相关γ中子源的单视图三维重建
Single-View 3D Reconstruction of Correlated Gamma-Neutron Sources
摘要：
本文介绍了一种对发射关联γ射线的中子源（如Cf-252、Am-Be）进行三维图像重建的新方法。这一类别包括绝大多数在核威胁调查、保障监督和不扩散方面很重要的中子源。该技术不需要源的多个视图，而是依赖于源的符合伽马和中子发射的固有特性。因此，仅需要源的单视图测量来执行3D重建。原则上，任何对伽马射线和中子敏感的散射照相机，只要有足够的时间和相互作用位置分辨率，都可以进行这种重建。利用中子双散射技术，我们可以计算出可能的源位置的圆锥面。通过包括到相关伽马的时间，我们通过求解沿着所述圆锥的表面的源到检测器的距离来进一步约束三维中的源位置。作为一个概念的证明，我们采用这些重建技术的测量与移动成像仪的中子应急响应（MINER）。两个Cf-252源测量在50和60厘米从中心的探测器被解决在其不同的深度与平均径向距离相对分辨率为26%。为了证明该技术的潜力与优化的系统，我们模拟MCNPX-PoliMi中的测量，假设定时分辨率为200 ps（从当前系统中的2 ns）和源相互作用位置分辨率为5 mm（从3 cm）。散射相机性能的这些模拟改进导致径向距离相对分辨率降低到平均11%。
英文摘要：
We describe a new method of 3D image reconstruction of neutron sources that emit correlated gammas (e.g. Cf-252, Am-Be). This category includes a vast majority of neutron sources important in nuclear threat search, safeguards and non-proliferation. Rather than requiring multiple views of the source this technique relies on the source's intrinsic property of coincidence gamma and neutron emission. As a result only a single-view measurement of the source is required to perform the 3D reconstruction. In principle, any scatter camera sensitive to gammas and neutrons with adequate timing and interaction location resolution can perform this reconstruction. Using a neutron double scatter technique, we can calculate a conical surface of possible source locations. By including the time to a correlated gamma we further constrain the source location in three-dimensions by solving for the source-to-detector distance along the surface of said cone. As a proof of concept we applied these reconstruction techniques on measurements taken with the the Mobile Imager of Neutrons for Emergency Responders (MINER). Two Cf-252 sources measured at 50 and 60 cm from the center of the detector were resolved in their varying depth with average radial distance relative resolution of 26%. To demonstrate the technique's potential with an optimized system we simulated the measurement in MCNPX-PoliMi assuming timing resolution of 200 ps (from 2 ns in the current system) and source interaction location resolution of 5 mm (from 3 cm). These simulated improvements in scatter camera performance resulted in radial distance relative resolution decreasing to an average of 11%.
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