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 1.25  2000/10/18 19:11:27  hristov
  19 Division by zero fixed
  20
  21 Revision 1.24  2000/09/18 10:41:35  morsch
  22 Add possibility to use nuclear structure functions from PDF library V8.
  23
  24 Revision 1.23  2000/09/14 14:05:40  morsch
  25 dito
  26
  27 Revision 1.22  2000/09/14 14:02:22  morsch
  28 - Correct conversion from mm to cm when passing particle vertex to MC.
  29 - Correct handling of fForceDecay == all.
  30
  31 Revision 1.21  2000/09/12 14:14:55  morsch
  32 Call fDecayer->ForceDecay() at the beginning of Generate().
  33
  34 Revision 1.20  2000/09/06 14:29:33  morsch
  35 Use AliPythia for event generation an AliDecayPythia for decays.
  36 Correct handling of "nodecay" option
  37
  38 Revision 1.19  2000/07/11 18:24:56  fca
  39 Coding convention corrections + few minor bug fixes
  40
  41 Revision 1.18  2000/06/30 12:40:34  morsch
  42 Pythia takes care of vertex smearing. Correct conversion from Pythia units (mm) to
  43 Geant units (cm).
  44
  45 Revision 1.17  2000/06/09 20:34:07  morsch
  46 All coding rule violations except RS3 corrected
  47
  48 Revision 1.16  2000/05/15 15:04:20  morsch
  49 The full event is written for fNtrack = -1
  50 Coding rule violations corrected.
  51
  52 Revision 1.15  2000/04/26 10:14:24  morsch
  53 Particles array has one entry more than pythia particle list. Upper bound of
  54 particle loop changed to np-1 (R. Guernane, AM)
  55
  56 Revision 1.14  2000/04/05 08:36:13  morsch
  57 Check status code of particles in Pythia event
  58 to avoid double counting as partonic state and final state particle.
  59
  60 Revision 1.13  1999/11/09 07:38:48  fca
  61 Changes for compatibility with version 2.23 of ROOT
  62
  63 Revision 1.12  1999/11/03 17:43:20  fca
  64 New version from G.Martinez & A.Morsch
  65
  66 Revision 1.11  1999/09/29 09:24:14  fca
  67 Introduction of the Copyright and cvs Log
  68 */
  69
  70 #include "AliGenPythia.h"
  71 #include "AliDecayerPythia.h"
  72 #include "AliRun.h"
  73 #include "AliPythia.h"
  74 #include "AliPDG.h"
  75 #include <TParticle.h>
  76 #include <TSystem.h>
  77
  78  ClassImp(AliGenPythia)
  79
  80 AliGenPythia::AliGenPythia()
  81                  :AliGenerator()
  82 {
  83 // Default Constructor
  84   fDecayer = new AliDecayerPythia();
  85 }
  86
  87 AliGenPythia::AliGenPythia(Int_t npart)
  88                  :AliGenerator(npart)
  89 {
  90 // default charm production at 5. 5 TeV
  91 // semimuonic decay
  92 // structure function GRVHO
  93 //
  94     fXsection  = 0.;
  95     fNucA1=0;
  96     fNucA2=0;
  97     fParentSelect.Set(5);
  98     fChildSelect.Set(5);
  99     for (Int_t i=0; i<5; i++) fParentSelect[i]=fChildSelect[i]=0;
 100     SetProcess();
 101     SetStrucFunc();
 102     SetForceDecay();
 103     SetPtHard();
 104     SetEnergyCMS();
 105     fDecayer = new AliDecayerPythia();
 106 }
 107
 108 AliGenPythia::AliGenPythia(const AliGenPythia & Pythia)
 109 {
 110 // copy constructor
 111 }
 112
 113 AliGenPythia::~AliGenPythia()
 114 {
 115 // Destructor
 116 }
 117
 118 void AliGenPythia::Init()
 119 {
 120 // Initialisation
 121   SetMC(AliPythia::Instance());
 122     fPythia=(AliPythia*) fgMCEvGen;
 123 //
 124     fParentWeight=1./Float_t(fNpart);
 125 //
 126 //  Forward Paramters to the AliPythia object
 127     //    gSystem->Exec("ln -s $ALICE_ROOT/data/Decay.table fort.1");
 128     //    fPythia->Pyupda(2,1);
 129     //    gSystem->Exec("rm fort.1");
 130
 131     fDecayer->SetForceDecay(fForceDecay);
 132     fDecayer->Init();
 133
 134
 135     fPythia->SetCKIN(3,fPtHardMin);
 136     fPythia->SetCKIN(4,fPtHardMax);
 137     if (fNucA1 > 0 && fNucA2 > 0) fPythia->SetNuclei(fNucA1, fNucA2);
 138     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
 139
 140     //    fPythia->Pylist(0);
 141     //    fPythia->Pystat(2);
 142 //  Parent and Children Selection
 143     switch (fProcess)
 144     {
 145     case charm:
 146
 147         fParentSelect[0]=411;
 148         fParentSelect[1]=421;
 149         fParentSelect[2]=431;
 150         fParentSelect[3]=4122;
 151         break;
