Problem 2487

Summary: Wrong transition probability computation in U234 level with 1e20 IC coefficient
Product: Geant4 Reporter: Andrea <niso2012>
Component: processes/hadronic/models/de_excitation/photon_evaporationAssignee: Vladimir.Ivantchenko
Status: ASSIGNED ---    
Severity: normal    
Priority: P4    
Version: 11.0   
Hardware: All   
OS: All   

Description Andrea 2022-04-13 16:50:39 CEST
As explained in this post

https://geant4-forum.web.cern.ch/t/decay-of-pa234-u238/313/9

the problem is the following:
In the PhotonEvaporation data files are reported the gamma relative intensities and the internal conversion coefficients of each transition, but for the 7-0 (809.907) transition of U234 (maybe also for other nuclides and transitions), the transition intensity is the total one and not the gamma.
As a consequence the computation done by the G4LevelReader class to compute the correct branching ratio is wrong.

I think there are two possible solutions: modify the G4LevelReader source code adding an exception for these types of transitions (if alpha = 1e20 then the intensity must be treated as total and not gamma), or modify the data file with the correct gamma intensity.
I think that for consistency in the data files and if there are no cons, the second option is better, but the correct value should be 0.72e-15 (instead of 0.72e-20) because alpha 1e20 is converted into 1e15.

Better values, based on ENSDF data, are 0.63e-15 and 0.36 for the intensity of the 7-0 (809.9) and 7-1 (766) transitions.

I hope that an official fix will be implemented.