AliGeant4/AliPrimaryGeneratorAction.cxx

   1 // $Id$
   2 // Category: run
   3 //
   4 // Author: I. Hrivnacova
   5 //
   6 // Class AliPrimaryGeneratorAction
   7 // -------------------------------
   8 // See the class description in the header file.
   9
  10 #include "AliPrimaryGeneratorAction.h"
  11 #include "AliPrimaryGeneratorMessenger.h"
  12 #include "AliParticleGun.h"
  13 #include "AliGunParticle.h"
  14 #include "AliGlobals.h"
  15
  16 #include "TG4G3Units.h"
  17 #include "TG4PrimaryGeneratorAction.h"
  18 #include "TG4TrackingAction.h"
  19
  20 #include <G4Event.hh>
  21 #include <G4ParticleTable.hh>
  22 #include <G4ParticleDefinition.hh>
  23
  24 #include <Randomize.hh>
  25
  26 #include <TParticle.h>
  27 #include <TVirtualMCApplication.h>
  28
  29 //_____________________________________________________________________________
  30 AliPrimaryGeneratorAction::AliPrimaryGeneratorAction()
  31   : AliVerbose("primaryGeneratorAction"),
  32     fGenerator(kStack),
  33     fNofGunParticles(1),
  34     fParticleGun(),
  35     fMessenger(this) {
  36 //
  37 }
  38
  39 //_____________________________________________________________________________
  40 AliPrimaryGeneratorAction::~AliPrimaryGeneratorAction() {
  41 //
  42 }
  43
  44 // private methods
  45
  46 //_____________________________________________________________________________
  47 void AliPrimaryGeneratorAction::ConstructGenerator()
  48 {
  49 // Constructs selected generator.
  50 // ---
  51
  52   switch (fGenerator) {
  53     case kGun:
  54       // gun is constructed interactively
  55       return;
  56     case kGeantino:
  57       ConstructGeantinoGenerator(false);
  58       return;
  59     case kChargedGeantino:
  60       ConstructGeantinoGenerator(true);
  61       return;
  62     case kStack:
  63       return;
  64   }
  65 }
  66
  67 //_____________________________________________________________________________
  68 void AliPrimaryGeneratorAction::ConstructGeantinoGenerator(G4bool isCharged)
  69 {
  70 // Geantino with random momentum direction
  71 // (the default generator).
  72 // ---
  73
  74   // reset gun
  75   fParticleGun.Reset();
  76
  77   G4ParticleTable* particleTable
  78     = G4ParticleTable::GetParticleTable();
  79
  80   for (G4int i=0; i< fNofGunParticles; i++)
  81   {
  82     G4ParticleDefinition* particleDef = 0;
  83     if (!isCharged)
  84       particleDef = particleTable->FindParticle("geantino");
  85     else
  86       particleDef = particleTable->FindParticle("chargedgeantino");
  87
  88     if (!particleDef) {
  89       G4String text = "AliPrimaryGeneratorAction::GenerateGeantino:\n";
  90       text = text + "   G4ParticleTable::FindParticle() failed.";
  91       AliGlobals::Exception(text);
  92     }
  93
  94     G4double rn[3];
  95     RandFlat::shootArray(3,rn);
  96     G4double px=rn[0];
  97     G4double py=rn[1];
  98     G4double pz=rn[2];
  99     G4ThreeVector momentumDir(px, py, pz);
 100
 101     G4double energy = 1.*GeV;
 102     G4ThreeVector position(0.,0.,0.);
 103     G4double time = 0.;
 104     G4ThreeVector polarization(0.,0.,0.);
 105
 106     AliGunParticle * gunParticle
 107       = new AliGunParticle(particleDef, momentumDir, energy, position, time,
 108               polarization);
 109
 110     fParticleGun.AddParticle(gunParticle);
 111   }
 112   if (VerboseLevel() > 1) {
 113     G4cout << "Geantino generator has been built." << G4endl;
 114   }
 115 }
 116
 117 // public methods
 118
 119 //_____________________________________________________________________________
 120 void AliPrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
 121 {
 122 // Generates primary particles by the selected generator.
 123 // ---
 124
 125   if (fGenerator == kStack)  {
 126
 127     // Use MC stack
 128     TG4PrimaryGeneratorAction action;
 129     action.GeneratePrimaries(event);
 130
 131     // Do not save primary particles
 132     // (they would be stored twice)
 133     TG4TrackingAction* trackingAction
 134       =  TG4TrackingAction::Instance();
 135     if (trackingAction) trackingAction->SetSavePrimaries(false);
 136   }
 137   else {
 138
 139     // Begin of Event
 140     TVirtualMCApplication::Instance()->BeginEvent();
 141
 142     // Construct particle gun
 143     ConstructGenerator();
 144
 145     // Generate primary vertices
 146     fParticleGun.GeneratePrimaryVertex(event);
 147
 148     // Primary particles have to be saved in stack
 149     TG4TrackingAction* trackingAction
 150       =  TG4TrackingAction::Instance();
 151     if (trackingAction) trackingAction->SetSavePrimaries(true);
 152   }
 153 }
 154
 155 //_____________________________________________________________________________
 156 void AliPrimaryGeneratorAction::SetGenerator(AliPrimaryGenerator generator)
 157 {
 158 // Sets generator.
 159 // ---
 160
 161   fGenerator = generator;
 162 }
 163
 164 //_____________________________________________________________________________
 165 void AliPrimaryGeneratorAction::SetNofGunParticles(G4int nofParticles)
 166 {
 167 // Sets number of primary particles.
 168 // This method is applied only to "gun" type generators
 169 // (and not to AliGenerator from AliRoot).
 170 // ---
 171
 172   fNofGunParticles = nofParticles;
 173 }