| Summary: | G4PhotoNuclearProcess | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | michel.maire |
| Component: | processes/hadronic/processes | Assignee: | dennis.herbert.wright |
| Status: | RESOLVED WONTFIX | ||
| Severity: | normal | ||
| Priority: | P5 | ||
| Version: | 9.5 | ||
| Hardware: | All | ||
| OS: | All | ||
|
Description
michel.maire
2012-07-01 13:06:58 CEST
Running tests now. I have reproduced the problem. For 10 MeV gammas on 100Mo, I get no interaction 7% of the time. As I raise the energy to 15 MeV, this problem goes away, and all appears to fine. The problem is that at these low energies all the gamma-nucleon cross sections on which the Bertini cascade is based are zero. The only non-zero cross sections are the quasi-deuteron ones, where a gamma is absorbed on a nucleon pair. As the projectile energy goes below 15 MeV, the nucleons from the quasi-deuteron absorption are less likely to rise above the nuclear potential. When that happens, the precompound and de-excitation models are called which may or may not produce secondaries. If no secondaries can be produced after several tries, Bertini returns a "no interaction". This is the designed behavior of the model and therefore not a bug. To improve the situation would require a hadronic model of gammma-nuclear reactions in which the nucleus is treated coherently. I believe this would have to be a data-driven model much like HP neutrons. |