Dear @samuel_grima,
- The normalisation factor you apply is correct. The FLUKA output is per ONE primary/particle, that is why you use the source activity to convert into particles/s. I assume also you meant that you convert from seconds to minutes and then to hours.
- Of course experimentally obtaining the X-ray tube’s energy spectrum might be the most accurate, but also this depends on your time/resources. Typically, manufacturers of X-ray tubes provide the energy spectrum, or one can use an ideal one.
I can point you towards this question, for example. You just require a file with the actual energy distribution, and then some minimal changes/adjustments.