AliGeant4/AliPrimaryGeneratorAction.cxx

   1 // $Id$
   2 // Category: run
   3 //
   4 // See the class description in the header file.
   5
   6 #include "AliPrimaryGeneratorAction.h"
   7 #include "AliPrimaryGeneratorMessenger.h"
   8 #include "AliTrackingAction.h"
   9 #include "AliParticleGun.h"
  10 #include "AliGunParticle.h"
  11 #include "AliGlobals.h"
  12 #include "AliRun.h"
  13 #include "AliGenerator.h"
  14
  15 #include "TG4G3Units.h"
  16
  17 #include <G4Event.hh>
  18 #include <G4ParticleTable.hh>
  19 #include <G4ParticleDefinition.hh>
  20
  21 #include <Randomize.hh>
  22
  23 #include <TParticle.h>
  24
  25 AliPrimaryGeneratorAction::AliPrimaryGeneratorAction()
  26   : fGenerator(kAliGenerator),
  27     fNofGunParticles(1),
  28     fVerboseLevel(0)
  29 {
  30 //
  31   fParticleGun = new AliParticleGun();
  32   fMessenger = new AliPrimaryGeneratorMessenger(this);
  33 }
  34
  35 AliPrimaryGeneratorAction::AliPrimaryGeneratorAction(
  36                                     const AliPrimaryGeneratorAction& right) {
  37 //
  38   AliGlobals::Exception(
  39     "AliPrimaryGeneratorAction is protected from copying.");
  40 }
  41
  42 AliPrimaryGeneratorAction::~AliPrimaryGeneratorAction() {
  43 //
  44   delete fMessenger;
  45   delete fParticleGun;
  46 }
  47
  48 // operators
  49
  50 AliPrimaryGeneratorAction&
  51 AliPrimaryGeneratorAction::operator=(const AliPrimaryGeneratorAction &right)
  52 {
  53   // check assignement to self
  54   if (this == &right) return *this;
  55
  56   AliGlobals::Exception(
  57     "AliPrimaryGeneratorAction is protected from assigning.");
  58
  59   return *this;
  60 }
  61
  62 // private methods
  63
  64 void AliPrimaryGeneratorAction::ConstructGenerator()
  65 {
  66 // Constructs selected generator.
  67 // ---
  68
  69   switch (fGenerator) {
  70     case kGun:
  71       // gun is constructed interactively
  72       return;
  73     case kGeantino:
  74       ConstructGeantinoGenerator(false);
  75       return;
  76     case kChargedGeantino:
  77       ConstructGeantinoGenerator(true);
  78       return;
  79     case kAliGenerator:
  80       ConstructAliGenerator();
  81       return;
  82   }
  83 }
  84
  85 void AliPrimaryGeneratorAction::ConstructGeantinoGenerator(G4bool isCharged)
  86 {
  87 // Geantino with random momentum direction
  88 // (the default generator).
  89 // ---
  90
  91   // reset gun
  92   fParticleGun->Reset();
  93
  94   G4ParticleTable* particleTable
  95     = G4ParticleTable::GetParticleTable();
  96
  97   for (G4int i=0; i< fNofGunParticles; i++)
  98   {
  99     G4ParticleDefinition* particleDef = 0;
 100     if (!isCharged)
 101       particleDef = particleTable->FindParticle("geantino");
 102     else
 103       particleDef = particleTable->FindParticle("chargedgeantino");
 104
 105     if (!particleDef) {
 106       G4String text = "AliPrimaryGeneratorAction::GenerateGeantino:\n";
 107       text = text + "   G4ParticleTable::FindParticle() failed.";
 108       AliGlobals::Exception(text);
 109     }
 110
 111     G4double rn[3];
 112     RandFlat::shootArray(3,rn);
 113     G4double px=rn[0];
 114     G4double py=rn[1];
 115     G4double pz=rn[2];
 116     G4ThreeVector momentumDir(px, py, pz);
 117
 118     G4double energy = 1.*GeV;
 119     G4ThreeVector position(0.,0.,0.);
 120     G4double time = 0.;
 121     G4ThreeVector polarization(0.,0.,0.);
 122
 123     AliGunParticle * gunParticle
 124       = new AliGunParticle(particleDef, momentumDir, energy, position, time,
 125               polarization);
 126
 127     fParticleGun->AddParticle(gunParticle);
 128   }
 129   if (fVerboseLevel>1) {
 130     G4cout << "Geantino generator has been built." << G4endl;
 131   }
 132 }
 133
 134 void AliPrimaryGeneratorAction::ConstructAliGenerator()
 135 {
 136 // Generator from AliRoot
 137 // AliGenerator::Generate() fills the AliRun::fParticles array.
 138 // ---
 139
 140   // check if AliGenerator is set
 141   AliGenerator* generator = gAlice->Generator();
 142   if (!generator) {
 143     G4String text = "AliPrimaryGeneratorAction::ConstructGenerator:\n";
 144     text = text + "   No AliGenerator is defined in gAlice.";
 145     AliGlobals::Exception(text);
 146   }
 147   // fill AliRun::fParticleMap array
 148   generator->Generate();
 149 }
 150
 151 void AliPrimaryGeneratorAction::GenerateAliGeneratorPrimaries(G4Event* event)
 152 {
 153 // Creates a new G4PrimaryVertex objects for each TParticle
 154 // in fParticles array.
