pi- production spectrum from proton (10GeV/c) interaction does not fit the experimental data: Simulated pi- spectra in different Geant4 hadron codes (MARS,QGSC,PRECO) have peaks in forward and backward directions and almost zero production into intermediate angles. Hadron code from DMX example gives a little bit more pions into 0<theta<180deg region but insufficient with acomparison to experimental spectrum. FLUKA from GEant3 simulation gives correct pion spectrum (with probably factor 2 lower multiplicity which is minor problem). It will be good to implement similar code in Geant4. pi- spectrum parametrization is available in C++ code, if it is possible some how use it in proton beam simulation with tracing of proton secondary interactions, it will be usefull too... The shape of experimental spectrum, simulated spectra from all available codes, and C++ parametrization of pi- spectrum you can find on my web page: http://meco.ps.uci.edu/~tumakov/geant4_probems.html Regards, Vladimir Tumakov
Hi Vladimir, thank you for the information. I'll try and come with a physics list to give you a better description. Many greetings, Hans-Peter.
Hi, I have looked into this now rather deeply, and find that there is no current physics list for your case. Still we likely can do better than what you found with geant3. The best I can offer currently is our quark gluon string model implementation. To get it, you can pick the QGSP physics list for WWW. You then will have to edit one of the builders from the Packaging package: HadronPhysicsQGSP.cc Please replace thePro.RegisterMe(&theQGSPPro); thePro.RegisterMe(&theLEPPro); theLEPPro.SetMaxEnergy(25*GeV); with thePro.RegisterMe(&theQGSPPro); theQGSPPro.SetMinEnergy(5*GeV); thePro.RegisterMe(&theLEPPro); theLEPPro.SetMaxEnergy(5.1*GeV); I have put a few plots into /afs/cern.ch/user/h/hpw/public/ForTumakov reproducing some of the distributions you show. They seem reasonable, or at least better than your geant3 plots. Many greetings, Hans-Peter.
