闪光照相中X光能谱对有效吸收系数的影响

 研究闪光照相中影响材料有效吸收系数的两个主要因素，即X光的能谱效应和散射影响。用Monte-Carlo方法对闪光照相系统的客体各种组成材料的有效吸收系数进行数值模拟；求出不考虑散射而仅受能谱影响的有效吸收系数及其空间分布，发现该分布类似于医学CT数的分布规律，在高光程数对应的位置上该吸收系数较低；也得到了在20MeV闪光机情况下，客体各种组成材料的单个平均吸收系数。结果表明：钨、铝和铁的平均等效吸收系数分别近似为0.830，0.080和0.265cm ^-1。

Effect of X-ray penetration spectrum on attenuation coefficient in flash radiography

The paper analytically discusses two factors, the spectrum of photon and the scattered radiation by the detector, which affect the attenuation efficient of the object in flash X-ray radiography. The effective attenuation efficient for the object components is evaluated simulating X-photon transport process in radiographic system using Monte Carlo method. The effective attenuation efficient and its distribution on the image are obtained regardless of scattered effect. The distribution shape is similar to the CT number profile in medical CT reconstruction. The larger the optical path of the photon projecting an image, the smaller the effective attenuation efficient corresponding to the projecting point in the image. It is shown that the average effective attenuation efficient is 0.830cm~(-1) for tungsten with precision of 2.5%, 0.080cm~(-1) for aluminum with precision of 2.0%, and 0.265cm~(-1) for stainless steel with precision of 1.0%.