Monte-Carlo simulations of neutron shielding for the ATLAS forward region

The effectiveness of different types of neutron shielding for the ATLAS forward region has been studied by means of Monte-Carlo simulations and compared with the results of an experiment performed at the CERN PS. The simulation code is based on GEANT, FLUKA, MICAP and GAMLIB. GAMLIB is a new library including processes with γ-rays produced in (n, γ), (n, n′γ) neutron reactions and is interfaced to the MICAP code. The effectiveness of different types of shielding against neutrons and γ-rays, composed from different types of material, such as pure polyethylene, borated polyethylene, lithium-filled polyethylene, lead and iron, were compared. The results from Monte-Carlo simulations were compared to the results obtained from the experiment. The simulation results reproduce the experimental data well. This agreement supports the correctness of the simulation code used to describe the generation, spreading and absorption of neutrons (up to thermal energies) and γ-rays in the shielding materials. The simulation code provides a powerful tool which allows the extrapolation to the ATLAS forward region of the shielding concept tested at the CERN PS. Based on the results of Monte-Carlo simulations, a comparison between various proposed types of neutron and γ-rays shielding for the ATLAS forward region is presented.