I’m trying to score neutrons due to spontaneous fission from uranium fuel. I am able to score alphas successfully but I’m not getting any data for neutrons. I tried running example rdecay02 with macro u238c.mac which should model the decay of stationary u238 nuclei but I’m having the same problem where there are no neutrons scored in the secondary particle output file. In my own model I have implemented the physics list and biasing physics from rdecay02 and also used /process/had/rdm/BRbias true in my macro to switch on branching ratio biasing but no luck so far. Am I missing something?
I am bumping this old thread because of a recent post and because it is the top result on google for this very common problem.
What I encoutnered is that RDbias simulates the gamma multiplicity but not the neutrons for fission sources. The most general solution I found was to provide a custom decay file to
/process/had/rdm/setRadioactiveDecayFile Z A <your_file.txt>
The conventions for the file are buried in a readme in a location like …/Geant4/data/RadioactiveDecay5.X as well as the files used specifically for the radioactive decay module. The current version of the readme with 4.11.3 is attached. There are copies of these files elsewhere. You can use the attachment posted in this thread as an example.