I have been investigating this further and I am getting more and more puzzled. Based on some work I did regarding another post Why is there difference between simulation results and theory in gamma-ray distribution from the deexcitation of Cd-114, I thought that the NeutronHP parameters might be affecting agreement between the NNDC data (which are essentially adjusted and raw experimental values) and the Geant4 simulations. My original results as mentioned above used the following parameters:
====== ParticleHP Physics Parameters ========
UseOnlyPhotoEvaporation ? 1
SkipMissingIsotopes ? 1
NeglectDoppler ? 1
DoNotAdjustFinalState ? 1
ProduceFissionFragments ? 0
UseWendtFissionModel ? 0
UseNRESP71Model ? 0
I tried varying all of the parameters for several nuclei and, as expected, the only one that seemed to have an effect on results was UseOnlyPhotoEvaporation. So I did another set of runs with UseOnlyPhotoEvaporation set to 0. (Geometry is the same. Sample thickness is 1 cm, all materials other than target are still G4_Galactic.):
====== ParticleHP Physics Parameters ========
UseOnlyPhotoEvaporation ? 0
SkipMissingIsotopes ? 0
NeglectDoppler ? 0
DoNotAdjustFinalState ? 1
ProduceFissionFragments ? 0
UseWendtFissionModel ? 0
UseNRESP71Model ? 0
This made results for most light nuclei significantly better but those for some heavier ones worse. Specifically, with UseOnlyPhotoEvaporation=1:
Isotope Agreement with NNDC
Li-6 Poor
Li-7 Poor
Be-9 Fair
B-10 Fair
C natural Good
N-14 Good
Al-27 Fair
Ni-58 Poor
Ni-60 Good
Gd-155 Fair
Good means gamma ray energies and intensity ratios agree well with NNDC data. Fair means energies mainly agree but intensities do not. Poor means neither do. I have the details in spreadsheets, but I cannot upload them since this forum does not accept the file format (LibreOffice .ods).
With UseOnlyPhotoEvaporation=0, I got:
Isotope Agreement with NNDC
Li-6 Good
Li-7 Good
Be-9 Good
B-10 Good
C natural Good
N-14 Good
Al-27 Good
Ni-58 Fair
Ni-60 Fair
Gd-155 Poor
Additionally some weird results occurred with UseOnlyPhotoEvaporation=0. Even though the peaks in the Ni-58 and Ni-60 spectra were at the correct energies, they all had saw-tooth shapes about 100 keV wide:
Other spectra, such as for Co-59 were blocky and lacked distinct peaks.
I can find very little documentation on the proper use of the ParticleHP parameters. There seems to be no detailed description of how to properly select the correct values for UseOnlyPhotoEvaporation orDoNotAdjustFinalState for a particular nucleus in advance. Is anyone aware that such a description even exists?