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 //_____________________________________________________________________________
  26 AliPrimaryGeneratorAction::AliPrimaryGeneratorAction()
  27   : fGenerator(kAliGenerator),
  28     fNofGunParticles(1),
  29     fVerboseLevel(0)
  30 {
  31 //
  32   fParticleGun = new AliParticleGun();
  33   fMessenger = new AliPrimaryGeneratorMessenger(this);
  34 }
  35
  36 //_____________________________________________________________________________
  37 AliPrimaryGeneratorAction::AliPrimaryGeneratorAction(
  38                                     const AliPrimaryGeneratorAction& right) {
  39 //
  40   AliGlobals::Exception(
  41     "AliPrimaryGeneratorAction is protected from copying.");
  42 }
  43
  44 //_____________________________________________________________________________
  45 AliPrimaryGeneratorAction::~AliPrimaryGeneratorAction() {
  46 //
  47   delete fMessenger;
  48   delete fParticleGun;
  49 }
  50
  51 // operators
  52
  53 //_____________________________________________________________________________
  54 AliPrimaryGeneratorAction&
  55 AliPrimaryGeneratorAction::operator=(const AliPrimaryGeneratorAction &right)
  56 {
  57   // check assignement to self
  58   if (this == &right) return *this;
  59
  60   AliGlobals::Exception(
  61     "AliPrimaryGeneratorAction is protected from assigning.");
  62
  63   return *this;
  64 }
  65
  66 // private methods
  67
  68 //_____________________________________________________________________________
  69 void AliPrimaryGeneratorAction::ConstructGenerator()
  70 {
  71 // Constructs selected generator.
  72 // ---
  73
  74   switch (fGenerator) {
  75     case kGun:
  76       // gun is constructed interactively
  77       return;
  78     case kGeantino:
  79       ConstructGeantinoGenerator(false);
  80       return;
  81     case kChargedGeantino:
  82       ConstructGeantinoGenerator(true);
  83       return;
  84     case kAliGenerator:
  85       ConstructAliGenerator();
  86       return;
  87   }
  88 }
  89
  90 //_____________________________________________________________________________
  91 void AliPrimaryGeneratorAction::ConstructGeantinoGenerator(G4bool isCharged)
  92 {
  93 // Geantino with random momentum direction
  94 // (the default generator).
  95 // ---
  96
  97   // reset gun
  98   fParticleGun->Reset();
  99
 100   G4ParticleTable* particleTable
 101     = G4ParticleTable::GetParticleTable();
 102
 103   for (G4int i=0; i< fNofGunParticles; i++)
 104   {
 105     G4ParticleDefinition* particleDef = 0;
 106     if (!isCharged)
 107       particleDef = particleTable->FindParticle("geantino");
 108     else
 109       particleDef = particleTable->FindParticle("chargedgeantino");
 110
 111     if (!particleDef) {
 112       G4String text = "AliPrimaryGeneratorAction::GenerateGeantino:\n";
 113       text = text + "   G4ParticleTable::FindParticle() failed.";
 114       AliGlobals::Exception(text);
 115     }
 116
 117     G4double rn[3];
 118     RandFlat::shootArray(3,rn);
 119     G4double px=rn[0];
 120     G4double py=rn[1];
 121     G4double pz=rn[2];
 122     G4ThreeVector momentumDir(px, py, pz);
 123
 124     G4double energy = 1.*GeV;
 125     G4ThreeVector position(0.,0.,0.);
 126     G4double time = 0.;
 127     G4ThreeVector polarization(0.,0.,0.);
 128
 129     AliGunParticle * gunParticle
 130       = new AliGunParticle(particleDef, momentumDir, energy, position, time,
 131               polarization);
 132
 133     fParticleGun->AddParticle(gunParticle);
 134   }
 135   if (fVerboseLevel>1) {
 136     G4cout << "Geantino generator has been built." << G4endl;
 137   }
 138 }
 139
 140 //_____________________________________________________________________________
 141 void AliPrimaryGeneratorAction::ConstructAliGenerator()
 142 {
 143 // Generator from AliRoot
 144 // AliGenerator::Generate() fills the AliRun::fParticles array.
 145 // ---
 146
 147   // check if AliGenerator is set
 148   AliGenerator* generator = gAlice->Generator();
 149   if (!generator) {
 150     G4String text = "AliPrimaryGeneratorAction::ConstructGenerator:\n";
 151     text = text + "   No AliGenerator is defined in gAlice.";
 152     AliGlobals::Exception(text);
 153   }
 154   // fill AliRun::fParticleMap array
 155   generator->Generate();
 156 }
 157
 158 //_____________________________________________________________________________
 159 void AliPrimaryGeneratorAction::GenerateAliGeneratorPrimaries(G4Event* event)
 160 {
 161 // Creates a new G4PrimaryVertex objects for each TParticle
 162 // in fParticles array.
