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 <TParticle.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->SetCKIN(3,fPtHardMin);
  52     fPythia->SetCKIN(4,fPtHardMax);
  53     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
  54     fPythia->ForceDecay(fForceDecay);
  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     case mb:
  91         break;
  92     }
  93
  94     switch (fForceDecay)
  95     {
  96     case semielectronic:
  97     case dielectron:
  98     case b_jpsi_dielectron:
  99     case b_psip_dielectron:
 100         fChildSelect[0]=11;
 101         break;
 102     case semimuonic:
 103     case dimuon:
 104     case b_jpsi_dimuon:
 105     case b_psip_dimuon:
 106     case pitomu:
 107     case katomu:
 108         fChildSelect[0]=13;
 109         break;
 110     }
 111 }
 112
 113 void AliGenPythia::Generate()
 114 {
 115
 116     Float_t polar[3] =   {0,0,0};
 117     Float_t origin[3]=   {0,0,0};
 118     Float_t origin_p[3]= {0,0,0};
 119     Float_t origin0[3]=  {0,0,0};
 120     Float_t p[3], p_p[4], random[6];
 121 //  converts from mm/c to s
 122     const Float_t kconv=0.001/2.999792458e8;
 123
 124
 125 //
 126     Int_t nt=0;
 127     Int_t nt_p=0;
 128     Int_t jev=0;
 129     Int_t j;
 130
 131     fTrials=0;
 132     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 133     if(fVertexSmear==perEvent) {
 134         gMC->Rndm(random,6);
 135         for (j=0;j<3;j++) {
 136             origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 137                 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 138             fPythia->SetMSTP(151,0);
 139         }
 140     } else if (fVertexSmear==perTrack) {
 141         fPythia->SetMSTP(151,0);
 142         for (j=0;j<3;j++) {
 143             fPythia->SetPARP(151+j, fOsigma[j]*10.);
 144         }
 145     }
 146     while(1)
 147     {
 148         fPythia->PyEvnt();
 149         fTrials++;
 150         TObjArray* particles = fPythia->ImportParticles();
 151         Int_t np = particles->GetEntriesFast();
 152         printf("\n **************************************************%d\n",np);
 153         Int_t nc=0;
 154         if (np == 0 ) continue;
 155         if (fProcess != mb) {
 156             for (Int_t i = 0; i<np; i++) {
 157                 TParticle *  iparticle = (TParticle *) particles->At(i);
 158                 Int_t kf = iparticle->GetPdgCode();
 159                 fChildWeight=(fPythia->GetBraPart(kf))*fParentWeight;
 160 //
 161 // Parent
 162                 if (ParentSelected(TMath::Abs(kf))) {
 163                     if (KinematicSelection(iparticle)) {
 164                         if (nc==0) {
 165 //
 166 // Store information concerning the hard scattering process
 167 //
 168                             Float_t mass_p = fPythia->GetPARI(13);
 169                             Float_t   pt_p = fPythia->GetPARI(17);
 170                             Float_t    y_p = fPythia->GetPARI(37);
 171                             Float_t  xmt_p = sqrt(pt_p*pt_p+mass_p*mass_p);
 172                             Float_t     ty = Float_t(TMath::TanH(y_p));
 173                             p_p[0] = pt_p;
 174                             p_p[1] = 0;
 175                             p_p[2] = xmt_p*ty/sqrt(1.-ty*ty);
 176                             p_p[3] = mass_p;
 177                             gAlice->SetTrack(0,-1,-1,
 178                                              p_p,origin_p,polar,
 179                                              0,"Hard Scat.",nt_p,fParentWeight);
 180                             gAlice->KeepTrack(nt_p);
 181                         }
 182                         nc++;
 183 //
 184 // store parent track information
 185                         p[0]=iparticle->Px();
 186                         p[1]=iparticle->Py();
 187                         p[2]=iparticle->Pz();
 188                         origin[0]=origin0[0]+iparticle->Vx()/10;
 189                         origin[1]=origin0[1]+iparticle->Vy()/10;
 190                         origin[2]=origin0[2]+iparticle->Vz()/10;
 191
 192                         Int_t ifch=iparticle->GetFirstDaughter();
 193                         Int_t ilch=iparticle->GetLastDaughter();
 194                         if (ifch !=0 && ilch !=0) {
 195                             gAlice->SetTrack(0,nt_p,kf,
 196                                              p,origin,polar,
 197                                              0,"Primary",nt,fParentWeight);
 198                             gAlice->KeepTrack(nt);
 199                             Int_t iparent = nt;
 200 //
 201 // Children
 202
 203                             for (Int_t j=ifch; j<=ilch; j++)
 204                             {
 205                                 TParticle *  ichild =
 206                                     (TParticle *) particles->At(j-1);
 207                                 Int_t kf = ichild->GetPdgCode();
 208 //
 209 //
 210                                 if (ChildSelected(TMath::Abs(kf))) {
