Ultra-high brilliance multi-MeV $\gamma$-ray beam from non-linear Thomson scattering

TL;DR

This paper demonstrates the generation of a highly brilliant, narrow-divergence, multi-MeV gamma-ray beam via non-linear Thomson scattering using laser-wakefield accelerated electrons and intense laser fields, with the highest brilliance reported in this energy range.

Contribution

It reports the first experimental realization of a multi-MeV gamma-ray source with ultra-high brilliance from non-linear Thomson scattering.

Findings

Gamma-ray beam energy up to 18 MeV.

Narrow divergence of approximately 2.5 mrad.

Highest brilliance in multi-MeV gamma-ray regime reported to date.

Abstract

We report on the generation of a narrow divergence ($\theta\approx 2.5$ mrad), multi-MeV ($E_\text{MAX} = 18$ MeV) and ultra-high brilliance ($\approx 2\times10^{19}$ photons s$^{-1}$ mm$^{-2}$ mrad $^{-2}$ 0.1\% BW) $\gamma$-ray beam from the scattering of an ultra-relativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude $a_0\approx2$). The spectrum of the generated $\gamma$-ray beam is measured, with MeV resolution, seamlessly from 6 MeV to 18 MeV, giving clear evidence of the onset of non-linear Thomson scattering. The photon source has the highest brilliance in the multi-MeV regime ever reported in the literature.