void runLaserMC(TString jobname, int nEvents=1, unsigned int seed=0) {
  
  // ------------------------------------------------------------------------
  gRandom->SetSeed(seed);
  
  // ========================================================================
  // Verbosity level (0=quiet, 1=event level, 2=track level, 3=debug)
  Int_t iVerbose = 1;
  FairRunSim *fRun = new FairRunSim();
  
  // set the MC version used
  // --------------------------------------------------
  TString mcMode = "TGeant3";
  fRun->SetName(mcMode);
  
  
  TString outfile = jobname;
  outfile.Append(".mc.root");
  TString copy = outfile;
  
  std::cout<<outfile<<std::endl;
  fRun->SetOutputFile(outfile);
  std::cout<<"Set output file to "<<outfile<<std::endl;
  TString parfile = copy.ReplaceAll("mc.root","param.root");
  TString digifile = gSystem->Getenv("VMCWORKDIR");
  digifile+="/tpc/parfiles/tpc.par";
  
  FairRuntimeDb *rtdb=fRun->GetRuntimeDb();
  FairParAsciiFileIo* parIo1 = new FairParAsciiFileIo();
  parIo1->open(digifile.Data(),"in");
  rtdb->setFirstInput(parIo1);       
  Bool_t kParameterMerged=kTRUE;
  
  FairParRootFileIo* parOut=new FairParRootFileIo(kParameterMerged);
  parOut->open(parfile.Data());
  rtdb->setOutput(parOut);
  
  
   
  // In general, the following parts need not be touched
  // ========================================================================


  // -----   Timer   --------------------------------------------------------
  TStopwatch timer;
  timer.Start();
  // ------------------------------------------------------------------------
  

  // Set Material file Name
  //-----------------------
  fRun->SetMaterials("media_pnd.geo");

  // Create and add detectors
  //-------------------------
  FairModule *Cave= new PndCave("CAVE");
  Cave->SetGeometryFileName("pndcave.geo");
  fRun->AddModule(Cave); 

  FairModule *Magnet= new PndMagnet("MAGNET");
  Magnet->SetGeometryFileName("FullSuperconductingSolenoid_v831.root");
  fRun->AddModule(Magnet);
    
  FairModule *Pipe= new PndPipe("PIPE");
  fRun->AddModule(Pipe);
  
  TpcDetector *Tpc = new TpcDetector("TPC", kTRUE);
  Tpc->SetGeometryFileName("TPC_V1.1.root");    //new ROOT geometry
  if(mcMode=="TGeant3")  Tpc->SetAliMC();
  fRun->AddModule(Tpc);


  FairPrimaryGenerator* primGen = new FairPrimaryGenerator();
  fRun->SetGenerator(primGen);

  FairBoxGenerator* boxGen = new FairBoxGenerator(11, 1); 
  boxGen->SetPRange(2,2); // GeV/c
  boxGen->SetPhiRange(0, 360); // Azimuth angle range [degree]
  boxGen->SetThetaRange(0, 1); // Polar angle in lab system range [degree]
  boxGen->SetXYZ(0., 0., 0.); 
  primGen->AddGenerator(boxGen);


  // Create and Set Magnetic Field
  //-------------------------------
  fRun->SetBeamMom(15);
  //PndMultiField *fField= new PndMultiField("FULL");
  //fRun->SetField(fField);
  
  //constant zero-field 
  PndConstField *fMagField=new PndConstField();
  fMagField->SetField(0., 0. ,0. ); // values are in kG
  fMagField->SetFieldRegion(-50, 50,-50, 50, -2000, 2000);
  fRun->SetField(fMagField);
  
  /**Initialize the session*/
  fRun->Init();
  
  //rtdb->setOutput(output);
  rtdb->saveOutput();
  rtdb->print();

  // Transport nEvents
  // -----------------
  fRun->Run(nEvents);


  timer.Stop();
  Double_t rtime = timer.RealTime();
  Double_t ctime = timer.CpuTime();
  cout << endl << endl;
  cout << "Macro finished succesfully." << endl;
  cout << "Output file is "    << outfile << endl;
  cout << "Parameter file is " << parfile << endl;
  cout << "Real time " << rtime << " s, CPU time " << ctime << " s" << endl;
  cout << endl;
  // ------------------------------------------------------------------------


}