• Created by Unknown User (stanitz), last modified on Sep 07, 2008

This tutorial builds directly on Tutorial 3 A Simple Analysis using Reconstructed Particles, so all the requirements apply.

 The Code

import hep.physics.jet.EventShape;
import hep.physics.jet.FixNumberOfJetsFinder;
import hep.physics.jet.JetFinder;
import hep.physics.vec.BasicHepLorentzVector;
import hep.physics.vec.HepLorentzVector;
import hep.physics.vec.VecOp;

import java.util.ArrayList;
import java.util.List;

import org.lcsim.event.EventHeader;
import org.lcsim.event.MCParticle;
import org.lcsim.event.ReconstructedParticle;
import org.lcsim.event.util.JetDriver;
import org.lcsim.util.Driver;
import org.lcsim.util.aida.AIDA;

public class SimpleAnalysis extends Driver{
	int ievt = 0;
	private AIDA aida = AIDA.defaultInstance();
	String reconname = "PPRReconParticles";


	public SimpleAnalysis() {

	}

	// process events
	protected void process(EventHeader event) {
		super.process(event);
		// the particle lists
                List<MCParticle> mcparticles = event
				.get(MCParticle.class, "MCParticle");
		List<ReconstructedParticle> jets = event.get(
				ReconstructedParticle.class, "Jets");
		List<ReconstructedParticle>recparticles =
		event.get(ReconstructedParticle.class,"PPRReconParticles");





		for (MCParticle particle : mcparticles) {
			 aida.cloud1D("MC particle energy").fill(particle.getEnergy());
			 if ( particle.getGeneratorStatus()==MCParticle.FINAL_STATE) {
				 aida.cloud1D("MC particle energy final").fill(particle.getEnergy());
			 }
			 if (Math.abs(particle.getPDGID())==22) {
				 aida.cloud1D("MC particle energy photon").fill(particle.getEnergy());
			 }
		}
		ArrayList<HepLorentzVector> recothrustlist =new ArrayList<HepLorentzVector>();
		for (ReconstructedParticle particle : recparticles) {
			recothrustlist.add(particle.asFourVector());
		}
		EventShape myrecoshape = new EventShape();
		myrecoshape.setEvent(recothrustlist);
		aida.cloud1D("Rec Particle Thrust").fill(myrecoshape.thrust().x());

		// print out a status line
		if (ievt % 50 == 0) {
			System.out.println("Processed Events  " + ievt);
		}
		ievt++;
	}
}

There are two more advanced schemes build in here , looking at MC particle detailsand using the event shape utilities

 MCParticle Analysis

We can query Mc particles for their ID or if they are stable or not

 for (MCParticle particle : mcparticles) {
	aida.cloud1D("MC particle energy").fill(particle.getEnergy());
	 if ( particle.getGeneratorStatus()==MCParticle.FINAL_STATE) {
		 aida.cloud1D("MC particle energy final").fill(particle.getEnergy());
	}
	if (Math.abs(particle.getPDGID())==22) {
		aida.cloud1D("MC particle energy photon").fill(particle.getEnergy());
	}
}

 We loop over all particles in the MCParticle collection, with

 particle.getGeneratorStatus()==MCParticle.FINAL_STATE)

we ask, whether the particle is stable  and with

 Math.abs(particle.getPDGID())==22

we ask whether this particle is a photon (PDG ID=22). all the methods are well documented in the LCIO documentation.

 Thrust from the EventShape Package

 The EventShape package from FreeHep Libraryalso contains a Thrust implementation, which is used in this example

ArrayList<HepLorentzVector> recothrustlist =new ArrayList<HepLorentzVector>();
for (ReconstructedParticle particle : recparticles) {
	recothrustlist.add(particle.asFourVector());
}

EventShape myrecoshape = new EventShape();
myrecoshape.setEvent(recothrustlist);
aida.cloud1D("Rec Particle Thrust").fill(myrecoshape.thrust().x()); 

 The EventShape package needs a List of HepLorentzVectors, which we provide by looping over all reconstructed particles

 ArrayList<HepLorentzVector> recothrustlist =new ArrayList<HepLorentzVector>();
for (ReconstructedParticle particle : recparticles) {
	recothrustlist.add(particle.asFourVector());
}

 then we make a new EventShape Object, pass it the ArrayList and plot the Event Thrust (the first component of 3 member array)

EventShape myrecoshape = new EventShape();
myrecoshape.setEvent(recothrustlist);
aida.cloud1D("Rec Particle Thrust").fill(myrecoshape.thrust().x());
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