An ongoing programme investigating the active detection of special nuclear material (SNM) is being undertaken by the Atomic Weapons Establishment (AWE) in collaboration with the Naval Research Laboratory (NRL). As part of this programme, the NRL Mercury IVA was operated in negative polarity mode to produce an 8 MeV endpoint Bremsstrahlung spectrum, which in turn was used to induce photofission in a depleted uranium (DU) sample. Twenty-six experiments were fielded in March 2011 and good data was obtained for high-Z (lead) and hydrogenous (borated polyethylene) shielding configurations where a positive detection was made up to the maximum shielding tested, 75 g/cm2. In December 2012 further experiments were conducted to directly determine performance through high-Z (steel) shielding at the same facility. With over 80 detectors fielded on more than 70 experiments, this further experimental series represents a step change in performance evaluation of pulsed power driven active detection. We report on analysis of the six liquid scintillation detectors (Eljen 301) which demonstrated a positive detection (>5 σ above background) at the highest shielding level tested.
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机译：原子武器机构（AWE）与海军研究实验室（NRL）合作，正在进行一项研究计划，以主动检测特殊核材料（SNM）。作为该计划的一部分，NRL Mercury IVA以负极性模式运行，以产生8 MeV端点的ms致辐射光谱，而该光谱又被用于诱导贫铀（DU）样品中的光致裂变。 2011年3月进行了26项实验，获得了高Z（铅）和氢（硼酸聚乙烯）屏蔽配置的良好数据，其中阳性检测达到所测试的最大屏蔽值75 g / cm 2 。 2012年12月，进行了进一步的实验，以通过同一设施的高Z（钢）屏蔽层直接确定性能。随着80多个检测器在70多个实验中的应用，这个进一步的实验系列代表了脉冲功率驱动有源检测性能评估中的一步变化。我们报告了六个液体闪烁检测器（Eljen 301）的分析结果，这些检测器在测试的最高屏蔽水平下显示出阳性检测结果（比背景高出5σ）。
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