Relation of the differential and cumulative fluences in USRBDX and USRTRACK

Dear FLUKA experts,

I am using USRTRACK to estimate track-length fluence of photons in order to obtain tungsten x ray spectrum. But, I could not determine the relation between Cumul. Flux (Part/cmq/pr) and Flux (Part/GeV/cmq/pr). The normalization factor changes depending on electron beam energy, number of histories and cycle number. What is the formula for normalization to convert Cumul. Flux into Flux or vice versa.

Best regards,

Dear Selman,

the cumulative fluence values are integrated values of the fluence down to the actual bin’s energy.

I.e. The fluence result is multiplied with the energy bin width, and then it is summed up with the integrated value of the higher energy bins.

While the results certainly depend on the beam energy, they should not change with the number of primaries / cycles (if good statistics have been reached).


Repeating @horvathd’s words in semi-formulaic fashion:

Cumul. Flux at E = Integral of Flux dN/dE in dE between E and E_max

Dear Dávid and Francesco,

Thank you for your replies.