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->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     AliMC* pMC = AliMC::GetMC();
 116
 117     Float_t polar[3] =   {0,0,0};
 118     Float_t origin[3]=   {0,0,0};
 119     Float_t origin_p[3]= {0,0,0};
 120     Float_t origin0[3]=  {0,0,0};
 121     Float_t p[3], p_p[4], random[6];
 122 //  converts from mm/c to s
 123     const Float_t kconv=0.001/2.999792458e8;
 124
 125
 126 //
 127     Int_t nt=0;
 128     Int_t nt_p=0;
 129     Int_t jev=0;
 130     Int_t j;
 131
 132     fTrials=0;
 133     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 134     if(fVertexSmear==perEvent) {
 135         pMC->Rndm(random,6);
 136         for (j=0;j<3;j++) {
 137             origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 138                 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 139             fPythia->SetMSTP(151,0);
 140         }
 141     } else if (fVertexSmear==perTrack) {
 142         fPythia->SetMSTP(151,0);
 143         for (j=0;j<3;j++) {
 144             fPythia->SetPARP(151+j, fOsigma[j]*10.);
 145         }
 146     }
 147     while(1)
 148     {
 149         fPythia->PyEvnt();
 150         fTrials++;
 151         TObjArray* particles = fPythia->GetPrimaries() ;
 152         Int_t np = particles->GetEntriesFast();
 153         printf("\n **************************************************%d\n",np);
 154         Int_t nc=0;
 155         if (np == 0 ) continue;
 156         if (fProcess != mb) {
 157             for (Int_t i = 0; i<np; i++) {
 158                 TMCParticle *  iparticle = (TMCParticle *) particles->At(i);
 159                 Int_t kf = iparticle->GetKF();
 160                 fChildWeight=(fPythia->GetBraPart(kf))*fParentWeight;
 161 //
 162 // Parent
 163                 if (ParentSelected(TMath::Abs(kf))) {
 164                     if (KinematicSelection(iparticle)) {
 165                         if (nc==0) {
 166 //
 167 // Store information concerning the hard scattering process
 168 //
 169                             Float_t mass_p = fPythia->GetPARI(13);
 170                             Float_t   pt_p = fPythia->GetPARI(17);
 171                             Float_t    y_p = fPythia->GetPARI(37);
 172                             Float_t  xmt_p = sqrt(pt_p*pt_p+mass_p*mass_p);
 173                             Float_t     ty = Float_t(TMath::TanH(y_p));
 174                             p_p[0] = pt_p;
 175                             p_p[1] = 0;
 176                             p_p[2] = xmt_p*ty/sqrt(1.-ty*ty);
 177                             p_p[3] = mass_p;
 178                             gAlice->SetTrack(0,-1,-1,
 179                                              p_p,origin_p,polar,
 180                                              0,"Hard Scat.",nt_p,fParentWeight);
 181                             gAlice->KeepTrack(nt_p);
 182                         }
 183                         nc++;
 184 //
 185 // store parent track information
 186                         p[0]=iparticle->GetPx();
 187                         p[1]=iparticle->GetPy();
 188                         p[2]=iparticle->GetPz();
 189                         origin[0]=origin0[0]+iparticle->GetVx()/10;
 190                         origin[1]=origin0[1]+iparticle->GetVy()/10;
 191                         origin[2]=origin0[2]+iparticle->GetVz()/10;
 192
 193                         Int_t ifch=iparticle->GetFirstChild();
 194                         Int_t ilch=iparticle->GetLastChild();
 195                         if (ifch !=0 && ilch !=0) {
 196                             gAlice->SetTrack(0,nt_p,fPythia->GetGeantCode(kf),
 197                                              p,origin,polar,
 198                                              0,"Primary",nt,fParentWeight);
 199                             gAlice->KeepTrack(nt);
 200                             Int_t iparent = nt;
 201 //
 202 // Children
 203
 204                             for (Int_t j=ifch; j<=ilch; j++)
 205                             {
 206                                 TMCParticle *  ichild =
 207                                     (TMCParticle *) particles->At(j-1);
 208                                 Int_t kf = ichild->GetKF();
 209 //
 210 //
 211                                 if (ChildSelected(TMath::Abs(kf))) {
 212                                     Int_t kg=fPythia->GetGeantCode(kf);
 213                                     origin[0]=ichild->GetVx();
 214                                     origin[1]=ichild->GetVy();
 215                                     origin[2]=ichild->GetVz();
 216                                     p[0]=ichild->GetPx();
 217                                     p[1]=ichild->GetPy();
