Geant4 User's Guide for Application Developers - Geant4 - CERN

Toolkit Fundamentalsdifferential flux corresponding to this spectrum The weight, direction, position , kinetic energy and type of the lastadjoint particle that reaches the external source, and that would represents the primary of a forward simulation,can be get from G4AdjointSimManager by using for example the following line of codesG4AdjointSimManager* theAdjointSimManager = G4AdjointSimManager::GetInstance();G4String particle_name = theAdjointSimManager->GetFwdParticleNameAtEndOfLastAdjointTrack();G4int PDGEncoding= theAdjointSimManager->GetFwdParticlePDGEncodingAtEndOfLastAdjointTrack();G4double weight = theAdjointSimManager->GetWeightAtEndOfLastAdjointTrack();G4double Ekin = theAdjointSimManager->GetEkinAtEndOfLastAdjointTrack();G4double Ekin_per_nuc=theAdjointSimManager->GetEkinNucAtEndOfLastAdjointTrack(); // in case of ionsG4ThreeVector dir = theAdjointSimManager->GetDirectionAtEndOfLastAdjointTrack();G4ThreeVector pos = theAdjointSimManager->GetPositionAtEndOfLastAdjointTrack();In order to have a code working for both forward and adjoint simulation mode, the extra code needed in useractions or analysis manager for the adjoint simulation mode can be separated to the code needed only for thenormal forward simulation by using the following public method of G4AdjointSimManager:G4bool GetAdjointSimMode();that returns true if an adjoint simulation is running and false if not.The following code example shows how to normalize a detector signal and compute an answer matrix in the caseof an adjoint simulation.Example 3.5. Normalization in the case of an adjoint simulation. The detector signal Scomputed during the forward tracking phase is normalized to a primary source of e- witha differential directional flux given by the function F. An answer matrix of the signal isalso computed.G4double S = ...; // signalin the sensitive volume computed during a forward tracking phase//Normalization of the signal for an adjoint simulationG4AdjointSimManager* theAdjSimManager = G4AdjointSimManager::GetInstance();if (theAdjSimManager->GetAdjointSimMode()) {G4double normalized_S=0.; //normalized to a given e- primary spectrumG4double S_for_answer_matrix=0.; //for e- answer matrixif (theAdjSimManager->GetFwdParticleNameAtEndOfLastAdjointTrack() == "e-"){G4double ekin_prim = theAdjSimManager->GetEkinAtEndOfLastAdjointTrack();G4ThreeVector dir_prim = theAdjointSimManager->GetDirectionAtEndOfLastAdjointTrack();G4double weight_prim = theAdjSimManager->GetWeightAtEndOfLastAdjointTrack();S_for_answer_matrix = S*weight_prim;normalized_S = S_for_answer_matrix*F(ekin_prim,dir); //F(ekin_prim,dir_prim) gives the differential directional}//follows the code where normalized_S and S_for_answer_matrix are registered or whatever....}//analysis/normalization code for forward simulationelse {...}...3.7.3.3. Control of an adjoint simulationThe G4UI commands in the directory /adjoint. allow the user to :• Define the adjoint source where adjoint primaries are generated• Define the external source till which adjoint particles are tracked• Start an adjoint simulation63