1. V.Ivanchenko, J.M.Quesada 16 th Geant4 Workshop 19-23 September 2011 SLAC, Stanford, CA, USA Update of pre-compound, de-excitation and photon evaporation interfaces

2. Main modifications for FermiBreakUp 2 Condition of transition from pre-compound to de-excitation models: (Z<9 && A < 17) ¦¦ (Eex < 10 keV) Equilibrium of excitation and decay Logic in G4ExcitationHandler: Only one Fermi-BreakUp reaction – products may only have photon evaporation G4FermiFragmentsPool is now singleton 113 states Z<9, A < 17 About 1000 reaction channels Initialized once Model is the same but implementation is understandable both to me and J.M.Quesada G4Evaporation loop is stopped when (Z<9 && A < 17) 16-th Geant4 Workshop

3. FBU/GEM/PhotonEvaporation 3 GEM model was fixed (many lost states were recovered) There is inconsistency between FBU/GEM/PhotonEvaporation: Excited states hardcoded in 3 models independently J.M.Quesada by hand fix values of excitation energies in FBU Number of levels disagree, for example, for C12: FBU – 2 main states GEM – 26 states Photon Evaporation – 7 states Is such difference acceptable from physics and software point of view? 16-th Geant4 Workshop

4. Specific problems of photon evaporation 4 The model is used in two places: G4ExcitationHandler for nuclear de-excitation In Radioactive decay In high energy nuclear reaction produced fragments are fully stripped In nuclear capture and in radioactive decay nuclear fragments keep electronic shells and probability of internal conversion may be significant Dominates for forbidden transitions Radioactive decay data likely available for the second case and should be modified for nuclear reaction

5. Software issues 5 Currently information about transitions are kept inside G4PhotonEvaporation class Why not in G4Fragment? Currently old interface for EM atomic de-excitation is used G4PhotonEvaporation object is created and deleted at each radioactive decay G4PhotonEvaporation is created once for G4ExcitationHandler

6. What can be improved? 6 Investigate how many nuclear levels should be taken into account and how to apply FBU/GEM/PhotonEvaporation consistently Keep information about electronic shell in G4Fragment class Find out a way to modify probabilities of transition for stripped fragments Find our a consistent way to set options: Activate de-excitation Activate internal conversion