diff -u -r1.5 -r1.6
--- compact.xml	18 Sep 2013 19:40:30 -0000	1.5
+++ compact.xml	2 Oct 2013 05:06:04 -0000	1.6
@@ -23,6 +23,14 @@

         <constant name="tracking_region_min" value="5.0*cm"/>
         <constant name="tracking_region_zmax" value="100.0*cm"/>
         

+        <!--  dipole magnet and  B-field -->
+         <constant name="dipoleMagnetHeight" value="17.78*cm"/>
+         <constant name="dipoleMagnetWidth" value="41.6052*cm"/>
+         <constant name="startOfFieldZ" value="0"/>
+         <constant name="endOfFieldZ" value="99.5"/>
+         <constant name="constBFieldY" value="-0.5"/>
+         
+        

         <!-- ECAL crystal dimensions -->
         <constant name="ecal_front" value="13.3/2*mm" />
         <constant name="ecal_back" value="16/2*mm" />

@@ -208,10 +216,15 @@

     </define>
     
     <materials>

+        <!-- Set the world material to vacuum. -->
+        <material name="WorldMaterial">
+            <D type="density" unit="g/cm3" value="0.0000000000000001"/>
+            <fraction n="1.0" ref="Vacuum" />
+        </material>

         <!-- Set tracking material to vacuum. -->
         <material name="TrackingMaterial">
             <D type="density" unit="g/cm3" value="0.0000000000000001"/>

-            <fraction n="1.0" ref="Air" />

+            <fraction n="1.0" ref="Vacuum" />

         </material>
         <!-- ECal crystal material. -->
         <material name="LeadTungstate">

@@ -311,21 +324,28 @@

         </detector>     
         
         

-         <detector id="99" name="TrackerThin" type="HPSTracker2">

+         <detector id="99" name="TrackerFieldDef" type="HPSTracker2" readout="TrackerHitsThin" >

             <comment>The Silicon Vertex Tracker</comment>

-            <module name="TestRunModuleThin">

+            <module name="TestRunModuleFieldDef">

                 <box x="moduleLength*2" y="moduleWidth*2" />

-                <module_component thickness="0.00001*cm" material = "Vacuum" sensitive="false">
-                    <dimensions x="sensorLength*2" y="sensorWidth*2" /> 

+                <module_component thickness="0.000000001*cm" material = "Vacuum" sensitive="false">
+                    <dimensions x="dipoleMagnetWidth" y="dipoleMagnetHeight" /> 

                 </module_component>

-                <module_component thickness="0.000001*cm" material = "Vacuum" sensitive="false"/> 

+                <module_component thickness="0.000000001*cm" material = "Vacuum" sensitive="false"/> 

             </module>            
             <layer id="1">

-                <module_placement name="TestRunModuleThin" id="0" x="z1t*sin(y_rot)+(x1t+x_off)*cos(y_rot)" y="y1t" z="0" rx="0" ry="0" rz="-PI/2"/>

+                <module_placement name="TestRunModuleFieldDef" id="0" x="0" y="0" z="startOfFieldZ" rx="0" ry="0" rz="-PI/2"/>
+                <!-- 
+                <module_placement name="TestRunModuleThinFieldDefUp" id="0" x="z1t*sin(y_rot)+(x1t+x_off)*cos(y_rot)" y="y1t" z="0" rx="0" ry="0" rz="-PI/2"/>
+            	-->

             </layer>
             <layer id="2">

-                <module_placement name="TestRunModuleThin" id="0" x="z2t*sin(y_rot)+(x2t+x_off)*cos(y_rot)" y="y2t" z="0" rx="0" ry="0" rz="-3*PI/2"/>

+                <module_placement name="TestRunModuleFieldDef" id="0" x="0" y="0" z="endOfFieldZ" rx="0" ry="0" rz="-PI/2"/>
+				<!-- 
+                <module_placement name="TestRunModuleThinFieldDefUp" id="0" x="z2t*sin(y_rot)+(x2t+x_off)*cos(y_rot)" y="y2t" z="0" rx="0" ry="0" rz="-3*PI/2"/>
+            	-->

             </layer>

+            

            
         </detector>     
         

@@ -350,6 +370,9 @@

         <readout name="TrackerHits">
             <id>system:6,barrel:3,layer:4,module:12,sensor:1,side:32:-2,strip:12</id> 
         </readout>

+        <readout name="TrackerHitsThin">
+            <id>system:6,barrel:3,layer:4,module:12,sensor:1,side:32:-2,strip:12</id> 
+        </readout>

         <!--         <readout name="TargetHits">
             <id>system:6,barrel:3,layer:4,wedge:4,module:12,sensor:1,side:32:-2,strip:12</id>
         </readout>-->

@@ -362,8 +385,11 @@

     </readouts>
 
     <fields>

-        <field type="BoxDipole" name="AnalyzingDipole" x="2.117*cm" y="0*cm" z="45.72*cm" dx="22.86*cm" dy="7.62*cm" dz="45.72*cm" bx="0.0" by="-0.5" bz="0.0">     

+        <field type="BoxDipole" name="AnalyzingDipole" x="0*cm" y="0*cm" z="endOfFieldZ/2.0" dx="dipoleMagnetWidth/2.0" dy="dipoleMagnetHeight/2.0" dz="endOfFieldZ/2.0" bx="0.0" by="constBFieldY" bz="0.0" />     
+		<!-- 
+        <field type="BoxDipole" name="AnalyzingDipole" x="2.117*cm" y="0*cm" z="45.72*cm" dx="22.86*cm" dy="7.62*cm" dz="45.72*cm" bx="0.0" by="-0.5" bz="0.0" >     

         </field>

+        -->

     </fields>
 
     <includes>