neutron soil-moisture meter

neutron soil-moisture meter

[′nü‚trän ′sȯil ‚mȯis·chər ‚mēd·ər] (engineering) An instrument for measuring the water content of soil and rocks as indicated by the scattering and absorption of neutrons emitted from a source, and resulting gamma radiation received by a detector, in a probe lowered into an access hole.