]> git.uio.no Git - u/mrichter/AliRoot.git/blobdiff - EVGEN/AliGenPythia.cxx
- Some coded moved to AliGenMC
[u/mrichter/AliRoot.git] / EVGEN / AliGenPythia.cxx
index 7a963133585f40ecc81975a60f56fadd3bd67b4c..d4cf4fc270ad3beb5d2646d7c076fe6d26fca637 100644 (file)
 
 /*
 $Log$
+Revision 1.37  2001/06/28 11:17:28  morsch
+SetEventListRange setter added. Events in specified range are listed for
+debugging. (Yuri Kharlov)
+
+Revision 1.36  2001/03/30 07:05:49  morsch
+Final print-out in finish run.
+Write parton system for jet-production (preliminary solution).
+
+Revision 1.35  2001/03/09 13:03:40  morsch
+Process_t and Struc_Func_t moved to AliPythia.h
+
+Revision 1.34  2001/02/14 15:50:40  hristov
+The last particle in event marked using SetHighWaterMark
+
+Revision 1.33  2001/01/30 09:23:12  hristov
+Streamers removed (R.Brun)
+
+Revision 1.32  2001/01/26 19:55:51  hristov
+Major upgrade of AliRoot code
+
+Revision 1.31  2001/01/17 10:54:31  hristov
+Better protection against FPE
+
+Revision 1.30  2000/12/18 08:55:35  morsch
+Make AliPythia dependent generartors work with new scheme of random number generation
+
+Revision 1.29  2000/12/04 11:22:03  morsch
+Init of sRandom as in 1.15
+
+Revision 1.28  2000/12/02 11:41:39  morsch
+Use SetRandom() to initialize random number generator in constructor.
+
+Revision 1.27  2000/11/30 20:29:02  morsch
+Initialise static variable sRandom in constructor: sRandom = fRandom;
+
+Revision 1.26  2000/11/30 07:12:50  alibrary
+Introducing new Rndm and QA classes
+
+Revision 1.25  2000/10/18 19:11:27  hristov
+Division by zero fixed
+
+Revision 1.24  2000/09/18 10:41:35  morsch
+Add possibility to use nuclear structure functions from PDF library V8.
+
+Revision 1.23  2000/09/14 14:05:40  morsch
+dito
+
+Revision 1.22  2000/09/14 14:02:22  morsch
+- Correct conversion from mm to cm when passing particle vertex to MC.
+- Correct handling of fForceDecay == all.
+
+Revision 1.21  2000/09/12 14:14:55  morsch
+Call fDecayer->ForceDecay() at the beginning of Generate().
+
+Revision 1.20  2000/09/06 14:29:33  morsch
+Use AliPythia for event generation an AliDecayPythia for decays.
+Correct handling of "nodecay" option
+
+Revision 1.19  2000/07/11 18:24:56  fca
+Coding convention corrections + few minor bug fixes
+
+Revision 1.18  2000/06/30 12:40:34  morsch
+Pythia takes care of vertex smearing. Correct conversion from Pythia units (mm) to
+Geant units (cm).
+
+Revision 1.17  2000/06/09 20:34:07  morsch
+All coding rule violations except RS3 corrected
+
+Revision 1.16  2000/05/15 15:04:20  morsch
+The full event is written for fNtrack = -1
+Coding rule violations corrected.
+
+Revision 1.15  2000/04/26 10:14:24  morsch
+Particles array has one entry more than pythia particle list. Upper bound of
+particle loop changed to np-1 (R. Guernane, AM)
+
+Revision 1.14  2000/04/05 08:36:13  morsch
+Check status code of particles in Pythia event
+to avoid double counting as partonic state and final state particle.
+
+Revision 1.13  1999/11/09 07:38:48  fca
+Changes for compatibility with version 2.23 of ROOT
+
+Revision 1.12  1999/11/03 17:43:20  fca
+New version from G.Martinez & A.Morsch
+
 Revision 1.11  1999/09/29 09:24:14  fca
 Introduction of the Copyright and cvs Log
 */
 
