论文部分内容阅读
Nuclear nonproliferation is of critical impor-tance for global security.Dangerous fissile materials including highly enriched uranium and weapons-grade plutonium are especially important to detect.Active interrogation techniques may result in much better sensi-tivity but are difficult with conventional portal monitors that rely on detecting thermal neutrons.Also,most con-ventional portal monitoring systems rely on 3He,which has a finite and continually decreasing supply.By designing a highly segmented array of organic scintillators,we posit that we can accurately and quickly identify fissile materi-als,including weapons-grade plutonium and highly enri-ched uranium,being smuggled.We propose a new design for a fast-neutron detector that overcomes the limitations of the current generation of portal monitors.MCNP6 simulations have been performed in conjunction with the UMPBT statistical model to determine the sensitivity limitations of the proposed detector.Results suggest that the proposed detector may be ～ 10 times more efficient than current-generation thermal neutron detectors and may be able to positively identify a ～ 81 mg 235U source in as little as 192 seconds utilizing active interrogation techniques.