Dear FLUKA experts,
I noticed a strange phenomenon when I was calculating isotope production. When I bombard a Li-7 target (pure Li-7) with neutrons of energy 5 MeV, no nuclides are produced (e.g. He-4,T). This is very strange.The energy threshold for Li-7 to react with neutrons is about 3 MeV, which clearly satisfies the energy requirement.The ENDF cross-section database shows that the interaction cross-section of neutrons with Li-7 at 5 NeV is not 0. But in FLUKA, I really don’t see any He-4 production. My input file is as follows, cy.inp.And even more strangely, when another friend of mine runs the cy.inp file using his FLUKA, he can see He-4 and T production, resulting in Figure 1.But on my computer (both laptop and desktop) I don’t see He-4 and T generated with the result in Figure 2.The most outrageous thing is that when I continue to run my friend’s flair file, again I don’t see He-4 and T generated.I don’t know why, I have the latest versions of both FLUKA and FLAIR.
My friend’s output file is yes.zip. My output file is no.zip.
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
cy.inp (1.9 KB)
yes.zip (844.6 KB)
no.zip (624.9 KB)
Thanks Lin for reporting. Indeed your friend’s FLUKA version (4-4.0) has in this case a more correct behavior, which was unfortunately lost in the latest version (4-4.1) you are using. This is because in the latter, compliance was enforced with the neutron library channels, which for Li-7 include (n,n’) but not explicitly (n,n’t) nor (n,n’a), where t and a stand for H-3 and He-4. Therefore, you only see now de-excitation gammas from Li-7, while its 4.630 MeV level may lead to break-up and H-3 and He-4 generation. The new upcoming major version (4-5.0), to be released early 2025, will restore it.
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Thank you very much for your reply. Looking forward to the new FLUKA version.