Question about the correct energy units in read_phase_space_file

Dear Fluka experts,
I have a doubt about which energy unit i have to use in the read_phase_space_file function.
The process I use to create the phase space file is the following:

  1. Run a simulation using an electron beam
  2. Sample neutrons on a surface
  3. Create a ROOT multi dimensional histogram (THnSparse) with the variables needed for the phase_space_file
  4. Use the function GetRandom to regenerate the distributions and print a phase space file

On step 3 I fill the histogram with the variable PTRACK from the file TRACKR, obtained from a custom mgdraw.f

Here 5.3. Physical units — FLUKA Manual I read that the energy unit of this variable should be GeV/c.

My doubt arises from the fact that “energy_logical_flag” variable is false by default. So, by default, in the second column of my phase space file I have to put a momentum.

So, what energy unit should I put in read_phase_space_file if energy_logical_flag=.false. considering that I already have a momentum in GeV/c?

I ask this because I had the doubt that maybe when the variable is set to false it automatically convert the second column to a momentum, and in this case I only have to put GeV as unit.

Sorry if the question seems stupid but I can’t figure it out by myself.
Thanks in advance,

Dear Antonino,

the energy_units in the read_phase_space_file() subroutine is only a normalization factor, it doesn’t change between momentum and energy.

GeV/c and GeV both translated to the normalisation factor equal 1.0, so it doesn’t matter much which one you use.


Thanks David for clearing my doubt!