EVGEN/AliGenPythia.cxx

   1 #include "AliGenerator.h"
   2 #include "AliGenPythia.h"
   3 #include "TGeant3.h"
   4 #include "AliRun.h"
   5 #include "AliPythia.h"
   6 #include <TDirectory.h>
   7 #include <TFile.h>
   8 #include <TTree.h>
   9 #include <stdlib.h>
  10 #include <AliPythia.h>
  11 #include <TMCParticle.h>
  12 #include <GParticle.h>
  13  ClassImp(AliGenPythia)
  14
  15 AliGenPythia::AliGenPythia()
  16                  :AliGenerator()
  17 {
  18 }
  19
  20 AliGenPythia::AliGenPythia(Int_t npart)
  21                  :AliGenerator(npart)
  22 {
  23 // default charm production at 5. 5 TeV
  24 // semimuonic decay
  25 // structure function GRVHO
  26 //
  27     fXsection  = 0.;
  28     fParentSelect.Set(5);
  29     fChildSelect.Set(5);
  30     for (Int_t i=0; i<5; i++) fParentSelect[i]=fChildSelect[i]=0;
  31     SetProcess();
  32     SetStrucFunc();
  33     ForceDecay();
  34     SetPtHard();
  35     SetEnergyCMS();
  36 }
  37
  38 AliGenPythia::~AliGenPythia()
  39 {
  40 }
  41
  42 void AliGenPythia::Init()
  43 {
  44     SetMC(new AliPythia());
  45     fPythia=(AliPythia*) fgMCEvGen;
  46 //
  47     fParentWeight=1./Float_t(fNpart);
  48 //
  49 //  Forward Paramters to the AliPythia object
  50     fPythia->DefineParticles();
  51     fPythia->ForceDecay(fForceDecay);
  52     fPythia->SetCKIN(3,fPtHardMin);
  53     fPythia->SetCKIN(4,fPtHardMax);
  54     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
  55     fPythia->LuList(0);
  56     fPythia->PyStat(2);
  57 //  Parent and Children Selection
  58     switch (fProcess)
  59     {
  60     case charm:
  61
  62         fParentSelect[0]=411;
  63         fParentSelect[1]=421;
  64         fParentSelect[2]=431;
  65         fParentSelect[3]=4122;
  66         break;
  67     case charm_unforced:
  68
  69         fParentSelect[0]=411;
  70         fParentSelect[1]=421;
  71         fParentSelect[2]=431;
  72         fParentSelect[3]=4122;
  73         break;
  74     case beauty:
  75         fParentSelect[0]=511;
  76         fParentSelect[1]=521;
  77         fParentSelect[2]=531;
  78         fParentSelect[3]=5122;
  79         break;
  80     case beauty_unforced:
  81         fParentSelect[0]=511;
  82         fParentSelect[1]=521;
  83         fParentSelect[2]=531;
  84         fParentSelect[3]=5122;
  85         break;
  86     case jpsi_chi:
  87     case jpsi:
  88         fParentSelect[0]=443;
  89         break;
  90     }
  91
  92     switch (fForceDecay)
  93     {
  94     case semielectronic:
  95     case dielectron:
  96     case b_jpsi_dielectron:
  97     case b_psip_dielectron:
  98         fChildSelect[0]=11;
  99         break;
 100     case semimuonic:
 101     case dimuon:
 102     case b_jpsi_dimuon:
 103     case b_psip_dimuon:
 104         fChildSelect[0]=13;
 105         break;
 106     }
 107 }
 108
 109 void AliGenPythia::Generate()
 110 {
 111     AliMC* pMC = AliMC::GetMC();
 112
 113     Float_t polar[3] = {0,0,0};
 114     Float_t origin[3]= {0,0,0};
 115     Float_t origin0[3]= {0,0,0};
 116     Float_t p[3], random[6];
 117
 118
 119 //
 120     printf("Generate event");
 121     Int_t nt=0;
 122     Int_t jev=0;
 123     Int_t j;
 124
 125     fTrials=0;
 126     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 127     if(fVertexSmear==perEvent) {
 128         pMC->Rndm(random,6);
 129         for (j=0;j<3;j++) {
 130             origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 131                 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 132             fPythia->SetMSTP(151,0);
 133         }
 134     } else if (fVertexSmear==perTrack) {
 135         fPythia->SetMSTP(151,0);
 136         for (j=0;j<3;j++) {
 137             fPythia->SetPARP(151+j, fOsigma[j]*10.);
 138         }
 139     }
 140
 141
 142     while(1)
 143     {
 144         fPythia->PyEvnt();
 145         fTrials++;
 146         TObjArray* particles = fPythia->GetPrimaries() ;
 147         Int_t np = particles->GetEntriesFast();
 148         printf("\n **************************************************%d\n",np);
 149         Int_t nc=0;
 150         if (np == 0 ) continue;
 151         for (Int_t i = 0; i<np; i++) {
 152             TMCParticle *  iparticle = (TMCParticle *) particles->At(i);
 153             Int_t kf = iparticle->GetKF();
 154             fChildWeight=(fPythia->GetBraPart(kf))*fParentWeight;
 155 //
 156 // Parent
 157             if (ParentSelected(TMath::Abs(kf))) {
 158
 159                 if (KinematicSelection(iparticle)) {
 160                     nc++;
 161 //
 162 // store parent track information
 163                     p[0]=iparticle->GetPx();
 164                     p[1]=iparticle->GetPy();
 165                     p[2]=iparticle->GetPz();
 166                     origin[0]=origin0[0]+iparticle->GetVx()/10;