 152     case charm_unforced:
 153
 154         fParentSelect[0]=411;
 155         fParentSelect[1]=421;
 156         fParentSelect[2]=431;
 157         fParentSelect[3]=4122;
 158         break;
 159     case beauty:
 160         fParentSelect[0]=511;
 161         fParentSelect[1]=521;
 162         fParentSelect[2]=531;
 163         fParentSelect[3]=5122;
 164         break;
 165     case beauty_unforced:
 166         fParentSelect[0]=511;
 167         fParentSelect[1]=521;
 168         fParentSelect[2]=531;
 169         fParentSelect[3]=5122;
 170         break;
 171     case jpsi_chi:
 172     case jpsi:
 173         fParentSelect[0]=443;
 174         break;
 175     case mb:
 176         break;
 177     }
 178
 179     switch (fForceDecay)
 180     {
 181     case semielectronic:
 182     case dielectron:
 183     case b_jpsi_dielectron:
 184     case b_psip_dielectron:
 185         fChildSelect[0]=kElectron;
 186         break;
 187     case semimuonic:
 188     case dimuon:
 189     case b_jpsi_dimuon:
 190     case b_psip_dimuon:
 191     case pitomu:
 192     case katomu:
 193         fChildSelect[0]=kMuonMinus;
 194         break;
 195     case hadronicD:
 196       fChildSelect[0]=kPiPlus;
 197       fChildSelect[1]=kKPlus;
 198       break;
 199     case all:
 200     case nodecay:
 201       break;
 202     }
 203 }
 204
 205 void AliGenPythia::Generate()
 206 {
 207 // Generate one event
 208     fDecayer->ForceDecay();
 209
 210     Float_t polar[3] =   {0,0,0};
 211     Float_t origin[3]=   {0,0,0};
 212     Float_t originP[3]= {0,0,0};
 213     Float_t origin0[3]=  {0,0,0};
 214     Float_t p[3], pP[4];
 215 //    Float_t random[6];
 216     static TClonesArray *particles;
 217 //  converts from mm/c to s
 218     const Float_t kconv=0.001/2.999792458e8;
 219
 220
 221 //
 222     Int_t nt=0;
 223     Int_t ntP=0;
 224     Int_t jev=0;
 225     Int_t j, kf;
 226
 227     if(!particles) particles=new TClonesArray("TParticle",1000);
 228
 229     fTrials=0;
 230     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 231     if(fVertexSmear==kPerEvent) {
 232         fPythia->SetMSTP(151,1);
 233         for (j=0;j<3;j++) {
 234             fPythia->SetPARP(151+j, fOsigma[j]/10.);
 235         }
 236     } else if (fVertexSmear==kPerTrack) {
 237         fPythia->SetMSTP(151,0);
 238     }
 239
 240     while(1)
 241     {
 242         fPythia->Pyevnt();
 243 //      fPythia->Pylist(1);
 244         fTrials++;
 245         fPythia->ImportParticles(particles,"All");
 246         Int_t np = particles->GetEntriesFast();
 247         printf("\n **************************************************%d\n",np);
 248         Int_t nc=0;
 249         if (np == 0 ) continue;
 250         if (fProcess != mb) {
 251             for (Int_t i = 0; i<np-1; i++) {
 252                 TParticle *  iparticle = (TParticle *) particles->At(i);
 253                 Int_t ks = iparticle->GetStatusCode();
 254                 kf = CheckPDGCode(iparticle->GetPdgCode());
 255                 if (ks==21) continue;
 256
 257                 fChildWeight=(fDecayer->GetPartialBranchingRatio(kf))*fParentWeight;
 258 //
 259 // Parent
 260                 if (ParentSelected(TMath::Abs(kf))) {
 261                     if (KinematicSelection(iparticle)) {
 262                         if (nc==0) {
 263 //
 264 // Store information concerning the hard scattering process
 265 //
 266                             Float_t massP  = fPythia->GetPARI(13);
 267                             Float_t   ptP  = fPythia->GetPARI(17);
 268                             Float_t    yP  = fPythia->GetPARI(37);
 269                             Float_t  xmtP  = sqrt(ptP*ptP+massP*massP);
 270                             Float_t    ty  = Float_t(TMath::TanH(yP));
 271                             pP[0] = ptP;
 272                             pP[1] = 0;
 273                             pP[2] = xmtP*ty/sqrt(1.-ty*ty);
 274                             pP[3] = massP;
 275                             gAlice->SetTrack(0,-1,-1,
 276                                              pP,originP,polar,
 277                                              0,kPPrimary,ntP,fParentWeight);
