With advancements in laser electron acceleration, laser-driven γ rays could be generated with extremely high intensities^[1]. The accurate monitors of the electron beams and γ-ray fluxes are very important for laser-driven photonuclear studies^[2,3,4,5]. Here we measured the flux-weighted average cross sections and average cross sections per equivalent quantum of ²⁷Al(γ, x; x = 2pn, pd, 3He)²⁴Na reaction above the giant dipole resonance region through activation methods^[6]. Laser-driven ultra-intense bremsstrahlung γ-rays, generated by laser wakefield accelerated quasi-monoenergetic electrons, were used in the experiment at the 200 TW laser facility of the Compact Laser Plasma Accelerator Laboratory (CLAPA), Peking University. The averaged intensities of the bremsstrahlung γ-ray more than 10⁸ (γ-ray energies ≥ 8 MeV) were given by the Turbo-ICT and the energy spectrum was simulated using GEANT4 codes. The results demonstrated good agreement with previous works and were compared with theoretical values given by TALYS 1.9 calculations. The experimental cross sections were confirmed to be 2.4 times higher than TALYS 1.9 with default options. This work proved the feasibility of using the ²⁷Al(γ, x) ²⁴Na reaction as monitors for laser wakefield accelerated electrons and their bremsstrahlung γ-ray fluxes.

laser-driven γ-ray,27Al(γ, x; x = 2pn, pd, 3He) 24Na reaction,γ-ray flux monitor,photonuclear reaction,cross section