G4RadioactiveDecayPhysics forces Auger electron production with zero production threshold

[Alexei_Ulyanov]

Geant4 Version: 11.4
Operating System: Ubuntu 22.04

Whenever I include G4RadioactiveDecayPhysics in my Physics list or just use a reference list like QGSP_BIC_HP where it’s included, Auger electron production is activated and the deexcitationIgnoreCut flag is set to true. Moreover, I can no longer control these settings using

UImanager->ApplyCommand("/process/em/auger false");
UImanager->ApplyCommand(“/process/em/deexcitationIgnoreCut false”);

or

G4EmParameters::Instance()->SetDeexcitationIgnoreCut(false);

before or after initialising the run manager. These settings appear to be overridden by G4RadioactiveDeacayPhysics, so regardless of my settings I always get a bunch of low energy-energy Auger electrons produced and Geant4 prints the following:

=======================================================================
======                 Atomic Deexcitation Parameters          ========
=======================================================================
Fluorescence enabled                               1
Directory in G4LEDATA for fluorescence data files  fluor
Auger electron cascade enabled                     1
PIXE atomic de-excitation enabled                  0
De-excitation module ignores cuts                  1
Type of PIXE cross section for hadrons             Empirical
Type of PIXE cross section for e+-                 Livermore
=======================================================================

### ===  Deexcitation model UAtomDeexcitation is activated for 1 region:
          DefaultRegionForTheWorld  1  1  0
### ===  Auger flag: 1
### ===  Ignore cuts flag:   1

and further

======================================================================
======          Radioactive Decay Physics Parameters           =======
======================================================================
min MeanLife (from G4NuclideTable)                1 ns 
Max life time (from G4DeexPrecoParameters)        1000 ps 
Internal e- conversion flag                       1
Stored internal conversion coefficients           1
Enabled atomic relaxation mode                    1
Enable correlated gamma emission                  0
Max 2J for sampling of angular correlations       10
Atomic de-excitation enabled                      1
Auger electron emission enabled                   1
Check EM cuts disabled for atomic de-excitation   1
Use Bearden atomic level energies                 0
Use ANSTO fluorescence model                      0
Threshold for very long decay time at rest        1 y  
======================================================================

This behaviour is different form an earlier Geant4 version 10.2, where Auger production was disabled by default and I could control it by setting the flags. I can still control it in version 11.4 if G4RadioactiveDecayPhysics is not included.

If this is the intended behaviour, I have two questions:

1. Is there a reason why ‘/process/em/deexcitationIgnoreCut’ is enabled by default by G4RadioactiveDecayPhysics? I thought in the majority of use cases one wouldn’t want to produce and track locally absorbed particles.
2. Is it still possible to override this behaviour and impose a cut or disable Auger electrons?

[dkonst]

It may still be possible to override this after initialization. Please try:

/run/initialize
/process/em/auger false
/process/em/deexcitationIgnoreCut false
/run/physicsModified
/process/em/printParameters

G4RadioactiveDecayPhysics appears to force these settings during initialization, so the override may need to be done afterward…

[Alexei_Ulyanov]

It works. Many thanks!