Possibility to change sign of Pz event by event, needed for pA, Ap simulation in

[u/mrichter/AliRoot.git] / THijing / AliGenHijing.cxx

diff --git a/THijing/AliGenHijing.cxx b/THijing/AliGenHijing.cxx
index d4addb10f968b419801efe812b3b9ccb7bf0aeec..2cd1c1500e151f84638230ea20b49a0c855aa127 100644 (file)
--- a/THijing/AliGenHijing.cxx
+++ b/THijing/AliGenHijing.cxx
@@ -18,10 +18,10 @@
 // Generator using HIJING as an external generator
 // The main HIJING options are accessable for the user through this interface.
 // Uses the THijing implementation of TGenerator.
+// Author:
+// Andreas Morsch    (andreas.morsch@cern.ch)
 //
-// andreas.morsch@cern.ch
 
-#include <TArrayI.h>
 #include <TGraph.h>
 #include <THijing.h>
 #include <TLorentzVector.h>
@@ -111,7 +111,7 @@ void AliGenHijing::Init()
                      fAProjectile, fZProjectile, fATarget, fZTarget, 
                      fMinImpactParam, fMaxImpactParam));
 
-    fHijing=(THijing*) fgMCEvGen;
+    fHijing=(THijing*) fMCEvGen;
     fHijing->SetIHPR2(2,  fRadiation);
     fHijing->SetIHPR2(3,  fTrigger);
     fHijing->SetIHPR2(6,  fShadowing);
@@ -190,12 +190,16 @@ void AliGenHijing::Generate()
       for (j=0; j < 3; j++) origin0[j] = fVertex[j];
   } 
 
+
+  Float_t sign = (fRandomPz && (Rndm() < 0.5))? -1. : 1.;
   while(1)
   {
 //    Generate one event
 // --------------------------------------------------------------------------
-      fSpecn   = 0;  
-      fSpecp   = 0;
+      fProjectileSpecn    = 0;  
+      fProjectileSpecp    = 0;
+      fTargetSpecn        = 0;  
+      fTargetSpecp        = 0;
 // --------------------------------------------------------------------------
       fHijing->GenerateEvent();
       fTrials++;
@@ -271,9 +275,13 @@ void AliGenHijing::Generate()
          
 // --------------------------------------------------------------------------
 // Count spectator neutrons and protons
-         if(ks == 0 || ks == 1 || ks == 10 || ks == 11){
-             if(kf == kNeutron) fSpecn += 1;
-             if(kf == kProton)  fSpecp += 1;
+         if(ks == 0 || ks == 1){
+             if(kf == kNeutron) fProjectileSpecn += 1;
+             if(kf == kProton)  fProjectileSpecp += 1;
+         }
+         else if(ks == 10 || ks == 11){
+             if(kf == kNeutron) fTargetSpecn += 1;
+             if(kf == kProton)  fTargetSpecp += 1;
          }
 // --------------------------------------------------------------------------
 //         
@@ -303,7 +311,7 @@ void AliGenHijing::Generate()
              ks   = iparticle->GetStatusCode();
              p[0] = iparticle->Px();
              p[1] = iparticle->Py();
-             p[2] = iparticle->Pz();
+             p[2] = iparticle->Pz() * sign;
              origin[0] = origin0[0]+iparticle->Vx()/10;
              origin[1] = origin0[1]+iparticle->Vy()/10;
              origin[2] = origin0[2]+iparticle->Vz()/10;
@@ -462,7 +470,7 @@ Bool_t AliGenHijing::SelectFlavor(Int_t pid)
     return res;
 }
 
-Bool_t AliGenHijing::Stable(TParticle*  particle)
+Bool_t AliGenHijing::Stable(TParticle*  particle) const
 {
 // Return true for a stable particle
 //
@@ -490,7 +498,8 @@ void AliGenHijing::MakeHeader()
                                                       fHijing->GetN01(),
                                                       fHijing->GetN10(),
                                                       fHijing->GetN11());
-    ((AliGenHijingEventHeader*) header)->SetSpectators(fSpecn, fSpecp);
+    ((AliGenHijingEventHeader*) header)->SetSpectators(fProjectileSpecn, fProjectileSpecp,
+                                                      fTargetSpecn,fTargetSpecp);
 
 // 4-momentum vectors of the triggered jets.
 //
@@ -519,7 +528,7 @@ void AliGenHijing::MakeHeader()
     ((AliGenHijingEventHeader*) header)->SetTrials(fTrials);
 // Event Vertex
     header->SetPrimaryVertex(fVertex);
-    gAlice->SetGenEventHeader(header);   
+    if (gAlice) gAlice->SetGenEventHeader(header);   
     fCollisionGeometry = (AliGenHijingEventHeader*)  header;
 }
 
@@ -581,7 +590,7 @@ Bool_t AliGenHijing::CheckTrigger()
 }
 
 
-void AliGenHijing::Copy(AliGenHijing &) const
+void AliGenHijing::Copy(TObject &) const
 {
   Fatal("Copy","Not implemented!\n");
 }