 167                     origin[1]=origin0[1]+iparticle->GetVy()/10;
 168                     origin[2]=origin0[2]+iparticle->GetVz()/10;
 169
 170                     Int_t ifch=iparticle->GetFirstChild();
 171                     Int_t ilch=iparticle->GetLastChild();
 172                     if (ifch !=0 && ilch !=0) {
 173                         gAlice->SetTrack(0,-1,fPythia->GetGeantCode(kf),
 174                                          p,origin,polar,
 175                                          0,"Primary",nt,fParentWeight);
 176                         Int_t iparent = nt;
 177 //
 178 // Children
 179
 180                         for (Int_t j=ifch; j<=ilch; j++)
 181                         {
 182                             TMCParticle *  ichild =
 183                                 (TMCParticle *) particles->At(j-1);
 184                             Int_t kf = ichild->GetKF();
 185 //
 186 //
 187                             if (ChildSelected(TMath::Abs(kf))) {
 188                                 Int_t kg=fPythia->GetGeantCode(kf);
 189                                 origin[0]=ichild->GetVx();
 190                                 origin[1]=ichild->GetVy();
 191                                 origin[2]=ichild->GetVz();
 192                                 p[0]=ichild->GetPx();
 193                                 p[1]=ichild->GetPy();
 194                                 p[2]=ichild->GetPz();
 195                                 Float_t tof=ichild->GetTime();
 196                                 gAlice->SetTrack(1, iparent, kg,
 197                                                  p,origin,polar,
 198                                                  tof,"Decay",nt,fChildWeight);
 199                                 gAlice->KeepTrack(nt);
 200                             } // select child
 201                         } // child loop
 202                     }
 203                 } // kinematic selection
 204             } // select particle
 205         } // particles
 206         if (nc > 0) {
 207             jev++;
 208             if (jev >= fNpart) {
 209                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 210                 printf("\n Trials: %i\n",fTrials);
 211                 break;
 212             }
 213         }
 214     } // event loop
 215 //  adjust weight due to kinematic selection
 216     AdjustWeights();
 217 //  get cross-section
 218     fXsection=fPythia->GetPARI(1);
 219 }
 220
 221 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 222 {
 223     for (Int_t i=0; i<5; i++)
 224     {
 225         if (fParentSelect[i]==ip) return kTRUE;
 226     }
 227     return kFALSE;
 228 }
 229
 230 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 231 {
 232     for (Int_t i=0; i<5; i++)
 233     {
 234         if (fChildSelect[i]==ip) return kTRUE;
 235     }
 236     return kFALSE;
 237 }
 238
 239 Bool_t AliGenPythia::KinematicSelection(TMCParticle *particle)
 240 {
 241     Float_t px=particle->GetPx();
 242     Float_t py=particle->GetPy();
 243     Float_t pz=particle->GetPz();
 244     Float_t  e=particle->GetEnergy();
 245
 246 //
 247 //  transverse momentum cut
 248     Float_t pt=TMath::Sqrt(px*px+py*py);
 249     if (pt > fPtMax || pt < fPtMin)
 250     {
 251 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 252         return kFALSE;
 253     }
 254 //
 255 // momentum cut
 256     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 257     if (p > fPMax || p < fPMin)
 258     {
 259 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 260         return kFALSE;
 261     }
 262
 263 //
 264 // theta cut
 265     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(p)));
 266     if (theta > fThetaMax || theta < fThetaMin)
 267     {
 268 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 269         return kFALSE;
 270     }
 271
 272 //
 273 // rapidity cut
 274     Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 275     if (y > fYMax || y < fYMin)
 276     {
 277 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 278         return kFALSE;
 279     }
 280
 281 //
 282 // phi cut
 283     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)))+TMath::Pi();
 284     if (phi > fPhiMax || phi < fPhiMin)
 285     {
 286 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 287         return kFALSE;
 288     }
 289
 290     return kTRUE;
 291 }
 292 void AliGenPythia::AdjustWeights()
 293 {
 294     TClonesArray *PartArray = gAlice->Particles();
 295     GParticle *Part;
 296     Int_t ntrack=gAlice->GetNtrack();
 297     for (Int_t i=0; i<ntrack; i++) {
 298         Part= (GParticle*) PartArray->UncheckedAt(i);
 299         Part->SetWgt(Part->GetWgt()*fKineBias);
 300     }
 301 }
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