-#include "AliGenerator.h"
 #include "AliGenPythia.h"
+#include "AliGenPythiaEventHeader.h"
+#include "AliDecayerPythia.h"
 #include "AliRun.h"
 #include "AliPythia.h"
-#include <TDirectory.h>
-#include <TFile.h>
-#include <TTree.h>
-#include <stdlib.h>
-#include <AliPythia.h>
+#include "AliPDG.h"
 #include <TParticle.h>
-//#include <GParticle.h>
+#include <TSystem.h>
+
  ClassImp(AliGenPythia)
 
 AliGenPythia::AliGenPythia()
-                 :AliGenerator()
+                 :AliGenMC()
 {
+// Default Constructor
+  fDecayer = new AliDecayerPythia();
+  SetEventListRange();
 }
 
 AliGenPythia::AliGenPythia(Int_t npart)
-                 :AliGenerator(npart)
+                 :AliGenMC(npart)
 {
 // default charm production at 5. 5 TeV
 // semimuonic decay
 // structure function GRVHO
 //
     fXsection  = 0.;
-    fParentSelect.Set(5);
-    fChildSelect.Set(5);
-    for (Int_t i=0; i<5; i++) fParentSelect[i]=fChildSelect[i]=0;
+    fNucA1=0;
+    fNucA2=0;
     SetProcess();
     SetStrucFunc();
     SetForceDecay();
     SetPtHard();
     SetEnergyCMS();
+    fDecayer = new AliDecayerPythia();
+    // Set random number generator 
+    sRandom=fRandom;
+    SetEventListRange();
+    fFlavorSelect   = 0;
+    // Produced particles  
+    fParticles = new TClonesArray("TParticle",1000);
+}
+
+AliGenPythia::AliGenPythia(const AliGenPythia & Pythia)
+{
+// copy constructor
 }
 
 AliGenPythia::~AliGenPythia()
 {
+// Destructor
+}
+
+void AliGenPythia::SetEventListRange(Int_t eventFirst, Int_t eventLast)
+{
+  // Set a range of event numbers, for which a table
+  // of generated particle will be printed
+  fDebugEventFirst = eventFirst;
+  fDebugEventLast  = eventLast;
+  if (fDebugEventLast==-1) fDebugEventLast=fDebugEventFirst;
 }
 
