Measurement of Room Return Neutrons

It is often difficult to determine accurately the number of neutrons incident on a detector because of room return, the scattering of neutrons from nearby material into the detector. We have developed a neutron detection platform mounted on a scissor lift so that room return can be minimized in our counting experiments. I am measuring the neutron counting rate as a function of the height of the platform above a concrete slab located below the lift. I am doing this measurement with a cadmium capture-gated neutron detector with neutrons from a 252-Cf source located at a fixed position on the platform.