// Function converting pseudorapidity
// interval to polar angle interval. It is used to set
// the limits in the generator
Float_t EtaToTheta(Float_t arg){
  return (180./TMath::Pi())*2.*atan(exp(-arg));
}

// Set Random Number seed using the current time
TDatime dat;
static UInt_t sseed = dat.Get();

void Config()
{
  gRandom->SetSeed(sseed);
  cout"Seed for random number generation= "GetSeed()

  // Load GEANT 3 library. It has to be in LD_LIBRARY_PATH
  gSystem->Load("libgeant321");

  // Instantiation of the particle transport package. gMC is set internaly
  new TGeant3TGeo("C++ Interface to Geant3");

  // Create run loader and set some properties
  AliRunLoader* rl = AliRunLoader::Open("galice.root", AliConfig::GetDefaultEventFolderName(), "recreate");
  if (!rl) Fatal("Config.C","Can not instatiate the Run Loader");
  rl->SetCompressionLevel(2);
  rl->SetNumberOfEventsPerFile(3);

  // Register the run loader in gAlice
  gAlice->SetRunLoader(rl);

  // Set external decayer
  TVirtualMCDecayer *decayer = new AliDecayerPythia();
  decayer->SetForceDecay(kAll); // kAll means no specific decay is forced
  decayer->Init();

  // Register the external decayer in the transport package
  gMC->SetExternalDecayer(decayer);

  // STEERING parameters FOR ALICE SIMULATION
  // Specify event type to be transported through the ALICE setup
  // All positions are in cm, angles in degrees, and P and E in GeV
  // For the details see the GEANT 3 manual
 
  // Switch on/off the physics processes (global)
  // Please consult the file data/galice.cuts for detector
  // specific settings, i.e. DRAY
  gMC->SetProcess("DCAY",1); // Particle decay
  gMC->SetProcess("PAIR",1); // Pair production
  gMC->SetProcess("COMP",1); // Compton scattering
  gMC->SetProcess("PHOT",1); // Photo effect
  gMC->SetProcess("PFIS",0); // Photo fission
  gMC->SetProcess("DRAY",0); // Delta rays
  gMC->SetProcess("ANNI",1); // Positron annihilation
  gMC->SetProcess("BREM",1); // Bremstrahlung
  gMC->SetProcess("MUNU",1); // Muon nuclear interactions
  gMC->SetProcess("CKOV",1); // Cerenkov production
  gMC->SetProcess("HADR",1); // Hadronic interactions
  gMC->SetProcess("LOSS",2); // Energy loss (2=complete fluct.)
  gMC->SetProcess("MULS",1); // Multiple scattering
  gMC->SetProcess("RAYL",1); // Rayleigh scattering
 
  // Set the transport package cuts
  Float_t cut = 1.e-3; // 1MeV cut by default
  Float_t tofmax = 1.e10;
 
  gMC->SetCut("CUTGAM", cut); // Cut for gammas
  gMC->SetCut("CUTELE", cut); // Cut for electrons
  gMC->SetCut("CUTNEU", cut); // Cut for neutral hadrons
  gMC->SetCut("CUTHAD", cut); // Cut for charged hadrons
  gMC->SetCut("CUTMUO", cut); // Cut for muons
  gMC->SetCut("BCUTE", cut); // Cut for electron brems.
  gMC->SetCut("BCUTM", cut); // Cut for muon brems.
  gMC->SetCut("DCUTE", cut); // Cut for electron delta-rays
  gMC->SetCut("DCUTM", cut); // Cut for muon delta-rays
  gMC->SetCut("PPCUTM", cut); // Cut for e+e- pairs by muons
  gMC->SetCut("TOFMAX", tofmax); // Time of flight cut
 
  // Set up the particle generation
 
  // AliGenCocktail permits to combine several different generators
  AliGenCocktail *gener = new AliGenCocktail();
 
  // The phi range is always inside 0-360
  gener->SetPhiRange(0, 360);
 
  // Set pseudorapidity range from -8 to 8.
  Float_t thmin = EtaToTheta(8); // theta min. ­-> eta max
  Float_t thmax = EtaToTheta(-8); // theta max. ­-> eta min
  gener->SetThetaRange(thmin,thmax);
  gener->SetOrigin(0, 0, 0); // vertex position
  gener->SetSigma(0, 0, 5.3); // Sigma in (X,Y,Z) (cm) on IP position
  gener->SetCutVertexZ(1.); // Truncate at 1 sigma
  gener->SetVertexSmear(kPerEvent);
 
