diff -u -r1.15 -r1.16
--- SvtUtils.java	30 Jul 2013 00:53:07 -0000	1.15
+++ SvtUtils.java	3 Oct 2013 20:34:21 -0000	1.16
@@ -20,14 +20,13 @@

 import org.lcsim.geometry.Detector;
 
 import org.lcsim.hps.util.Pair;

-import org.lcsim.hps.recon.tracking.StereoPair;

 import org.lcsim.hps.recon.tracking.StereoPair.detectorVolume;
 
 /**
  * A class providing various utilities related to the HPS SVT. 
  *
  * @author Omar Moreno <[log in to unmask]>

- * @version $Id: SvtUtils.java,v 1.15 2013/07/30 00:53:07 omoreno Exp $

+ * @version $Id: SvtUtils.java,v 1.16 2013/10/03 20:34:21 meeg Exp $

  */
 public class SvtUtils {
 

@@ -59,7 +58,7 @@

     String subdetectorName = "Tracker";
     ConditionsManager manager = ConditionsManager.defaultInstance();
     int maxModuleNumber = 0;

-    int maxPlaneNumber = 0;

+    int maxLayerNumber = 0;

     private Set<Integer> fpgaNumbers = new HashSet<Integer>();
     private boolean isSetup = false;
     boolean debug = true;

@@ -138,16 +137,16 @@

     }
 
     /**

-     * Get a sensor by its plane and module id.

+     * Get a sensor by its plane and module id. Both are zero-indexed.

      * 
      *  @param moduleNumber : module id

-     *  @param planeNumber : layer (plane) id

+     *  @param planeNumber : plane id (typically 1 less than the layer id)

      *  @return sensor 
      */
     public SiSensor getSensor(int moduleNumber, int planeNumber) {

-        if (moduleNumber < 0 || moduleNumber >= maxModuleNumber) {

+        if (moduleNumber < 0 || moduleNumber > maxModuleNumber) {

             throw new RuntimeException("Module number " + moduleNumber + " is out of range!");

-        } else if (planeNumber <= 0 || planeNumber > maxPlaneNumber) {

+        } else if (planeNumber < 0 || planeNumber >= maxLayerNumber) {

             throw new RuntimeException("Plane number " + planeNumber + " is out of range!");
         }
         return sensorArray[moduleNumber][planeNumber];

@@ -299,7 +298,7 @@

         
         // Instantiate 'sensorArray' which allows for retrieval of a SiSensor
         // by module and layer id

-        sensorArray = new SiSensor[maxModuleNumber + 1][maxPlaneNumber];

+        sensorArray = new SiSensor[maxModuleNumber + 1][maxLayerNumber];

 
         // Get all of the sensors composing the SVT and add them to the set of all sensors
         IDetectorElement detectorElement = detector.getDetectorElement().findDetectorElement(subdetectorName);

@@ -398,7 +397,7 @@

                     // is used when instantiating 'sensorArray' and when creating
                     // stereo pairs.
                     maxModuleNumber = Math.max(maxModuleNumber, module);

-                    maxPlaneNumber = Math.max(maxPlaneNumber, layer);

+                    maxLayerNumber = Math.max(maxLayerNumber, layer);

                    
                     // A pair is used to relate an FPGA value to a hybrid number
                     Pair<Integer, Integer> daqPair = new Pair<Integer, Integer>(fpga, hybrid);

@@ -464,7 +463,7 @@

     	int trackerLayer = 0; 
     	
     	// 

-    	for(int layerNumber = 1; layerNumber <= maxPlaneNumber; layerNumber+=2 ){

+    	for(int layerNumber = 1; layerNumber <= maxLayerNumber; layerNumber+=2 ){

     		for(int sensorNumber = 0; sensorNumber < (maxModuleNumber+1)/2; sensorNumber++){
     			
     			firstSensor = this.getTopSensor(layerNumber, sensorNumber);