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
- JAS3
- latest org.lcsim from CVS (see here)
- Output from either Tutorial 1 FastSim and Jet Clustering or Tutorial 2 PPFA and Jet Clustering
The Code
Here is the sample driver Code
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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++;
}
}
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This driver opens three LCIO collections
- MC Particles (the truth)
- The reconstructedparticles made by the org.lcsim construction (either PPFA or FastMC)
- The Jets clustered before
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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
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aida.cloud1D("n MC particles").fill(mcparticles.size());
aida.cloud1D("n jets").fill(jets.size());
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we can then loop over the Jet collection
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// 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()));
}
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and fill information about the Jets into the AIDA file
Finally we can make a Z peak using the Jets clustered before
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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());
}
}
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where we use all the operations from the VecOp package which takes care of FourVector operations
e.g.
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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