 void AliGenPythia::Init()
 {
-    SetMC(new AliPythia());
+// Initialisation
+  SetMC(AliPythia::Instance());
     fPythia=(AliPythia*) fgMCEvGen;
 //
     fParentWeight=1./Float_t(fNpart);
 //
 //  Forward Paramters to the AliPythia object
-    fPythia->DefineParticles();
+    fDecayer->SetForceDecay(fForceDecay);    
+    fDecayer->Init();
+
+
     fPythia->SetCKIN(3,fPtHardMin);
     fPythia->SetCKIN(4,fPtHardMax);    
+    if (fNucA1 > 0 && fNucA2 > 0) fPythia->SetNuclei(fNucA1, fNucA2);  
     fPythia->ProcInit(fProcess,fEnergyCMS,fStrucFunc);
-    fPythia->ForceDecay(fForceDecay);
-    fPythia->LuList(0);
-    fPythia->PyStat(2);
+
+    //    fPythia->Pylist(0);
+    //    fPythia->Pystat(2);
 //  Parent and Children Selection
     switch (fProcess) 
     {
-    case charm:
-
-       fParentSelect[0]=411;
-       fParentSelect[1]=421;
-       fParentSelect[2]=431;
-       fParentSelect[3]=4122;  
-       break;
-    case charm_unforced:
-
-       fParentSelect[0]=411;
-       fParentSelect[1]=421;
-       fParentSelect[2]=431;
-       fParentSelect[3]=4122;  
+    case kPyCharm:
+       fParentSelect[0] =  411;
+       fParentSelect[1] =  421;
+       fParentSelect[2] =  431;
+       fParentSelect[3] = 4122;        
+       fFlavorSelect    = 4;
        break;
-    case beauty:
-       fParentSelect[0]=511;
-       fParentSelect[1]=521;
-       fParentSelect[2]=531;
-       fParentSelect[3]=5122;  
+    case kPyCharmUnforced:
+       fParentSelect[0] =  411;
+       fParentSelect[1] =  421;
+       fParentSelect[2] =  431;
+       fParentSelect[3]=  4122;
+       fFlavorSelect    = 4;   
        break;
-    case beauty_unforced:
-       fParentSelect[0]=511;
-       fParentSelect[1]=521;
-       fParentSelect[2]=531;
-       fParentSelect[3]=5122;  
+    case kPyBeauty:
+       fParentSelect[0]=  511;
+       fParentSelect[1]=  521;
+       fParentSelect[2]=  531;
+       fParentSelect[3]= 5122;
+       fParentSelect[4]= 5132;
+       fParentSelect[5]= 5232;
+       fParentSelect[6]= 5332;
+       fFlavorSelect   = 5;    
        break;
-    case jpsi_chi:
-    case jpsi:
-       fParentSelect[0]=443;
-       break;
-    case mb:
-       break;
-    }
-
-    switch (fForceDecay) 
-    {
-    case semielectronic:
-    case dielectron:
-    case b_jpsi_dielectron:
-    case b_psip_dielectron:
-       fChildSelect[0]=11;     
+    case kPyBeautyUnforced:
+       fParentSelect[0] =  511;
+       fParentSelect[1] =  521;
+       fParentSelect[2] =  531;
+       fParentSelect[3] = 5122;
+       fParentSelect[4] = 5132;
+       fParentSelect[5] = 5232;
+       fParentSelect[6] = 5332;
+       fFlavorSelect    = 5;   
        break;
-    case semimuonic:
-    case dimuon:
-    case b_jpsi_dimuon:
-    case b_psip_dimuon:
-    case pitomu:
-    case katomu:
-       fChildSelect[0]=13;
+    case kPyJpsiChi:
+    case kPyJpsi:
+       fParentSelect[0] = 443;
        break;
-    case all:
-    case nodecay:
+    case kPyMb:
+    case kPyJets:
+    case kPyDirectGamma:
        break;
     }
+    AliGenMC::Init();
 }
 
 void AliGenPythia::Generate()
 {
+// Generate one event
+    fDecayer->ForceDecay();
 
