Compact high energy x-ray spectrometer based on forward Compton scattering for high intensity laser plasma experiments

This article describes the design and presents recent results from testing and calibration of a forward Compton scattering gamma-ray spectrometer. The calibration was performed using a bremsstrahlung source on the photon scattering facility at the ELBE accelerator at Helmholtz-Zentrum Dresden-Rossendorf, which provides gamma-ray photons with energies up to 18 MeV. The calibration was conducted at different bremsstrahlung end point energies - 10.5, 13, 15 and 18 MeV. Experimental spectra show systematic increase in the maximum energy, photon temperature and flux. The spectrometer is effective for an energy range of 4 to 20 MeV with 20 to 30% energy resolution. The article also describes the design and shielding considerations which helped to achieve a dynamic range greater than 30 with this spectrometer. The comparison between experimental results and Monte Carlo simulations are also presented.