I am trying to model my source like a compound instead of a single ion, LaBr3(Ce). The idea is to get an estimate of the internal activity of a LaBr3 detector due to the presence of 138La. ( 0.089 relative abundance).
The other approach is to model a 138La cylindrical source with a given length and diameter.
I am not clear as to how to incorporate the natural abundance of 138La (0.089%) in that volume. Is there any command to control the activity/amount of ions?
Or is it possible to model a radioactive source with a compound(here LaBr3(Ce)) instead of an ion?