MpdHypYPtGenerator.cxx

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// -------------------------------------------------------------------------
// -----         CbmAnaHypYPtGenerator source file                     -----
// -----          Created 03/10/04  by E. Kryshen                      -----
// -----  Updated 10/02/10  by A. Zinchenko for MPD (with name change) -----
// -------------------------------------------------------------------------
 
#include "TRandom.h"
#include "MpdHypYPtGenerator.h"
#include "FairPrimaryGenerator.h"
#include "TParticlePDG.h"
#include "TDatabasePDG.h"
#include "TF1.h"
#include "TMath.h"
 
// ------------------------------------------------------------------------
MpdHypYPtGenerator::MpdHypYPtGenerator() : FairGenerator()
{
   // Default constructor
 
   fPDGType = -1;
   fMult    = 0;
}
 
// ------------------------------------------------------------------------
MpdHypYPtGenerator::MpdHypYPtGenerator(Int_t pdgid, Int_t mult, Double_t yield)
   : FairGenerator(), fPDGType(pdgid), fMult(mult), fYield(yield)
{
   // Constructor. Set default distributions
 
   SetDistributionPt();
   SetDistributionY();
   SetRangePt();
}
// ------------------------------------------------------------------------
Bool_t MpdHypYPtGenerator::Init()
{
   // Initialize generator
 
   // Check for particle type
   TDatabasePDG *pdgBase  = TDatabasePDG::Instance();
   TParticlePDG *particle = pdgBase->GetParticle(fPDGType);
   if (!particle) {
      Fatal("CbmAnaHypYPtGenerator", "PDG code %d not defined.", fPDGType);
      return kFALSE;
   }
   fPDGMass = particle->Mass();
   // gRandom->SetSeed(0);
   fDistPt = new TF1("distPt", "x*exp(-sqrt(x*x+[1]*[1])/[0])", fPtMin, fPtMax);
   fDistPt->SetParameters(fT, fPDGMass, fY0, fSigma);
   Info("Init", "pdg=%i y0=%4.2f sigma_y=%4.2f T_pt=%6.4f", fPDGType, fY0, fSigma, fT);
   return kTRUE;
}
 
// ------------------------------------------------------------------------
Bool_t MpdHypYPtGenerator::ReadEvent(FairPrimaryGenerator *primGen)
{
 
   Double_t phi, pt, y, mt, px, py, pz;
   gRandom->Rndm();
   if (fYield > 0 && gRandom->Rndm() > fYield) return kTRUE;
 
   // Generate particles
 
   for (Int_t k = 0; k < fMult; k++) {
 
      phi = gRandom->Uniform(0, TMath::TwoPi());
      pt  = fDistPt->GetRandom(fPtMin, fPtMax);
      px  = pt * TMath::Cos(phi);
      py  = pt * TMath::Sin(phi);
      y   = gRandom->Gaus(fY0, fSigma);
      mt  = TMath::Sqrt(fPDGMass * fPDGMass + pt * pt);
      pz  = mt * TMath::SinH(y);
      Info("ReadEvent", "Particle generated: pdg=%i pt=%f y=%f\n", fPDGType, pt, y);
      primGen->AddTrack(fPDGType, px, py, pz, 0, 0, 0);
   }
   return kTRUE;
}
// ------------------------------------------------------------------------