Advanced active interrogation sources for remote detection of special nuclear material
AWE has recently commenced a research programme to develop techniques for the remote detection of illicitly trafficked, special nuclear material. Three techniques that are being investigated as part of this programme utilise an active interrogation source to stimulate a radiation signature within SNM. A photonuclear technique and nuclear resonance fluorescence require an active gamma source while a technique stimulating fission with low energy neutrons requires a low energy neutron source. The potential for consolidation of the photonuclear and neutron technique is discussed. Conceptual designs of intense, pulsed, ion beam diodes to generate suitable sources of 6-7MeV gamma photons for the photonuclear technique and ≪100keV neutron sources for the active neutron technique are presented. The sources required for remote detection via the 60keV neutron or photofission techniques are contrasted with the source requirements for nuclear resonance fluorescence.
Nuclear resonance fluorescence imaging in non-intrusive cargo inspection
Abstract Nuclear resonance fluorescence is able to non-intrusively interrogate a region space and measure the isotopic content of the material in that space for any element with atomic number greater than that of helium. The technique involves exposing material to a continuous energy distribution of photons and detecting the scattered photons that have a discrete energy distribution unique to an isotope. The interrogating photons, which range from 2 to 8 MeV, are the most penetrating probes and can “see” through many inches of steel. Determination of the chemical components of the material occupying a region of space greatly enhances the identification of threats such as explosives, fissile materials, toxic materials and weapons of mass destruction. Systems can be designed to involve minimal operator intervention, to minimize dose to the sample, and to provide high throughput at commercial seaports, airports and other entry points.
Efficient High-Energy Pulse-Train Generation Using a 2 n-Pulse Michelson Interferometer.
We demonstrate a novel, Michelson-based, ultrafast multiplexer with a throughput approaching 100% for a polarization-multiplexed train and 50% for a linearly polarized train, which is compatible with a high-energy pulse train and shaped-pulse generation. The interpulse spacings in the resultant 2(n)-pulse train can be adjusted continuously from multinanoseconds through zero. Using this interferometer, we also demonstrate generation of a 16-pulse train of terahertz pulses.