Tracz, P.S. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-MOPO009 English 59-61 MOPO009 laser linac gun electron experiment Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-MOPO009 http://jacow.org/linac2018/papers/mopo009.pdf The Gamma Beam System at the ELI-NP under construction in Magurele/Bucharest Romania, aims at producing high brilliance gamma-rays based on the laser Compton back-scattering, up to 3.5 and 19.5 MeV out of two interaction chambers. The design of warm RF electron linac is optimized to meet the unique source specification i.e. high brilliance, small relative bandwidth, tunable energy, and high spectral density. Together with technological development in field of high energy/high quality lasers it will open new opportunities for nuclear physics research in fields like nuclear photonics, nuclear astrophysics, photo-fission, and production of exotic nuclei, applications in industry, medicine, and space science. S-band laser driven RF photo-gun and two accelerating structures constitute the injector. The beam is then accelerated by C-band linac up to 350MeV (low energy linac), and up to 720MeV (high energy linac). The GBS was designed and is being constructed by the EuroGammaS - a consortium of European academic and research institutions and industrial partners. This paper gives an overview of the facility, describes the main linac systems and summarizes the project status.