Data-Model.md

@@ -10,6 +10,7 @@ The hit struct represent the segment along which a particle's energy deposit occ
 | Type | Name | Description |
 | ------ | ------ | ------ |
 | std::string | det | Name of the volume where the energy deposit occurs. The reference geoemtry is *EDepSimGeometry* in the input edep-sim file |
+| int | did | detector id, i.e. unique id of straw tube |
 | double | x1 | X cordinate of the start point of the segment |
 | double | y1 | Y cordinate of the start point of the segment |
 | double | z1 | Z cordinate of the start point of the segment |