# Normalize for the real number of primaries

Dear FLUKA experts,
I am running a simulation where I produce neutrons with spallation using
Carbon ions. The results that i get with scoring, for example the usrbin,
for the Carbon ions are normalized for the number of Carbon ions (the
primaries). To normalize to the neutrons what I have to do?I have seen
that for a proton produces in average 12 neutron.
Best regards and thank you for your time.
Xiaoman

Dear Xiaoman @xiaoman.li,

The answer is partly in your question. The number of neutrons produced by each impinging ion is a statistical quantity (indeed you mention its average value). This is not the case for the primary particles that you can use to precisely normalise to a given (integrated) beam current.

If instead for whatever reason the goal is indeed to normalise your results (e.g. a scoring of energy deposition, or fluence etc.) to the total neutron yield (rather than to the incident beam) you can do so by detemining the yield (e.g. 12 neutrons/ion) and normalising by this value, knowing however that in this case the normalisation factor itself comes with an uncertainty.

Having said that, I am not sure how to interpret the title of your question (“Normalize for the real number of primaries”). What do you mean by real? It would seem to me that all quantities need to somehow refer to the impinging beam rather than the produced secondary particles.

Regards,
Andrea