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