Hi amario thanks for your reply. I am sorry that my previous description was not thorough enough,I didn’t build a model, but what I am trying to create is a more complex volume source composed of multiple bodies(yellow in the picture), I find a similar topic like this:Volumetric source of complex geometry - #2 by horvathd. They use the source.f but I have no fortran programming experience. I used the source_newgen.f, and I know source_newgen.f is a new version of source.f. So can you give me the source_newgen.f?