US3654464A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resonant scattering of gamma rays as selective means for determining an element of interest
Assignee: Atlantic Richfield Co
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Filing: 1970-01-22
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Granted: 1972-04-04
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Expires: 1990-01-22
Abstract
Abstract A radioactive logging method and apparatus for quantitatively determining an element of interest in subsurface formations traversed by a borehole. Earth formations are bombarded with fast neutrons causing the various elements to emit characteristic gamma rays. These gammas strike resonant scatter material which is specially selected to elastically scatter only those gammas derived from the element of interest. The scattered gammas thus obtained are detected with a scintillator and a photomultiplier.
Inventors
- 👤 Walter H Johnson Jr
- 👤 William C Pritchett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:42
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
133 words
A radioactive logging tool adapted to traverse a borehole comprising a. a neutron source for irradiating a subsurface formation with fast neutrons, b. a resonant scatterer for selectively detecting prompt capture gamma rays emitted by an element of interest in said subsurface formation in response to said fast neutrons, said resonant scatterer comprised of a material selected to have a high cross section for resonantly scattering gamma rays emitted by said element of interest and a low cross section for resonantly scattering gamma rays of other energies, c. a scintillation crystal spaced apart from said resonant scatterer for detecting gamma rays resonantly scattered by said resonant scatterer, and d. a photomultiplier optically coupled to said Scintillation crystal, e. said resonant scatterer located intermediate between said neutron source and said gamma ray detecting means.
Claim 2
Dependent Claim
133 words
A radioactive logging tool adapted to traverse a borehole comprising a. a neutron source for irradiating a subsurface formation with fast neutrons, b. a resonant scatterer for selectively detecting prompt capture gamma rays emitted by an element of interest in said subsurface formation in response to said fast neutrons, said resonant scatterer comprised of a material selected to have a high cross section for resonantly scattering gamma rays emitted by said element of interest and a low cross section for resonantly scattering gamma rays of other energies, c. a scintillation crystal spaced apart from said resonant scatterer for detecting gamma rays resonantly scattered by said resonant scatterer, and d. a photomultiplier optically coupled to said Scintillation crystal, e. said resonant scatterer located intermediate between said neutron source and said gamma ray detecting means.
Claim 3
Dependent Claim
20 words
A logging tool according to claim 1 where said resonant scatterer is connected to and rotated by a synchronous motor.
Claim 4
Dependent Claim
23 words
A logging tool according to claim 1 where said resonant scatterer is selected from the group of materials consisting of praseodymium and lanthanum.
References Cited (Backward Citations)
US2949535A
Cited
US3508052A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-04 | 1975-10-04 | 1976-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-04 | 1979-10-04 | 1980-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-04 | 1983-10-04 | 1984-04-04 | $7700.00 | Window Closed / Lapsed |