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