Created attachment 201 [details] Gamma spectrum for radioactive decay chain of U238, Th234, Pa 234 and U234 G4 version: 9.6 data: Photon Evaporation 2.3 Radioactive Decay 3.6 Hello sir: I use the previous config to simulate the gamma spectrum of U238 (in secular equilibrium ). The gamma is recorded when it is generated. The spectrum of U238 chain has some unusual lines between 0.8 MeV and 0.9 MeV. I have used example of examples/extended/radioactivedecay/rdecay02 to produce the gamma spectrum and get the same results. Then I use isotopes Th234, Pa234, Pa234m and U234 as primary ion to produce the gamma spectrum. Only the U234 has reasonable gamma spectrum. The spectra of these isotopes are show in attachment.
Please update to Geant4 10.0 and use the database files RadioactiveDecay4.0 and PhotonEvaporation3.0. I expect this will give you better results.
