US4045676A
Expired / Lapsed
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Determining element concentrations in samples
Assignee: EG&G Instruments Inc
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Filing: 1975-03-13
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Granted: 1977-08-30
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Expires: 1995-03-13
Abstract
Abstract The invention provides a method and apparatus for determining the concentration of an element such as a heavy metal in a matrix of a material such as rock by the X-ray or gamma-ray fluorescence technique. It allows the use of this technique where a sample to be analyzed has a rough or jagged surface. The effect of the rough surface is eliminated by adjusting the distance between the source and/or detector from the sample so that the rate of detection of radiation in a reference energy band is maintained constant for all samples, including reference samples used for calibration. The reference band is at least partly outside the band or bands characteristic of the element sought.
Inventors
- 👤 Rainer Rolle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:15
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/22; G01N23/223; G01N2223/00; G01N2223/07; G01N2223/076
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
247 words
A method of determining the concentration of an element in a sample which has a rough surface comprising the steps of: A. irradiating at least one calibration sample of known concentration of the element to excite rdiation from the element in a known energy band characteristic of the element and i. measuring such radiation to establish a relationship between the measured characteristic radiation and the concentration of the element, and ii. measuring under substantially the same geometrical conditions of irradiation and detection as in step A.i., the rate of emission of detected radiation in a reference energy range, said reference energy range being relatively wide compared to said characteristic band such that the ratio of the characteristic radiation to reference range radiation is small, such rate establishing a reference value for that range; and B. irradiating the rough surfaced sample to be analyzed, i. first measuring the rate of emission of detected radiation from that sample in said reference energy range, while varying the geometrical conditions of irradiation and detection until the measured rate of detected radiation in the reference energy range is equal to the established reference value, and ii. then, under the same geometrical conditions for which said measured rate of detected radiation in the reference energy range equaled said established reference value in step B.i., measuring the excited radiation of that sample in only the characteristic band, and from such measurement and the established relationship, determining the concentration of the element in that sample.
Claim 2
Independent Claim
247 words
A method of determining the concentration of an element in a sample which has a rough surface comprising the steps of: A. irradiating at least one calibration sample of known concentration of the element to excite rdiation from the element in a known energy band characteristic of the element and i. measuring such radiation to establish a relationship between the measured characteristic radiation and the concentration of the element, and ii. measuring under substantially the same geometrical conditions of irradiation and detection as in step A.i., the rate of emission of detected radiation in a reference energy range, said reference energy range being relatively wide compared to said characteristic band such that the ratio of the characteristic radiation to reference range radiation is small, such rate establishing a reference value for that range; and B. irradiating the rough surfaced sample to be analyzed, i. first measuring the rate of emission of detected radiation from that sample in said reference energy range, while varying the geometrical conditions of irradiation and detection until the measured rate of detected radiation in the reference energy range is equal to the established reference value, and ii. then, under the same geometrical conditions for which said measured rate of detected radiation in the reference energy range equaled said established reference value in step B.i., measuring the excited radiation of that sample in only the characteristic band, and from such measurement and the established relationship, determining the concentration of the element in that sample.
Claim 3
Dependent Claim
18 words
The method of claim 1 in which irradiation and detection take place in spaces having a common axis.
Claim 4
Dependent Claim
40 words
The method of claim 2 in which the geometrical conditions are varied by maintaining the positions at which irradiation and detection take place a constant distance apart and moving both such positions relatively to the sample along the common axis.
Claim 5
Dependent Claim
31 words
The method of claim 2 in which the geometrical conditions are varied by moving the positions at which irradiation and detection take place relatively to each other along the common axis.
Claim 6
Dependent Claim
28 words
The method of claim 1 in which the element whose concentration is to be determined is gold and the characteristic energy band is substantially 77.5 to 78.5 keV.
Claim 7
Dependent Claim
25 words
The method of claim 1 in which the sample is irradiated by radiation from a Cd - 109 source which is shielded by tungsten sheet.
Claim 8
Dependent Claim
15 words
The method of claim 1 in which the samples are effectively of infinitely large size.
Claim 9
Dependent Claim
14 words
The method of claim 1 in which the calibration samples has a rough surface.
Claim 10
Dependent Claim
28 words
The method of claim 1 in which the element whose concentration is to be determined is gold and the reference energy range is substantially 20 to 88 keV.
Claim 11
Dependent Claim
25 words
The method of claim 1 in which the sample to be analysed is part of a rock face and the method is applied in situ.
Claim 12
Dependent Claim
40 words
The method of claim 1 in which there are a plurality of calibration samples each having a smooth surface and the measurements on them are carried out by irradiating them in sequence along an axis normal to their smooth surfaces.
