diff -u -r1.1 -r1.2
--- HPS-Test-JLAB-v3pt1.lcdd	13 Oct 2011 21:09:50 -0000	1.1
+++ HPS-Test-JLAB-v3pt1.lcdd	17 Oct 2011 20:20:58 -0000	1.2
@@ -1,8 +1,8 @@

 <?xml version="1.0" encoding="UTF-8"?>
 <lcdd xmlns:lcdd="http://www.lcsim.org/schemas/lcdd/1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" xs:noNamespaceSchemaLocation="http://www.lcsim.org/schemas/lcdd/1.0/lcdd.xsd">
   <header>

-    <detector name="HPS-Test-JLAB-v3pt0" />
-    <generator name="GeomConverter" version="1.0" file="/home/omoreno/workdir/scipp/hps/software/software/hps-detectors/detectors/HPS-Test-JLAB-v3pt1/compact.xml" checksum="2158775782" />

+    <detector name="HPS-Test-JLAB-v3pt1" />
+    <generator name="GeomConverter" version="1.0" file="./compact.xml" checksum="2517967858" />

     <author name="NONE" />
     <comment>HPS Test Proposal detector</comment>
   </header>

@@ -1900,6 +1900,10 @@

         <fraction n="0.234" ref="O" />
         <fraction n="0.012" ref="Ar" />
       </material>

+      <material name="TrackingMaterial">
+        <D type="density" unit="g/cm3" value="0.0000000001" />
+        <fraction n="1.0" ref="Air" />
+      </material>

       <material name="LeadTungstate">
         <D value="8.28" unit="g/cm3" type="density" />
         <composite n="1" ref="Pb" />

@@ -3714,7 +3718,7 @@

         <solidref ref="split_0" />
       </volume>
       <volume name="tracking_volume">

-        <materialref ref="Air" />

+        <materialref ref="TrackingMaterial" />

         <solidref ref="tracking_cylinder" />
         <physvol>
           <volumeref ref="TungstenTargetVolume" />