-    Float_t polar[3] =   {0,0,0};
-    Float_t origin[3]=   {0,0,0};
-    Float_t origin_p[3]= {0,0,0};
-    Float_t origin0[3]=  {0,0,0};
-    Float_t p[3], p_p[4], random[6];
-    static TClonesArray *particles;
+    Float_t polar[3]   =   {0,0,0};
+    Float_t origin[3]  =   {0,0,0};
+    Float_t origin0[3] =   {0,0,0};
+    Float_t p[3];
 //  converts from mm/c to s
     const Float_t kconv=0.001/2.999792458e8;
-    
-    
 //
     Int_t nt=0;
-    Int_t nt_p=0;
     Int_t jev=0;
     Int_t j, kf;
-
-    if(!particles) particles=new TClonesArray("TParticle",1000);
-    
     fTrials=0;
+
+//  Set collision vertex position 
     for (j=0;j<3;j++) origin0[j]=fOrigin[j];
-    if(fVertexSmear==perEvent) {
-       gMC->Rndm(random,6);
-       for (j=0;j<3;j++) {
-           origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
-               TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
-           fPythia->SetMSTP(151,0);
-       }
-    } else if (fVertexSmear==perTrack) {
-       fPythia->SetMSTP(151,0);
+    if(fVertexSmear==kPerEvent) {
+       fPythia->SetMSTP(151,1);
        for (j=0;j<3;j++) {
            fPythia->SetPARP(151+j, fOsigma[j]*10.);
        }
+    } else if (fVertexSmear==kPerTrack) {
+       fPythia->SetMSTP(151,0);
     }
+//  event loop    
     while(1)
     {
-       fPythia->PyEvnt();
+       fPythia->Pyevnt();
+       if (gAlice->GetEvNumber()>=fDebugEventFirst &&
+           gAlice->GetEvNumber()<=fDebugEventLast) fPythia->Pylist(1);
        fTrials++;
-       fPythia->ImportParticles(particles,"All");
-       Int_t np = particles->GetEntriesFast();
+       fPythia->ImportParticles(fParticles,"All");
+
+//
+//
+//
+       Int_t i;
+       
+       Int_t np = fParticles->GetEntriesFast();
+       Int_t* pParent   = new Int_t[np];
+       Int_t* pSelected = new Int_t[np];
+       Int_t* trackIt   = new Int_t[np];
+       for (i=0; i< np-1; i++) {
+           pParent[i]   = -1;
+           pSelected[i] =  0;
+       }
        printf("\n **************************************************%d\n",np);
-       Int_t nc=0;
+       Int_t nc = 0;
        if (np == 0 ) continue;
-       if (fProcess != mb) {
-           for (Int_t i = 0; i<np; i++) {
-               TParticle *  iparticle = (TParticle *) particles->At(i);
+       if (fProcess != kPyMb && fProcess != kPyJets && fProcess != kPyDirectGamma) {
+           for (i = 0; i<np-1; i++) {
+               TParticle *  iparticle = (TParticle *) fParticles->At(i);
+               Int_t ks = iparticle->GetStatusCode();
                kf = CheckPDGCode(iparticle->GetPdgCode());
-               fChildWeight=(fPythia->GetBraPart(kf))*fParentWeight;     
+// No initial state partons
+               if (ks==21) continue;
 //
-// Parent
-               if (ParentSelected(TMath::Abs(kf))) {
-                   if (KinematicSelection(iparticle)) {
-                       if (nc==0) {
+// Heavy Flavor Selection
 //
-// Store information concerning the hard scattering process
+               // quark ?
+               kf = TMath::Abs(kf);
+               Int_t kfl = kf;
