Explanation of particle types in USRBDX

Scoring and Biasing
#1

Dear FLUKA Experts,

I have been using FLUKA to simulate a proton beam on an apparatus of gold, copper, aluminum, and niobium. I then use RESNUCLE and RADDECAY to track the radioisotopes after irradiation with the proton beam. I am now trying to score the radiation from these decaying isotopes with USRBDX. Thanks to @horvathd I now believe I am doing this successfully for photons between 1 and 100 keV. (Thanks David!)

Now I want to look at other potential particles coming from the decaying activation products. Starting with alpha particles I assume I would select “4-HELIUM” in What(2) of USRBDX. I have searched the manual but cannot find more descriptions of what the different particle options mean, for example: does LGH-IONS mean light ions below a certain mass number? Is there a reference available that gives an explanation for each of the particle type options?

Also I am curious about how FLUKA calculates these values, is it an analytic solution based on the isotopes produced, their activity, and their locations? or is it another round of Monte Carlo simulations taking place using the output of the original activation and decay as an input to the new simulation?

These are some of my initial questions but really I was wondering if there is a resource that you can point me to where I can find answers to these types of things?

Thank you!
-Jason

#3

Hi @Jason_O, the first reference is in fact the manual, where all your questions above are answered.
In particular, only electrons, positrons and gammas are transported for the time being in the decay phase (see note 4 of RADDECAY), so you cannot score any other kind of particle type (alphas are planned to come, while the alpha decay itself is already taken into account for isotope calculation purposes).
LGH-IONS include alphas and all ions lighter than alphas (deuterons, tritons, and 3-He), as indicated in the list of Chapter 5.
FLUKA adopts both the analytic solution (as calculations at specific cooling times are requested) and the Monte Carlo approach (as a radioactive source is simulated), see again RADDECAY, note 1.

#4

Thank You very much, I was stuck on looking in USRBDX and didn’t think to look in RADDECAY

#5