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

This tutorial shows you how to run a simple analysis using a LCIO reconstructed Particle Collection either generated by fastMC (Tutorial 1) or PerfectPFA( Tutorial 2 PPFA and Jet Clustering) and making a nice Z mass peak

 Requirements

  1. JAS3
  2. latest org.lcsim from CVS (see here)
  3. Output from either Tutorial 1 FastSim and Jet Clustering or Tutorial 2 PPFA and Jet Clustering

 The Code

 Here is the sample driver Code

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();
// change this to 	MCFastReconstructedParticles for running with MCfast
	String reconname = "PPRReconParticles";

	String mcparticlename = "MCParticles";
	String jetlistname = "Jets";
	public SimpleAnalysis() {


	}

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

		aida.cloud1D("n MC particles").fill(mcparticles.size());
		aida.cloud1D("n jets").fill(jets.size());



		// loop over the jet collection
		for (ReconstructedParticle jet : jets) {
			aida.cloud1D("Jet energy").fill(jet.getEnergy());
			aida.cloud1D("Jet angle").fill(VecOp.cosTheta(jet.getMomentum()));

		}

		// look at two jets only
		if (jets.size() == 2) {
			HepLorentzVector Z = new BasicHepLorentzVector();
			// Get the sum of the 4-vectors (momentum and energy)
			Z = VecOp.add(jets.get(0).asFourVector(), jets.get(1)
					.asFourVector());
			aida.cloud1D("Z mass").fill(Z.magnitude());

			// look at Barrel
			if ((VecOp.cosTheta(jets.get(0).getMomentum()) < 0.7)
					&& (VecOp.cosTheta(jets.get(1).getMomentum()) < 0.7)) {
				aida.cloud1D("Z mass barrel").fill(Z.magnitude());
			}
			// look at endcap
			if ((VecOp.cosTheta(jets.get(0).getMomentum()) > 0.7)
					&& (VecOp.cosTheta(jets.get(1).getMomentum()) < 0.7)) {
				aida.cloud1D("Z mass endcap").fill(Z.magnitude());
			}
		}

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

This driver opens three LCIO collections

  1. MC Particles (the truth)
  2. The reconstructedparticles made by the org.lcsim construction (either PPFA or FastMC)
  3. The Jets clustered before
List<MCParticle> mcparticles = event
				.get(MCParticle.class, mcparticlename);
List<ReconstructedParticle> jets = event.get(
				ReconstructedParticle.class, jetlistname);
List<ReconstructedParticle>recparticles =
		event.get(ReconstructedParticle.class,reconname);

 The simple aida plots contains the number of particles in this collection

aida.cloud1D("n MC particles").fill(mcparticles.size());
aida.cloud1D("n jets").fill(jets.size());

we can then loop over the Jet collection

// loop over the jet collection
		for (ReconstructedParticle jet : jets) {
			aida.cloud1D("Jet energy").fill(jet.getEnergy());
			aida.cloud1D("Jet angle").fill(VecOp.cosTheta(jet.getMomentum()));

		}

and fill information about the Jets into the AIDA file

Finally we can make a Z peak using the Jets clustered before

if (jets.size() == 2) {
			HepLorentzVector Z = new BasicHepLorentzVector();
			// Get the sum of the 4-vectors (momentum and energy)
			Z = VecOp.add(jets.get(0).asFourVector(), jets.get(1)
					.asFourVector());
			aida.cloud1D("Z mass").fill(Z.magnitude());

			// look at Barrel
			if ((VecOp.cosTheta(jets.get(0).getMomentum()) < 0.7)
					&& (VecOp.cosTheta(jets.get(1).getMomentum()) < 0.7)) {
				aida.cloud1D("Z mass barrel").fill(Z.magnitude());
			}
			// look at endcap
			if ((VecOp.cosTheta(jets.get(0).getMomentum()) > 0.7)
					&& (VecOp.cosTheta(jets.get(1).getMomentum()) > 0.7)) {
				aida.cloud1D("Z mass endcap").fill(Z.magnitude());
			}
		}

where we use all the operations from the VecOp package which takes care of FourVector operations

e.g.

Z = VecOp.add(jets.get(0).asFourVector(), jets.get(1)
					.asFourVector());

will add the FourVectors from the two Jets.


The Two plots show the mass of the Z done with PPFA (top) and FastMc (bottom), using then same code for Analysis

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