I tried to simulate 12C ions with a water target (incident kinetic energy 400 MeV/u).
I used two different models in the DEFAULTS card, i.e. Precision and Hadrontherapy.
Then I tried to output the stopping powers, dE/dx by using the DELTARAY card.
What is printed in the output file is the restricted stopping power (following the 2nd expression you point above).
Using DEFAULTS with HADROTHE, the delta-ray production threshold is 300 keV.
Using DEFAULTS with PRECISIOn, the delta-ray production threshold is 100 keV, i.e. more of the ionization losses are sampled explicitly as delta rays instead of in an aggregate manner along the step via a stopping power, hence the PRECISIO stopping power is lower than that with HADROTHE in your plot.
Thanks a lot for your explanation!
But according to Table 7.1 of the FLUKA manual, the default value of delta-ray production threshold is 100 keV for both DEFAULTS and PRECISIOn (WHAT(1) of DELTARAY is 0.0001). I’m not sure whether I understand the Table correctly.
I fail to find this table in the FLUKA manual as distributed in https://fluka.cern , where instead you’ll find (the “Delta ray production” line is what matters here):
If you run a quick input simply changing the DEFAULTS from PRECISIO to HADROTHE and you look for differences in the output file you’ll retrieve the aforementioned values (note that delta-ray production cuts are printed as total energy i.e. rest mass + kinetic energy).
Thank you very much for your explanation.
I ran a quick input using HADROTHE and indeed it showed
" ***** Delta ray production activated above 3.0000E-04 GeV ***** "
But is this a typo for DELTARAY in the online manual, where it shows