|Message: Re: Coherent Diffusion of gamma in physics list||Not Logged In (login)|
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Hi, Let's take the case of lead for gamma energy of about 100 keV. For this example, I will take the "Compilation of X-Ray Cross section" from Lawrence radiation Laboratory (Livermore). These are old data from 1969 but still good enough for our discussion. What do we see in this table ?
At 100keV : --> PhotoCrossSection = 1777 barns/atom --> CoherentCrossSection (Rayleigh) = 67.27 barns/atom --> IncoherentCrossSection (Compton) = 34.34 barns/atom
It is true that, compared to photoelectric effect, coherent diffusion of gamma is very small. But, on the other hand, Compton diffusion is taking into account by the physics list (LHEP_PRECO_HP), although the cross section of Compton process is very small compared to photo effect. It is even smaller than coherent scattering. So, it is logical to include Rayleigh process if Compton process is included, even far above 1keV gamma energy. But there is another possibility : I misunderstood what they called "coherent" and "incoherent" in these tables. Anyway, any comment would be appreciated...
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