 278 //                                           0,"Hard Scat.",ntP,fParentWeight);
 279                             gAlice->KeepTrack(ntP);
 280                         }
 281                         nc++;
 282 //
 283 // store parent track information
 284                         p[0]=iparticle->Px();
 285                         p[1]=iparticle->Py();
 286                         p[2]=iparticle->Pz();
 287                         origin[0]=origin0[0]+iparticle->Vx()/10.;
 288                         origin[1]=origin0[1]+iparticle->Vy()/10.;
 289                         origin[2]=origin0[2]+iparticle->Vz()/10.;
 290
 291                         Int_t ifch=iparticle->GetFirstDaughter();
 292                         Int_t ilch=iparticle->GetLastDaughter();
 293
 294                         if ((ifch !=0 && ilch !=0) || fForceDecay == nodecay) {
 295                           Int_t trackit=0;
 296                           if (fForceDecay == nodecay) trackit = 1;
 297                             gAlice->SetTrack(trackit,ntP,kf,
 298                                              p,origin,polar,
 299                                              0,kPPrimary,nt,fParentWeight);
 300                             gAlice->KeepTrack(nt);
 301                             Int_t iparent = nt;
 302 //
 303 // Children
 304                             if (fForceDecay != nodecay) {
 305                               for (j=ifch; j<=ilch; j++)
 306                                 {
 307                                   TParticle *  ichild =
 308                                     (TParticle *) particles->At(j-1);
 309                                   kf = CheckPDGCode(ichild->GetPdgCode());
 310 //
 311 //
 312                                   if (ChildSelected(TMath::Abs(kf))) {
 313                                     origin[0]=origin0[0]+ichild->Vx()/10.;
 314                                     origin[1]=origin0[1]+ichild->Vy()/10.;
 315                                     origin[2]=origin0[2]+ichild->Vz()/10.;
 316                                     p[0]=ichild->Px();
 317                                     p[1]=ichild->Py();
 318                                     p[2]=ichild->Pz();
 319                                     Float_t tof=kconv*ichild->T();
 320                                     gAlice->SetTrack(fTrackIt, iparent, kf,
 321                                                      p,origin,polar,
 322                                                      tof,kPDecay,nt,fChildWeight);
 323                                     gAlice->KeepTrack(nt);
 324                                   } // select child
 325                                 } // child loop
 326                             }
 327                         }
 328                     } // kinematic selection
 329                 } // select particle
 330             } // particle loop
 331         } else {
 332             for (Int_t i = 0; i<np-1; i++) {
 333                 TParticle *  iparticle = (TParticle *) particles->At(i);
 334                 kf = CheckPDGCode(iparticle->GetPdgCode());
 335                 Int_t ks = iparticle->GetStatusCode();
 336
 337                 if (ks==1 && kf!=0 && KinematicSelection(iparticle)) {
 338                         nc++;
 339 //
 340 // store track information
 341                         p[0]=iparticle->Px();
 342                         p[1]=iparticle->Py();
 343                         p[2]=iparticle->Pz();
 344                         origin[0]=origin0[0]+iparticle->Vx()/10.;
 345                         origin[1]=origin0[1]+iparticle->Vy()/10.;
 346                         origin[2]=origin0[2]+iparticle->Vz()/10.;
 347                         Float_t tof=kconv*iparticle->T();
 348                         gAlice->SetTrack(fTrackIt,-1,kf,p,origin,polar,
 349                                          tof,kPPrimary,nt);
 350                         gAlice->KeepTrack(nt);
 351                 } // select particle
 352             } // particle loop
 353             printf("\n I've put %i particles on the stack \n",nc);
 354         } // mb ?