 211                                     origin[0]=ichild->Vx();
 212                                     origin[1]=ichild->Vy();
 213                                     origin[2]=ichild->Vz();
 214                                     p[0]=ichild->Px();
 215                                     p[1]=ichild->Py();
 216                                     p[2]=ichild->Pz();
 217                                     Float_t tof=kconv*ichild->T();
 218                                     gAlice->SetTrack(fTrackIt, iparent, kf,
 219                                                      p,origin,polar,
 220                                                      tof,"Decay",nt,fChildWeight);
 221                                     gAlice->KeepTrack(nt);
 222                                 } // select child
 223                             } // child loop
 224                         }
 225                     } // kinematic selection
 226                 } // select particle
 227             } // particle loop
 228         } else {
 229             for (Int_t i = 0; i<np; i++) {
 230                 TParticle *  iparticle = (TParticle *) particles->At(i);
 231                 Int_t kf = iparticle->GetPdgCode();
 232                 Int_t ks = iparticle->GetStatusCode();
 233                 if (ks==1 && kf!=0 && KinematicSelection(iparticle)) {
 234                         nc++;
 235 //
 236 // store track information
 237                         p[0]=iparticle->Px();
 238                         p[1]=iparticle->Py();
 239                         p[2]=iparticle->Pz();
 240                         origin[0]=origin0[0]+iparticle->Vx()/10;
 241                         origin[1]=origin0[1]+iparticle->Vy()/10;
 242                         origin[2]=origin0[2]+iparticle->Vz()/10;
 243                         Float_t tof=kconv*iparticle->T();
 244                         gAlice->SetTrack(fTrackIt,-1,kf,p,origin,polar,
 245                                          tof,"Primary",nt);
 246                         gAlice->KeepTrack(nt);
 247                 } // select particle
 248             } // particle loop
 249             printf("\n I've put %i particles on the stack \n",nc);
 250         } // mb ?
 251         if (nc > 0) {
 252             jev+=nc;
 253             if (jev >= fNpart) {
 254                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 255                 printf("\n Trials: %i\n",fTrials);
 256                 break;
 257             }
 258         }
 259     } // event loop
 260 //  adjust weight due to kinematic selection
 261     AdjustWeights();
 262 //  get cross-section
 263     fXsection=fPythia->GetPARI(1);
 264 }
 265
 266 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 267 {
 268     for (Int_t i=0; i<5; i++)
 269     {
 270         if (fParentSelect[i]==ip) return kTRUE;
 271     }
 272     return kFALSE;
 273 }
 274
 275 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 276 {
 277     for (Int_t i=0; i<5; i++)
 278     {
 279         if (fChildSelect[i]==ip) return kTRUE;
 280     }
 281     return kFALSE;
 282 }
 283
 284 Bool_t AliGenPythia::KinematicSelection(TParticle *particle)
 285 {
 286     Float_t px=particle->Px();
 287     Float_t py=particle->Py();
 288     Float_t pz=particle->Pz();
 289     Float_t  e=particle->Energy();
 290
 291 //
 292 //  transverse momentum cut
 293     Float_t pt=TMath::Sqrt(px*px+py*py);
 294     if (pt > fPtMax || pt < fPtMin)
 295     {
 296 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 297         return kFALSE;
 298     }
 299 //
 300 // momentum cut
 301     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 302     if (p > fPMax || p < fPMin)
 303     {
 304 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 305         return kFALSE;
 306     }
 307
 308 //
 309 // theta cut
 310     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
 311     if (theta > fThetaMax || theta < fThetaMin)
 312     {
 313 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 314         return kFALSE;
 315     }
 316
 317 //
 318 // rapidity cut
 319     Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 320     if (y > fYMax || y < fYMin)
 321     {
 322 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 323         return kFALSE;
 324     }
 325
 326 //
 327 // phi cut
 328     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)))+TMath::Pi();
 329     if (phi > fPhiMax || phi < fPhiMin)
 330     {
 331 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 332         return kFALSE;
 333     }
 334
 335     return kTRUE;
 336 }
 337 void AliGenPythia::AdjustWeights()
 338 {
 339     TClonesArray *PartArray = gAlice->Particles();
 340     TParticle *Part;
 341     Int_t ntrack=gAlice->GetNtrack();
 342     for (Int_t i=0; i<ntrack; i++) {
 343         Part= (TParticle*) PartArray->UncheckedAt(i);
 344         Part->SetWeight(Part->GetWeight()*fKineBias);
 345     }
 346 }
 347
 348
 349
 350
 351
 352
 353
 354
 355