tkittel
commented
3 years ago Just wanted to bring @ramic-k and @marquezj into this thread, since they have been performing the investigations above (and also validating the embedded ncrystal DB of scattering lengths at the same time). I am hoping that we will eventually get a list of isotopes and the threshold energy (suitably defined), and then we can go ahead and implement this.
When using NCrystal in Geant4, we currently hardcode a transition threshold between G4 and NCrystal at 5eV (=0.128Å). There might be isotopes/atoms where nuclear resonances reach that far down, so we should consider making this threshold more dynamic.
It could be that the list of isotopes with resonances at such low energies is short enough that we can simply hard-code it inside NCrystal for simplicity. And find an easy way to communicate it (i.e. "5eV unless isotopes X,Y,Z where it is 2eV and isotopes W,V where it is 1eV"). We should probably require some minimal fraction of that isotope before moving the threshold, to avoid threshold jumping around due to tiny trace of something.