| 摘要 |
A neutron generator in a well logging instrument is periodically pulsed and has an off period between pulses of 1000 microseconds. A neutron detector is gated on at intervals of 400-500, 550-650, and 700-800 microseconds, respectively, following the termination of each burst of fast neutrons. Circuitry is provided for determining the background radiation by the equation: <IMAGE> where B is the background, and N1, N2 and N3 are the counts observed during the three gates, respectively. Circuitry is also provided for determining the macroscopic absorption ( SIGMA ) from the equation: <IMAGE> where V is the velocity of thermal neutrons, being a constant and DELTA t represents an increment of time.
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