EVGEN/AliGenPythia.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
   5  * Contributors are mentioned in the code where appropriate.              *
   6  *                                                                        *
   7  * Permission to use, copy, modify and distribute this software and its   *
   8  * documentation strictly for non-commercial purposes is hereby granted   *
   9  * without fee, provided that the above copyright notice appears in all   *
  10  * copies and that both the copyright notice and this permission notice   *
  11  * appear in the supporting documentation. The authors make no claims     *
  12  * about the suitability of this software for any purpose. It is          *
  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 /*
  17 $Log$
  18 Revision 1.21  2000/09/12 14:14:55  morsch
  19 Call fDecayer->ForceDecay() at the beginning of Generate().
  20
  21 Revision 1.20  2000/09/06 14:29:33  morsch
  22 Use AliPythia for event generation an AliDecayPythia for decays.
  23 Correct handling of "nodecay" option
  24
  25 Revision 1.19  2000/07/11 18:24:56  fca
  26 Coding convention corrections + few minor bug fixes
  27
  28 Revision 1.18  2000/06/30 12:40:34  morsch
  29 Pythia takes care of vertex smearing. Correct conversion from Pythia units (mm) to
  30 Geant units (cm).
  31
  32 Revision 1.17  2000/06/09 20:34:07  morsch
  33 All coding rule violations except RS3 corrected
  34
  35 Revision 1.16  2000/05/15 15:04:20  morsch
  36 The full event is written for fNtrack = -1
  37 Coding rule violations corrected.
  38
  39 Revision 1.15  2000/04/26 10:14:24  morsch
  40 Particles array has one entry more than pythia particle list. Upper bound of
  41 particle loop changed to np-1 (R. Guernane, AM)
  42
  43 Revision 1.14  2000/04/05 08:36:13  morsch
  44 Check status code of particles in Pythia event
  45 to avoid double counting as partonic state and final state particle.
  46
  47 Revision 1.13  1999/11/09 07:38:48  fca
  48 Changes for compatibility with version 2.23 of ROOT
  49
  50 Revision 1.12  1999/11/03 17:43:20  fca
  51 New version from G.Martinez & A.Morsch
  52
  53 Revision 1.11  1999/09/29 09:24:14  fca
  54 Introduction of the Copyright and cvs Log
  55 */
  56
  57 #include "AliGenPythia.h"
  58 #include "AliDecayerPythia.h"
  59 #include "AliRun.h"
  60 #include "AliPythia.h"
  61 #include "AliPDG.h"
  62 #include <TParticle.h>
  63 #include <TSystem.h>
  64
  65  ClassImp(AliGenPythia)
  66
  67 AliGenPythia::AliGenPythia()
  68                  :AliGenerator()
  69 {
  70 // Default Constructor
  71   fDecayer = new AliDecayerPythia();
  72 }
  73
  74 AliGenPythia::AliGenPythia(Int_t npart)
  75                  :AliGenerator(npart)
  76 {
  77 // default charm production at 5. 5 TeV
  78 // semimuonic decay
  79 // structure function GRVHO
  80 //
  81     fXsection  = 0.;
  82     fParentSelect.Set(5);
  83     fChildSelect.Set(5);
  84     for (Int_t i=0; i<5; i++) fParentSelect[i]=fChildSelect[i]=0;
  85     SetProcess();
  86     SetStrucFunc();
  87     SetForceDecay();
  88     SetPtHard();
  89     SetEnergyCMS();
  90     fDecayer = new AliDecayerPythia();
  91 }
  92
  93 AliGenPythia::AliGenPythia(const AliGenPythia & Pythia)
  94 {
  95 // copy constructor
  96 }
  97
  98 AliGenPythia::~AliGenPythia()
  99 {
 100 // Destructor
 101 }
 102
 103 void AliGenPythia::Init()
 104 {
 105 // Initialisation
 106   SetMC(AliPythia::Instance());
 107     fPythia=(AliPythia*) fgMCEvGen;
 108 //
 109     fParentWeight=1./Float_t(fNpart);
 110 //
 111 //  Forward Paramters to the AliPythia object
 112     //    gSystem->Exec("ln -s $ALICE_ROOT/data/Decay.table fort.1");
 113     //    fPythia->Pyupda(2,1);
 114     //    gSystem->Exec("rm fort.1");
 115
 116     fDecayer->SetForceDecay(fForceDecay);
 117     fDecayer->Init();
 118
 119
 120     fPythia->SetCKIN(3,fPtHardMin);
 121     fPythia->SetCKIN(4,fPtHardMax);
 122     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
 123
 124     //    fPythia->Pylist(0);
 125     //    fPythia->Pystat(2);
 126 //  Parent and Children Selection
 127     switch (fProcess)
 128     {
 129     case charm:
 130