 218                                     p[2]=ichild->GetPz();
 219                                     Float_t tof=kconv*ichild->GetTime();
 220                                     gAlice->SetTrack(fTrackIt, iparent, kg,
 221                                                      p,origin,polar,
 222                                                      tof,"Decay",nt,fChildWeight);
 223                                     gAlice->KeepTrack(nt);
 224                                 } // select child
 225                             } // child loop
 226                         }
 227                     } // kinematic selection
 228                 } // select particle
 229             } // particle loop
 230         } else {
 231             for (Int_t i = 0; i<np; i++) {
 232                 TMCParticle *  iparticle = (TMCParticle *) particles->At(i);
 233                 Int_t kf = iparticle->GetKF();
 234                 Int_t ks = iparticle->GetKS();
 235                 Int_t gc = fPythia->GetGeantCode(kf);
 236                 if (ks==1 && gc!=0 && KinematicSelection(iparticle)) {
 237                         nc++;
 238 //
 239 // store track information
 240                         p[0]=iparticle->GetPx();
 241                         p[1]=iparticle->GetPy();
 242                         p[2]=iparticle->GetPz();
 243                         origin[0]=origin0[0]+iparticle->GetVx()/10;
 244                         origin[1]=origin0[1]+iparticle->GetVy()/10;
 245                         origin[2]=origin0[2]+iparticle->GetVz()/10;
 246                         Float_t tof=kconv*iparticle->GetTime();
 247                         gAlice->SetTrack(fTrackIt,-1,gc,p,origin,polar,
 248                                          tof,"Primary",nt);
 249                         gAlice->KeepTrack(nt);
 250                 } // select particle
 251             } // particle loop
 252             printf("\n I've put %i particles on the stack \n",nc);
 253         } // mb ?
 254         if (nc > 0) {
 255             jev+=nc;
 256             if (jev >= fNpart) {
 257                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 258                 printf("\n Trials: %i\n",fTrials);
 259                 break;
 260             }
 261         }
 262     } // event loop
 263 //  adjust weight due to kinematic selection
 264     AdjustWeights();
 265 //  get cross-section
 266     fXsection=fPythia->GetPARI(1);
 267 }
 268
 269 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 270 {
 271     for (Int_t i=0; i<5; i++)
 272     {
 273         if (fParentSelect[i]==ip) return kTRUE;
 274     }
 275     return kFALSE;
 276 }
 277
 278 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 279 {
 280     for (Int_t i=0; i<5; i++)
 281     {
 282         if (fChildSelect[i]==ip) return kTRUE;
 283     }
 284     return kFALSE;
 285 }
 286
 287 Bool_t AliGenPythia::KinematicSelection(TMCParticle *particle)
 288 {
 289     Float_t px=particle->GetPx();
 290     Float_t py=particle->GetPy();
 291     Float_t pz=particle->GetPz();
 292     Float_t  e=particle->GetEnergy();
 293
 294 //
 295 //  transverse momentum cut
 296     Float_t pt=TMath::Sqrt(px*px+py*py);
 297     if (pt > fPtMax || pt < fPtMin)
 298     {
 299 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 300         return kFALSE;
 301     }
 302 //
 303 // momentum cut
 304     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 305     if (p > fPMax || p < fPMin)
 306     {
 307 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 308         return kFALSE;
 309     }
 310
 311 //
 312 // theta cut
 313     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
 314     if (theta > fThetaMax || theta < fThetaMin)
 315     {
 316 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 317         return kFALSE;
 318     }
 319
 320 //
 321 // rapidity cut
 322     Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 323     if (y > fYMax || y < fYMin)
 324     {
 325 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 326         return kFALSE;
 327     }
 328
 329 //
 330 // phi cut
 331     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)))+TMath::Pi();
 332     if (phi > fPhiMax || phi < fPhiMin)
 333     {
 334 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 335         return kFALSE;
 336     }
 337
 338     return kTRUE;
 339 }
 340 void AliGenPythia::AdjustWeights()
 341 {
 342     TClonesArray *PartArray = gAlice->Particles();
 343     GParticle *Part;
 344     Int_t ntrack=gAlice->GetNtrack();
 345     for (Int_t i=0; i<ntrack; i++) {
 346         Part= (GParticle*) PartArray->UncheckedAt(i);
 347         Part->SetWgt(Part->GetWgt()*fKineBias);
 348     }
 349 }
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