Resolve "Implement fi_B0_TRK"

Closes #26 (closed)

compact/B0_tracker.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<lccdd>
+  <define>
+    <comment>
+      ---------------------------------
+      Far Forward B0 Tracker Parameters
+      ---------------------------------
+    </comment>
+    <constant name="B0Tracker_zpos" value="B0PF_CenterPosition + B0PF_Length/2.0 + 20.0*cm"/>
+  </define>
+
+  <detectors>
+    <detector 
+      id="B0Tracker_ID"
+      name="B0Tracker"
+      readout="B0TrackerHits" 
+      type="ref_RectangularTracker"
+      insideTrackingVolume="true"
+      reflect="false"
+      vis="Argonne_Red">
+      <position x="0" y="0" z="B0Tracker_zpos"/>
+      <layer id="1" 
+        vis="Argonne_Blue"
+        x="20.0*cm" 
+        y="10.0*cm" >
+        <slice material="Air" thickness="1.0*cm" vis="Argonne_Blue" sensitive="true" />
+        <slice material="Air" thickness="1.0*cm" vis="Argonne_Blue" sensitive="true" />
+        <slice material="Air" thickness="1.0*cm" vis="Argonne_Blue" sensitive="true" />
+        <slice material="Air" thickness="1.0*cm" vis="Argonne_Blue" sensitive="true" />
+      </layer>
+    </detector>
+  </detectors>
+
+  <readouts>
+    <readout name="B0TrackerHits">
+      <segmentation type="CartesianGridXY" grid_size_x="1.0*mm" grid_size_y="1.0*mm" />
+      <id>system:8,barrel:3,layer:4,slice:4,x:32:-16,y:-16</id>  
+    </readout>
+  </readouts>
+
+</lccdd>