First commit.

diff --git a/EVGEN/AliGenBeamGas.cxx b/EVGEN/AliGenBeamGas.cxx
new file mode 100644 (file)
index 0000000..d5596ed
--- /dev/null
+++ b/EVGEN/AliGenBeamGas.cxx
@@ -0,0 +1,133 @@
+/**************************************************************************
+ * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
+ *                                                                        *
+ * Author: The ALICE Off-line Project.                                    *
+ * Contributors are mentioned in the code where appropriate.              *
+ *                                                                        *
+ * Permission to use, copy, modify and distribute this software and its   *
+ * documentation strictly for non-commercial purposes is hereby granted   *
+ * without fee, provided that the above copyright notice appears in all   *
+ * copies and that both the copyright notice and this permission notice   *
+ * appear in the supporting documentation. The authors make no claims     *
+ * about the suitability of this software for any purpose. It is          *
+ * provided "as is" without express or implied warranty.                  *
+ **************************************************************************/
+
+/*
+$Log$
+*/
+
+
+// Event generator that using an instance of type AliGenReader
+// reads particles from a file and applies cuts. 
+
+
+#include "AliGenBeamGas.h"
+#include "AliRun.h"
+
+#include <TParticle.h>
+#include <TFile.h>
+#include <TTree.h>
+
+
+ ClassImp(AliGenBeamGas)
+
+AliGenBeamGas::AliGenBeamGas()
+  :AliGenExtFile()
+{
+//  Constructor
+//
+    fInteractions = 1;
+}
+
+AliGenBeamGas::AliGenBeamGas(const AliGenBeamGas & ExtFile)
+{
+// copy constructor
+}
+//____________________________________________________________
+
+AliGenBeamGas::~AliGenBeamGas()
+{
+// Destructor
+    delete fReader;
+}
+
+//___________________________________________________________
+void AliGenBeamGas::Init()
+{
+// Initialize
+    AliGenExtFile::Init();
+}
+
+    
+void AliGenBeamGas::Generate()
+{
+// Generate particles
+
+  Float_t polar[3]  = {0,0,0};
+  Float_t origin[3] = {0,0,0};
+  Float_t p[3];
+  Float_t random[2];
+  Int_t i, nt;
+  Int_t nInt = 0;
+  
+  while(nInt < fInteractions) {
+//
+      Rndm(random,2);
+//
+//  Interaction vertex
+//
+      origin[2] = 4000. * random[0] - 2000.;
+//
+//    beam 1 or 2
+//      
+      Float_t ibeam = (random[1] < 0.5) ? -1. : 1.;
+      
+//
+//    Read next event
+//      
+      Int_t nTracks = fReader->NextEvent();    
+      if (nTracks == 0) {
+         // printf("\n No more events !!! !\n");
+         Warning("AliGenBeamGas::Generate",
+                 "\nNo more events in external file!!!\n Last event may be empty or incomplete.\n");
+         return;
+      }
+      
+      //
+      // Stack filling loop
+      //
+      for (i = 0; i < nTracks; i++) {
+         TParticle* iparticle = fReader->NextParticle();
+         p[0] = iparticle->Px();
+         p[1] = iparticle->Py();
+         p[2] = iparticle->Pz() * ibeam;
+       
+         Int_t idpart     = iparticle->GetPdgCode();
+         Int_t decayed    = iparticle->GetFirstDaughter();
+         Int_t doTracking = fTrackIt && (decayed < 0) && (TMath::Abs(idpart) > 10);
+         SetTrack(doTracking,-1,idpart,p,origin,polar,0,kPPrimary,nt);
+         KeepTrack(nt);
+      } // track loop
+      nInt++;
+  } // event loop
+//
+  SetHighWaterMark(nt);
+//
+  CdEventFile();
+}
+
+
+//AliGenBeamGas& AliGenBeamGas::operator=(const  AliGenBeamGas& rhs)
+//{
+// Assignment operator
+//    return *this;
+//}
+
+
+
+
+
+
+
+

diff --git a/EVGEN/AliGenBeamGas.h b/EVGEN/AliGenBeamGas.h
new file mode 100644 (file)
index 0000000..ce0056f
--- /dev/null
+++ b/EVGEN/AliGenBeamGas.h
@@ -0,0 +1,39 @@
+#ifndef ALIGENBEAMGAS_H
+#define ALIGENBEAMGAS_H
+/* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
+ * See cxx source for full Copyright notice                               */
+
+/* $Id$ */
+
+
+#include "AliGenExtFile.h"
+#include "AliGenReader.h"
+
+class TTree;
+
+class AliGenBeamGas : public AliGenExtFile
+{
+ public:
+    AliGenBeamGas();
+    AliGenBeamGas(const AliGenBeamGas &ext);
+    virtual ~AliGenBeamGas();
+    //
+    virtual void SetNumberOfInteractions(Int_t n) 
+       {fInteractions = n;}
+    // Initialise 
+    virtual void Init();
+    // generate event
+    virtual void Generate();
+ protected:
+    Int_t fInteractions;
+    
+    ClassDef(AliGenBeamGas,1) //Generate particles from external file
+       
+};
+#endif
+
+
+
+
+
+