| Summary: | photons emitted in inelastic (n,n')-reaction | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | Artem Zontikov <zontikov.a> |
| Component: | processes/hadronic/models/neutron_hp | Assignee: | tkoi |
| Status: | RESOLVED WONTFIX | ||
| Severity: | trivial | ||
| Priority: | P5 | ||
| Version: | 10.1 | ||
| Hardware: | PC | ||
| OS: | Linux | ||
| Attachments: | photon spectrum | ||
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Description
Artem Zontikov
2015-04-27 12:25:19 CEST
Created attachment 339 [details]
photon spectrum
It looks like somewhere the energy of transition from the 1st level to the ground state is confused with the level energy itself. Level energy: 4.438910e+03 MeV Energy of transition: 4.438030e+03 MeV Hi Thank you for reporting. I successfully reproduced the phenomena you see. I will do further investigation later. Tatsumi The origins of gammas are identified. There are two sources of gammas. One is defined in ENDF data and the other is Gamma cascade code in NeutronHP. The energy of gamma from the former source is 4.439000MeV and the later is 4.438030MeV. Energy dependent behavior comes from, (n,n’_1st) reaction gives 4.439000MeV gammas because the energy of gamma from the first excitation is defined in the ENDF data. But that kind of definitions do not exist in higher states, thus Geant4 use internal gamma cascade codes to generate final states so we will have 4.438030MeV gammas from (n,n’_2nd and higher). Increasing energy of projectile neutrons also increases the gammas from higher excitation states. We respect ENDF data as much as possible and also you are setting “not adjusting final state” flag, so I close this report as “WONTFIX”. Anyway, thank you very much for reporting this, the behavior is new for me. Tatsumi Thank you for detailed explanation. Would you be so kind to clarify some issues regarding the topic? Please, correct me if I wrong. 1. I suspect that Geant4 generates gammas from (n,n’_1st) reaction using multiplicities defined in MF=12 section of ENDF data. So, if such section is missing (unfortunately, it happens sometimes) Geant4 will use internal gamma cascade code for the 1st excited state as well as for higher levels. 2. Is it safe to set energy of transition for the 1st state equal to the 1st level energy in text files under $G4NEUTRONHPDATA/Inelastic/Gammas/ to achieve consistency with ENDF data? 1) Correct Probably you are already aware that is only given for (n,n’_1st) and not for higher. 2)I think so, (but this is my personal impression) The value is derived from ENSDF library, so it will not be modified by us. Tatsumi |