NOVELTY - The system has a drilling assembly that comprises a first portion (111) with first diameter (115) and a second portion (116) with second diameter that is greater than the first diameter. A sensor pair (114) comprising combination of induction-type sensor, Hall effect magnetometer sensor, and magnetic gradiometer, is formed proximate to an outer radial surface of second portion of drilling assembly. A processor is in communication with drilling apparatus, to determine gradient measurement based on outputs of sensor pair.    USE - System for optimizing gradient measurements in ranging operations (all claimed) such as well drilling operations. Can also be used in other drilling operations such as target intersecting, target locating, well twinning in steam assist gravity drainage (SAGD) well structures, drilling relief wells for blowout wells, river crossings, construction tunneling, as well as horizontal, vertical, deviated, multilateral, u-tube connection, intersection, bypass or nonlinear wellbores in any type of subterranean formation used in injection wells, natural production wells such as resource production wells such as hydrogen sulfide, hydrocarbons or geothermal wells and borehole construction for river crossing tunneling and other such tunneling boreholes for near surface construction purposes or borehole u-tube pipelines.    ADVANTAGE - The gradient measurement is effectively determined based on outputs of sensor pair. The accuracy and or sensitivity is increased by increasing the distance between the individual sensors of the sensor pair within the sensor extension housing in order to measure the maximum difference in the superimposed electromagnetic field over the earth's magnetic field.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a method for optimizing gradient measurements in ranging operations; and    (2) a drilling apparatus for using in ranging operations.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the drilling system.    Drilling system (100)    Rig (101)    Portion (111)    Sensor pair (114)    Diameter (115,116)