Dear FLUKA experts,
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.
But the output of dE/dx by using the two models differ a lot, as shown below.
Is this correct? Which one is more reliable? Can anyone help me understand the physics?
One more question, which of the following is the printed dE/dx from the DELTARAY card (the 2nd column)?
What is printed in the output file is the restricted stopping power (following the 2nd expression you point above).
HADROTHE, the delta-ray production threshold is 300 keV.
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.
You may also want to take a look at this post.
Hope this helps,
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
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
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).
With kind regards,
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
You are right, it shall be fixed in the note 9 of the DELTARAY card. Thanks for that!
Thanks, well spotted! Will be amended and included in the manual for the next release.