WELL-LOGGING APPARATUS INCLUDING AXIALLY-SPACED, NOBLE GAS-BASED DETECTORS

A well-logging device may include a housing to be positioned within a borehole of a subterranean formation and at least one radiation source carried by the housing to direct radiation into the subterranean formation. The well-logging device may also include noble gas-based radiation detectors carried by the housing to detect radiation from the subterranean formation. At least one of the noble detectors is at a first axial spacing from the at least one radiation source, and at least one other of the noble gas-based radiation detectors is at a second axial spacing from the at least one radiation source different from the first axial spacing. A controller may determine at least one property of the subterranean formation based upon the detected radiation from the noble gas-based radiation detectors.