Reconstruction of the laser Compton scattered gamma-ray distribution in the energy-angle phase space from crystal diffraction data

Abstract

The distribution of laser Compton scattered (LCS) photons in the energy-angle phase space reflects the parameters of the laser and electron beams at the collision point and provides the spectral density and bandwidth available in the LCS source. Diagnosis of the energy-angle phase space is thus crucial for developing high-flux and narrow-bandwidth LCS sources. Such diagnosis has been utilized for photon energies below 100 keV, but not realized for photon energies above 1 MeV. We demonstrated reconstruction of the energy-angle phase space distribution of an LCS photon beam at an energy of 1.7 MeV by utilizing photon diffraction with a silicon mosaic crystal and a silicon comb crystal, both of which have enlarged integrated reflectivity. The reconstructed photon distribution is well reproduced by numerical simulations. The demonstrated diagnostic technique is an efficient tool for the development of LCS photon sources and is beneficial to the use of existing LCS facilities.