Creation of super-high-flux photo-neutrons and gamma-rays > 8 MeV using a petawatt laser to irradiate high-Z solid targets

TL;DR

This paper demonstrates the generation of extremely high-flux gamma-rays and photo-neutrons (>8 MeV) using a petawatt laser irradiating high-Z targets, enabling advanced nuclear physics research and potential nuclear energy applications.

Contribution

It reports the first creation of super-high-flux gamma-rays and neutrons (>10^27 gammas/cm^2/sec and >10^20 neutrons/cm^2/sec) with a petawatt laser, surpassing previous experimental flux levels.

Findings

Generated gamma-ray flux >8 MeV reached ~10^27 gammas/cm^2/sec.

Produced photo-neutron flux reached ~10^20 neutrons/cm^2/sec.

Detected up to several trillion gamma-rays and billions of neutrons per shot.

Abstract

We report the creation of super-high-flux gamma-rays with energy >8 MeV and photo-neutrons via the (g,n) reaction near giant dipole resonance energies (8 - 20 MeV), using the ~130 J Texas Petawatt laser to irradiate high-Z (Au, Pt, Re, W) targets of mm - cm thickness, at laser intensities up to ~5x1021W/cm2. We detected up to ~ several x 1012 gamma-rays > 8 MeV (~3% of incident laser energy) and ~ 1010 photo-neutrons per shot. Due to the short pulse and narrow gamma-ray cone (~17o half-width) around laser forward, the peak emergent gamma-ray flux >8 MeV reached ~1027 gammas/cm2/sec, and the peak emergent neutron flux reached ~1020 neutrons/cm2/sec. Such intense gamma-ray and neutron fluxes are among the highest achieved for short-pulse laser experiments. They will facilitate the study of nuclear reactions requiring super-high-flux of gamma-rays or neutrons, such as the creation of r-process elements. These results may also have far-reaching applications for nuclear energy, such as the transmutation of nuclear waste, isotope production and inertial fusion.