 131         fParentSelect[0]=411;
 132         fParentSelect[1]=421;
 133         fParentSelect[2]=431;
 134         fParentSelect[3]=4122;
 135         break;
 136     case charm_unforced:
 137
 138         fParentSelect[0]=411;
 139         fParentSelect[1]=421;
 140         fParentSelect[2]=431;
 141         fParentSelect[3]=4122;
 142         break;
 143     case beauty:
 144         fParentSelect[0]=511;
 145         fParentSelect[1]=521;
 146         fParentSelect[2]=531;
 147         fParentSelect[3]=5122;
 148         break;
 149     case beauty_unforced:
 150         fParentSelect[0]=511;
 151         fParentSelect[1]=521;
 152         fParentSelect[2]=531;
 153         fParentSelect[3]=5122;
 154         break;
 155     case jpsi_chi:
 156     case jpsi:
 157         fParentSelect[0]=443;
 158         break;
 159     case mb:
 160         break;
 161     }
 162
 163     switch (fForceDecay)
 164     {
 165     case semielectronic:
 166     case dielectron:
 167     case b_jpsi_dielectron:
 168     case b_psip_dielectron:
 169         fChildSelect[0]=kElectron;
 170         break;
 171     case semimuonic:
 172     case dimuon:
 173     case b_jpsi_dimuon:
 174     case b_psip_dimuon:
 175     case pitomu:
 176     case katomu:
 177         fChildSelect[0]=kMuonMinus;
 178         break;
 179     case hadronicD:
 180       fChildSelect[0]=kPiPlus;
 181       fChildSelect[1]=kKPlus;
 182       break;
 183     case all:
 184     case nodecay:
 185       break;
 186     }
 187 }
 188
 189 void AliGenPythia::Generate()
 190 {
 191 // Generate one event
 192     fDecayer->ForceDecay();
 193
 194     Float_t polar[3] =   {0,0,0};
 195     Float_t origin[3]=   {0,0,0};
 196     Float_t originP[3]= {0,0,0};
 197     Float_t origin0[3]=  {0,0,0};
 198     Float_t p[3], pP[4];
 199 //    Float_t random[6];
 200     static TClonesArray *particles;
 201 //  converts from mm/c to s
 202     const Float_t kconv=0.001/2.999792458e8;
 203
 204
 205 //
 206     Int_t nt=0;
 207     Int_t ntP=0;
 208     Int_t jev=0;
 209     Int_t j, kf;
 210
 211     if(!particles) particles=new TClonesArray("TParticle",1000);
 212
 213     fTrials=0;
 214     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 215     if(fVertexSmear==kPerEvent) {
 216         fPythia->SetMSTP(151,1);
 217         for (j=0;j<3;j++) {
 218             fPythia->SetPARP(151+j, fOsigma[j]/10.);
 219         }
 220     } else if (fVertexSmear==kPerTrack) {
 221         fPythia->SetMSTP(151,0);
 222     }
 223
 224     while(1)
 225     {
 226         fPythia->Pyevnt();
 227 //      fPythia->Pylist(1);
 228         fTrials++;
 229         fPythia->ImportParticles(particles,"All");
 230         Int_t np = particles->GetEntriesFast();
 231         printf("\n **************************************************%d\n",np);
 232         Int_t nc=0;
 233         if (np == 0 ) continue;
 234         if (fProcess != mb) {
 235             for (Int_t i = 0; i<np-1; i++) {
 236                 TParticle *  iparticle = (TParticle *) particles->At(i);
 237                 Int_t ks = iparticle->GetStatusCode();
 238                 kf = CheckPDGCode(iparticle->GetPdgCode());
 239                 if (ks==21) continue;
 240
 241                 fChildWeight=(fDecayer->GetPartialBranchingRatio(kf))*fParentWeight;
 242 //
 243 // Parent
 244                 if (ParentSelected(TMath::Abs(kf))) {
 245                     if (KinematicSelection(iparticle)) {
 246                         if (nc==0) {
 247 //
 248 // Store information concerning the hard scattering process
 249 //
 250                             Float_t massP  = fPythia->GetPARI(13);
 251                             Float_t   ptP  = fPythia->GetPARI(17);
 252                             Float_t    yP  = fPythia->GetPARI(37);
 253                             Float_t  xmtP  = sqrt(ptP*ptP+massP*massP);
 254                             Float_t    ty  = Float_t(TMath::TanH(yP));
 255                             pP[0] = ptP;
 256                             pP[1] = 0;
 257                             pP[2] = xmtP*ty/sqrt(1.-ty*ty);
 258                             pP[3] = massP;
 259                             gAlice->SetTrack(0,-1,-1,
