years. Short pulse laser driven neutron could be relatively cheap way produce neutrons with energies excess 10 MeV. For more than decade experiments have tried obtain numbers sufficient Our demonstrated an...
We report on the acceleration of ion beams from ultrathin diamondlike carbon foils thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities approximately 7 x 10;{19} W/cm;{2}. An unprecedented maximum energy 185 MeV (15 MeV/u) for fully ionized atoms is observed optimum 30 nm. The enhanced attributed to self-induced transparency, leading strong volumetric heating classically overdense electron population in bulk target. Our experimental results are supported...
We present measurements of the pseudorapidity (η) distribution charged particles (dNchdη) produced within |η|≤3.5 in proton-antiproton collisions at √s 630 and 1800 GeV. measure dNchdη η=0 to be 3.18±0.06(stat)±0.10(syst) GeV, 3.95±0.03 (stat)±0.13(syst) Many systematic errors ratio two energies cancel, we 1.26±0.01±0.04 for GeV that |η|≤3. Comparing lower-energy data, observe an increase faster than ln(s) η=0.Received 2 October 1989DOI:https://doi.org/10.1103/PhysRevD.41.2330©1990 American...
Measurements of inclusive transverse-momentum spectra for charged particles produced in proton-antiproton collisions at √2 630 and 1800 GeV are presented compared with data taken lower energies.Received 8 June 1988DOI:https://doi.org/10.1103/PhysRevLett.61.1819©1988 American Physical Society
We have performed a search at the Bevatron for decays ${{K}_{L}}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}},{e}^{+}{e}^{\ensuremath{-}}, \mathrm{and} {\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}{e}^{\ensuremath{\mp}}$ with double magnetic spectrometer using wire spark chambers. Over ${10}^{6}$ observed ${{K}_{L}}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ determine normalization di-lepton decay modes....
A new and simple electron microscope has been designed for small cylindrical filaments. Die marks are found to be prominent in the images of all drawn wires. The activation thoriated tungsten studied. Electron emission from single crystals grown pure filaments varies around wire circumference depends systematically on crystallographic direction. This variation with direction is more pronounced complex when filament allowed self-activate cesium or potassium vapor.
The activation energy ${Q}_{x}$ for diffusion in a dilute metallic solution cannot be less than the ${Q}_{0}$ self-diffusion, if solute atoms can move only through medium of "holes" which diffuse to them from solvent lattice, displace them, and leave another direction. Since experiments show that generally ${Q}_{x}<{Q}_{0}$ an alternative mechanism is required. Solute are not so firmly bound lattice as will tend trap holes form solute-hole molecules. These molecules units dense by cycles...
We describe the status of our effort to realize a first neutrino factory and progress made in understanding problems associated with collection cooling muons towards that end. summarize physics can be done factories as well intense cold beams muons. The potential muon colliders is reviewed, both Higgs Factories compact high energy lepton colliders. timescale research development reviewed latest designs channels including promise ring coolers achieving longitudinal transverse simultaneously....
A diffraction-limited laser interacts with a plasma whose conditions are uniform on the scale of focused spot. Two distinct, narrow waves observed in backscattered spectrum phase velocities ${v}_{\ensuremath{\varphi}}{/v}_{e}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.4\ifmmode\pm\else\textpm\fi{}0.08$ and $4.2\ifmmode\pm\else\textpm\fi{}0.1$, where ${v}_{e}$ is electron thermal speed. The high-velocity wave ordinary stimulated Raman scattering (SRS) from Langmuir wave. low-velocity...
Keywords WARWICK UNIVERSITY BRIDGES, GIRDERS, PLATES, WEBS, CORRUGATED, STEEL, BOX, COMPOSITE, RESEARCH, BUCKLING, SPANS, CONCRETE, FLANGES, DESIGN, TESTS, SHEAR, TRANSFER, STIFFNESS, ELASTIC, ANALYSIS, FINITE ELEMENTS, RESISTANCE, ULTIMATE, GLOBAL, LOCAL, INTERACTIVE FRANCE... Show All
A search for the top quark in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at a center-of-mass energy of 1.8 TeV using Collider Detector Fermilab is described. study events selected by requiring an energetic electron, missing transverse energy, and two or more jets excludes 95% confidence level standard-model production decay tt\ifmmode\bar\else\textasciimacron\fi{} pairs if top-quark mass between 40 77 GeV/${c}^{2}$. The observed electron + multijet data are consistent with W-boson...
