task2b exercise :  only Geantino particle is defined 

open task3/task3b/src/PhysicsList.cc, copy the text defined below and paste it into task2b/src/PhysicsList.cc

 --------
 
 // gamma  
G4Gamma::GammaDefinition();    

// e+/-  
G4Electron::ElectronDefinition();  
G4Positron::PositronDefinition();    

// muon  
G4MuonPlus::MuonPlusDefinition();  G4MuonMinus::MuonMinusDefinition();  

// neutrino  G4NeutrinoE::NeutrinoEDefinition();  G4AntiNeutrinoE::AntiNeutrinoEDefinition();  G4NeutrinoMu::NeutrinoMuDefinition();  G4AntiNeutrinoMu::AntiNeutrinoMuDefinition();        

// proton  
G4Proton::ProtonDefinition();  

// neutron  
G4Neutron::NeutronDefinition();

---------