Energy Flash Photography Midline Absorption Coefficient

The flash X-ray radiography can detect the density of the unknown object. Before getting the result of the density distribution of the object from the flash X-ray radiography with the " CT(Computerized tomography) method, The attenuation coefficient of the object must be known first. And the attenuation coefficient only can be got from the known object.In this- paper not only the theory of the spectrum effect and the scatter impact has been consummated, but also the spectrum effect and scatter impact of FTO (French Test Object) has been given with different methods. By researching on the known object , The relation between the LAC (linear attenuation coefficient) and the thickness of the material has been concluded, which supplies the valuable coefficient fort he unknown object. On the side of the theory, The formulation of LACOS (the linear attenuation coefficient over the spectrum) is given at any space point, And the theoretic explain of the spectrum effect is worked out.In order to realize the spectrum effect, three kinds of methods, analytical method, absorption pieces method and MC (Monte-Carlo) particle transmission method, are used. The same results is got out from the different methods. The result of analytical method is that the AELACs (average effective linear attenuation coefficient) of tungsten and copper are, uW=0.843 (1.37%) cm-1, uCu=0.299 (1.44%) cm-1, the result of absorption pieces method is uW=0.8442 (1.38%) cm-1, uCu=0.298 (1.12%) cm-1, and the result of MC particle transmission method is uW =0.832 (0.87%) cm-1, uCu =0.299 (0.61%) cm-1. The spectrum effect makes LACOS lower via the deeper thickness of the material, and the rms error of the AELAC is less than 2%, in another word, the spectrum effect on the LAC is less then 2%.The MC particle transmission method and MHC (multiple holes collimator) method is brought out on the scatter impact. The results show that the impact of greater scatter on the LAC exceeds 40%. the result of MC particle transmission method on scatteri mpact is uW=0.835 (0.89%) cm-1, uCu=0.294 (0.40%) cm-1, and the result of MHC method is uW=0.825 (1.53%) cm-1, uCu=0.296 (0.49%)cm-1. The spectrum hardening of the back protection causes the results of scatter impact lower than the result of the spectrum effect.For the characteristic of the attenuation coefficient of different material, the numerical value of research result is only valuable for the same kind model. But the research methods are always usable for any model.