 260                                              pP,originP,polar,
 261                                              0,"Hard Scat.",ntP,fParentWeight);
 262                             gAlice->KeepTrack(ntP);
 263                         }
 264                         nc++;
 265 //
 266 // store parent track information
 267                         p[0]=iparticle->Px();
 268                         p[1]=iparticle->Py();
 269                         p[2]=iparticle->Pz();
 270                         origin[0]=origin0[0]+iparticle->Vx()*10.;
 271                         origin[1]=origin0[1]+iparticle->Vy()*10.;
 272                         origin[2]=origin0[2]+iparticle->Vz()*10.;
 273
 274                         Int_t ifch=iparticle->GetFirstDaughter();
 275                         Int_t ilch=iparticle->GetLastDaughter();
 276
 277                         if ((ifch !=0 && ilch !=0) || fForceDecay == nodecay) {
 278                           Int_t trackit=0;
 279                           if (fForceDecay == nodecay) trackit = 1;
 280                             gAlice->SetTrack(trackit,ntP,kf,
 281                                              p,origin,polar,
 282                                              0,"Primary",nt,fParentWeight);
 283                             gAlice->KeepTrack(nt);
 284                             Int_t iparent = nt;
 285 //
 286 // Children
 287                             if (fForceDecay != nodecay) {
 288                               for (j=ifch; j<=ilch; j++)
 289                                 {
 290                                   TParticle *  ichild =
 291                                     (TParticle *) particles->At(j-1);
 292                                   kf = CheckPDGCode(ichild->GetPdgCode());
 293 //
 294 //
 295                                   if (ChildSelected(TMath::Abs(kf))) {
 296                                     origin[0]=origin0[0]+ichild->Vx()/10.;
 297                                     origin[1]=origin0[1]+ichild->Vy()/10.;
 298                                     origin[2]=origin0[2]+ichild->Vz()/10.;
 299                                     p[0]=ichild->Px();
 300                                     p[1]=ichild->Py();
 301                                     p[2]=ichild->Pz();
 302                                     Float_t tof=kconv*ichild->T();
 303                                     gAlice->SetTrack(fTrackIt, iparent, kf,
 304                                                      p,origin,polar,
 305                                                      tof,"Decay",nt,fChildWeight);
 306                                     gAlice->KeepTrack(nt);
 307                                   } // select child
 308                                 } // child loop
 309                             }
 310                         }
 311                     } // kinematic selection
 312                 } // select particle
 313             } // particle loop
 314         } else {
 315             for (Int_t i = 0; i<np-1; i++) {
 316                 TParticle *  iparticle = (TParticle *) particles->At(i);
 317                 kf = CheckPDGCode(iparticle->GetPdgCode());
 318                 Int_t ks = iparticle->GetStatusCode();
 319
 320                 if (ks==1 && kf!=0 && KinematicSelection(iparticle)) {
 321                         nc++;
 322 //
 323 // store track information
 324                         p[0]=iparticle->Px();
 325                         p[1]=iparticle->Py();
 326                         p[2]=iparticle->Pz();
 327                         origin[0]=origin0[0]+iparticle->Vx()/10.;
 328                         origin[1]=origin0[1]+iparticle->Vy()/10.;
 329                         origin[2]=origin0[2]+iparticle->Vz()/10.;
 330                         Float_t tof=kconv*iparticle->T();
 331                         gAlice->SetTrack(fTrackIt,-1,kf,p,origin,polar,
 332                                          tof,"Primary",nt);
 333                         gAlice->KeepTrack(nt);
 334                 } // select particle
 335             } // particle loop
 336             printf("\n I've put %i particles on the stack \n",nc);
 337         } // mb ?