 155 // ---
 156
 157   G4PrimaryVertex* previousVertex = 0;
 158   G4ThreeVector previousPosition = G4ThreeVector();
 159   G4double previousTime = 0.;
 160
 161   G4int nofParticles = gAlice->GetNtrack();
 162   // add verbose
 163   //G4cout << " nofParticles: " <<  nofParticles << G4endl;
 164   for( G4int i=0; i<nofParticles; i++ ) {
 165
 166     // get the particle from AliRun stack
 167     TParticle* particle = gAlice->Particle(i);
 168
 169
 170     if (!particle->TestBit(kDoneBit)) {
 171       // only particles that didn't die (decay) in primary generator
 172       // will be transformed to G4 objects
 173
 174       // get particle definition from G4ParticleTable
 175       G4int pdgEncoding = particle->GetPdgCode();
 176       G4ParticleTable* particleTable
 177         = G4ParticleTable::GetParticleTable();
 178       G4ParticleDefinition* particleDefinition = 0;
 179       if (pdgEncoding != 0)
 180         particleDefinition = particleTable->FindParticle(pdgEncoding);
 181       else {
 182         G4String name = particle->GetName();
 183         if (name == "Rootino")
 184             particleDefinition = particleTable->FindParticle("geantino");
 185       }
 186
 187       if (particleDefinition==0) {
 188         G4cout << "pdgEncoding: " << pdgEncoding << G4endl;
 189         G4String text =
 190             "AliPrimaryGeneratorAction::GenerateAliGeneratorPrimaries:\n";
 191         text = text + "   G4ParticleTable::FindParticle() failed.";
 192         AliGlobals::Exception(text);
 193       }
 194
 195       // get/create vertex
 196       G4ThreeVector position
 197         = G4ThreeVector(particle->Vx()*TG4G3Units::Length(),
 198                         particle->Vy()*TG4G3Units::Length(),
 199                         particle->Vz()*TG4G3Units::Length());
 200       G4double time = particle->T()*TG4G3Units::Time();
 201       G4PrimaryVertex* vertex;
 202       if ( i==0 || position != previousPosition || time != previousTime ) {
 203         // create a new vertex
 204         // in case position and time of gun particle are different from
 205         // previous values
 206         // (vertex objects are destroyed in G4EventManager::ProcessOneEvent()
 207         // when event is deleted)
 208         vertex = new G4PrimaryVertex(position, time);
 209         event->AddPrimaryVertex(vertex);
 210
 211         previousVertex = vertex;
 212         previousPosition = position;
 213         previousTime = time;
 214       }
 215       else
 216         vertex = previousVertex;
 217
 218       // create a primary particle and add it to the vertex
 219       // (primaryParticle objects are destroyed in G4EventManager::ProcessOneEvent()
 220       // when event and then vertex is deleted)
 221       G4double px = particle->Px()*TG4G3Units::Energy();
 222       G4double py = particle->Py()*TG4G3Units::Energy();
 223       G4double pz = particle->Pz()*TG4G3Units::Energy();
 224       G4PrimaryParticle* primaryParticle
 225         = new G4PrimaryParticle(particleDefinition, px, py, pz);
 226
 227       // set polarization
 228       TVector3 polarization;
 229       particle->GetPolarisation(polarization);
 230       primaryParticle
 231         ->SetPolarization(polarization.X(), polarization.Y(), polarization.Z());
 232
 233       // add primary particle to the vertex
 234       vertex->SetPrimary(primaryParticle);
 235     }
 236   }
 237 }
 238
 239 // public methods
 240
 241 void AliPrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
 242 {
 243 // Generates primary particles by the selected generator.
 244 // ---
 245
 246   // reset AliRun
 247   gAlice->BeginEvent();
 248
 249   // fill particle gun/particle array
 250   ConstructGenerator();
 251
 252   // generate primary vertices
 253   if (fGenerator == kAliGenerator)  {
 254     // use AliGenerator if set
 255     GenerateAliGeneratorPrimaries(event);
 256
 257     // do not save primary particles
 258     // (they would be stored twice)
 259     AliTrackingAction* trackingAction
 260       =  AliTrackingAction::Instance();
 261     trackingAction->SetSavePrimaries(false);
 262   }
 263   else {
 264     // use particle gun otherwise
 265     fParticleGun->GeneratePrimaryVertex(event);
 266
 267     // primary particles have to be saved
 268     AliTrackingAction* trackingAction
 269       =  AliTrackingAction::Instance();
 270     trackingAction->SetSavePrimaries(true);
 271   }
 272 }
 273
 274 void AliPrimaryGeneratorAction::SetGenerator(AliPrimaryGenerator generator)
 275 {
 276 // Sets generator.
 277 // ---
 278
 279   fGenerator = generator;
 280 }
 281
 282 void AliPrimaryGeneratorAction::SetNofGunParticles(G4int nofParticles)
 283 {
 284 // Sets number of primary particles.
 285 // This method is applied only to "gun" type generators
 286 // (and not to AliGenerator from AliRoot).
 287 // ---
 288
 289   fNofGunParticles = nofParticles;
 290 }
 291
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