Neutron angular distribution in (γ, n) reactions with linearly polarized γ-ray beam generated by laser Compton scattering

In 1957, Agodi predicted that the neutron angular distribution in (γ, n) reactions with a 100% linearly polarized γ  -ray beam for dipole excitation should be anisotropic and universally described by the simple function of a+b⋅cos⁡(2ϕ)a+b⋅cos⁡(2ϕ) at the polar angle θ=90°θ=90°, where ϕ is the azimuthal angle. However, this prediction has not been experimentally confirmed in over half a century. We have verified experimentally this angular distribution in the (γ, n) reaction for 197Au, 127I, and natural Cu targets using linearly polarized laser Compton scattering γ  -rays. The result suggests that the (γ→, n) reaction is a novel tool to study nuclear physics in the giant dipole resonance region.