Dear David,
To give you a satisfying answer to your question we would like to point out a preliminary consideration: in reality, all energy deposition is performed by electrons. It is always important to keep this in mind, when working with artificial filtering methods like the AUXSCORE card. In fact, with the latter, the energy deposition is attributed to the particle undergoing an interaction (e.g., a neutron or a photon) if the products of the latter - which are the ones actually responsible for the energy deposition, through the generation of secondary electrons by ionization - fall below the simulation thresholds and are not explicitly tracked. Therefore, as stated in the following slides, the amount of energy distribution that is attributed to the selected particle type depends on the simulation thresholds (EMFCUT for example). If you do not set them explicitly, the code takes the default transport values (have a look under PRECISIon) into account. So depending on the chosen thresholds, you will obtain more or less energy deposition by your selected particle type. This is really well explained in the slides of the Advanced FLUKA Course.
Then, technically speaking, if you want to filter the (absorbed) dose for photons, the Set field is irrelevant, as this is only required for dose equivalent scoring. So in your case, you can ignore this entry. In this regard, I don’t manage to reproduce your error. Even with a low number of primaries I achieve enough data to produce a plot. If your problem persists, please let us know, what error message you get.
Regarding your second question: 1) For obtaining dose values, using the USRTRACK does not work as it only provides you with a transported particle spectrum but not with the energy deposition. 2) A possible solution to achieve what you want, is to work with the user routine comscw.f, which is activated by the USERWEIGht card and allows you to implement a logic that excludes energy deposition outside your neutron energy range (but again: if the neutron reaction products are explicitly tracked, being above their transport threshold, the resulting energy deposition is attributed to them and not to the original neutron).
Kind regards,
Barbara