Carbon Ion Spectrum question

Hello Fluka experts
I have designed an easy carbon beam transported in a water box. And i am trying to simulate primary carbon beam and fragment particles differential energy spectrum.So i divided waterbox into small pieces as figure 1 shows,the UsrTrack has been attached with thos small water box

waterbox.pdf (19.8 KB)

When i set primary beam as proton or alpha or other beams the spectrum works well and the spectrum of primary particle looks like this,primary mainly distributed around entry energy.
proton and Alpha.pdf (190.1 KB)

But when i set the beam particle to heavy ion ,the resultgoes wrong ,there seems no primary partilce at entrence bin,And i do not know why.Would you mind give me any suggestion for this?Thanks a lot!
CARBON.pdf (112.1 KB)

Dear @liweiguang,

Please also upload the *.inp file, such that I can assist you better.

When you want to use the heavy ion as beam particles, you should also have a HI-PROPErt card that specifies the ion properties (I do not see it in the CARBON.pdf file). Please consult the user manual, explicitly at SDUM, the second paragraph onwards.

Nevertheless, the BEAM card with HEAVYION assumes as default 12C, which suits your case. Please note that the energy/momentum you put in the BEAM is per nucleon, while the USRTRACK will score the total kinetic energy of the nucleus and not per nucleon. This implies that your expected peak should actually be at 0.2 Gev/nucleon x 12 nucleons = 2.4 GeV, but your USRTRACK has a 500 MeV upper limit.

I set up a dummy example of your beam into a target with associated scorings as you have, and please find attached the results (also in log scale), which confirms the above.
usrtrack_full_energy_range.pdf (12.4 KB)
usrtrack_full_energy_range_loglog.pdf (12.2 KB)

Please let me know how can I further help you.



Dear Daniel
Thank you so much for your kind help.Now i have already get the out as i wished.The main wrong setting is USRTRACK particle energy setting.Appreciated your help again
Best wishes
Richard Lee