An activation database for materials used at high-intensity laser acceleration facilities

The ELI Beamlines facility will be the high-energy, high repetition-rate laser pillar of the Extreme Light Infrastructure (ELI). The goal of ELI Beamlines is to deliver ultra-short, high-energy laser pulses for the generation and applications of high-brightness X-ray sources and accelerated particles. Particle beams are expected to operate in an unprecedented energy range for laser-driven accelerators, going up to 10 GeV for electrons and 250 MeV for protons, with envisaged upgrade to higher energies (up to 50 GeV for electrons and to 3 GeV for protons). Depending on the experimental setup, the number of particles per laser shot is expected to be 109 -1011. The high energy and the large current per shot of the produced beams, together with the possibility to operate at 10 Hz laser repetition rate, require an adequate evaluation of activation in structural materials. Several radiation protection problems, such as minimization of residual dose rates and management of activated materials (short and long-term storage and eventual decommissioning), must be assessed.
A comprehensive database covering all the energies and materials of interest is being developed using FLUKA, a Monte Carlo transport code successfully benchmarked for the production of radioactive nuclides. Results for electrons and protons at different energies are presented. These results, although focused on the needs of laser-driven accelerators, are likely to be useful also when designing more conventional facilities.