METHOD AND APPARATUS FOR AERIAL RADIOACTIVITY SURVEYING FOR SURFACE MINERAL DEPOSITS WHICH COMPENSATES FOR THE RADIOACTIVE DECAY PRODUCTS IN THE ATMOSPHERE OF THE EARTH
First Claim
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1. A method of prospecting for mineral deposits comprising:
- sensing the energy spectrum of gamma radiation from the surface of the earth during an aerial traverse of said surface, sensing the amount of Bi214 in the atmosphere of the earth with sufficient spatial resolution to determine naturally occurring variations therein, said spatial resolution being achieved by sensing at least once during each of a plurality of 5 mile intervals of said aerial traverse, and correcting the sensed energy spectrum of said gamma radiation to reduce inaccuracies created by the sensed Bi214 borne in the atmosphere.
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Abstract
An airborne gamma ray detection system is flown over the surface of the earth at a predetermined height. The energy spectrum of gamma radiation from the surface of the earth is detected and recorded at locations spaced along the travel path of the system. The gamma radiation emanating from uranium decay products borne by the atmosphere of the earth is also sensed and recorded with sufficient regularity to detect naturally occurring variations therein. The gamma radiation data detected from the surface of the earth is then corrected in order to reduce the inaccuracies created by the gamma radiation sources present in the atmosphere.
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Citations
12 Claims
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1. A method of prospecting for mineral deposits comprising:
- sensing the energy spectrum of gamma radiation from the surface of the earth during an aerial traverse of said surface, sensing the amount of Bi214 in the atmosphere of the earth with sufficient spatial resolution to determine naturally occurring variations therein, said spatial resolution being achieved by sensing at least once during each of a plurality of 5 mile intervals of said aerial traverse, and correcting the sensed energy spectrum of said gamma radiation to reduce inaccuracies created by the sensed Bi214 borne in the atmosphere.
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2. The method of claim 1 wherein the gamma radiation from the surface of the earth is excluded from the sensing of the amount of Bi214 in the atmosphere.
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3. The method of radioactivity aerial surveying comprising:
- traversing a travel path over the surface of the earth at a predetermined height, detecting at locations along said travel path the energy spectrum of gamma radiation from the surface of the earth, measuring at locations along said travel path the gamma radiation emanating from Bi214 in the atmosphere above said predetermined height while excluding measurement of gamma radiation emanating from below said predetermined height, such measurements being conducted at least once in each of a plurality of 5 mile intervals of said traverse to detect naturally occurring variations in the amount of gamma radiation sources present in the atmosphere, and correcting the detected energy spectrum of gamma radiation from the surface of the earth in order to reduce the effect of the Bi214 present in the atmosphere.
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4. The method of claim 3 and further comprising:
- multiplexing the detected energy ospectrum of gamma radiation with the measured gamma radiation from the atmosphere for storage on a single channel magnetic recording medium.
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5. The method of claim 3 wherein the energy spectrum of gamma radiation from the surface of the earth is detected by a plurality of parallel gamma ray detectors transported along said travel path.
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6. In a system for eliminating the effects of airborne radiation on aerial radioactivity surveying for mineral deposits, the improvement comprising:
- airborne means including a plurality of gamma radiation detectors for detecting the energy spectrum of gamma radiation from the surface of the earth and from sources in the atmosphere, means included with said airborne means for exclusively detecting the amount of Bi214 in the atmosphere at least once during each of a plurality of 5 mile intervals to define naturally occurring variations in said amount, whereby the effects of the detected amount of airborne Bi214 may be eliminated from the detected energy spectrum of gamma radiation.
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7. The system of claim 6 wherein said gamma radiation detectors comprise:
- thallium-activated sodium iodide crystals.
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8. The system of claim 6 wherein said gamma radiation detectors comprise:
- six thallium-activated sodium iodide crystals connected in parallel.
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9. The system of claim 6 wherein said means for exclusively detecting comprises:
- gamma ray detector means mounted in an aircraft with structure provided to exclude gamma radiation emanating from the surface of the earth.
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10. The system of claim 9 wherein said structure comprises:
- gamma radiation shielding means placed between said detector means and the surface of the earth.
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11. The system of claim 9 wherein said detector means comprises:
- thallium-activated sodium iodide crystals.
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12. The system of claim 9 and further comprising:
- means for multiplexing the outputs of each of said means for detecting for recording on a single chanNel recording medium.
Specification