PWG2/FEMTOSCOPY/AliFemto/AliFemtoModelGausLCMSFreezeOutGenerator.cxx

   1 ////////////////////////////////////////////////////////////////////////////////
   2 ///                                                                          ///
   3 /// AliFemtoModelGausLCMSFreezeOutGenerator - freeze-out                     ///
   4 /// coordinates generator, generating a 3D gaussian ellipsoid in LCMS        ///
   5 /// Authors: Adam Kisiel kisiel@mps.ohio-state.edu                           ///
   6 ///                                                                          ///
   7 ////////////////////////////////////////////////////////////////////////////////
   8 #ifdef __ROOT__
   9   ClassImp(AliFemtoModelGausLCMSFreezeOutGenerator, 1)
  10 #endif
  11
  12 #include "math.h"
  13 #include "AliFemtoModelGausLCMSFreezeOutGenerator.h"
  14 #include "AliFemtoModelHiddenInfo.h"
  15 #include "AliFemtoLorentzVector.h"
  16
  17 //_______________________
  18 AliFemtoModelGausLCMSFreezeOutGenerator::AliFemtoModelGausLCMSFreezeOutGenerator() :
  19   fSizeOut(0), fSizeSide(0), fSizeLong(0)
  20 {
  21   // Default constructor
  22   fRandom = new TRandom2();
  23 }
  24
  25 //_______________________
  26 AliFemtoModelGausLCMSFreezeOutGenerator::AliFemtoModelGausLCMSFreezeOutGenerator(const AliFemtoModelGausLCMSFreezeOutGenerator &aModel):
  27   fSizeOut(0), fSizeSide(0), fSizeLong(0)
  28 {
  29   // Copy constructor
  30   fRandom = new TRandom2();
  31   SetSizeOut(aModel.GetSizeOut());
  32   SetSizeSide(aModel.GetSizeSide());
  33   SetSizeLong(aModel.GetSizeLong());
  34 }
  35 //_______________________
  36 AliFemtoModelGausLCMSFreezeOutGenerator::~AliFemtoModelGausLCMSFreezeOutGenerator()
  37 {
  38   if (fRandom) delete fRandom;
  39 }
  40 //_______________________
  41 void AliFemtoModelGausLCMSFreezeOutGenerator::GenerateFreezeOut(AliFemtoPair *aPair)
  42 {
  43   // Generate two particle emission points with respect
  44   // to their pair momentum
  45   // The source is the 3D Gaussian ellipsoid in the LCMS frame
  46   AliFemtoModelHiddenInfo *inf1 = (AliFemtoModelHiddenInfo *) aPair->Track1()->HiddenInfo();
  47   AliFemtoModelHiddenInfo *inf2 = (AliFemtoModelHiddenInfo *) aPair->Track2()->HiddenInfo();
  48
  49   if ((!inf1) || (!inf2)) { cout << "Hidden info not created! "  << endl; exit(kFALSE); }
  50
  51   Double_t tPx = inf1->GetTrueMomentum()->x() + inf2->GetTrueMomentum()->x();
  52   Double_t tPy = inf1->GetTrueMomentum()->y() + inf2->GetTrueMomentum()->y();
  53   Double_t tPz = inf1->GetTrueMomentum()->z() + inf2->GetTrueMomentum()->z();
  54   Double_t tM1 = inf1->GetMass();
  55   Double_t tM2 = inf2->GetMass();
  56   Double_t tE1 = sqrt(tM1*tM1 + inf1->GetTrueMomentum()->mag2());
  57   Double_t tE2 = sqrt(tM2*tM2 + inf2->GetTrueMomentum()->mag2());
  58   Double_t tEs = tE1 + tE2;
  59
  60   Double_t tPt = sqrt(tPx*tPx + tPy*tPy);
  61
  62   Double_t tRout = fRandom->Gaus(0.0, fSizeOut);
  63   Double_t tRside = fRandom->Gaus(0.0, fSizeSide);
  64   Double_t tRlong = fRandom->Gaus(0.0, fSizeLong);
  65
  66   Double_t tXout = (tPx * tRout + tPy * tRside)/tPt;
  67   Double_t tXside = (tPy * tRout - tPx * tRside)/tPt;
  68
  69   Double_t tBetaz = tPz/tEs;
  70   Double_t tGammaz = 1.0/(1-tBetaz*tBetaz);
  71
  72   Double_t tXlong = tGammaz * (tRlong + tBetaz * 0);
  73   Double_t tXtime = tGammaz * (0 + tBetaz * tRlong);
  74
  75   if (!(inf1->GetEmissionPoint())) {
  76     AliFemtoLorentzVector *tPos = new AliFemtoLorentzVector(0,0,0,0);
  77     inf1->SetEmissionPoint(tPos);
  78   }
  79   else
  80     inf1->SetEmissionPoint(0,0,0,0);
  81   if (!(inf2->GetEmissionPoint())) {
  82     AliFemtoLorentzVector *tPos = new AliFemtoLorentzVector(tXout,tXside,tXlong,tXtime);
  83     inf2->SetEmissionPoint(tPos);
  84   }
  85   else
  86     inf2->SetEmissionPoint(tXout, tXside, tXlong, tXtime);
  87 }
  88
  89 //_______________________
  90 void AliFemtoModelGausLCMSFreezeOutGenerator::SetSizeOut(Double_t aSizeOut)
  91 {
  92   fSizeOut = aSizeOut;
  93 }
  94 //_______________________
  95 void AliFemtoModelGausLCMSFreezeOutGenerator::SetSizeSide(Double_t aSizeSide)
  96 {
  97   fSizeSide = aSizeSide;
  98 }
  99 //_______________________
 100 void AliFemtoModelGausLCMSFreezeOutGenerator::SetSizeLong(Double_t aSizeLong)
 101 {
 102   fSizeLong = aSizeLong;
 103 }
 104
 105 //_______________________
 106 Double_t AliFemtoModelGausLCMSFreezeOutGenerator::GetSizeOut() const
 107 {
 108   return fSizeOut;
 109 }
 110 //_______________________
 111 Double_t AliFemtoModelGausLCMSFreezeOutGenerator::GetSizeSide() const
 112 {
 113   return fSizeSide;
 114 }
 115 //_______________________
 116 Double_t AliFemtoModelGausLCMSFreezeOutGenerator::GetSizeLong() const
 117 {
 118   return fSizeLong;
 119 }
 120 //_______________________
 121 AliFemtoModelFreezeOutGenerator* AliFemtoModelGausLCMSFreezeOutGenerator::Clone() const
 122 {
 123   return GetGenerator();
 124 }
 125 //_______________________
 126 AliFemtoModelFreezeOutGenerator* AliFemtoModelGausLCMSFreezeOutGenerator::GetGenerator() const
 127 {
 128   AliFemtoModelFreezeOutGenerator* tModel = new AliFemtoModelGausLCMSFreezeOutGenerator(*this); return tModel;
 129 }