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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Article
Lawrence Berkeley National Laboratory (2007)
    Cover page: Recent Progress at LBNL on Characterization of Laser Wakefield Accelerated Electron Bunches using Coherent Transition Radiation
    • Article
    Lawrence Berkeley National Laboratory (2008)

    An optical injection scheme for a laser-plasma based accelerator which employs a non-collinear counter-propagating laser beam to push background electrons in the focusing and acceleration phase via ponderomotive beat with the trailing part of the wakefield driver pulse is discussed. Preliminary experiments were performed using a drive beam of a_0 = 2.6 and colliding beam of a_1 = 0.8 both focused on the middle of a 200 mu m slit jet backed with 20 bar, which provided ~; 260 mu m long gas plume. The enhancement in the total charge by the colliding pulse was observed with sharp dependence on the delay time of the colliding beam. Enhancement of the neutron yield was also measured, which suggests a generation of electrons above 10 MeV.

      Cover page: Colliding pulse injection experiments in non-collinear geometry for controlled laser plasma wakefield acceleration of electrons
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2025)
      Excitation of long-lived states in bromine nuclei using a tabletop laser-plasma accelerator providing pulsed (<100  fs) electron beams provided a sensitive probe of γ strength and level densities in the nuclear quasicontinuum and may indicate angular momentum coupling through electron-nuclear interactions. Solid-density active LaBr_{3} targets absorb real and virtual photons up to 35±2.5  MeV and deexcite through γ cascade into different states. A factor of 4.354±0.932 enhancement of the ^{80}Br^{m}/^{80}Br^{g} isomeric ratio was observed following electron irradiation, as compared to bremsstrahlung. Additional angular momentum transfer could possibly occur through nuclear-plasma or electron-nuclear interactions enabled by the ultrashort electron beam. Further investigation of these mechanisms could have far-reaching impact including decreased storage of long-term nuclear waste and an improved understanding of heavy element formation in astrophysical settings.
        Cover page: Enhanced Isomer Population via Direct Irradiation of Solid-Density Targets Using a Compact Laser-Plasma AcceleratorCreative Commons 'BY-NC' version 4.0 license
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