EVGEN/AliGenPythia.cxx

   1 #include "AliGenerator.h"
   2 #include "AliGenPythia.h"
   3 #include "AliRun.h"
   4 #include "AliPythia.h"
   5 #include <TDirectory.h>
   6 #include <TFile.h>
   7 #include <TTree.h>
   8 #include <stdlib.h>
   9 #include <AliPythia.h>
  10 #include <TParticle.h>
  11 //#include <GParticle.h>
  12  ClassImp(AliGenPythia)
  13
  14 AliGenPythia::AliGenPythia()
  15                  :AliGenerator()
  16 {
  17 }
  18
  19 AliGenPythia::AliGenPythia(Int_t npart)
  20                  :AliGenerator(npart)
  21 {
  22 // default charm production at 5. 5 TeV
  23 // semimuonic decay
  24 // structure function GRVHO
  25 //
  26     fXsection  = 0.;
  27     fParentSelect.Set(5);
  28     fChildSelect.Set(5);
  29     for (Int_t i=0; i<5; i++) fParentSelect[i]=fChildSelect[i]=0;
  30     SetProcess();
  31     SetStrucFunc();
  32     ForceDecay();
  33     SetPtHard();
  34     SetEnergyCMS();
  35 }
  36
  37 AliGenPythia::~AliGenPythia()
  38 {
  39 }
  40
  41 void AliGenPythia::Init()
  42 {
  43     SetMC(new AliPythia());
  44     fPythia=(AliPythia*) fgMCEvGen;
  45 //
  46     fParentWeight=1./Float_t(fNpart);
  47 //
  48 //  Forward Paramters to the AliPythia object
  49     fPythia->DefineParticles();
  50     fPythia->SetCKIN(3,fPtHardMin);
  51     fPythia->SetCKIN(4,fPtHardMax);
  52     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
  53     fPythia->ForceDecay(fForceDecay);
  54     fPythia->LuList(0);
  55     fPythia->PyStat(2);
  56 //  Parent and Children Selection
  57     switch (fProcess)
  58     {
  59     case charm:
  60
  61         fParentSelect[0]=411;
  62         fParentSelect[1]=421;
  63         fParentSelect[2]=431;
  64         fParentSelect[3]=4122;
  65         break;
  66     case charm_unforced:
  67
  68         fParentSelect[0]=411;
  69         fParentSelect[1]=421;
  70         fParentSelect[2]=431;
  71         fParentSelect[3]=4122;
  72         break;
  73     case beauty:
  74         fParentSelect[0]=511;
  75         fParentSelect[1]=521;
  76         fParentSelect[2]=531;
  77         fParentSelect[3]=5122;
  78         break;
  79     case beauty_unforced:
  80         fParentSelect[0]=511;
  81         fParentSelect[1]=521;
  82         fParentSelect[2]=531;
  83         fParentSelect[3]=5122;
  84         break;
  85     case jpsi_chi:
  86     case jpsi:
  87         fParentSelect[0]=443;
  88         break;
  89     case mb:
  90         break;
  91     }
  92
  93     switch (fForceDecay)
  94     {
  95     case semielectronic:
  96     case dielectron:
  97     case b_jpsi_dielectron:
  98     case b_psip_dielectron:
  99         fChildSelect[0]=11;
 100         break;
 101     case semimuonic:
 102     case dimuon:
 103     case b_jpsi_dimuon:
 104     case b_psip_dimuon:
 105     case pitomu:
 106     case katomu:
 107         fChildSelect[0]=13;
 108         break;
 109     }
 110 }
 111
 112 void AliGenPythia::Generate()
 113 {
 114
 115     Float_t polar[3] =   {0,0,0};
 116     Float_t origin[3]=   {0,0,0};
 117     Float_t origin_p[3]= {0,0,0};
 118     Float_t origin0[3]=  {0,0,0};
 119     Float_t p[3], p_p[4], random[6];
 120     static TClonesArray *particles;
 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     if(!particles) particles=new TClonesArray("TParticle",1000);
 132
 133     fTrials=0;
 134     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 135     if(fVertexSmear==perEvent) {
 136         gMC->Rndm(random,6);
 137         for (j=0;j<3;j++) {
 138             origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 139                 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 140             fPythia->SetMSTP(151,0);
 141         }
 142     } else if (fVertexSmear==perTrack) {
 143         fPythia->SetMSTP(151,0);
 144         for (j=0;j<3;j++) {
