diff -u -r1.7 -r1.8
--- HPSEcal.java	13 Apr 2011 23:32:37 -0000	1.7
+++ HPSEcal.java	14 Apr 2011 22:15:46 -0000	1.8
@@ -20,7 +20,7 @@

 /**
  * LCDD model for the HPS inner ECal.
  * 

- * The dimensions element defines x1, x2, y1, y2, and z as half the full dimension.

+ * The dimensions element defines x1, x2, y1, y2, and z as half the full dimension of a crystal.

  * 
  * The layout element defines the placement of the crystals.  The beamgap defines the
  * offset from the beamline in the Y coordinate, in the natural Geant4 coordinate system.

@@ -28,10 +28,13 @@

  * defines the number of crystals in Y, on each side of the beamline.  For example, to 
  * get 4 rows of crystals in Y, then ny would be 2.
  * 

+ * The position element has a z attribute that defines the distance from the origin
+ * to the front face of the crystal array.
+ * 

  * @author Jeremy McCormick
  * @author Tim Nelson
  * 

- * @version $Id: HPSEcal.java,v 1.7 2011/04/13 23:32:37 jeremy Exp $

+ * @version $Id: HPSEcal.java,v 1.8 2011/04/14 22:15:46 jeremy Exp $

  */
 public class HPSEcal extends LCDDSubdetector
 {

@@ -39,7 +42,7 @@

     static final double tolerance = 0.1;
     
     // Tolerance factor for separating crystals to avoid overlaps.

-    static final double crystalTolerance = 0.2;

+    static final double crystalTolerance = 0.1;

     
     HPSEcal(Element node) throws JDOMException
     {

@@ -68,11 +71,13 @@

         Element layout = node.getChild("layout");
         double beamgap = layout.getAttribute("beamgap").getDoubleValue();
         int nx = layout.getAttribute("nx").getIntValue();

-        int ny = layout.getAttribute("ny").getIntValue();       

+        int ny = layout.getAttribute("ny").getIntValue();
+        double dface = layout.getAttribute("dface").getDoubleValue();

         
         System.out.println("beamgap="+beamgap);
         System.out.println("nx="+nx);
         System.out.println("ny="+ny);

+        System.out.println("dface="+dface);

         
         Trapezoid crystalTrap = new Trapezoid("crystal_trap", dx1, dx2, dy1, dy2, dz);
         Volume crystalLogVol = new Volume("crystal_volume", crystalTrap, lcdd.getMaterial(materialName));

@@ -81,18 +86,17 @@

         lcdd.add(crystalLogVol);
         
         Define define = lcdd.getDefine();

-        //Volume mother = lcdd.pickMotherVolume(this);

         
         // Mother volume dimensions.
         double mx, my, mz;
         double margin = 1.1;

-        mx = nx*Math.max(dx2,dx1);
-        //mx *= margin;
-        my = ny*Math.max(dy2, dy1);
-        //my *= margin;
-        mz = dz;  
-        //mz *= margin;
-        Box momBox = new Box("mom_box", mx*2*margin, my*2*margin, mz*2*margin);