Measurements of Neutrons from Photonuclear Reactions Using Laser Compton Scattering Gamma Rays

Abstract

The laser Compton scattering gamma ray beamline at the synchrotron light facility NewSUBARU supplies a quasi-monochromatic, polarized, high-energy photon beam. A gamma ray flux of more than 10 7 photons/s is generated at a photon energy range of 1-73 MeV. Emission distributions of the fast neutrons generated from different target materials were measured as a function of the polarization angle of the linear polarized gamma-ray beam using a time-of-flight method with fast plastic scintillators. The neutron distributions were consistent with a previous theoretical result. The relatively slow neutrons were measured via an activation method. The result demonstrated the small anisotropy of the slow neutron emission.

Spatial profiles of collimated laser Compton-scattering γ-ray beams

“…Thus, the LCS 𝛾-ray beam time structure follows the slow laser and the fast electron time structure. Neutron emission spectra measurements with the time-of-flight method make use of synchronized laser and single-bunch electron beams [38,39], where only one electron bunch circulates in the ring and collides with the laser pulse at a designed position. The electron beam current for the single-bunch operation mode is limited to ∼20-30 mA.…”