The determination of a neutron source position in an unknown homogeneous medium: The planar case

The possibility of localization of an unknown neutron source in various bulky homogeneous media (box) was studied. For the planar case, two 3He detectors on the opposite faces of the box were used. A constant polypropylene shield around the box and detectors was used to eliminate the varying contribution from the environment to increase count rates of the detectors and to protect the experimentalist. It is shown that the location of a single small neutron emitting source in a large box can be found to a better than 7% by using two neutron detectors positioned on parallel faces of the box, coplanar with the source. The localization requires measurement of the count rate of both the unknown source and an extra source positioned on one of the faces of the box. The localization is based on the finding that the ratio of the count rates of the two detectors is an exponential function of the distance of the source from one of the detectors.