For most physics lists, when one looks at the tracks presented in the user stacking action routine, the recoiling nucleus is present. This is e.g. the case for the QGSP_BIC example physics list. But for interactions of 800MeV protons on Pb (and presumably for other materials/energies etc as well), every few hundred events I see only a single outgoing track, which is in most cases a p, but occasionally a pi or n. I saw this with Geant4 5.2 on CERN RedHat 7.3, gcc 3.2, PACK 0.5 and QGSP_BIC version 2.1.
Hi Gunter, can you look at this? Many greetings, Hans-Peter.