  // First cocktail component: 100 ``background'' particles
  AliGenHIJINGpara *hijingparam = new AliGenHIJINGpara(100);
  hijingparam->SetMomentumRange(0.2, 999);
  gener->AddGenerator(hijingparam,"HIJING PARAM",1);
 
  // Second cocktail component: one gamma in PHOS direction
  AliGenBox *genbox = new AliGenBox(1);
  genbox->SetMomentumRange(10,11.);
  genbox->SetPhiRange(270.5,270.7);
  genbox->SetThetaRange(90.5,90.7);
  genbox->SetPart(22);
  gener->AddGenerator(genbox,"GENBOX GAMMA for PHOS",1);
 
  gener->Init(); // Initialization of the coctail generator
 
  // Field (the last parameter is 1 => L3 0.4 T)
  AliMagFMaps* field = new AliMagFMaps("Maps","Maps", 2, 1., 10., 1);
  gAlice->SetField(field);
 
  // Make sure the current ROOT directory is in galice.root
  rl->CdGAFile();
 
  // Build the setup and set some detector parameters
 
  // ALICE BODY parameters. BODY is always present
  AliBODY *BODY = new AliBODY("BODY", "ALICE envelop");
 
  // Start with Magnet since detector layouts may be depending
  // on the selected Magnet dimensions
  AliMAG *MAG = new AliMAG("MAG", "Magnet");
 
  AliABSO *ABSO = new AliABSOv0("ABSO", "Muon Absorber"); // Absorber
 
  AliDIPO *DIPO = new AliDIPOv2("DIPO", "Dipole version 2"); // Dipole magnet
 
  AliHALL *HALL = new AliHALL("HALL", "ALICE Hall"); // Hall
 
  AliFRAMEv2 *FRAME = new AliFRAMEv2("FRAME", "Space Frame"); // Space frame
 
  AliSHIL *SHIL = new AliSHILv2("SHIL", "Shielding Version 2"); // Shielding
 
  AliPIPE *PIPE = new AliPIPEv0("PIPE", "Beam Pipe"); // Beam pipe
 
  // ITS parameters
  AliITSvPPRasymmFMD *ITS = new AliITSvPPRasymmFMD("ITS", "ITS PPR detailed version with asymmetric services");
  ITS->SetMinorVersion(2); // don't change it if you're not an ITS developer
  ITS->SetReadDet(kFALSE); // don't change it if you're not an ITS developer
  ITS->SetThicknessDet1(200.);  // detector thickness on layer 1:[100,300] mkm
  ITS->SetThicknessDet2(200.);  // detector thickness on layer 2:[100,300] mkm
  ITS->SetThicknessChip1(150.); // chip thickness on layer 1: [150,300] mkm
  ITS->SetThicknessChip2(150.); // chip thickness on layer 2: [150,300]
  ITS->SetRails(0);  // 1 ­> rails in ; 0 ­> rails out
  ITS->SetCoolingFluid(1); // 1 ­> water ; 0 ­> freon
  ITS->SetEUCLID(0); // no output for the EUCLID CAD system
 
  AliTPC *TPC = new AliTPCv2("TPC", "Default"); // TPC
 
  AliTOF *TOF = new AliTOFv5T0("TOF", "normal TOF"); // TOF
 
  AliHMPID *HMPID = new AliHMPIDv1("HMPID", "normal HMPID"); // HMPID
 
  AliZDC *ZDC = new AliZDCv2("ZDC", "normal ZDC"); // ZDC
 
  AliTRD *TRD = new AliTRDv1("TRD", "TRD slow simulator"); // TRD
 
  AliFMD *FMD = new AliFMDv1("FMD", "normal FMD"); // FMD
 
  AliMUON *MUON = new AliMUONv1("MUON", "default"); // MUON
 
  AliPHOS *PHOS = new AliPHOSv1("PHOS", "IHEP"); // PHOS
 
  AliPMD *PMD = new AliPMDv1("PMD", "normal PMD"); // PMD
 
  AliT0 *T0 = new AliT0v1("T0", "T0 Detector"); // T0
 
  // EMCAL
  AliEMCAL *EMCAL = new AliEMCALv2("EMCAL", "SHISH_77_TRD1_2X2_FINAL_110DEG");
 
  AliVZERO *VZERO = new AliVZEROv7("VZERO", "normal VZERO"); // VZERO
}