Hello forum,
I am trying to tally fission rate induced by uncollided neutrons (i.e. uncollied until triggering the fission reaction). What I was trying to do was to add a CollisionFilter([0]) to the reaction rate tally, but it seems I got some weird results:
The uncollided flux (tallied by flux + CollisionFilter[0]) looks like the following, which is mainly a 14 MeV peak:
But the uncollided fission rate (fission score + CollisionFilter[0]) in U238 is as following, with a significant non-14 MeV contribution.
Does anyone know what is exactly happening if I apply CollisionFilter([0]) to reaction rate tallies? Is it reaction rates by uncollided neutrons as I expected?
Xinyan Wang