 355         if (nc > 0) {
 356             jev+=nc;
 357             if (jev >= fNpart || fNpart == -1) {
 358                 fKineBias=Float_t(fNpart)/Float_t(fTrials);
 359                 printf("\n Trials: %i %i %i\n",fTrials, fNpart, jev);
 360 // Print x-section summary
 361                 fPythia->Pystat(1);
 362                 break;
 363             }
 364         }
 365     } // event loop
 366 //  adjust weight due to kinematic selection
 367     AdjustWeights();
 368 //  get cross-section
 369     fXsection=fPythia->GetPARI(1);
 370 }
 371
 372 Bool_t AliGenPythia::ParentSelected(Int_t ip)
 373 {
 374 // True if particle is in list of parent particles to be selected
 375     for (Int_t i=0; i<5; i++)
 376     {
 377         if (fParentSelect[i]==ip) return kTRUE;
 378     }
 379     return kFALSE;
 380 }
 381
 382 Bool_t AliGenPythia::ChildSelected(Int_t ip)
 383 {
 384 // True if particle is in list of decay products to be selected
 385     if (fForceDecay == all) return kTRUE;
 386
 387     for (Int_t i=0; i<5; i++)
 388     {
 389         if (fChildSelect[i]==ip) return kTRUE;
 390     }
 391     return kFALSE;
 392 }
 393
 394 Bool_t AliGenPythia::KinematicSelection(TParticle *particle)
 395 {
 396 // Perform kinematic selection
 397     Float_t px=particle->Px();
 398     Float_t py=particle->Py();
 399     Float_t pz=particle->Pz();
 400     Float_t  e=particle->Energy();
 401
 402 //
 403 //  transverse momentum cut
 404     Float_t pt=TMath::Sqrt(px*px+py*py);
 405     if (pt > fPtMax || pt < fPtMin)
 406     {
 407 //      printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
 408         return kFALSE;
 409     }
 410 //
 411 // momentum cut
 412     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 413     if (p > fPMax || p < fPMin)
 414     {
 415 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 416         return kFALSE;
 417     }
 418
 419 //
 420 // theta cut
 421     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
 422     if (theta > fThetaMax || theta < fThetaMin)
 423     {
 424 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 425         return kFALSE;
 426     }
 427
 428 //
 429 // rapidity cut
 430     if (e==pz) {
 431       return kFALSE;
 432     }
 433     else {
 434       Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
 435       if (y > fYMax || y < fYMin)
 436         {
 437 //      printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
 438           return kFALSE;
 439         }
 440     }
 441
 442 //
 443 // phi cut
 444     Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)));
 445     if (phi > fPhiMax || phi < fPhiMin)
 446     {
 447 //      printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
 448         return kFALSE;
 449     }
 450
 451     return kTRUE;
 452 }
 453 void AliGenPythia::AdjustWeights()
 454 {
 455 // Adjust the weights after generation of all events
 456 //
 457     TClonesArray *partArray = gAlice->Particles();
 458     TParticle *part;
 459     Int_t ntrack=gAlice->GetNtrack();
