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---

Author: [log in to unmask]
Date: Mon Aug  3 14:06:45 2015
New Revision: 3328

Log:
Added driver to analyze Moller Monte Carlo particle data.

Added:
    java/trunk/users/src/main/java/org/hps/users/kmccarty/ParticleMCAnalysisDriver.java

Added: java/trunk/users/src/main/java/org/hps/users/kmccarty/ParticleMCAnalysisDriver.java
 =============================================================================
--- java/trunk/users/src/main/java/org/hps/users/kmccarty/ParticleMCAnalysisDriver.java	(added)
+++ java/trunk/users/src/main/java/org/hps/users/kmccarty/ParticleMCAnalysisDriver.java	Mon Aug  3 14:06:45 2015
@@ -0,0 +1,121 @@
+package org.hps.users.kmccarty;
+
+import hep.aida.IHistogram1D;
+import hep.aida.IHistogram2D;
+import hep.physics.vec.Hep3Vector;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.lcsim.event.EventHeader;
+import org.lcsim.event.MCParticle;
+import org.lcsim.util.Driver;
+import org.lcsim.util.aida.AIDA;
+
+public class ParticleMCAnalysisDriver extends Driver {
+	// Store collection names.
+	private String particleCollectionName = "MCParticle";
+	
+	// Declare plots.
+	private AIDA aida = AIDA.defaultInstance();
+	private IHistogram1D chargedTracksPlot = aida.histogram1D("MC Analysis/Event Tracks", 10, -0.5, 9.5);
+	private IHistogram1D allPlot = aida.histogram1D("MC Analysis/Electron Energy Distribution", 110, 0, 2.2);
+	private IHistogram1D electronPlot = aida.histogram1D("MC Analysis/Electron Energy Distribution", 110, 0, 2.2);
+	private IHistogram1D positronPlot = aida.histogram1D("MC Analysis/Positron Energy Distribution", 110, 0, 2.2);
+	private IHistogram1D anglePlot = aida.histogram1D("MC Analysis/Positron\\Electron Pair Angle Distribution", 90, 0, 180);
+	private IHistogram1D momentumSumPlot = aida.histogram1D("MC Analysis/Positron\\Electron Momentum Sum Distribution", 220, 0, 2.2);
+	private IHistogram2D momentumPlot = aida.histogram2D("MC Analysis/Particle Momentum Distribution", 110, 0.0, 1.1, 110, 0.0, 1.1);
+	private IHistogram2D momentumSum2DPlot = aida.histogram2D("MC Analysis/Positron\\Electron 2D Momentum Distribution", 55, 0, 1.1, 55, 0, 1.1);
+	
+	@Override
+	public void process(EventHeader event) {
+		// Skip the event if there is no Monte Carlo collection.
+		if(!event.hasCollection(MCParticle.class, particleCollectionName)) {
+			return;
+		}
+		
+		// Get the list of Monte Carlo particles.
+		List<MCParticle> particleList = event.get(MCParticle.class, particleCollectionName);
+		
+		// Track the positive and negative particles.
+		List<MCParticle> electronList = new ArrayList<MCParticle>();
+		List<MCParticle> positronList = new ArrayList<MCParticle>();
+		
+		// Count the number of particles in the event.
+		int chargedParticles = 0;
+		
+		// Iterate through the particles.
+		for(MCParticle particle : particleList) {
+			// Look at only t = 0 particles.
+			if(particle.getProductionTime() == 0) {
+				// Plot the x/y momentum of each particle.
+				momentumPlot.fill(particle.getMomentum().x(), particle.getMomentum().y());
+				
+				// If the particle is charged, increment the charged
+				// particle count.
+				if(particle.getCharge() > 0) {
+					chargedParticles++;
+				}
+				
+				// Populate the general momentum plot.
+				allPlot.fill(particle.getMomentum().magnitude());
+				momentumPlot.fill(particle.getMomentum().x(), particle.getMomentum().y());
+				
+				// Store each particle based on its PID and populate
+				// the appropriate plot.
+				if(particle.getPDGID() == 11) {
+					electronList.add(particle);
+					electronPlot.fill(particle.getMomentum().magnitude());
+				} else if(particle.getPDGID() == -11) {
+					positronList.add(particle);
+					positronPlot.fill(particle.getMomentum().magnitude());
+				}
+			}
+		}
+		
+		// Populate the charged particles plot.
+		chargedTracksPlot.fill(chargedParticles);
+		
+		// Form all electron/positron pairs.
+		List<MCParticle[]> pairList = new ArrayList<MCParticle[]>();
+		for(MCParticle electron : electronList) {
+			for(MCParticle positron : positronList) {
+				pairList.add(new MCParticle[] { electron, positron });
+			}
+		}
+		
+		// Plot the positron/electron pair distributions.
+		for(MCParticle[] pair : pairList) {
+			anglePlot.fill(getVectorAngle(pair[0].getMomentum(), pair[1].getMomentum()));
+			momentumSumPlot.fill(getVectorSum(pair[0].getMomentum(), pair[1].getMomentum()));
+			momentumSum2DPlot.fill(pair[0].getMomentum().magnitude(), pair[1].getMomentum().magnitude());
+		}
+	}
+	
+	private static final double getVectorSum(Hep3Vector v1, Hep3Vector v2) {
+		// Calculate the sum of the sum of the vector components, squared.
+		double sum = 0;
+		for(int i = 0; i < 3; i++) {
+			sum += ((v1.v()[i] + v2.v()[i]) * (v1.v()[i] + v2.v()[i]));
+		}
+		
+		// Return the square root of the sum.
+		return Math.sqrt(sum);
+	}
+	
+	private static final double getVectorAngle(Hep3Vector v1, Hep3Vector v2) {
+		// The vector angle is defined as Acos[(v1 · v2) / (‖v1‖ × ‖v2‖)]
+		return Math.acos(getDotProduct(v1, v2) / (v1.magnitude() * v2.magnitude())) / Math.PI * 180.0;
+	}
+	
+	private static final double getDotProduct(Hep3Vector v1, Hep3Vector v2) {
+		// Calculate the sum of the vector element products.
+		int product = 0;
+		for(int i = 0; i < 3; i++) {
+			product += (v1.v()[i] * v2.v()[i]);
+		}
+		
+		// Return the result.
+		return product;
+	}
+}