Gain stabilization for radioactivity well logging apparatus
First Claim
1. In a radioactive well logging apparatus which bombards earth formations and fluids in a vicinity of a well borehole with neutrons from a neutron source and detects resulting gamma radiation with a detector which includes a scintillation crystal for emitting flashes of light in response to the gamma radiation, a photomultiplier tube which provides voltage pulses in response to the flashes of light furnished, a light emitting diode, oscillator means for causing said light emitting dioded to emit light scintillations, and means for mounting said light emitting diode between the scintillation crystal and the photomultiplier tube, said means for mounting further optically coupling light scintillations from said light emitting diode for gain stabilization and said scintillation crystal to said multiplier tube for well logging, an improvement comprising:
- temperature sensing means, andmeans connected between the light emitting diode and the oscillator means and to the temperature sensing means and being responsive to the temperature sensing means for maintaining the intensity of light emitted by the light emitting diode as the temperature changes.
1 Assignment
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Accused Products
Abstract
An improved gain stabilization system for radioactivity well logging apparatus of the type having a scintillation crystal optically coupled to a photomultiplier, a light emitting diode driven by a pulser and furnishing scintillations to the photomultiplier located in a sonde resulting in a stabilization pulse which is provided to electronic circuitry at the surface for stabilization purposes. The improvement includes a temperature sensor located in the sonde and circuitry for maintaining the intensity of the light provided by the light emitting diode in response to the operation of the temperature sensor.
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Citations
7 Claims
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1. In a radioactive well logging apparatus which bombards earth formations and fluids in a vicinity of a well borehole with neutrons from a neutron source and detects resulting gamma radiation with a detector which includes a scintillation crystal for emitting flashes of light in response to the gamma radiation, a photomultiplier tube which provides voltage pulses in response to the flashes of light furnished, a light emitting diode, oscillator means for causing said light emitting dioded to emit light scintillations, and means for mounting said light emitting diode between the scintillation crystal and the photomultiplier tube, said means for mounting further optically coupling light scintillations from said light emitting diode for gain stabilization and said scintillation crystal to said multiplier tube for well logging, an improvement comprising:
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temperature sensing means, and means connected between the light emitting diode and the oscillator means and to the temperature sensing means and being responsive to the temperature sensing means for maintaining the intensity of light emitted by the light emitting diode as the temperature changes. - View Dependent Claims (2, 3)
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4. In a radioactive well logging apparatus which bombards earth formations and fluid in the vicinity of a well borehole with neutrons from a neutron source and detects resulting gamma radiation with a detector including a scintillation crystal for emitting flashes of light in response to the gamma radiation, a photomultiplier tube which provides voltage pulses in response to flashes of light furnished thereto, a gain stabilization apparatus comprising:
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a light emitting diode; oscillator means for causing said light emitting diode to emit light scintillations; means for mounting said light emitting diode between the scintillation crystal and the photomultiplier tube, said means for mounting further optically coupling lights scintillations from said light emitting diode for gain stabilization and said scintillation crystal to said photomultiplier tube for well logging, and means for maintaining the intensity of the light emitted by the light emitting diode regardless of temperature change. - View Dependent Claims (5, 6, 7)
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Specification