GEDX_*

• Call sequence: call gedx_*

• For NEXT
  or NEAR
  or PICK if IGE_REG_TYP $<>$ cur_region_type
  (i.e. this GEDX is being called to veto point generated by another GEDX)
  1. If the detector element is rotated or translated away from the detector origin (at the centre of the acrylic vessel) use the data in the GEDP bank (or in the GE_ARRAY_DATA common block if the detector element is part of an array) to rotate and translate the particle position and rotate its direction cosines. These transformed coordinates are passed to the GEP.

  2. request_type = IGE_RQ_TYP
         if (request_type .EQ. KGE_PICK) then
         if (lge_pick_fail) return
         request_type = KGE_NEAR
     endif
     

  3. Call boundary manager to start new GEDX:-

     call geb_start_gedx(cur_region_type, cur_region_serial)
     

  4. Call GEP for list of OR primitives passing request_type.

  5. Call GEP for list of NOT primtives (if any) passing request_type.

  6. If the detector element is rotated then rotate the boundary normals in GED_CURRENT from detector element coordinates back to detector coordinates.

  7. Call boundary manager to end GEDX:-

     call geb_end_gedx
     

• For PICK if IGE_REG_TYP = cur_region_type (i.e. this GEDX is being called to generate PICK point).
  1. If more than one OR primitive select randomly on the basis of their relative volumes.

  2. Call boundary manager to start new GEDX:-

     call geb_start_gedx(cur_region_type, cur_region_serial)
     

  3. Call GEP for selected OR primitive passing request type KGE_PICK.

  4. Call GEP for remaining list of OR primtives (if any) passing request type = KGE_NEAR. If LGE_PICK_FAIL set go back to step 2. The purpose of this is to deal with overlaps by rejecting a fraction of points based on the number of overlaps.

  5. Call GEP for list of NOT primtives (if any) passing request type = KGE_NEAR. if LGE_PICK_FAIL set go back to step 2. The purpose of this is to reject any point that falls within a NOT primitive.

  6. Call boundary manager to end GEDX:-

     call geb_end_gedx
     

  7. If the detector element is rotated or translated away from the detector origin the rotate and translate the picked position from detector element coordinates back to detector coordinates.

  Note: This is the general model but there are cases when it will be crazy to do this. For example picking points in acrylic vessel. In this case the code will throw away almost all the points because they will lie within the D$_2$O external boundary. In this case the GEDX calls a special routine GEP_SHELL_PICK to do the PICKing.