FLUKA Simulation Studies for Radiation Transport, Shielding, and Activation in ZEUS and OPAL Laser Facilities

We present FLUKA-based Monte Carlo [1] simulations supporting shielding design and radiation safety in high-intensity laser facilities. Initial simulations were performed on the ZEUS Target Area 3 geometry at the University of Michigan to estimate dose to passive dosimeters from a series of experiments. The integrated dose calculated from the measured distribution of electron spectra of many laser shots on ZEUS shows good agreement with measurements, increasing confidence in the simulation. We then evaluated preliminary shielding for the planned NSF OPAL facility at the University of Rochester. Simulations cover proton (up to 500 MeV), deuteron (up to 200 MeV), neutron (up to 40 MeV), and 10 GeV electron beams. In electron simulations, we tested the effectiveness of the beam dump design developed for ZEUS Target Area 1 [2] in attenuating high-energy electrons produced at NSF OPAL and found it to be effective. We also assessed residual activation across shielding materials for long-term operations. A complementary muon study at ZEUS shows low production and escape at ~2 GeV, but as energies rise to 10 GeV, detectable muons beyond shielding are expected. This provides an opportunity to explore muon diagnostics and experiments even outside of the target area. This work supports shielding and experimental planning for next-generation laser systems at ZEUS and OPAL.