Dear expert，
I am sorry to disturb you.
I thought this is a quite simple question, but I don’t where the problem is now.
I used usrbdx to calculate the photons emitted from a irradiated isotpte target. And then using the photon spectrum as source(file enegy_spe.txt), I calcultaed the shielding width of Pb(shielding.inp).
The result seems to be strange and not right. When I used a normal monoenergy photon souce, it’s fine.
So is there any wrong with the secondary photon source profile? And where can I find the newest describtion for the source_newgen.f?what’s the unit of the intensity in chapter 3.4.5 in the file source_newgen.f?
Great thanks for your kind help.
Best regards,
I don’t see a problem with the energy sampling (you may want to energy_logical_flag to .true. to be pedantic, but this doesn’t matter for photons), but you need to have the isotropic direction sampling in the source routine as well.
The intensities don’t have a unit in the energy sampling because they are taken as relative values. The results will be normalized to one primary photon of the simulation. Then you need to scale the result of the actual intensity of the source.
Dear expert, thank you so much, your quick reply solved my problem.
I know now that this result are normalized to one primary in the calculation. Before that, I thought the big value I set in the spectrum file is meaningful, and it is the absolute value. Actually, they are relative values.