Neutron room return effect

The coefficient that relates the neutron source strength and room surface area with the thermal neutron fluence rates has been calculated for neutrons whose energy goes from 1 eV to 20 MeV. This coefficient was calculated using Monte Carlo methods for several room's radii where a point-like source was located at the center of the room while detectors were located along the room's radius. Calculations were performed with the room with air and in vacuum.