 145             fPythia->SetPARP(151+j, fOsigma[j]*10.);
 146         }
 147     }
 148     while(1)
 149     {
 150         fPythia->PyEvnt();
 151         fTrials++;
 152         fPythia->ImportParticles(particles,"All");
 153         Int_t np = particles->GetEntriesFast();
 154         printf("\n **************************************************%d\n",np);
 155         Int_t nc=0;
 156         if (np == 0 ) continue;
 157         if (fProcess != mb) {
 158             for (Int_t i = 0; i<np; i++) {
 159                 TParticle *  iparticle = (TParticle *) particles->At(i);
 160                 Int_t kf = iparticle->GetPdgCode();
 161                 fChildWeight=(fPythia->GetBraPart(kf))*fParentWeight;
 162 //
 163 // Parent
 164                 if (ParentSelected(TMath::Abs(kf))) {
 165                     if (KinematicSelection(iparticle)) {
 166                         if (nc==0) {
 167 //
 168 // Store information concerning the hard scattering process
 169 //
 170                             Float_t mass_p = fPythia->GetPARI(13);
 171                             Float_t   pt_p = fPythia->GetPARI(17);
 172                             Float_t    y_p = fPythia->GetPARI(37);
 173                             Float_t  xmt_p = sqrt(pt_p*pt_p+mass_p*mass_p);
 174                             Float_t     ty = Float_t(TMath::TanH(y_p));
 175                             p_p[0] = pt_p;
 176                             p_p[1] = 0;
 177                             p_p[2] = xmt_p*ty/sqrt(1.-ty*ty);
 178                             p_p[3] = mass_p;
 179                             gAlice->SetTrack(0,-1,-1,
 180                                              p_p,origin_p,polar,
 181                                              0,"Hard Scat.",nt_p,fParentWeight);
 182                             gAlice->KeepTrack(nt_p);
 183                         }
 184                         nc++;
 185 //
 186 // store parent track information
 187                         p[0]=iparticle->Px();
 188                         p[1]=iparticle->Py();
 189                         p[2]=iparticle->Pz();
 190                         origin[0]=origin0[0]+iparticle->Vx()/10;
 191                         origin[1]=origin0[1]+iparticle->Vy()/10;
 192                         origin[2]=origin0[2]+iparticle->Vz()/10;
 193
 194                         Int_t ifch=iparticle->GetFirstDaughter();
 195                         Int_t ilch=iparticle->GetLastDaughter();
 196                         if (ifch !=0 && ilch !=0) {
 197                             gAlice->SetTrack(0,nt_p,kf,
 198                                              p,origin,polar,
 199                                              0,"Primary",nt,fParentWeight);
 200                             gAlice->KeepTrack(nt);
 201                             Int_t iparent = nt;
 202 //
 203 // Children
 204
 205                             for (Int_t j=ifch; j<=ilch; j++)
 206                             {
 207                                 TParticle *  ichild =
 208                                     (TParticle *) particles->At(j-1);
 209                                 Int_t kf = ichild->GetPdgCode();
 210 //
 211 //
 212                                 if (ChildSelected(TMath::Abs(kf))) {
 213                                     origin[0]=ichild->Vx();
 214                                     origin[1]=ichild->Vy();
 215                                     origin[2]=ichild->Vz();
 216                                     p[0]=ichild->Px();
 217                                     p[1]=ichild->Py();
 218                                     p[2]=ichild->Pz();
 219                                     Float_t tof=kconv*ichild->T();
 220                                     gAlice->SetTrack(fTrackIt, iparent, kf,
 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                 TParticle *  iparticle = (TParticle *) particles->At(i);
