diff -u -r1.2 -r1.3
--- CDFSiSensorSim.java	13 May 2009 15:15:50 -0000	1.2
+++ CDFSiSensorSim.java	22 Sep 2009 18:45:25 -0000	1.3
@@ -276,7 +276,7 @@

 //                        System.out.println("col_steps : "+col_steps);
                         
 //                        System.out.println("transfer_efficiencies : "+transfer_efficiencies);

-                        

+

                         for (int irow = sense_row - row_steps; irow <= sense_row + row_steps; irow++)
                         {
                             

@@ -288,6 +288,7 @@

 //                                System.out.println("icol : "+icol);
                                 
                                 int sense_id = sense_electrodes.getCellID(irow,icol);

+                                if (sense_id < 0) continue;

                                 Hep3Vector sense_position = sense_electrodes.getCellPosition(sense_id);
                                 int readout_cell = readout_electrodes.getCellID(sense_position);