Generate cherenkov photons in geant4

• added a simple python example
• run python sim_test.py to see the GUI with cherenkov photons.

src/GenericDetectors/pid/compact/GenericRICH_example.xml

@@ -9,20 +9,75 @@
     <comment>A generic RICH detector</comment>        
   </info>
 
-  <includes>
-    <gdmlFile  ref="elements.xml"/>
-    <gdmlFile  ref="materials.xml"/>
-  </includes>
-  
   <define>
     <constant name="world_side" value="10*m"/>
     <constant name="world_x" value="world_side"/>
     <constant name="world_y" value="world_side"/>
     <constant name="world_z" value="world_side"/>
-    
     <constant name="CrossingAngle" value="0.020*rad"/>
+    <constant name="tracker_region_zmax" value="5*m"/>
+    <constant name="tracker_region_rmax" value="5*m"/>
+    <constant name="PhotMomWaveConv" value="1243.125*eV"/>
   </define>
 
+  <properties>
+    <matrix name="RINDEX__N2" coldim="2" values="  
+      1.0*eV 1.00033
+      4.0*eV 1.00033
+      5.1*eV 1.00033
+      "/>
+    <matrix name="RINDEX__Pyrex" coldim="2" values="  
+      1.0*eV 1.5
+      4.0*eV 1.5
+      5.1*eV 1.5
+      "/>
+    <matrix name= "REFLECTIVITY_mirror" coldim="2" values="  
+      1.0*eV  0.9
+      4.0*eV  0.9
+      5.1*eV  0.9
+    "/>
+
+  </properties>
+
+
+  <includes>
+    <gdmlFile  ref="elements.xml"/>
+    <gdmlFile  ref="materials.xml"/>
+  </includes>
+  
+  <materials>
+    <material name="N2cherenkov">
+      <D type="density" value="0.00125" unit="g/cm3"/>
+      <composite n="1" ref="N"/>
+      <property name="RINDEX"   ref="RINDEX__N2"/>
+    </material>
+    <material name="PyrexCherenkov">
+      <D type="density" value="2.23" unit="g/cm3"/>
+      <fraction n="0.806" ref="SiliconOxide"/>
+      <fraction n="0.130" ref="BoronOxide"/>
+      <fraction n="0.040" ref="SodiumOxide"/>
+      <fraction n="0.023" ref="AluminumOxide"/>
+      <property name="RINDEX"   ref="RINDEX__Pyrex"/>
+    </material>
+  </materials>
+
+  <surfaces>
+    <comment> For the values of "finish", model and type, see TGeoOpticalSurface.h !
+    </comment>
+    <opticalsurface finish="polished" model="glisur" name="MirrorOpticalSurface" type="dielectric_metal" value="0">
+      <property name="REFLECTIVITY" ref="REFLECTIVITY_mirror"/>
+      <property name="RINDEX"       coldim="2" values="1.034*eV  1.5   4.136*eV  1.5"/>
+      <!--<property name="EFFICIENCY"   ref="EFFICIENCY0x8b77240"/>-->
+    </opticalsurface>
+    <opticalsurface name="mirror2" finish="polished" model="glisur" type="dielectric_dielectric">
+      <property name="REFLECTIVITY"            coldim="2" values="1.034*eV  0.8   4.136*eV  0.9"/>
+      <property name="EFFICIENCY"              coldim="2" values="2.034*eV  0.8   4.136*eV  1.0"/>
+      <property name="RINDEX"                  coldim="2" values="1.034*eV  1.5   4.136*eV  1.5"/>
+    </opticalsurface>
+
+  </surfaces>
+
+
   <limits>
     <limitset name="cal_limits">
       <limit name="step_length_max" particles="*" value="5.0" unit="mm" />
@@ -60,7 +115,7 @@
   </display>
 
   <detectors>
-    <detector id="1" name="ForwardRICH" type="GenericRICH" readout="ForwardRICHHits" vis="RedVis">
+    <detector id="1" name="ForwardRICH" type="GenericRICH" readout="ForwardRICHHits" vis="RedVis" material="N2cherenkov">
       <dimensions rmin="10*cm" rmax1="40*cm" rmax2="80*cm" zmin="20*cm"  zmax="120*cm"/>
     </detector>
   </detectors>