abstract |
A tool suitable for borehole logging, including production oilwell borehole logging, contains a radioisotope neutron source (14), a fast neutron detector (15) and a gamma-ray detector (16). Gamma-ray detection events are selected for building spectra by coincidence or anticoincidence with detection of the associated neutron. In a development, additional information is derived from identification of which of a series of time intervals encompasses detection of a neutron after detection of a gamma-ray. |