Gamma beam collimation system and profile imager for ELI-NP

ELI-NP-GBS is a high-brilliance gamma source that will produce monochromatic beams in the energy range 0.2–19.5 MeV through inverse Compton scattering. In order to obtain a monochromatic beam a collimation of the emission is necessary. Depending on the energy, the angular aperture required to provide the design bandwidth ΔE/E=0.5% is between 70 and 700 μrad. This collimation is provided by a stack of 14 tungsten slits, arranged with a relative rotation around the beam axis, so that the overlap will be a continuously adjustable aperture. To monitor the operation and alignment of the collimation, a set of detectors will provide a complete characterization of the gamma beam, including the measurement of the transverse spatial distribution. For this task a gamma beam profile imager based on a thin scintillator screen and a high-resolution CCD-camera was developed. In this work we briefly present the status of the collimation system and beam profile imager, which were designed, assembled and are currently under test at INFN-Ferrara laboratories.