| Summary: | production of particle with Etot != Ekin+ m0 in BInary cascade | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | desorgher |
| Component: | processes/hadronic/models | Assignee: | Gunter.Folger |
| Status: | RESOLVED FIXED | ||
| Severity: | critical | CC: | desorgher, Gunter.Folger |
| Priority: | P1 | ||
| Version: | 6.1 | ||
| Hardware: | PC | ||
| OS: | Linux | ||
Hi Gunter, can you have a look? Many greetings, Hans-Peter. Vicente, I had little problem reproducing this report. Using 5Gev protons on Al, it seems the problem is coming from not from binary cascade itsself, but from PrecompoundModel. I see this error when precompound return many particles, and the discrepancy between mass/kinetic energy/4-vector appaers for the last particle. Several fixes in Geant4 6.2 should correct this. Dear Gunter, The bug is still appearing in Geant4.6.2 at least when using my code. Moreover the bug is still appearing when replacing my physics list with the LHEP_BIC list. I have done some debugging and have found that: 1.As you have already noticed the non conservation of energy appear only for the last emitted particle. Moreover it seems that it appears only if this last emitted particle is a proton, while before also neutron with Etot != Ekin+ m0 could be produced. 2. The source of the problem is in the deexcitation phase after the cascade and preequilibrium phase. Indeed sometimes the last emitted particle resulting from the evaporation model is a proton left with an excited energy Eex !=0. This leads to a secondary proton with Etot=E0+Ekin+Eex and therefore Etot!=E0+Ekin. I have also some question concerning the deexicitation. In the deexcitation phase only the evaporation model is used as MaxA and MaxZ parameters of Fermi Breakup model are set by default to 1 and 1 and as the excitation energy limit for MultiFragmentation are set to 4GeV/nucl. Does it means that the actual version of Evaporation models is also good for nucleon with A<17 and Eex<4GeV/nuc? If no, could it be the reason of the bug and why arent better MaxA and maximum Eex set by default? If yes in which case is the FermiBreakUp model still needed? Cheers Laurent Dear Gunter, The bug is still appearing in Geant4.6.2 at least when using my code. Moreover the bug is still appearing when replacing my physics list with the LHEP_BIC list. I have done some debugging and have found that: 1.As you have already noticed the non conservation of energy appear only for the last emitted particle. Moreover it seems that it appears only if this last emitted particle is a proton, while before also neutron with Etot != Ekin+ m0 could be produced. 2. The source of the problem is in the deexcitation phase after the cascade and preequilibrium phase. Indeed sometimes the last emitted particle resulting from the evaporation model is a proton left with an excited energy Eex !=0. This leads to a secondary proton with Etot=E0+Ekin+Eex and therefore Etot!=E0+Ekin. I have also some question concerning the deexicitation. In the deexcitation phase only the evaporation model is used as MaxA and MaxZ parameters of Fermi Breakup model are set by default to 1 and 1 and as the excitation energy limit for MultiFragmentation are set to 4GeV/nucl. Does it means that the actual version of Evaporation models is also good for nucleon with A<17 and Eex<4GeV/nuc? If no, could it be the reason of the bug and why arent better MaxA and maximum Eex set by default? If yes in which case is the FermiBreakUp model still needed? Cheers Laurent Was related resonance decay. Fixed with ghad-bin-V06-01-02, ghad-mod-util-V06-01-01 , and released in geant4 7.0 |
Dear Hans-Peter, When simulating the interaction of 1-10 GeV protons and neutrons with Air, Water and aluminum (other material have not been tested) using the binary cascade, some secondaries are produced with total energy that is not equal to the rest mass + kinetic energy Etot != Ekin+ m0 I have tried with both my G4 atmospheric code and the G4 mulassis code from Fan Lei and the same problem occurs. Below this email is an example of a part of the tracking information I have got when simulating neutrons of 5GeV on Air target. The last four lines are debugging information printed by my stepping action when a particle with E!