Interaction of proton beam with thin boron targets - which IONTRANS should I use?

Dear FLUKA experts,

I’m a FLUKA beginner and after I performed few preliminary simulations of proton beam (maximum energy 5MeV, minimum single keVs with custom, imported proton energy spectrum) a few questions arose:

  1. Assuming targets with thickness of tens of micrometers, is it reasonable to activate LAM-BIAS card? If so, should I aim to decrease inelastic scattering length to the level of the target itself? I’d be glad for some guidance with this one.
  2. If I’m interested in measuring number of alphas produced during interaction, is 4-Helium IONTRANS card just fine, or using full transport is required to obtain accurate results?
  3. Are any other Physics or Transport cards required to perform a meaningful, actually physical simulation?
  4. I am using USRTRCK to count number of alphas exiting the boron target to void sphere with Type: I1,LinE,LinΩ. To convert it to number of alpha particles, I am graphing with DX*Y plot for Y values and then multiply it with the number of primaries used. Is it correct calculation of total number of alphas from differential alpha particle flux which USRTRCK provides?
  5. I’m worried about cross-sections of p+B reaction. According to one of the topics I found on forum (from 2020) it seems like the 675keV protons won’t undergo any nuclear reactions with boron target. Did anything change in this matter and is there any way to include such reactions in my simulation?

Below you can find a *.inp file for simulations I performed.
preliminary.inp (2.0 KB)

Thanks in advance,

Best regards,
Przemysław