void fastGenEMCocktail(Int_t nev = 1, char* filename = "galice.root")
{
// load libraries

	gSystem->Load("liblhapdf.so");      // Parton density functions
	gSystem->Load("libpythia6.so");     // Pythia
	gSystem->Load("libEG");
	gSystem->Load("libEGPythia6");
	gSystem->Load("libAliPythia6.so");  // ALICE specific implementations

	// Runloader
		
	AliRunLoader* rl = AliRunLoader::Open("galice.root","FASTRUN","recreate");
		
	rl->SetCompressionLevel(2);
	rl->SetNumberOfEventsPerFile(nev);
	rl->LoadKinematics("RECREATE");
	rl->MakeTree("E");
	gAlice->SetRunLoader(rl);

	// Create stack
	rl->MakeStack();
	AliStack* stack      = rl->Stack();
	
	// Header
	AliHeader* header = rl->GetHeader();

	// Create and Initialize Generator

	AliGenEMCocktail *gener = new AliGenEMCocktail();

	//=======================================================================
	// Set External decayer
	TVirtualMCDecayer *decayer = new AliDecayerPythia();

	gener->SetNPart(1000);               // source multiplicity per event
	gener->SetPtRange(0.,20.);
	gener->SetYRange(-1.,1.);
	gener->SetPhiRange(0., 360.);
	gener->SetOrigin(0.,0.,0.); 
	gener->SetSigma(0.,0.,0.);
	gener->SetVertexSmear(kPerEvent);
	gener->SetTrackingFlag(0);
	gener->SelectMotherParticles(62591);
	gener->SetPtParamPi0(0);
	gener->SetPtParamEta(3);
	gener->SetPtParamOmega(3);
	gener->SetPtParamPhi(0);
	gener->SetCollisionSystem(2); 			//pp 7 TeV
	gener->SetCentrality(0);				// kpp

	gener->SetDecayMode(kGammaEM);    		// select cocktail:
											// kElectronEM   => single electron
											// kDiElectronEM => electron-positron
											// kGammaEM      => single photon
	gener->SetDecayer(decayer);
	gener->SetWeightingMode(kNonAnalog); 	// select weighting:
											// kNonAnalog => weight ~ dN/dp_T
											// kAnalog    => weight ~ 1
	gener->CreateCocktail();
	gener->Init();
	gener->SetStack(stack);

	//
	//                        Event Loop
	//
	Int_t iev;
		
	for (iev = 0; iev < nev; iev++) {

		printf("\n \n Event number %d \n \n", iev);
		
		// Initialize event
		header->Reset(0,iev);
		rl->SetEventNumber(iev);
		stack->Reset();
		rl->MakeTree("K");
		//  stack->ConnectTree();
		
		// Generate event
		gener->Generate();
		// Analysis
		Int_t npart = stack->GetNprimary();
		printf("Analyse %d Particles\n", npart);
		for (Int_t part=0; part<npart; part++) {
		TParticle *MPart = stack->Particle(part);
		Int_t mpart  = MPart->GetPdgCode();
		//      printf("Particle %d\n", mpart);
		}
		
		// Finish event
		header->SetNprimary(stack->GetNprimary());
		header->SetNtrack(stack->GetNtrack());  

		// I/O
		//	
		stack->FinishEvent();
		header->SetStack(stack);
		rl->TreeE()->Fill();
		rl->WriteKinematics("OVERWRITE");

	} // event loop

	//
	//                         Termination
	// Generator
	gener->FinishRun();
	// Write file
	rl->WriteHeader("OVERWRITE");
	gener->Write();
	rl->Write();
}