Gamma beam collimation and characterization system for ELI-NP-GBS

ELI-NP-GBS is a gamma source based on inverse Compton interaction that will provide photons with tunable average energy ranging from 0.2 to 19.5 MeV, energy bandwidth down to 0.5% and average flux of about 108 photons/s in ultra-short pulses. Given these challenging characteristics, dedicated devices and techniques were developed to measure and monitor the gamma beam parameters during the commissioning and the operational phase. Futhermore an adjustable collimation system was developed to fulfill the beam monochromaticity requirement. The gamma beam characterization and collimation apparatus, currently assembled and under test at INFN-Ferrara laboratories, is described in this work