fix drich segmentation

compact/drich.xml

@@ -23,6 +23,9 @@
     <constant name="DRICH_rmax2"              value="200*cm"/>  <!-- cylinder radius; 20 cm gap between dRICh and HCalBarrel -->
     <!-- additional parameters -->
     <constant name="DRICH_aerogel_thickness"  value="4.0*cm"/>  <!-- aerogel thickness -->
+    <constant name="DRICH_sensor_size"        value="48.0*mm"/> <!-- sensor side length -->
+    <constant name="DRICH_sensor_thickness"   value="35.0*mm"/> <!-- sensor thickness -->
+    <constant name="DRICH_num_px"             value="16"/> <!-- number of pixels along one side of the sensor -->
   </define>
 
   <detectors>
@@ -127,8 +130,8 @@
           material="Silicon"
           surface="SensorSurface_DRICH"
           vis="DRICH_sensor_vis"
-          side="48*mm"
-          thickness="35*mm"
+          side="DRICH_sensor_size"
+          thickness="DRICH_sensor_thickness"
           gap="0.5*(52-48)*mm + 2*mm"
           />
         <!-- sensors will be tiled on this sphere
@@ -165,15 +168,25 @@
 
   <readouts>
     <readout name="DRICHHits">
-      <segmentation type="CartesianGridXY" grid_size_x="3*mm" grid_size_y="3*mm"/>
+    <!-- segmentation: square matrix of pixels
+         - note: for `grid_size`, divide sensor size by 1 less than the
+           number of pixels, to account for fenceposting
+         -->
+      <segmentation
+	 type="CartesianGridXY"
+	 grid_size_x="DRICH_sensor_size/(DRICH_num_px-1)"
+	 grid_size_y="DRICH_sensor_size/(DRICH_num_px-1)"
+	 offset_x="-DRICH_sensor_size/2.0"
+	 offset_y="-DRICH_sensor_size/2.0"
+	 />
       <!-- cellID: 64bits
-           - bits 1-8:   dRICh ID
-           - bits 9-16:  sector number
-           - bits 17-32: photosensor number
-           - bits 33-48: x pixel (signed)
-           - bits 49-64: y pixel (signed)
+	   - offset 0,  length 8: dRICh ID
+	   - offset 8,  length 3: sector number
+	   - offset 11, length 12: photosensor number
+	   - offset 23, length 16: x pixel
+	   - offset 39, length 16: y pixel
            -->
-      <id>system:8,sector:8,module:16,x:32:-16,y:-16</id>
+      <id>system:8,sector:3,module:12,x:23:16,y:16</id>
     </readout>
   </readouts>
 

src/DRich_geo.cpp

@@ -296,7 +296,7 @@ static Ref_t createDetector(Detector& desc, xml::Handle_t handle, SensitiveDetec
      */
 
     // initialize module number for this sector
-    int imod=1; 
+    int imod=0;
 
     // thetaGen loop: iterate less than "0.5 circumference / sensor size" times
     double nTheta = M_PI*sensorSphRadius / (sensorSide+sensorGap); 
@@ -354,8 +354,12 @@ static Ref_t createDetector(Detector& desc, xml::Handle_t handle, SensitiveDetec
               * RotationZ(thetaGen) // rotate about `yGen`
               * Translation3D(sensorSphRadius, 0., 0.) // push radially to spherical surface
               * RotationY(M_PI/2) // rotate sensor to be compatible with generator coords
+              * RotationZ(-M_PI/2) // correction for readout segmentation mapping
               );
 
+	  // generate LUT for module number -> sensor position, for readout mapping tests
+	  //if(isec==0) printf("%d %f %f\n",imod,sensorPV.position().x(),sensorPV.position().y());
+
           // properties
           sensorPV.addPhysVolID("sector", isec).addPhysVolID("module", imod);
           DetElement sensorDE(det, Form("sensor_de%d_%d", isec, imod), 10000*isec+imod);