 460     for (Int_t i=0; i<ntrack; i++) {
 461         part= (TParticle*) partArray->UncheckedAt(i);
 462         part->SetWeight(part->GetWeight()*fKineBias);
 463     }
 464 }
 465
 466 Int_t AliGenPythia::CheckPDGCode(Int_t pdgcode)
 467 {
 468 //
 469 //  If the particle is in a diffractive state, then take action accordingly
 470   switch (pdgcode) {
 471   case 91:
 472     return 92;
 473   case 110:
 474     //rho_diff0 -- difficult to translate, return rho0
 475     return 113;
 476   case 210:
 477     //pi_diffr+ -- change to pi+
 478     return 211;
 479   case 220:
 480     //omega_di0 -- change to omega0
 481     return 223;
 482   case 330:
 483     //phi_diff0 -- return phi0
 484     return 333;
 485   case 440:
 486     //J/psi_di0 -- return J/psi
 487     return 443;
 488   case 2110:
 489     //n_diffr -- return neutron
 490     return 2112;
 491   case 2210:
 492     //p_diffr+ -- return proton
 493     return 2212;
 494   }
 495   //non diffractive state -- return code unchanged
 496   return pdgcode;
 497 }
 498
 499
 500 void AliGenPythia::SetNuclei(Int_t a1, Int_t a2)
 501 {
 502 // Treat protons as inside nuclei with mass numbers a1 and a2
 503     fNucA1 = a1;
 504     fNucA2 = a2;
 505 }
 506
 507
 508 AliGenPythia& AliGenPythia::operator=(const  AliGenPythia& rhs)
 509 {
 510 // Assignment operator
 511     return *this;
 512 }
 513
 514
 515
 516 void AliGenPythia::Streamer(TBuffer &R__b)
 517 {
 518    // Stream an object of class AliGenPythia.
 519
 520    if (R__b.IsReading()) {
 521       Version_t R__v = R__b.ReadVersion(); if (R__v) { }
 522       AliGenerator::Streamer(R__b);
 523       R__b >> (Int_t&)fProcess;
 524       R__b >> (Int_t&)fStrucFunc;
 525       R__b >> (Int_t&)fForceDecay;
 526       R__b >> fEnergyCMS;
 527       R__b >> fKineBias;
 528       R__b >> fTrials;
 529       fParentSelect.Streamer(R__b);
 530       fChildSelect.Streamer(R__b);
 531       R__b >> fXsection;
 532 //      (AliPythia::Instance())->Streamer(R__b);
 533       R__b >> fPtHardMin;
 534       R__b >> fPtHardMax;
 535 //      if (fDecayer) fDecayer->Streamer(R__b);
 536    } else {
 537       R__b.WriteVersion(AliGenPythia::IsA());
 538       AliGenerator::Streamer(R__b);
 539       R__b << (Int_t)fProcess;
 540       R__b << (Int_t)fStrucFunc;
 541       R__b << (Int_t)fForceDecay;
 542       R__b << fEnergyCMS;
 543       R__b << fKineBias;
 544       R__b << fTrials;
 545       fParentSelect.Streamer(R__b);
 546       fChildSelect.Streamer(R__b);
 547       R__b << fXsection;
 548 //      R__b << fPythia;
 549       R__b << fPtHardMin;
 550       R__b << fPtHardMax;
 551       //     fDecayer->Streamer(R__b);
 552    }
 553 }
 554
 555
 556
 557 #ifndef WIN32
 558 #define pyr    pyr_
 559 #define pyrset pyrset_
 560 #define pyrget pyrget_
 561 #else
 562 #define pyr    PYR
 563 #define pyrset PYRSET
 564 #define pyrget PYRGET
 565 #endif
 566
 567 extern "C" {
 568   Double_t pyr(Int_t*) {return sRandom->Rndm();}
 569   void pyrset(Int_t*,Int_t*) {}
 570   void pyrget(Int_t*,Int_t*) {}
 571 }