Patent ID: 7605366

Claim:
A nuclear density gauge comprising a base having a surface adapted to be positioned on a surface of a material sample; at least one gamma radiation detector carried by said base and mounted at a predetermined location relative to an axis extending longitudinally of the base; a gamma radiation source; and a source mount carried by the base and mounting the gamma radiation source for movement along a path between an active first position located at a first longitudinal distance from said at least one detector and an active second position located at a second longitudinal distance from said detector, the active first and second positions being substantially equidistant from the surface of the base, wherein said at least one gamma radiation detector is positioned and arranged to detect gamma radiation emanating from said source and backscattered from the underlying material sample through a first path of travel when the source mount is at said first active position and through a second path of travel when the source mount is at said second active position.