Abstract: A downhole logging tool includes a radiation generation source operable to emit radiation into a formation surrounding the tool and a radiation detector operable to detect backscattered radiation from the formation surrounding the tool. The tool also includes a sleeve positioned around the radiation generation source, the sleeve including at least one aperture for forming a pathway for a radiation beam, emitted from the radiation generation source, to enter the formation, the sleeve being rotatable about an axis of the tool to change a position of the aperture to distinctly inspect different regions of the formation.

Abstract: A downhole logging tool includes a radiation generation source operable to emit radiation into a formation surrounding the tool, a radiation detector fixed relative to the radiation generation source and operable to detect backscattered radiation from the formation surrounding the tool, and a sleeve positioned around the radiation detector to shield the radiation detector from a first portion of the backscattered radiation. The sleeve includes at least one aperture for exposing the radiation detector to a second portion of the backscattered radiation, in which the second portion of the backscattered radiation emanates from an inspected region of the formation facing the at least one aperture. A signal measured at the radiation detector corresponds to the inspected region of the formation, and the position of the at least one aperture is changeable with respect to the formation to distinctly inspect different regions of the formation.