diff -u -r1.15 -r1.16
--- DiskTracker.java	1 Dec 2005 04:11:10 -0000	1.15
+++ DiskTracker.java	22 Mar 2006 00:29:07 -0000	1.16
@@ -127,9 +127,12 @@

             solids.addContent(tube1);
             structure.addContent(volume1);
         }

+        
+        setCombineHits(node, sens);

     }

+    

     public boolean isTracker()
     {
         return true;
     }

-}

+}

\ No newline at end of file

diff -u -r1.7 -r1.8
--- LCDDSubdetector.java	28 Oct 2005 00:34:20 -0000	1.7
+++ LCDDSubdetector.java	22 Mar 2006 00:29:07 -0000	1.8
@@ -8,41 +8,48 @@

 import org.lcsim.geometry.compact.converter.lcdd.util.Region;
 import org.lcsim.geometry.compact.converter.lcdd.util.SensitiveDetector;
 import org.lcsim.geometry.compact.converter.lcdd.util.Volume;

+import org.lcsim.geometry.compact.converter.lcdd.util.Tracker;

 import org.lcsim.geometry.layer.Layering;
 
 /**

- *

+ * 

  * @author tonyj
  */
 public abstract class LCDDSubdetector extends Subdetector
 {
     protected Element node;

+

     protected Layering layers;

-    

+

     LCDDSubdetector(Element c) throws JDOMException
     {
         super(c);
         node = c;

-        

+

         /* make compact layering descr for thickness calcs in addToLCDD */

-        if ( layers == null )

+        if (layers == null)

         {
             layers = org.lcsim.geometry.layer.Layering.makeLayering(c);
         }
     }

-    
-    abstract void addToLCDD(LCDD lcdd, SensitiveDetector sens) throws JDOMException;
-    

+
+    abstract void addToLCDD(LCDD lcdd, SensitiveDetector sens)
+            throws JDOMException;
+

     public Element getElement()
     {
         return node;
     }

-  

+

     /**

-     * set limits for this volume 
-     * @param lcdd LCDD object currently being processed
-     * @param node Current DOM node (e.g. detector, layer, slice, etc.)
-     * @param volume The volume corresponding to the DOM node

+     * Set limits of an LCDD volume
+     * 
+     * @param lcdd
+     *            LCDD object currently being processed
+     * @param node
+     *            Current DOM node (e.g. detector, layer, slice, etc.)
+     * @param volume
+     *            The volume corresponding to the DOM node

      */
     public void setLimitSet(LCDD lcdd, Element node, Volume volume)
     {

@@ -50,17 +57,30 @@

         {
             String limitref = node.getAttributeValue("limits");
             LimitSet limitset = lcdd.getLimitSet(limitref);

-            if ( limitset != null )

+            if (limitset != null)

             {
                 volume.setLimitSet(limitset);
             }

-            else 

+            else

             {

-                throw new RuntimeException("limitset " + limitref + " does not exist");

+                throw new RuntimeException("limitset " + limitref
+                        + " does not exist");

             }
         }
     }

-    

+
+    /**
+     *
+     * Set the region of an LCDD volume
+     *      
+     * @param lcdd
+     *            LCDD object currently being processed
+     * @param node
+     *            Current DOM node (e.g. detector, layer, slice, etc.)
+     * @param volume
+     *            The volume corresponding to the DOM node 
+     * 
+     */

     public void setRegion(LCDD lcdd, Element node, Volume volume)
     {
         if (node.getAttribute("region") != null)

@@ -69,11 +89,40 @@

             Region region = lcdd.getRegion(regionref);
             if (region != null)
             {

-                volume.setRegion(region);                

+                volume.setRegion(region);
+            }
+            else
+            {
+                throw new RuntimeException("Region " + regionref
+                        + " does not exist");
+            }
+        }
+    }
+
+    /**     
+     * 
+     * Set combine_hits attribute of LCDD sensitive detector
+     * 
+     * @param node detector XML node
+     * @param sens sensitive detector which should be of type Tracker
+     */
+    public void setCombineHits(Element node, SensitiveDetector sens)
+    {
+        if (node.getAttribute("combineHits") != null)
+        {
+            try
+            {
+                if (node.getAttribute("combineHits").getBooleanValue() == true)
+                {
+                    if (sens instanceof Tracker)
+                    {
+                        sens.setAttribute("combine_hits", "true");
+                    }
+                }

             }

-            else 

+            catch (Exception e)

             {

-                throw new RuntimeException("Region " + regionref + " does not exist");

+                throw new RuntimeException(e);

             }
         }
     }

diff -u -r1.14 -r1.15
--- MultiLayerTracker.java	7 Feb 2006 17:09:03 -0000	1.14
+++ MultiLayerTracker.java	22 Mar 2006 00:29:07 -0000	1.15
@@ -93,6 +93,8 @@

          solids.addSolid(tube1);
          structure.addVolume(volume1);
       }

+      
+      setCombineHits(node, sens);

    }
    public boolean isTracker()
    {