Abstract: The disclosed innovative, interceptor seeker discriminator system has the capability to home in on targets containing nuclear materials by detecting the gamma fissions. The gamma signatures can be obtained from activating the nuclear material by a Neutral Particle Beam Weapon, or by detecting the natural fission emissions of the warhead. This system is innovative, in that the following properties are identified: 1) This system uses interactive discrimination techniques, which allows the gamma seeker to accurately home in on a true RV by comparing the return gamma emissions of objects. In this manner, the gamma seeker discriminator is expected to obtain substantially better discrimination K factor performance, when compared to using only IR techniques. 2) This system uses an interceptor/seeker to perform interactive discrimination and gamma sensors in conjunction with infrared sensors on the same interceptor platform (i.e., sensor fusion).