Patent Number: 050948083
Section: claims

1. An apparatus for detecting and measuring water flow in a well, comprising: a housing;  neutron generation means for activating oxygen atoms in any water flowing in or in the vicinity of said well;  at least four (4) detector means longitudinally spaced within said housing for measuring gamma rays resulting from operation of said neutron generation means; the spacings between said neutron generation means and said detector means being such that said gamma rays are detected before they decay below a predetermined percentage of their original population and said spacings ranging, respectively, from 12.5" to 17", from 21" to 28.5", from 37.5" to 50.5", and from 48" to 65"; and  means for deriving characteristics of the water flow from said gamma rays.  gate means to create a plurality of several millisecond cycles of time during which said detector means measure oxygen activation and background gamma ray radiation levels in the well about 30% of the total cycle time.  gate means to create a plurality of several millisecond cycles of time during which said detector means measure oxygen activation and background gamma ray radiation levels in the well about 30% of the total cycle time.  a discriminator means eliminates counts of gamma rays which have an energy level of less than about 3 Mev.  time delay means for preselecting a discrete time band after operation of said neutron generation means for measurements to be made by said detector means.  discrimination means to substantially exclude from measurement by said detector means gamma ray counts resulting from sources other than oxygen atoms activation.  said discriminator means eliminates counts of gamma rays which have an energy level of less than about 3 Mev.  time delay means for preselecting a discrete time band after operation of said neutron generation means for measurements to be made by said detector means. 2. The apparatus of claim 1 wherein said detector means also serve to sense background gamma radiation levels pre-existing in the well. 3. The apparatus of claim 1, further comprising 4. The apparatus of claim 1, further comprising 5. The apparatus of claim 1, wherein 6. The apparatus of claim 4, further comprising 7. The apparatus of claim 1, further comprising 8. The apparatus of claim 7, wherein 9. The apparatus of claim 3, further comprising