Production of Monochromatic γ Rays from Thin Crystal of Silicon

Abstract

An experiment has been made on production of monochromatic gamma rays by strongly collimating the coherent bremsstrahlung from a single crystal of silicon around the beam axis. The internal electron beam with the energy of 1 GeV in the synchrotron was collimated on the crystal target by a set of beam scrapers distributed at the straight sections.
The energy spectrum shows a sharp spike at the photon energy k=185 MeV with the signal-to-background ratio as large as 12 and the width at the half maximum intensity of Δk=±8 MeV. The maximum intensity of 2×10⁴ photons/MeV · sec has been obtained at the spike.
The obtained spectrum is in good agreement with theory based on Überall’s treatment, if the primary angular divergence of the incident electrons and the multiple Coulomb scattering in the radiator are taken into account.