 163 // ---
 164
 165   G4PrimaryVertex* previousVertex = 0;
 166   G4ThreeVector previousPosition = G4ThreeVector();
 167   G4double previousTime = 0.;
 168
 169   G4int nofParticles = gAlice->GetNtrack();
 170   // add verbose
 171   //G4cout << " nofParticles: " <<  nofParticles << G4endl;
 172   for( G4int i=0; i<nofParticles; i++ ) {
 173
 174     // get the particle from AliRun stack
 175     TParticle* particle = gAlice->Particle(i);
 176
 177
 178     if (!particle->TestBit(kDoneBit)) {
 179       // only particles that didn't die (decay) in primary generator
 180       // will be transformed to G4 objects
 181
 182       // get particle definition from G4ParticleTable
 183       G4int pdgEncoding = particle->GetPdgCode();
 184       G4ParticleTable* particleTable
 185         = G4ParticleTable::GetParticleTable();
 186       G4ParticleDefinition* particleDefinition = 0;
 187       if (pdgEncoding != 0)
 188         particleDefinition = particleTable->FindParticle(pdgEncoding);
 189       else {
 190         G4String name = particle->GetName();
 191         if (name == "Rootino")
 192             particleDefinition = particleTable->FindParticle("geantino");
 193       }
 194
 195       if (particleDefinition==0) {
 196         G4cout << "pdgEncoding: " << pdgEncoding << G4endl;
 197         G4String text =
 198             "AliPrimaryGeneratorAction::GenerateAliGeneratorPrimaries:\n";
 199         text = text + "   G4ParticleTable::FindParticle() failed.";
 200         AliGlobals::Exception(text);
 201       }
 202
 203       // get/create vertex
 204       G4ThreeVector position
 205         = G4ThreeVector(particle->Vx()*TG4G3Units::Length(),
 206                         particle->Vy()*TG4G3Units::Length(),
 207                         particle->Vz()*TG4G3Units::Length());
 208       G4double time = particle->T()*TG4G3Units::Time();
 209       G4PrimaryVertex* vertex;
 210       if ( i==0 || position != previousPosition || time != previousTime ) {
 211         // create a new vertex
 212         // in case position and time of gun particle are different from
 213         // previous values
 214         // (vertex objects are destroyed in G4EventManager::ProcessOneEvent()
 215         // when event is deleted)
 216         vertex = new G4PrimaryVertex(position, time);
 217         event->AddPrimaryVertex(vertex);
 218
 219         previousVertex = vertex;
 220         previousPosition = position;
 221         previousTime = time;
 222       }
 223       else
 224         vertex = previousVertex;
 225
 226       // create a primary particle and add it to the vertex
 227       // (primaryParticle objects are destroyed in G4EventManager::ProcessOneEvent()
 228       // when event and then vertex is deleted)
 229       G4double px = particle->Px()*TG4G3Units::Energy();
 230       G4double py = particle->Py()*TG4G3Units::Energy();
 231       G4double pz = particle->Pz()*TG4G3Units::Energy();
 232       G4PrimaryParticle* primaryParticle
 233         = new G4PrimaryParticle(particleDefinition, px, py, pz);
 234
 235       // set polarization
 236       TVector3 polarization;
 237       particle->GetPolarisation(polarization);
 238       primaryParticle
 239         ->SetPolarization(polarization.X(), polarization.Y(), polarization.Z());
 240
 241       // add primary particle to the vertex
 242       vertex->SetPrimary(primaryParticle);
 243     }
 244   }
 245 }
 246
 247 // public methods
 248
 249 //_____________________________________________________________________________
 250 void AliPrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
 251 {
 252 // Generates primary particles by the selected generator.
 253 // ---
 254
 255   // reset AliRun
 256   gAlice->BeginEvent();
 257
 258   // fill particle gun/particle array
 259   ConstructGenerator();
 260
 261   // generate primary vertices
 262   if (fGenerator == kAliGenerator)  {
 263     // use AliGenerator if set
 264     GenerateAliGeneratorPrimaries(event);
 265
 266     // do not save primary particles
 267     // (they would be stored twice)
 268     AliTrackingAction* trackingAction
 269       =  AliTrackingAction::Instance();
 270     trackingAction->SetSavePrimaries(false);
 271   }
 272   else {
 273     // use particle gun otherwise
 274     fParticleGun->GeneratePrimaryVertex(event);
 275
 276     // primary particles have to be saved
 277     AliTrackingAction* trackingAction
 278       =  AliTrackingAction::Instance();
 279     trackingAction->SetSavePrimaries(true);
 280   }
 281 }
 282
 283 //_____________________________________________________________________________
 284 void AliPrimaryGeneratorAction::SetGenerator(AliPrimaryGenerator generator)
 285 {
 286 // Sets generator.
 287 // ---
 288
 289   fGenerator = generator;
 290 }
 291
 292 //_____________________________________________________________________________
 293 void AliPrimaryGeneratorAction::SetNofGunParticles(G4int nofParticles)
 294 {
 295 // Sets number of primary particles.
 296 // This method is applied only to "gun" type generators
 297 // (and not to AliGenerator from AliRoot).
 298 // ---
 299
 300   fNofGunParticles = nofParticles;
 301 }