+               // meson ?
+               if  (kfl > 10) kfl/=100;
+               // baryon
+               if (kfl > 10) kfl/=10;
+               if (kfl > 10) kfl/=10;
+
+               Int_t ipa = iparticle->GetFirstMother()-1;
+               Int_t kfMo = 0;
+               
+               if (ipa > -1) {
+                   TParticle *  mother = (TParticle *) fParticles->At(ipa);
+                   kfMo = TMath::Abs(mother->GetPdgCode());
+               }
+//             printf("\n particle (all)  %d %d %d", i, pSelected[i], kf);
+               if (kfl >= fFlavorSelect) { 
 //
-                           Float_t mass_p = fPythia->GetPARI(13);
-                           Float_t   pt_p = fPythia->GetPARI(17);
-                           Float_t    y_p = fPythia->GetPARI(37);
-                           Float_t  xmt_p = sqrt(pt_p*pt_p+mass_p*mass_p);
-                           Float_t     ty = Float_t(TMath::TanH(y_p));
-                           p_p[0] = pt_p;
-                           p_p[1] = 0;
-                           p_p[2] = xmt_p*ty/sqrt(1.-ty*ty);
-                           p_p[3] = mass_p;
-                           gAlice->SetTrack(0,-1,-1,
-                                            p_p,origin_p,polar,
-                                            0,"Hard Scat.",nt_p,fParentWeight);
-                           gAlice->KeepTrack(nt_p);
-                       }
-                       nc++;
+// Heavy flavor hadron or quark
 //
-// store parent track information
-                       p[0]=iparticle->Px();
-                       p[1]=iparticle->Py();
-                       p[2]=iparticle->Pz();
-                       origin[0]=origin0[0]+iparticle->Vx()/10;
-                       origin[1]=origin0[1]+iparticle->Vy()/10;
-                       origin[2]=origin0[2]+iparticle->Vz()/10;
-
-                       Int_t ifch=iparticle->GetFirstDaughter();
-                       Int_t ilch=iparticle->GetLastDaughter();        
-                       if (ifch !=0 && ilch !=0) {
-                           gAlice->SetTrack(0,nt_p,kf,
-                                            p,origin,polar,
-                                            0,"Primary",nt,fParentWeight);
-                           gAlice->KeepTrack(nt);
-                           Int_t iparent = nt;
+// Kinematic seletion on final state heavy flavor mesons
+                   if (ParentSelected(kf) && !KinematicSelection(iparticle, 0)) 
+                   {
+                       nc = -1;
+                       break;
+                   }
+                   pSelected[i] = 1;
+//                 printf("\n particle (HF)  %d %d %d", i, pSelected[i], kf);
+               } else {
+// Kinematic seletion on decay products
+                   if (fCutOnChild && ParentSelected(kfMo) && ChildSelected(kf) 
+                       && !KinematicSelection(iparticle, 1))
+                   {
+                       nc = -1;
+                       break;
+                   }
 //
-// Children        
+// Decay products 
+// Select if mother was selected and is not tracked
 