 338         if (nc > 0) {
 339             jev+=nc;
 340             if (jev >= fNpart || fNpart == -1) {
 341                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 342                 printf("\n Trials: %i %i %i\n",fTrials, fNpart, jev);
 343                 break;
 344             }
 345         }
 346     } // event loop
 347 //  adjust weight due to kinematic selection
 348     AdjustWeights();
 349 //  get cross-section
 350     fXsection=fPythia->GetPARI(1);
 351 }
 352
 353 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 354 {
 355 // True if particle is in list of parent particles to be selected
 356     for (Int_t i=0; i<5; i++)
 357     {
 358         if (fParentSelect[i]==ip) return kTRUE;
 359     }
 360     return kFALSE;
 361 }
 362
 363 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 364 {
 365 // True if particle is in list of decay products to be selected
 366     if (fForceDecay == all) return kTRUE;
 367
 368     for (Int_t i=0; i<5; i++)
 369     {
 370         if (fChildSelect[i]==ip) return kTRUE;
 371     }
 372     return kFALSE;
 373 }
 374
 375 Bool_t AliGenPythia::KinematicSelection(TParticle *particle)
 376 {
 377 // Perform kinematic selection
 378     Float_t px=particle->Px();
 379     Float_t py=particle->Py();
 380     Float_t pz=particle->Pz();
 381     Float_t  e=particle->Energy();
 382
 383 //
 384 //  transverse momentum cut
 385     Float_t pt=TMath::Sqrt(px*px+py*py);
 386     if (pt > fPtMax || pt < fPtMin)
 387     {
 388 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 389         return kFALSE;
 390     }
 391 //
 392 // momentum cut
 393     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 394     if (p > fPMax || p < fPMin)
 395     {
 396 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 397         return kFALSE;
 398     }
 399
 400 //
 401 // theta cut
 402     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
 403     if (theta > fThetaMax || theta < fThetaMin)
 404     {
 405 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 406         return kFALSE;
 407     }
 408
 409 //
 410 // rapidity cut
 411     Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 412     if (y > fYMax || y < fYMin)
 413     {
 414 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 415         return kFALSE;
 416     }
 417
 418 //
 419 // phi cut
 420     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)));
 421     if (phi > fPhiMax || phi < fPhiMin)
 422     {
 423 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 424         return kFALSE;
 425     }
 426
 427     return kTRUE;
 428 }
 429 void AliGenPythia::AdjustWeights()
 430 {
 431 // Adjust the weights after generation of all events
 432 //
 433     TClonesArray *partArray = gAlice->Particles();
 434     TParticle *part;
 435     Int_t ntrack=gAlice->GetNtrack();
 436     for (Int_t i=0; i<ntrack; i++) {
 437         part= (TParticle*) partArray->UncheckedAt(i);
 438         part->SetWeight(part->GetWeight()*fKineBias);
 439     }
 440 }
 441
 442 Int_t AliGenPythia::CheckPDGCode(Int_t pdgcode)
 443 {
 444 //
 445 //  If the particle is in a diffractive state, then take action accordingly
 446   switch (pdgcode) {
 447   case 91:
 448     return 92;
 449   case 110:
 450     //rho_diff0 -- difficult to translate, return rho0
 451     return 113;
 452   case 210:
 453     //pi_diffr+ -- change to pi+
 454     return 211;
 455   case 220:
 456     //omega_di0 -- change to omega0
 457     return 223;
 458   case 330:
 459     //phi_diff0 -- return phi0
 460     return 333;
 461   case 440:
 462     //J/psi_di0 -- return J/psi
 463     return 443;
 464   case 2110:
 465     //n_diffr -- return neutron
 466     return 2112;
 467   case 2210:
 468     //p_diffr+ -- return proton
 469     return 2212;
 470   }
 471   //non diffractive state -- return code unchanged
 472   return pdgcode;
 473 }
 474
 475 AliGenPythia& AliGenPythia::operator=(const  AliGenPythia& rhs)
 476 {
 477 // Assignment operator
 478     return *this;
 479 }
 480
 481
 482 void AliGenPythia::Streamer(TBuffer &R__b)
 483 {
 484    // Stream an object of class AliGenPythia.
 485
 486    if (R__b.IsReading()) {
 487       Version_t R__v = R__b.ReadVersion(); if (R__v) { }
 488       AliGenerator::Streamer(R__b);
 489       R__b >> (Int_t&)fProcess;
 490       R__b >> (Int_t&)fStrucFunc;
 491       R__b >> (Int_t&)fForceDecay;
 492       R__b >> fEnergyCMS;
 493       R__b >> fKineBias;
 494       R__b >> fTrials;
 495       fParentSelect.Streamer(R__b);
 496       fChildSelect.Streamer(R__b);
 497       R__b >> fXsection;
 498 //      (AliPythia::Instance())->Streamer(R__b);
 499       R__b >> fPtHardMin;
 500       R__b >> fPtHardMax;
 501 //      if (fDecayer) fDecayer->Streamer(R__b);
 502    } else {
 503       R__b.WriteVersion(AliGenPythia::IsA());
 504       AliGenerator::Streamer(R__b);
 505       R__b << (Int_t)fProcess;
 506       R__b << (Int_t)fStrucFunc;
 507       R__b << (Int_t)fForceDecay;
 508       R__b << fEnergyCMS;
 509       R__b << fKineBias;
 510       R__b << fTrials;
 511       fParentSelect.Streamer(R__b);
 512       fChildSelect.Streamer(R__b);
 513       R__b << fXsection;
 514 //      R__b << fPythia;
 515       R__b << fPtHardMin;
 516       R__b << fPtHardMax;
 517       //     fDecayer->Streamer(R__b);
 518    }
 519 }
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