Shielding design for a neutron-antineutron oscillation experiment

A complete analysis of the neutron flux distribution and of the gamma-rays generation and transport in a facility for an experiment on the n-n-bar oscillation to be performed at Pavia is presented. The DOT 3.5 code was used for the analysis of the reactor region and of the neutron streaming in the experimental channel, while the MORSE code was employed for the evaluation of the neutron and gamma-ray transport in the detector area and in the beam catcher room. During this study shielding solutions were proposed in order to keep the dose rate outside the neutron flight channel, in the detectors region and in the environment outside the building below the allowable levels. A concrete with a high baryte and colemanyte content, whose thickness varies from 100 to 70 cm according to the distance from the core, is used for the shielding of the channel. The radiation level on the detectors can be reduced by proper modifications of the geometrical and material arrangement of the system. (author)