Dear Geant4 experts,
I am trying to produce muon pairs from gammas. My case involves gammas with relatively low energy (200 MeV to 1-2 GeV). I have plotted a cross section for my process and I found a huge discontinuity in the region below ~500 MeV. I am attaching a plot of the cross section for gamma energies starting above 500 MeV and the same plot from 200 MeV. The first one looks like the plot shown in the official physics reference manual. In the second one, one can see flat values with enormous cross section. I believe the cross section should be very small in this region, instead of very large. (The single point at 200 MeV with cross section = 0 is physically correct. This process has a threshold at ~211 MeV).
This is the code I am using to get the cross section values:
muPairProc = new G4GammaConversionToMuons();
muPairProc->ComputeCrossSectionPerAtom(gamma_energy, Z=82);
I have tried versions 11.1.1 and 11.3.2 (newest) on linux.
Is there something wrong with the way I am trying to get the cross-section values? Or is this some artifact of the parameterization that is being used when evaluating it?
Best,
Martin
