Different scoring results with mgdraw.f between FLUKA4.4 and 4.3

Dear experts

Recently I upgraded the FLUKA-4.3.3 to FLUKA-4.4.0 which performs point-wise neutron interactions below 20 MeV by default. However, I encountered a problem when simulating recoil protons generated by neutrons.

In FLUKA-4.3.3, I recorded the position and energy of recoil protons produced in PE with 4.3.flair,4.3.inp,mgdraw.f (USDRAW entry) in the attachment successfully.
4.3.flair (2.7 KB)
4.3.inp (1.5 KB)
mgdraw.f (2.6 KB)

However, in FLUKA-4.4.0,I try to record the recoil protons with 4.4.flair,4.4.inp, mgdraw.f in the attachment which are same with 4.3.inp except a LOW-PWXS card, but there is no proton in output file. But I recorded the protons in the surface of PE with BXDRAW entry in
surfacemgdraw.f, which means there are protons generated in fact.
4.4.flair (2.7 KB)
4.4.inp (1.5 KB)
mgdraw.f (2.6 KB)
surfacemgdraw.f (2.7 KB)

I found in FLUKA-4.4.0, the NP (number of secondary particles) of ICODE = 300(low-neutron interactions) are 1 for all interactions, which means there are only neutrons after interaction. And While in FLUKA-4.3.3 NP are 2 for ICODE = 300, the particles after interaction including protons and neutrons. I have no idea about the reason of the different results from two versions, and how to record recoil protons produced by neutrons in FLUKA-4.4.0.

Best wishes

Dear @22111140001,

Thank you for your question. As you correctly mention, in FLUKA 4-4.0 the point-wise neutron interactions are activated by default (no need for LOW-PWXS card), while in FLUKA 4-3.3 you need to explicitly add this card to enable the aforementioned interactions. Otherwise, the group-wise neutron interactions are used.

Precisely, in your two examples you compare these two approaches: group-wise in the 4.3 file (no LOW-PWXS card) and point-wise in the 4.4 file (LOW-PWXS card, redundant if you indeed use FLUKA 4-4.0). Each one has its own features and the proton recoils are treated differently. In the group-wise approach you mention accurately that the protons are dumped in mgdraw with the rest of hadrons in GENSTK. However, in the point-wise treatment the protons can be found with the rest of ion recoils (such as the carbon ions in the PE) in FHEAVY. For this you can use the same do loop up to NPHEAV and retrieve the information stored in TKHEAV(I), ICHEAV(KHEAVY(I)) and IBHEAV(KHEAVY(I)) - energy, charge and mass number respectively.

I hope this helps.

Best regards,


Thanks for your reply, I have recorded recoil protons successfully.