Hmmmm…I’m comparing our own RadioactiveDecay configuration with rdecay01. I see everything there except the SetARM() call. We will definitely try adding it and see if this problem reduces below few/10M.
It wasn’t easy to figure out where the documentation on that is located. I finally found the Electron Capture paragraph, The Radioactive Decay Module — Geant4 Documentation 11.3 documentation which says
More information on the ARM can be found in the Electromagnetic section of this manual.
but without a link to Atomic Relaxation — Geant4 Documentation 11.3 documentation