Claim 13
Dependent Claim
17 words
The method of claim 1 in which the detector is a solid-state detector cooled by liquid nitrogen.
Claim 14
Dependent Claim
13 words
The method of claim 12 in which the detector is a germanium detector.
Claim 15
Independent Claim
252 words
A method of determining the concentration of an element in a plurality of samples, some of which have a rough surface comprising the steps of: A. irradiating at least one calibration sample of known concentration of the element to excite radiation from the element in a known energy band characteristic of the element and i. measuring such radiation to establish a relationship between the measured characteristic radiation and the concentration of the element, and ii. measuring under substantially the same geometrical conditions of irradiation and detection as in step A.i., the rate of emission of detected radiation in a reference energy range, said reference energy range being relatively wide compared to said characteristic band such that the ratio of the characteristic radiation to reference range radiation is small, such rate establishing a reference value for that range; and B. irradiating a rough surfaced sample to be analyzed, and i. first measuring the rate of emission of detected radiation from that sample in said reference energy range, while varying the geometrical conditions of irradiation and detection until the measured rate of detected radiation in the reference energy range is equal to the established reference value, and ii. then, under the same geometrical conditions for which said measured rate of detected radiation in the reference energy range equaled said established reference value in step B.i., measuring the excited radiation of that sample in only the characteristic band, and from such measurement and the established relationship, determining the concentration of the element in that sample.
Claim 16
Independent Claim
252 words
A method of determining the concentration of an element in a plurality of samples, some of which have a rough surface comprising the steps of: A. irradiating at least one calibration sample of known concentration of the element to excite radiation from the element in a known energy band characteristic of the element and i. measuring such radiation to establish a relationship between the measured characteristic radiation and the concentration of the element, and ii. measuring under substantially the same geometrical conditions of irradiation and detection as in step A.i., the rate of emission of detected radiation in a reference energy range, said reference energy range being relatively wide compared to said characteristic band such that the ratio of the characteristic radiation to reference range radiation is small, such rate establishing a reference value for that range; and B. irradiating a rough surfaced sample to be analyzed, and i. first measuring the rate of emission of detected radiation from that sample in said reference energy range, while varying the geometrical conditions of irradiation and detection until the measured rate of detected radiation in the reference energy range is equal to the established reference value, and ii. then, under the same geometrical conditions for which said measured rate of detected radiation in the reference energy range equaled said established reference value in step B.i., measuring the excited radiation of that sample in only the characteristic band, and from such measurement and the established relationship, determining the concentration of the element in that sample.
Claim 17
Dependent Claim
28 words
The method of claim 14 in which the element whose concentration is to be determined is gold and the characteristic radiation band is substantially 77.5 to 78.5 keV.
Claim 18
Dependent Claim
15 words
The method of claim 14 in which the samples are effectively of infinitely large size.
Claim 19
Dependent Claim
14 words
The method of claim 14 in which the calibration sample has a rough surface.
Claim 20
Dependent Claim
28 words
The method of claim 14 in which the element whose concentration is to be determined is gold and the reference energy range is substantially 20 to 88 keV.
Claim 21
Dependent Claim
25 words
The method of claim 14 in which the sample to be analyzed is part of a rock face and the method is applied in situ.
Claim 22
Dependent Claim
40 words
The method of claim 14 in which there are a plurality of calibration samples each having a smooth surface and the measurements on them are carried out by irradiating them in sequence along an axis normal to their smooth surfaces.
Claim 23
Dependent Claim
23 words
The method of claim 14 in which the sample is irradiated by radiation from a Cd-109 source which is shielded by tungsten sheet.
Claim 24
Dependent Claim
18 words
The method of claim 14 in which the detector is a solid state detector cooled by liquid nitrogen.
Claim 25
Dependent Claim
13 words
The method of claim 22 in which the detector is a germanium detector.
Claim 26
Dependent Claim
18 words
The method of claim 14 in which irradiation and detection take place in spaces having a common axis.
Claim 27
Dependent Claim
40 words
The method of claim 24 in which the geometrical conditions are varied by maintaining the positions at which irradiation and detection take place a constant distance apart and moving both such positions relatively to the sample along the common axis.
Claim 28
Dependent Claim
31 words
The method of claim 24 in which the geometrical conditions are varied by moving the positions at which irradiation and detection take place relatively to each other along the common axis.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-29 | 1981-02-28 | 1981-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-29 | 1985-02-28 | 1985-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-29 | 1989-02-28 | 1989-08-30 | $7700.00 | Window Closed / Lapsed |