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 "MpdHypYPtGenerator.h"
 
#include "FairPrimaryGenerator.h"
#include "TDatabasePDG.h"
#include "TF1.h"
#include "TMath.h"
#include "TParticlePDG.h"
#include "TRandom.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;
}
// ------------------------------------------------------------------------