Neutron shielding simulations

Neutrons can create background in experiments built to search for rare events like neutrinoless double beta decays and dark matter induced recoils of nuclei. Neutrons activate the materials used in the experiment during transportation or storage. Although cosmic-ray neutrons themselves can be shielded during storage and transportation, muons penetrate and can produce neutrons inside the shield and the material to be shielded. Cosmic-ray neutrons and muons were simulated with the GEANT4 based framework MaGe, penetrating through different materials to determine the number of neutrons and the neutron energy spectrum at different shielding depths. This allows to determine the shielding indices of the used materials. In addition, the influence of neutron backscattering was investigated. Blocks with different thicknesses were simulated and the number of outgoing neutrons was compared with the number of neutrons at the corresponding depth within a 20 m thick block. Backscattering was found to be not negligible - especially for steel.