Year
2019
Abstract
A novel prototype handheld neutron scatter camera (NSC) composed of eight stilbene bars coupled to C-Series SensL silicon photomultipliers has been built for detecting and localizing special nuclear material (SNM). SNM emits neutrons either passively or when actively interrogated. Spontaneous or induced fission neutrons can be used as a key signature of the presence of SNM because neutrons do not make up a significant portion of background radiation. A crucial operational parameter for imagers is the number of events necessary to be confident in the location of a source. This parameter is of paramount importance for inspectors and emergency responders who need to be able to locate or verify the location of a source as fast as possible. To demonstrate this capability using the prototype handheld NSC, low-statistics images composed of up to 100 imageable events were analyzed from a Cf-252 spontaneous fission source to determine the variance in highest pixel location and full width at half max of the source location in the image. This analysis of the Cf-252 source was then compared to measurements of a ½” tungsten-reflected 4.5 kg sphere of alpha-phase weapons-grade plutonium, a 3.3 kg cylinder of weapons-grade plutonium oxide, and the two sources in the same field of view. These measurements demonstrate the capability of this imager to locate sources of SNM and identify multiple sources in the same field of view with relatively low statistics.