Design of a portable directional neutron source finder

An instrument that determines the direction of a remote existing neutron source has been designed. This instrument combines a polyethylene block and four 3He counter tubes. The advantages of the instrument are portability and good angular resolution. The count from the detector was varied with the neutron incident angle due to the moderator. Using this characteristic, the direction of the neutron source can be measured precisely by revising the axis of the instrument so that the difference between the four detectors measurements is minimized. Consequently, the direction of the central axis of the instrument in which the response difference of the four detectors reaches a minimum indicates the direction of the neutron source. The practical use of the instrument was demonstrated by 252Cf source irradiation experiment and MCNP simulation.