Problem 2211 - Cannot reproduce published thermal neutron on Gd IC e- spectrum with v.10.4.0+
Summary: Cannot reproduce published thermal neutron on Gd IC e- spectrum with v.10.4.0+
Status: RESOLVED FIXED
Alias: None
Product: Geant4
Classification: Unclassified
Component: processes/hadronic/models/de_excitation/photon_evaporation (show other problems)
Version: 10.4
Hardware: All All
: P4 normal
Assignee: dennis.herbert.wright
URL:
Depends on:
Blocks:
 
Reported: 2019-12-21 02:17 CET by Jan Christoph Terasa
Modified: 2020-02-27 16:00 CET (History)
1 user (show)

See Also:

Attachments
file containing plots, reference figure and code. (496.44 KB, application/x-zip-compressed)
2019-12-21 02:17 CET, Jan Christoph Terasa 		Details
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Description Jan Christoph Terasa 2019-12-21 02:17:54 CET 
Created attachment 598 [details]
file containing plots, reference figure and code.

Hi,

I have tried to reproduce the spectrum from IC e- when shooting neutrons with 25 meV at a Gd slab, as found in https://doi.org/10.1007/s10967-014-3083-4. With Geant4 v10.3.2 it worked with G4USE_ONLY_PHOTONEVAPORATION=1, but with v10.4.0 and newer I am no longer able to reproduce the spectrum.

I attached plots for the different versions, as well as the reference figure from the paper. I also included the source code I run. As can be see, only v10.3.2 can reproduce the measurement shown in the attached PNG file.

Am I missing to enable/disable some more options since v10.4.0? Is this known? Or is this a bug in v10.4.0+?


kind regards,
Christoph
Comment 1 dennis.herbert.wright 2020-01-22 22:40:28 CET 
Looking through the code, it appears that the environment variable G4NEUTRONHP_USE_ONLY_PHOTONEVAPORATION must be set to 1 

It looks like this is now the only way to invoke the photon evaporation code, so try setting this before you run your application.
   
I cannot find any occurrence of G4USE_ONLY_PHOTONEVAPORATION in the latest Geant4 versions; it may have been removed in 10.4 but I can find no documentation for that.