=Ekin+m0 occurs. Best Regards Laurent Desorgher **PostStepDoIt (after all invocations): ++List of invoked processes 1) Transportation 2) NeutronInelastic (Forced) ++G4Step Information Address of G4Track : 0xa865970 Step Length (mm) : 3.5e+04 Energy Deposit (MeV) : 0 ----------------------------------------------------------------------- StepPoint Information PreStep PostStep ----------------------------------------------------------------------- Position - x (mm) : 0 0 Position - y (mm) : 0 0 Position - z (mm) : 9.69e+04 1.32e+05 Global Time (ns) : 917 1.04e+03 Local Time (ns) : 917 1.04e+03 Proper Time (ns) : 145 164 Momentum Direct - x : 0 0 Momentum Direct - y : 0 0 Momentum Direct - z : 1 1 Momentum - x (MeV/c): 0 0 Momentum - y (MeV/c): 0 0 Momentum - z (MeV/c): 5.86e+03 0 Total Energy (MeV) : 5.94e+03 940 Kinetic Energy (MeV): 5e+03 0 Velocity (mm/ns) : 296 0 Volume Name : Layer-8 Layer-8 Safety (mm) : 0 3.74e+03 Polarization - x : 0 0 Polarization - y : 0 0 Polarization - Z : 0 0 Weight : 1 1 Step Status : Geom Limit PostStep Proc Process defined Step: Transportation NeutronInelastic ----------------------------------------------------------------------- ++List of secondaries generated (x,y,z,kE,t,PID): No. of secodaries = 17 [Note]Secondaries from AlongStepDoIt included. 0 0 1.32e+05 303 1.04e+03 pi0 0 0 1.32e+05 2.58e+03 1.04e+03 neutron 0 0 1.32e+05 392 1.04e+03 pi+ 0 0 1.32e+05 129 1.04e+03 neutron 0 0 1.32e+05 176 1.04e+03 neutron 0 0 1.32e+05 260 1.04e+03 neutron 0 0 1.32e+05 114 1.04e+03 proton 0 0 1.32e+05 30.4 1.04e+03 proton 0 0 1.32e+05 14.6 1.04e+03 neutron 0 0 1.32e+05 19.6 1.04e+03 proton 0 0 1.32e+05 59.6 1.04e+03 neutron 0 0 1.32e+05 8.74 1.04e+03 neutron 0 0 1.32e+05 103 1.04e+03 neutron 0 0 1.32e+05 68.3 1.04e+03 proton 0 0 1.32e+05 71.4 1.04e+03 proton 0 0 1.32e+05 29.5 1.04e+03 neutron 0 0 1.32e+05 17.7 1.04e+03 proton ++G4Track Information ----------------------------------------------- G4Track Information ----------------------------------------------- Step number : 9 Position - x (mm) : 0 Position - y (mm) : 0 Position - z (mm) : 1.32e+05 Global Time (ns) : 1.04e+03 Local Time (ns) : 1.04e+03 Momentum Direct - x : 0 Momentum Direct - y : 0 Momentum Direct - z : 1 Kinetic Energy (MeV): 0 Polarization - x : 0 Polarization - y : 0 Polarization - z : 0 Track Length : 3.07e+05 Track ID # : 1 Parent Track ID # : 0 Next Volume : Layer-8 Track Status : StopAndKill Vertex - x (mm) : 0 Vertex - y (mm) : 0 Vertex - z (mm) : -1.75e+05 Vertex - Px (MomDir): 0 Vertex - Py (MomDir): 0 Vertex - Pz (MomDir): 1 Vertex - KineE (MeV): 5e+03 Creator Process : Event Generator ----------------------------------------------- #Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 9 0 0 1.32e+05 0 0 3.5e+04 3.07e+05 Layer-8 NeutronInelastic ********************************************************************************************************* * G4Track Information: Particle = proton, Track ID = 18, Parent ID = 1 ********************************************************************************************************* Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 0 0 0 1.32e+05 17.7 0 0 0 Layer-8 initStep >>AlongStepDoIt (process by process): Process Name = Transportation ++G4Step Information Address of G4Track : 0xa86c650 Step Length (mm) : 610 Energy Deposit (MeV) : 0 ----------------------------------------------------------------------- StepPoint Information PreStep PostStep ----------------------------------------------------------------------- Position - x (mm) : 0 -85.8 Position - y (mm) : 0 603 Position - z (mm) : 1.32e+05 1.32e+05 Global Time (ns) : 1.04e+03 1.05e+03 Local Time (ns) : 0 11.9 Proper Time (ns) : 0 11.7 Momentum Direct - x : -0.141 -0.141 Momentum Direct - y : 0.988 0.988 Momentum Direct - z : -0.0569 -0.0569 Momentum - x (MeV/c): -28.8 -28.8 Momentum - y (MeV/c): 202 202 Momentum - z (MeV/c): -11.7 -11.7 Total Energy (MeV) : 1.2e+03 1.2e+03 Kinetic Energy (MeV): 17.7 17.7 Velocity (mm/ns) : 51.4 51.4 Volume Name : Layer-8 Layer-8 Safety (mm) : 0 0 Polarization - x : 0 0 Polarization - y : 0 0 Polarization - Z : 0 0 Weight : 1 1 Step Status : Undefined AlongStep Proc. Process defined Step: Undefined hIoni ----------------------------------------------------------------------- #Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 1 -77.9 604 1.32e+05 15.6 2.09 610 610 Layer-8 hIoni The particle will be stopped because E^2!= p*p-m0*m0 or E != Ekin+m0 particle: proton Creator process:NeutronInelastic E[MeV] Ekin P[MeV/c] m0 : 1.19e+03 15.6 192 938