Photo-transmutation of long-lived radionuclide Cs-135 by laser-plasma driven electron source

TL;DR

This paper demonstrates, through simulations, that laser-plasma driven electron sources can induce photonuclear reactions to transmute long-lived radionuclide Cs-135, highlighting optimal laser intensities and target geometries for maximum yield.

Contribution

It introduces a novel simulation-based analysis of laser-driven photo-transmutation of Cs-135, identifying optimal conditions for maximum reaction yield.

Findings

Maximum reaction yield of 10^8 per Joule at 10^{21} W/cm^2

Laser intensity and target geometry significantly affect transmutation efficiency

Optimal target sizes depend on laser intensity for best yield

Abstract

Relativistic electrons, accelerated by the laser ponderomotive force, can be focused onto a high-Z convertor to generate high-brightness beams of gamma-rays, which in turn can be used to induce photonuclear reactions. In this work, the possibility of photo-transmutation of long-lived radionuclide Cs-135 by laser-plasma driven electron source has been demonstrated through Geant4 simulations. High energy electron generation, bremsstrahlung and photonuclear reaction have been observed at four different laser intensities of 10^{20} W/cm^2, 5 times 10^{20} W/cm^2, 10^{21} W/cm^2 and 5 times 10^{21} W/cm^2, respectively. It was shown that the laser intensity and the target geometry have strong effect on the transmutation reaction yield. At different laser intensities the recommended target sizes were found to obtain the maximum reaction yield. The remarkable feature of this work is to evaluate the optimal laser intensity to produce maximum reaction yield of 10^8 per Joule in laser pulse energy, which is 10^{21} W/cm^2. Our study suggests photo-transmutation driven by laser-based electron source as a promising approach for experimental research into transmutation reactions, with potential applications to nuclear waste management.