-                           for (j=ifch; j<=ilch; j++)
-                           {
-                               TParticle *  ichild = 
-                                   (TParticle *) particles->At(j-1);
-                               kf = CheckPDGCode(ichild->GetPdgCode());
+                   if (pSelected[ipa] && 
+                       !trackIt[ipa]  &&     // mother will be  tracked ?
+                       kfMo !=  5 &&         // mother is b-quark, don't store fragments          
+                       kfMo !=  4 &&         // mother is c-quark, don't store fragments 
+                       kf   != 92)           // don't store string
+                   {
 //
+// Semi-stable or de-selected: diselect decay products:
 // 
-                               if (ChildSelected(TMath::Abs(kf))) {
-                                   origin[0]=ichild->Vx();
-                                   origin[1]=ichild->Vy();
-                                   origin[2]=ichild->Vz();             
-                                   p[0]=ichild->Px();
-                                   p[1]=ichild->Py();
-                                   p[2]=ichild->Pz();
-                                   Float_t tof=kconv*ichild->T();
-                                   gAlice->SetTrack(fTrackIt, iparent, kf,
-                                                    p,origin,polar,
-                                                    tof,"Decay",nt,fChildWeight);
-                                   gAlice->KeepTrack(nt);
-                               } // select child
-                           } // child loop
+//
+                       if (pSelected[i] == -1 ||  fDecayer->GetLifetime(kf) > 10e-15)
+                       {
+                           Int_t ipF = iparticle->GetFirstDaughter();
+                           Int_t ipL = iparticle->GetLastDaughter();   
+                           if (ipF > 0) for (j = ipF-1; j < ipL; j++) pSelected[j] = -1;
                        }
-                   } // kinematic selection
-               } // select particle
-           } // particle loop
-       } else {
-           for (Int_t i = 0; i<np; i++) {
-               TParticle *  iparticle = (TParticle *) particles->At(i);
-               kf = CheckPDGCode(iparticle->GetPdgCode());
-               Int_t ks = iparticle->GetStatusCode();
-               if (ks==1 && kf!=0 && KinematicSelection(iparticle)) {
-                       nc++;
+//                     printf("\n particle (decay)  %d %d %d", i, pSelected[i], kf);
+                       pSelected[i] = (pSelected[i] == -1) ? 0 : 1;
+                   }
+               }
+               if (pSelected[i] == -1) pSelected[i] = 0;
+               if (!pSelected[i]) continue;
+               nc++;
+// Decision on tracking
+               trackIt[i] = 0;
 //
-// store track information
-                       p[0]=iparticle->Px();
-                       p[1]=iparticle->Py();
-                       p[2]=iparticle->Pz();
-                       origin[0]=origin0[0]+iparticle->Vx()/10;
-                       origin[1]=origin0[1]+iparticle->Vy()/10;
-                       origin[2]=origin0[2]+iparticle->Vz()/10;
-                       Float_t tof=kconv*iparticle->T();
-                       gAlice->SetTrack(fTrackIt,-1,kf,p,origin,polar,
-                                        tof,"Primary",nt);
-                       gAlice->KeepTrack(nt);
-               } // select particle
-           } // particle loop 
-           printf("\n I've put %i particles on the stack \n",nc);
+// Track final state particle
+               if (ks == 1) trackIt[i] = 1;
+// Track semi-stable particles
+               if ((ks ==1) || (fDecayer->GetLifetime(kf)> 10e-15))  trackIt[i] = 1;
+// Track particles selected by process if undecayed. 
+               if (fForceDecay == kNoDecay) {
+                   if (ParentSelected(kf)) trackIt[i] = 1;
+               } else {
+                   if (ParentSelected(kf)) trackIt[i] = 0;
+               }
+//
+//
+
+           } // particle selection loop
+           if (nc > -1) {
+               for (i = 0; i<np-1; i++) {
+                   if (!pSelected[i]) continue;
+                   TParticle *  iparticle = (TParticle *) fParticles->At(i);
+                   kf = CheckPDGCode(iparticle->GetPdgCode());
+                   p[0]=iparticle->Px();
+                   p[1]=iparticle->Py();
+                   p[2]=iparticle->Pz();
+                   origin[0]=origin0[0]+iparticle->Vx()/10.;
+                   origin[1]=origin0[1]+iparticle->Vy()/10.;
+                   origin[2]=origin0[2]+iparticle->Vz()/10.;
+                   Float_t tof=kconv*iparticle->T();
+                   Int_t ipa = iparticle->GetFirstMother()-1;
+                   Int_t iparent = (ipa > -1) ? pParent[ipa] : -1;
+//                 printf("\n SetTrack %d %d %d %d", i, iparent, kf, trackIt[i]);
+                   gAlice->SetTrack(fTrackIt*trackIt[i] ,
+                                    iparent, kf, p, origin, polar, tof, kPPrimary, nt, 1.);
+                   pParent[i] = nt;
+                   gAlice->KeepTrack(nt); 
+               } //  SetTrack loop
+           }
+       } else {
+           nc = GenerateMB();
        } // mb ?
+
        if (nc > 0) {
            jev+=nc;
-           if (jev >= fNpart) {
+           if (jev >= fNpart || fNpart == -1) {
                fKineBias=Float_t(fNpart)/Float_t(fTrials);
-               printf("\n Trials: %i\n",fTrials);
+               printf("\n Trials: %i %i %i\n",fTrials, fNpart, jev);
                break;
            }
        }
     } // event loop
+    gAlice->SetHighWaterMark(nt);
 //  adjust weight due to kinematic selection
     AdjustWeights();
 //  get cross-section
     fXsection=fPythia->GetPARI(1);
 }
 
