diff -u -r1.2 -r1.3
--- SubdetectorLocator.java	7 Feb 2006 17:54:49 -0000	1.2
+++ SubdetectorLocator.java	8 Feb 2006 00:58:56 -0000	1.3
@@ -1,24 +1,57 @@

 package org.lcsim.util.event;
 
 import org.lcsim.event.EventHeader.LCMetaData;

-import org.lcsim.geometry.CalorimeterIDDecoder;

+import org.lcsim.geometry.IDDecoder;

 import org.lcsim.geometry.Subdetector;
 
 /**

- * This class enables us to find the subdector and sampling fraction from
- * a hit ID plus an LCMetaData. The problem is that LCIO format does not mandate
- * how this should be done. Two obvious possibilities are:

+ * This class enables us to find the subdector and sampling fraction from a hit
+ * ID plus an LCMetaData. The problem is that LCIO format does not mandate how
+ * this should be done. Two obvious possibilities are:

  * <ol>
  * <li>The ID contains a SystemID which leads us to the detector
  * <li>Each collection is associated to a specific subdetector.
  * </ol>
  * Currently it cheats and uses a method which should not exist.

+ * 

  * @author tonyj
  */
 class SubdetectorLocator
 {

-   static Subdetector locateSubdetector(LCMetaData d, long id)
-   {
-      return d.getIDDecoder().getSubdetector();
-   }

+    static Subdetector locateSubdetector(LCMetaData d, long rawid)
+    {
+        IDDecoder decoder = d.getIDDecoder();
+        decoder.setID(rawid);
+        Subdetector subdet = null;
+        
+        // First, try looking up using System ID.
+        int sysid = -1;
+        try
+        {
+            sysid = decoder.getSystemID();
+            //System.out.println("lookup sysid: " + sysid);
+            subdet = d.getEvent().getDetector().getSubdetector(sysid);                       
+        }
+        catch (Exception e)
+        {}
+        
+        // Next, try using the reference setup by Detector.
+        if (subdet == null)
+        {
+            subdet = d.getIDDecoder().getSubdetector();
+            
+            if (subdet.getSystemID() != sysid)
+            {
+                System.err.println("");
+            }
+        }
+
+        // If not found with either method, throw an exception.
+        if (subdet == null)
+        {
+            throw new RuntimeException("SubdetectorLocator unable to find Subdetector for " + d.getName());
+        }
+
+        return subdet;
+    }

 }

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