The peak intensity of short pulse lasers reached in the past 2 decades. Selected physics topics are highlighted for the related laser intensity region (based on a figure in Ref. 2, data courtesy of B. Kruer).
Hot electron energy spectra from shots with various laser energies on the solid targets measured by the electron spectrometers (dots) and their extrapolations (lines).
Electron-positron pair production rate per kilojoule of hot electrons as a function of the laser intensity for the ponderomotive scaling from Ref. 15.
Simulated electron-photon-positron shower when electrons interact with a gold disk. The laser strikes from left, electrons (green) lose energy as they interact with gold nuclei and emit bremsstrahlung photons (yellow). Positrons (red) are produced when those photons interact with gold nuclei through the BH process.
A picture of the experimental set up. The location of two spectrometers relative to the laser and target is marked.
The principle of magnetic electron/positron spectrometers used in our research.
The principle of a step filter spectrometer for high energy bremsstrahlung measurement.
Raw positron data image and lineouts. This shot used a pulse with of laser energy. The laser intensity was about . The target thickness was . Reprinted with permission from H. Chen et al., Phys. Rev. Lett.102, 105001 (2009). Copyright © 2009 American Physical Society.
Positron spectra from experiments with targets of Au (three upper traces), Sn (green), and Cu (purple). No positrons were detected for Cu and Sn targets. The inset shows the corresponding electron spectra for each shot (same color scheme).
Positron spectra from back (upper trace) and front (lower trace) of the target.
Energy spectra of electrons (red crosses) and positrons (blue solid squares) from experiments and EGS modeling (empty squares).
Positron yield per hot electron as a function of the Au target thickness. The short pulse duration was for all data points. The laser intensities were from , hot electron temperature from . Reprinted with permission from H. Chen et al., Phys. Rev. Lett.102, 105001 (2009). Copyright © 2009 American Physical Society.
Positron spectra for five Au targets at various thickness. For all spectra the short pulse duration was . The laser intensities were from , hot electron temperature from .
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