-Bool_t AliGenPythia::ParentSelected(Int_t ip)
+Int_t  AliGenPythia::GenerateMB()
 {
-    for (Int_t i=0; i<5; i++)
-    {
-       if (fParentSelect[i]==ip) return kTRUE;
-    }
-    return kFALSE;
-}
+    Int_t i, kf, nt, iparent;
+    Int_t nc = 0;
+    Float_t p[3];
+    Float_t polar[3]   =   {0,0,0};
+    Float_t origin[3]  =   {0,0,0};
+    Float_t origin0[3] =   {0,0,0};
+//  converts from mm/c to s
+    const Float_t kconv=0.001/2.999792458e8;
+    
+    Int_t np = fParticles->GetEntriesFast();
+    Int_t* pParent = new Int_t[np];
+    for (i=0; i< np-1; i++) pParent[i] = -1;
 
-Bool_t AliGenPythia::ChildSelected(Int_t ip)
-{
-    for (Int_t i=0; i<5; i++)
-    {
-       if (fChildSelect[i]==ip) return kTRUE;
-    }
-    return kFALSE;
-}
+    for (i = 0; i<np-1; i++) {
+       Int_t trackIt = 0;
+       TParticle *  iparticle = (TParticle *) fParticles->At(i);
+       kf = CheckPDGCode(iparticle->GetPdgCode());
+       Int_t ks = iparticle->GetStatusCode();
+       Int_t km = iparticle->GetFirstMother();
+//     printf("\n Particle: %d %d %d", i, kf, ks);
+       
+       if ((ks == 1  && kf!=0 && KinematicSelection(iparticle, 0)) ||
+           (ks != 1) ||
+           (fProcess == kPyJets && ks == 21 && km == 0 && i>1)) {
+           nc++;
+           if (ks == 1) trackIt = 1;
+           Int_t ipa = iparticle->GetFirstMother()-1;
 
-Bool_t AliGenPythia::KinematicSelection(TParticle *particle)
-{
-    Float_t px=particle->Px();
-    Float_t py=particle->Py();
-    Float_t pz=particle->Pz();
-    Float_t  e=particle->Energy();
+           iparent = (ipa > -1) ? pParent[ipa] : -1;
 
 //
-//  transverse momentum cut    
-    Float_t pt=TMath::Sqrt(px*px+py*py);
-    if (pt > fPtMax || pt < fPtMin) 
-    {
-//     printf("\n failed pt cut %f %f %f \n",pt,fPtMin,fPtMax);
-       return kFALSE;
-    }
-//
-// momentum cut
-    Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
-    if (p > fPMax || p < fPMin) 
-    {
-//     printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
-       return kFALSE;
-    }
-    
-//
-// theta cut
-    Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(pz)));
-    if (theta > fThetaMax || theta < fThetaMin) 
-    {
-//     printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
-       return kFALSE;
-    }
+// store track information
+           p[0]=iparticle->Px();
+           p[1]=iparticle->Py();
+           p[2]=iparticle->Pz();
+           origin[0]=origin0[0]+iparticle->Vx()/10.;
+           origin[1]=origin0[1]+iparticle->Vy()/10.;
+           origin[2]=origin0[2]+iparticle->Vz()/10.;
+           Float_t tof=kconv*iparticle->T();
+           gAlice->SetTrack(fTrackIt*trackIt, iparent, kf, p, origin, polar,
+                            tof, kPPrimary, nt);
+           gAlice->KeepTrack(nt);
+           pParent[i] = nt;
+       } // select particle
+    } // particle loop 
 
-//
-// rapidity cut
-    Float_t y = 0.5*TMath::Log((e+pz)/(e-pz));
-    if (y > fYMax || y < fYMin)
-    {
-//     printf("\n failed y cut %f %f %f \n",y,fYMin,fYMax);
-       return kFALSE;
-    }
+    if (pParent) delete[] pParent;
+    
+    printf("\n I've put %i particles on the stack \n",nc);
+    MakeHeader();
+    return nc;
+}
 
-//
-// phi cut
-    Float_t phi=Float_t(TMath::ATan2(Double_t(py),Double_t(px)))+TMath::Pi();
-    if (phi > fPhiMax || phi < fPhiMin)
-    {
-//     printf("\n failed phi cut %f %f %f \n",phi,fPhiMin,fPhiMax);
-       return kFALSE;
-    }
 
