Collimation and characterization of ELI-NP gamma beam

The ELI-NP facility, currently being built in Bucharest, Romania, will deliver an intense and almost monochromatic gamma beam with tunable energy between 0.2 and 20 MeV. The challenging energy bandwidth of <= 0.5% will be adjusted through the collimation system, while the main beam parameters will be measured through a devoted gamma-beam characterization system. 1 The gamma-beam characterization system, designed by the EuroGammaS collaboration, consists of four elements: a Compton spectrometer that measures the gamma energy spectrum; a sampling calorimeter for a fast combined measurement of the beam average energy and its intensity, which will be used also as a monitor during machine commissioning and development; a nuclear resonant scattering system for absolute energy inter-calibration of the other detectors; and a gamma beam profile imager to be used for alignment and diagnostics purposes. The collimation and characterization system will be presented in this article. These systems have already been built and tested, while the delivery at ELI-NP facility and the final commissioning is scheduled by Fall 2018.