Characterization results of the BNL ATF Compton X-ray source using K-edge absorbing foils

Abstract

Spectral and angular information of inverse Compton sources is shown to be obtainable using only an X-ray imaging device and various foils with K-edges in keV energy range. Beam parameters can be chosen such that on-axis photons are above the K-edge for a given material, where absorption is very strong and there is relatively zero transmission. Photons observed off-axis are red-shifted and fall below the K-edge, therefore being transmitted and creating a “ring” pattern in the ideal case. Starting with photon energies below the K-edge and aperturing for small angles on-axis allows one to scan the electron beam to higher energy until all scattered photons are above the K-edge and absorbed, thus presenting a method of bandwidth measurement. Using these methods, we present experimental results of the bandwidth and double differential spectrum (DDS) for angle and energy of Compton photons generated at the Brookhaven National Laboratory Accelerator Test Facility (BNL ATF).