-    return kTRUE;
+void AliGenPythia::FinishRun()
+{
+// Print x-section summary
+    fPythia->Pystat(1);
 }
+
 void AliGenPythia::AdjustWeights()
 {
-    TClonesArray *PartArray = gAlice->Particles();
-    TParticle *Part;
+// Adjust the weights after generation of all events
+//
+    TParticle *part;
     Int_t ntrack=gAlice->GetNtrack();
     for (Int_t i=0; i<ntrack; i++) {
-       Part= (TParticle*) PartArray->UncheckedAt(i);
-       Part->SetWeight(Part->GetWeight()*fKineBias);
+       part= gAlice->Particle(i);
+       part->SetWeight(part->GetWeight()*fKineBias);
     }
 }
-
-Int_t AliGenPythia::CheckPDGCode(Int_t pdgcode)
+    
+void AliGenPythia::SetNuclei(Int_t a1, Int_t a2)
 {
-//
-//  If the particle is in a diffractive state, then take action accordigly
-  switch (pdgcode) {
-  case 110:
-    //rho_diff0 -- difficult to translate, return rho0
-    return 113;
-  case 210:
-    //pi_diffr+ -- change to pi+
-    return 211;
-  case 220:
-    //omega_di0 -- change to omega0
-    return 223;
-  case 330:
-    //phi_diff0 -- return phi0
-    return 333;
-  case 440:
-    //J/psi_di0 -- return J/psi
-    return 443;
-  case 2110:
-    //n_diffr -- return neutron
-    return 2112;
-  case 2210:
-    //p_diffr+ -- return proton
-    return 2212;
-  }
-  //non diffractive state -- return code unchanged
-  return pdgcode;
+// Treat protons as inside nuclei with mass numbers a1 and a2  
+    fNucA1 = a1;
+    fNucA2 = a2;
 }
-                 
-
 
 
+void AliGenPythia::MakeHeader()
+{
+// Builds the event header, to be called after each event
+    AliGenEventHeader* header = new AliGenPythiaEventHeader("Pythia");
+   ((AliGenPythiaEventHeader*) header)->SetProcessType(fPythia->GetMSTI(1));
+   gAlice->SetGenEventHeader(header);
+}
+       
+         
+AliGenPythia& AliGenPythia::operator=(const  AliGenPythia& rhs)
+{
+// Assignment operator
+    return *this;
+}
 
 
 
+#ifdef never
+void AliGenPythia::Streamer(TBuffer &R__b)
+{
+   // Stream an object of class AliGenPythia.
 
+   if (R__b.IsReading()) {
+      Version_t R__v = R__b.ReadVersion(); if (R__v) { }
+      AliGenerator::Streamer(R__b);
+      R__b >> (Int_t&)fProcess;
+      R__b >> (Int_t&)fStrucFunc;
+      R__b >> (Int_t&)fForceDecay;
+      R__b >> fEnergyCMS;
+      R__b >> fKineBias;
+      R__b >> fTrials;
+      fParentSelect.Streamer(R__b);
+      fChildSelect.Streamer(R__b);
+      R__b >> fXsection;
+//      (AliPythia::Instance())->Streamer(R__b);
+      R__b >> fPtHardMin;
+      R__b >> fPtHardMax;
+//      if (fDecayer) fDecayer->Streamer(R__b);
+   } else {
+      R__b.WriteVersion(AliGenPythia::IsA());
+      AliGenerator::Streamer(R__b);
+      R__b << (Int_t)fProcess;
+      R__b << (Int_t)fStrucFunc;
+      R__b << (Int_t)fForceDecay;
+      R__b << fEnergyCMS;
+      R__b << fKineBias;
+      R__b << fTrials;
+      fParentSelect.Streamer(R__b);
+      fChildSelect.Streamer(R__b);
+      R__b << fXsection;
+//      R__b << fPythia;
+      R__b << fPtHardMin;
+      R__b << fPtHardMax;
+      //     fDecayer->Streamer(R__b);
+   }
+}
+#endif