I realized I forgot to ask for clarification on the definition of “Intensity” in the context of FLUKA user source routines. Is it defined as particles per second (particles/s), watts per square meter (W/m²), or something else entirely?
I plan to perform a simulation with a continuous X-ray spectrum, but I’m not sure if I should include the intensity as photons/s or photons/s/eV with the energy values in the second column.
In the source routine, the intensities don’t have to be in any unit, they are only used as a relative probability of the given energy bin/point.
The normalization to an absolute source intensity is done after the simulation, as with any other sources.
Thank you for your response.
Please correct me if I am mistaken.
This means that the units specified in the source user routine for the particle energy spectrum do not affect the units of the scoring estimators, which are “fixed”.
For example, estimators such as DOSE in USRBIN (GeV/g per primary) or FLUENCE in USRBDX (particles/cm²/GeV per primary after integration) maintain these units.
Therefore, any conversion to different units would be handled through post-simulation normalization.