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Geant4 Version: 11.4.1
Operating System: ubuntu 24.04
Compiler/Version: gcc 13.3.0
CMake Version: 3.28.3
I have question about simulation of the yield of fast neutrons. So, task is
next - deuterons with energy up to 1.5 MeV hit to natural lithium target (7Li/
6Li - 92.5/7.5). Main nuclear reaction are:
- 7Li(d,n)8Be, then 8Be->alpha+alpha
- 7Li(d,n)alpha+alpha
- 7Li(d,alpha)5He, then 5He->n+alpha
- 6Li(d,n)7Be
- 6Li(d,3He)5He, then 5He->n+alpha
I used G4VModularPhysicsList* phys_list = new QGSP_BIC_AllHP(0).
I see 3 resonances for 8Be - gs, 3.03 MeV and 11.25 MeV conditions from
7Li(d,n)8Be reactions (see the attachment, 3 lines correspond 3 resonances)
and few background up to 5 MeV. Background it seems coming from 3) and 5)
reactions.
Additionally info is next:
* creator process: dInelastic, neutronInelastic
* number of processes: 17
7Li(d,n): 2685413 (94.765%)
6Li(d,n): 77534 ( 2.736%)
7Li(d,n)n: 22789 ( 0.804%)
7Li(d,n)n_n: 17402 ( 0.614%)
7Li(d,n)n_n_n: 12690 ( 0.448%)
7Li(d,n)n_n_n_n: 8206 ( 0.290%)
7Li(d,n)n_n_n_n_n: 4483 ( 0.158%)
6Li(d,n)n: 1176 ( 0.041%)
6Li(d,n)n_n: 1022 ( 0.036%)
6Li(d,n)n_n_n: 790 ( 0.028%)
7Li(d,n)n_n_n_n_n_n: 784 ( 0.028%)
6Li(d,n)n_n_n_n: 650 ( 0.023%)
6Li(d,n)n_n_n_n_n: 438 ( 0.015%)
6Li(d,n)n_n_n_n_n_n: 256 ( 0.009%)
6Li(d,n)n_n_n_n_n_n_n: 131 ( 0.005%)
6Li(d,n)n_n_n_n_n_n_n_n: 5 ( 0.000%)
7Li(n,n)7Li_g: 2 ( 0.000%)
It is very strange - any alpha particles did not observed.
From 2) reaction I expected wide continuum, from 0 to 15 MeV, but I did not
see.
What is nature of secondary peaks for each resonance in 7Li(d,n)8Be reaction
(I mean 8Be in gs and 3.03 MeV) ? Why peak for 8Be in 3.03 is very narrow - it
has own width about 1.5 MeV. The same for 8Be in 11.35 condition (width is 3.5
MeV).
So, my question - what is right way to simulation yield of fast neutrons in
Geant4 (physics list, cuts and so on) ?
Best regards,
Viktor
