_Geant4 Version:_11.02.02
_Operating System:_Linux Fedora 40
_Compiler/Version:_GNU 114.2.1
_CMake Version:_3.28.2
In the thread Gamma spectrum from neutron activation of Cl37 and Ni60, I observed that using a Geant4 program of mine with a simple geometry, the neutron capture gamma ray spectrum for a 1 cm thick Ni60 target in vacuum would match the NNDC spectrum for certain choices of ParticleHP parameter settings and not for other choices for Geant4 v10.7.2. However it would not match the NNDC spectrum for any choices of settings for v11.2.2.
Since this result was for my own program, which I do not reasonably expect anyone to trust, I thought it best to confirm those results using the well-trusted and well-verified distribution example Hadr03. It can be set up to examine only the neutron capture process by switching off all other hadronic processes and by killing each event at the first interaction in a large target volume.
In short, these results verify what I found earlier with my own program. The neutron capture gamma ray spectrum matches the NNDC spectrum for certain choices of ParticleHP parameter settings (see below for details) and does not match NNDC for other ParticleHP parameter settings choices for Geant4 v10.7.2. More unsettling, however, is that the spectra do not match the NNDC spectrum for ANY settings for v11.2.2.
The details:
Hadr03 Results for Ni60 (.mac file below)
Geant4 v10.7.2:
Hadr03 is from the v10.7.2 distribution examples and compiled and linked using v10.7.2
hadronic physics specifics:
RegisterPhysics( new G4HadronElasticPhysicsXS(verb)); (but inactivated in .mac file)
RegisterPhysics( new G4HadronPhysicsQGSP_BIC_HP(verb));
defaults set in code to (but modified with UI commands in .mac file):
G4ParticleHPManager::GetInstance()->SetSkipMissingIsotopes( true );
G4ParticleHPManager::GetInstance()->SetDoNotAdjustFinalState( true );
G4ParticleHPManager::GetInstance()->SetUseOnlyPhotoEvaporation( true );
G4ParticleHPManager::GetInstance()->SetNeglectDoppler( true );
G4ParticleHPManager::GetInstance()->SetProduceFissionFragments( true );
G4ParticleHPManager::GetInstance()->SetUseWendtFissionModel( false );
G4ParticleHPManager::GetInstance()->SetUseNRESP71Model( false );
Geant4 v11.2.2:
Hadr03 is from the v11.2.2 distribution examples and compiled and linked using v11.2.2
hadronic physics specifics:
exactly the same as for the 10.7.2 version
For either version the command to run the example is:
./Hadr03 Ni60_nCapture.mac > Ni60_nCapture.out
and the macro file Ni60_nCapture.mac (same for v10.7.2 and v11.2.2) is attached:
Ni60_nCapture.mac.txt (627 Bytes)
Results:
In the following, the initial number before the result description indicates the state of the ParticleHP parameter settings 1=true, 0=false with the four parameters being from left to right
SkipMissingIsotopes, DoNotAdjustFinalState, UseOnlyPhotoEvaporation, NeglectDoppler. So for example, 1011 → SkipMissingIsotopes=true, DoNotAdjustFinalState=false, UseOnlyPhotoEvaporation=true, NeglectDoppler=true.
10.7.2
1001 broad triangular peaks, narrow spike at Q value
1011 narrow lines, spectrum matches NNDC energies and intensities (NNDC spectrum is NNDC Ni60 spectrum)
1101 broad triangular peaks but NO spike at Q value. (Aside from missing spike, spectrum is very similar to 1001)
1111 same as 1011 (narrow lines, spectrum matches NNDC energies and intensities)
11.2.2
1001 same as v10.7.2 1001 case (broad triangular peaks, narrow spike at Q value)
1011 narrow lines but different from 10.7.2. Energies, intensities do not match NNDC. There are more low energy lines.
1101 same as 10.7.2
1111 same as 1011
Conclusions:
In 10.7.2 UseOnlyPhotoEvaporation must be true to get a spectrum with discrete narrow lines which is a correct match of the number of gamma ray lines, their energy and intensities with the NNDC data base.
In 11.2.2 UseOnlyPhotoEvaporation must be true to get a spectrum with discrete narrow lines but the number of gamma ray lines, their energy and intensities does NOT match the NNDC capture gamma spectrum.
In both 10.7.2 and 11.2.2, UseOnlyPhotoEvaporation false gives broad triangular spectra unlike the NNDC spectrum.
In 10.7.2 and 11.2.2 DoNotAdjustFinalState being false gives a spike at the Q-value when also having UseOnlyPhotoEvaporation false; It does nothing otherwise.
In 10.7.2 and 11.2.2 DoNotAdjustFinalState being true gives NO spike at the Q-value when UseOnlyPhotoEvaporation is false; It does nothing otherwise.
I have attached spectra for ParticleHP parameter setting 1111 for Geant4 v10.7.2 :
I have also attached a expanded spectrum with the Q-value spike clipped for 1001 Geant4 v11.2.2