 233                 Int_t kf = iparticle->GetPdgCode();
 234                 Int_t ks = iparticle->GetStatusCode();
 235                 if (ks==1 && kf!=0 && KinematicSelection(iparticle)) {
 236                         nc++;
 237 //
 238 // store track information
 239                         p[0]=iparticle->Px();
 240                         p[1]=iparticle->Py();
 241                         p[2]=iparticle->Pz();
 242                         origin[0]=origin0[0]+iparticle->Vx()/10;
 243                         origin[1]=origin0[1]+iparticle->Vy()/10;
 244                         origin[2]=origin0[2]+iparticle->Vz()/10;
 245                         Float_t tof=kconv*iparticle->T();
 246                         gAlice->SetTrack(fTrackIt,-1,kf,p,origin,polar,
 247                                          tof,"Primary",nt);
 248                         gAlice->KeepTrack(nt);
 249                 } // select particle
 250             } // particle loop
 251             printf("\n I've put %i particles on the stack \n",nc);
 252         } // mb ?
 253         if (nc > 0) {
 254             jev+=nc;
 255             if (jev >= fNpart) {
 256                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 257                 printf("\n Trials: %i\n",fTrials);
 258                 break;
 259             }
 260         }
 261     } // event loop
 262 //  adjust weight due to kinematic selection
 263     AdjustWeights();
 264 //  get cross-section
 265     fXsection=fPythia->GetPARI(1);
 266 }
 267
 268 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 269 {
 270     for (Int_t i=0; i<5; i++)
 271     {
 272         if (fParentSelect[i]==ip) return kTRUE;
 273     }
 274     return kFALSE;
 275 }
 276
 277 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 278 {
 279     for (Int_t i=0; i<5; i++)
 280     {
 281         if (fChildSelect[i]==ip) return kTRUE;
 282     }
 283     return kFALSE;
 284 }
 285
 286 Bool_t AliGenPythia::KinematicSelection(TParticle *particle)
 287 {
 288     Float_t px=particle->Px();
 289     Float_t py=particle->Py();
 290     Float_t pz=particle->Pz();
 291     Float_t  e=particle->Energy();
 292
 293 //
 294 //  transverse momentum cut
 295     Float_t pt=TMath::Sqrt(px*px+py*py);
 296     if (pt > fPtMax || pt < fPtMin)
 297     {
 298 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 299         return kFALSE;
 300     }
 301 //
 302 // momentum cut
 303     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 304     if (p > fPMax || p < fPMin)
 305     {
 306 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 307         return kFALSE;
 308     }
 309
 310 //
 311 // theta cut
 312     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
 313     if (theta > fThetaMax || theta < fThetaMin)
 314     {
 315 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 316         return kFALSE;
 317     }
 318
 319 //
 320 // rapidity cut
 321     Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 322     if (y > fYMax || y < fYMin)
 323     {
 324 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 325         return kFALSE;
 326     }
 327
 328 //
 329 // phi cut
 330     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)))+TMath::Pi();
 331     if (phi > fPhiMax || phi < fPhiMin)
 332     {
 333 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 334         return kFALSE;
 335     }
 336
 337     return kTRUE;
 338 }
 339 void AliGenPythia::AdjustWeights()
 340 {
 341     TClonesArray *PartArray = gAlice->Particles();
 342     TParticle *Part;
 343     Int_t ntrack=gAlice->GetNtrack();
 344     for (Int_t i=0; i<ntrack; i++) {
 345         Part= (TParticle*) PartArray->UncheckedAt(i);
 346         Part->SetWeight(Part->GetWeight()*fKineBias);
 347     }
 348 }
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