Problem 2076

Summary: U-234 E0 transition incorrectly emitting gammas
Product: Geant4 Reporter: Glen Warren <glen.warren>
Component: processes/hadronic/models/de_excitation/photon_evaporationAssignee: Vladimir.Ivantchenko
Status: RESOLVED FIXED    
Severity: enhancement CC: kelsey
Priority: P4    
Version: 10.4   
Hardware: All   
OS: All   
URL: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/hadronprocess/1659.html

Description Glen Warren 2018-08-15 19:29:33 CEST 
When looking at the decay products of Pa-234m (-> U-234), I saw spurious 809-keV gammas generated by RDM.  There is a beta decay to the 809-keV level of U-234, that part is correct, but the transition from that excited state to the ground state is an E0 transition, which must occur through internal conversion.  Reviewing the data in PhotonEvaporations5.2, the multipolarity of the transition is correct, but the alpha is wrong (way too low), leading to photons when there shouldn't be.  I don't know how common this problem is among other E0 transitions, but simply knowing that the transition is E0 should be cause enough to not generate any gammas.  I originally thought that this might be caught in the code, but then realized that if there are other transitions from that level, one would likely not have an appropriate relative intensities for the transitions.  I recommend searching the database for other E0 transitions that have low alphas(<9E9 to trigger the no-photon emission).  Unfortunately, they will likely need to be fixed on a case by case basis.

I was using 10.4.p02.
Comment 1 Vladimir.Ivantchenko 2018-08-15 20:07:45 CEST 
Hello Glen,

thank you for the analysis. Now it seems to be not so simple but we will try to address it in general or for sub-set of levels.

VI
Comment 2 Michael Kelsey 2018-08-19 20:23:09 CEST 
See also Bugzilla #1986
Comment 3 Vladimir.Ivantchenko 2019-12-12 22:13:04 CET 
Hello,

Finally, the problem is fixed in PhotonEvaporation5.5, which is delivered with the new Geant4 10.6. This dataset may be used with previous with 10.5 as well. 


Vladimir