Keywords PARTIAL, SHEAR, CONNECTIONS, COMPOSITE, BEAMS, BUILDINGS, SLIP, CAPACITY, CONNECTORS, PARAMETERS, SPANS, RESEARCH, NON LINEAR, NUMERICAL, ANALYSIS, TESTS, DATA, PARAMETRIC, STUDIES, MATHEMATICS, MODELS, PROPERTIES, MATERIALS, PROGRAMS, STUDS, SLABS, STIFFNESS, STRENGTH, SECTIONS, HOT ROLLED, DESIGN, METHODS, STEEL, CONCRETE UK, FRANCE, EUROPE... Show All
We have determined mW=79.91±0.39 GeV/c2 from an analysis of W→eν and W→μν data the Collider Detector at Fermilab in p¯p collisions a c.m. energy √s =1.8 TeV. This result, together with world-average Z mass, determines weak mixing angle to be sin2θW=0.232±0.008. Bounds on top-quark mass are discussed.Received 13 August 1990DOI:https://doi.org/10.1103/PhysRevLett.65.2243©1990 American Physical Society
Single hot spot experiments offer several unique opportunities for developing a quantitative understanding of laser-plasma instabilities. These include the ability to perform direct numerical simulations experiment due finite interaction volume, isolation instabilities nearly ideal laser intensity distribution, and observation fine structure homogeneous plasma initial conditions. Experiments performed at Trident in single regime have focused on following issues. First, scaling stimulated...
An analysis of pp\ifmmode\bar\else\textasciimacron\fi{} collision events at \ensuremath{\surd}s =1.8 TeV with jets and large missing transverse energy finds no event >40 GeV. This result yields a 90%-C.L. limit on the cross section for one-jet-event production <0.1 nb jet in pseudorapidity range \ensuremath{\Vert}\ensuremath{\eta}\ensuremath{\Vert}<1.0 ${E}_{T}$>52 Limits masses squarks gluinos minimal supersymmetry model are also set. At 90% C.L., ${m}_{q\ifmmode \tilde{}\else...
Many features of the behavior luminescent sulphides can be correlated by means a mechanism based on energy-band theory solid insulator. It is imagined that after excitation, which essentially an ionization activator atom, dissociated electron highly likely to trapped and held localized in discrete energy level forbidden region, recombining with ion emitting characteristic luminescence only it has been freed from this state thermal excitation or other agencies. This picture, appropriate...
Laser-accelerated beams of Mega-electron volt protons have been produced at the Los Alamos Trident laser facility and used for high-resolution point-projection proton radiography Au grids. The effective source size affords an inherent resolution 2–3 μm in object plane. beam is characterized by ion time-of-flight Faraday cup measurements nuclear particle track detectors. Laser-driven appears promising as a valuable research tool probing plasmas or modest density objects.
A search for tt\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}e\ensuremath{\mu}+X in pp\ifmmode\bar\else\textasciimacron\fi{} collisions at s\ensuremath{\surd}\ifmmode\bar\else\textasciimacron\fi{} TeV is described. The production and decay of top-quark--antiquark pairs considered the context standard model. analysis based on data with an integrated luminosity 4.4 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ recorded Collider Detector Fermilab. An upper limit...
A reasonable low-energy chiral Lagrangian of vectors and pseudoscalars involves three a priori unknown coefficients for terms proportional to the Levi-Civita symbol ${\ensuremath{\epsilon}}_{\ensuremath{\mu}\ensuremath{\nu}\ensuremath{\alpha}\ensuremath{\beta}}$. We argue that these cannot, from theoretical standpoint, be reliably determined by consideration electromagnetic processes. Hence we use purely strong-interaction processes which enable us determine two out these. examine nucleon as...
We investigate the properties of a possible low-lying scalar glueball as well ordinary scalar-quark states using an effective chiral Lagrangian which satisfies trace anomaly and U(1${)}_{\mathrm{A}}$ QCD. An interesting mass bound for lightest particle in scalar-singlet channel is discussed. Detailed arguments against existence very light (less than 400 MeV) are presented. It shown that introduction derivative-coupling term usual type linear \ensuremath{\sigma} model cures problem...
Thomson scattering is used to measure Langmuir waves (LW) driven by stimulated Raman (SRS) in a diffraction limited laser focal spot. For SRS at wave numbers klambda(D) less similar 0.29, where k the LW number and lambda(D) Debye length, multiple are detected attributed decay instability (LDI) primary LW. At greater single wave, frequency-broadened spectrum observed. The transition from fluid kinetic regime qualitatively consistent with particle-in-cell simulations crossing of LDI amplitude...