Formation density logging using multiple detectors and sources

A device is described for use in a borehole traversing an earth formation comprising: gamma ray emitting means the means emitting collimated gamma ray beams along a first set of at least three trajectories, the trajectories projecting in an azimuthally symmetric pattern about the longitudinal axis of the device, intersecting at a first point on the axis of the device, and intersecting a first circle located in a sample of the formation to be measured; first gamma ray detecting means oriented to receive emitted gamma rays scattered from at least three locations within the formation sample along a second set of at least three trajectories, the trajectories projecting in an azimuthally symmetric pattern about the axis of the device intersecting a second point on the axis of the device and intersecting the first circle; and means for determining a first product of the counting rates of gamma rays received by the first detecting means from each of the at least three trajectories as scattered from each of the at least three locations within the formation sample. The first product is indicative of the average density of the formation sample