Detectors for Active Interrogation Applications

Clarke, S. D.; Hamel, M. C.; Bourne, M. M.; Pozzi, S. A.

doi:10.1016/j.phpro.2017.09.006

Title: Detectors for Active Interrogation Applications

Journal Article · Thu Oct 26 00:00:00 EDT 2017 · Physics Procedia

DOI:https://doi.org/10.1016/j.phpro.2017.09.006· OSTI ID:1454802

Clarke, S. D. ^[1]; Hamel, M. C. ^[1]; Bourne, M. M. ^[1]; Pozzi, S. A. ^[1]

Univ. of Michigan, Ann Arbor, MI (United States). Nuclear Engineering and Radiological Sciences

Active interrogation creates an environment that is particularly challenging from a radiation-detection standpoint: the elevated background levels from the source can mask the desired signatures from the SNM. Neutron based interrogation experiments have shown that nanosecond-level timing is required to discriminate induced-fission neutrons from the scattered source neutrons. Previous experiments using high-energy bremsstrahlung X-rays have demonstrated the ability to induce and detect prompt photofission neutrons from single target materials; however, a real-world application would require spectroscopic capability to discern between photofission neutrons emitted by SNM and neutrons emitted by other reactions in non-SNM. Using digital pulseshape discrimination, organic liquid scintillators are capable of reliably detecting neutrons in an intense gamma-ray field. Photon misclassification rates as low as 1 in 10⁶ have been achieved, which is approaching the level of gaseous neutron detectors such as ³He without the need for neutron moderation. These scintillators also possess nanosecond-timing resolution, making them candidates for both neutron-and photon-driven active interrogation systems. Lastly, we have applied an array of liquid and NaI(Tl) scintillators to successfully image 13.7 kg of HEU interrogated by a DT neutron generator; the system was in the direct presence of the accelerator during the experiment.

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