Subsurface Inspection with X-ray Generated Positrons

提出了一种用于金属和其他高密度材料无损检测的高能后向散射成像系统。由于高能x射线的电子/正电子对的高产量以及由此产生的韧致辐射和湮灭辐射的近各向同性性质，这种系统将用于高密度阻止康普顿反向散射的使用以及气隙阻止噪声比传输的应用。​pi先前的蒙特卡罗模拟表明，该后向散射系统能够将材料成像到允许0.511 MeV湮灭光子和轫致辐射光子出口的深度，这些光子主要由轫致辐射和正电子湮灭辐射组成。该系统的空间分辨率和对比度辨别很大程度上依赖于成像材料中电子的平均自由程。因此，有必要对原始散射剖面进行数学校准，以获得有关地下成分的形状、深度和组成的信息。这种技术在现有的无损检测中是无可替代的。

PIs' proposed the construction a high-energy backscatter imaging system designed for nondestructive testing of metals and other high density materials. Such a system will be useful for applications where high density prevents the use of Compton backscatter and where air gaps prevent the transmission of noise ratio because of the high yield of electron/positron pairs from high-energy X-rays and the near-isotropic nature of the resulting bremsstrahlung and annihilation radiation. PIs' previous Monte Carlo simulations show that this backscatter system is capable of imaging materials to depths that permit the exit of 0.511 MeV annihilation photons and bremsstrahlung photons composed primarily of bremsstrahlung and positron-annihilation radiation, the spatial resolution and contrast discrimination of the system are strongly dependent upon the mean free paths of the electrons in the materials imaged. For this reason, it is necessary to perform mathematical calibration of the raw scatter profiles to obtain information about the shape, depth and composition of the subsurface components. This technique has no substitute in existing nondestructive testing.