Dear FLUKA Expert：
I attempted to use SCORE and USRBIN to calculate fission (FISSIONS, HE-FISS, LE-FISS). The initial particle was a 0.1 eV neutron, and the target material was U-235. At this energy, the fission cross-section of U-235 is approximately 258.13 b, which is relatively large, so neutron-induced fission reactions are certain to occur. However, the output results from SCORE and USRBIN are 0, as shown in the figure below. However, residual nuclei are indeed produced (RESNUCLEL). I tried using both point cross-sections and grouped cross-sections based on the example in ( Query regarding ‘score’ card and activation of fission phenomena only - Scoring - FLUKA User Forum), but the results were still 0.
Another question: Are HE-FISS and LE-FISS separated by an energy threshold of 20 MeV? Does this apply to both photon-induced and neutron-induced fission ?
Thank you very much for your help and answer! Looking forward to your reply. Wish you the best of luck in everything.
Very thankful!!!
Lin
Unfortunately, this type of scoring is currently linked only to group-wise treatment for neutrons.
Please wait until the next minor release of FLUKA 4-5.1 (planned in a few weeks), which will enable such functionality for point-wise treatment of neutrons.
The thresholds for low-energy fissions by neutrons or photons are defined here (1st group):
Dear @vorodin ,
Thank you very much for your reply. Regarding the matter of point-wise versus group-wise neutron cross-sections treatments, I have obtained relevant clarification in “(Query regarding 'score' card and activation of fission phenomena only)” . Indeed, the current FISSIONS scoring can only be achieved under group-wise for neutrons, but why can’t I achieve it when I use group-wise? I used “LOW-NEUT” . Isn’t it “LOW-NEUT”?
You also have to switch your `DEFAULTS` SDUM to `NEUTRONS`, for example, to activate group-wise treatment for neutrons.
Edit: A more preferable option will be to use PRECISIO as recommended and enable group-wise handling for Uranium by changing WHAT(1) to -1 in the LOW-PWXS card:
Dear @vorodin ,
Thank you very much. By following the method you suggested, I’ve obtained the desired results. It seems that there was an issue with my previous handling of group-wise. I’m looking forward to your FLUKA 4-5.1 version. Thank you.
Lin
