Mehrkomponenten-Hohlraumstruktur für ein Explosivstoff-Detektorensystem.

摘要

A composite cavity structure for detecting explosive contained in objects, especially explosives, within an opening in the cavity structure by a detector structure located adjacent to the opening, including a plurality of thin nonclorinated hydrogenous wall members forming a passageway to define the opening in the cavity structure. A source of high energy neutrons located adjacent the passageway to direct neutrons into the passageway. A premoderator formed by nonchlorinated hydrocarbon material surrounding the source of high energy neutrons to slow down at least a portion of the neutrons to a lower energy. A first moderator means formed by heavy water surrounding the source of neutrons and the premoderator to slow down at least a further portion of the neutrons to a thermal energy. A second moderator formed by carbonaceous material at least partially surrounding the plurality of thin hydrogenous wall members and the first moderator to slow down at least an additional portion of the neutrons to a lower energy and reflect back the additional portion of neutrons into the opening. The plurality of thin hydrogenous wall members additionally forming a third moderator to additionally slow down high energy neutrons passing within the opening and with the combination of the premoderator and the first, second and third moderators moderating the neutrons produced by the neutron source to form a spectrum of neutrons in the opening having a peak value in the thermal energy portion of the spectrum to maximize the detection nitrogen by interacting the thermal neutrons with the nitrogen to produce gamma rays for detection by the detector structure.