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US5744803A
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Radiation detector assembly and method with discrimination between vibration and radiation induced events
Assignee: Saint Gobain Ceramics and Plastics Inc
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Filing: 1996-09-19
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Granted: 1998-04-28
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Expires: 2016-09-19
Abstract
Abstract A well logging instrument and method that remove vibration induced noise from the output of a detector including a scintillation crystal. The invention is based on a realization that pulses induced by vibration during MWD operations are characteristically periodic, whereas pulses generated down hole by gamma rays occur at random intervals and are characteristically non-periodic. The instrument and method involve positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, distinguishing the periodic events using a time history of the electrical signal, and removing the periodic events from the electrical signal to provide a corrected electrical signal from which vibration induced components have been removed. Also disclosed is a method for using the information gathered for vibration induced events to give an indication of the remaining lifetime of the scintillation crystal.
Inventors
- 👤 Carlos M. Grodsinsky
- 👤 Kevin D. Kimmich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:19
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/06; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/208
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
97 words
A method for making radiation-based measurements in a high vibration environment, comprising the steps of: positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, distinguishing the periodic events using a time history of the electrical signal, and using the distinguished periodic events to provide corrected data from which vibration induced components have been discriminated.
Claim 2
Independent Claim
97 words
A method for making radiation-based measurements in a high vibration environment, comprising the steps of: positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, distinguishing the periodic events using a time history of the electrical signal, and using the distinguished periodic events to provide corrected data from which vibration induced components have been discriminated.
Claim 3
Dependent Claim
42 words
A method as set forth in claim 1, wherein said distinguishing step includes taking a Fourier transform of the time history, identifying the frequencies of periodic events from strong peaks in the Fourier transform, and decimating the signal at the identified frequencies.
Claim 4
Dependent Claim
30 words
A method as set forth in claim 1, wherein said distinguishing step includes geometrically representing the time history and determining therefrom the frequencies of periodic components of the electrical signal.
Claim 5
Dependent Claim
104 words
A method as set forth in claim 1, wherein said distinguishing step includes representing the time history as a closed N-1 sided regular polygon where N is the number of samples in the time history, inscribing k sided regular polygons in the N-sided polygonal representation of the time signal over k-1 phase angles, counting the number of pulses which occur at each of the k vertices for each phase angle, and identifying peaks in a plot of the sum of the pulses per length of the side of the k sided polygon, thereby to determine the frequencies of periodic components of the electrical signal.
Claim 6
Dependent Claim
94 words
A radiation detector assembly for use in conditions of high vibration, comprising a scintillation crystal; a light sensing device optically coupled to said scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic; and a processor for using a time history of the electrical signal to distinguish the periodic events, and for using the distinguished periodic events to provide corrected data from which vibration induced components have been discriminated.
Claim 7
Dependent Claim
94 words
A radiation detector assembly for use in conditions of high vibration, comprising a scintillation crystal; a light sensing device optically coupled to said scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic; and a processor for using a time history of the electrical signal to distinguish the periodic events, and for using the distinguished periodic events to provide corrected data from which vibration induced components have been discriminated.
Claim 8
Dependent Claim
19 words
A radiation detector assembly as set forth in claim 5, wherein said light sensing device is a photomultiplier tube.
Claim 9
Dependent Claim
33 words
A radiation detector assembly as set forth in claim 6, wherein said scintillation crystal is enclosed with a casing having a window at one end for passage of photons to the photomultiplier tube.
Claim 10
Independent Claim
131 words
A method for determining wear or failure of a detector subjected to a high vibration environment, the detector including a scintillation crystal and a light sensing device optically coupled to the scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal, the method comprising the steps of positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, identifying and monitoring the frequency content of the detector signal, and providing an indication of wear or failure as a function of the monitored frequency content.
Claim 11
Independent Claim
131 words
A method for determining wear or failure of a detector subjected to a high vibration environment, the detector including a scintillation crystal and a light sensing device optically coupled to the scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal, the method comprising the steps of positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, identifying and monitoring the frequency content of the detector signal, and providing an indication of wear or failure as a function of the monitored frequency content.
Claim 12
Dependent Claim
66 words
A method as set forth in claim 8, wherein the identifying and monitoring step includes distinguishing the periodic events using a time history of the electrical signal and determining the strength of the identified frequency components of the vibration induced noise signal; and the providing step includes providing an indication of wear or failure as a function of the determined strength of the identified frequency components.
Claim 13
Dependent Claim
56 words
A method as set forth in claim 8, wherein the identifying and monitoring step includes distinguishing the periodic events using a time history of the electrical signal; and the providing step includes providing an indication of wear or failure of the detector as a function of a change in the frequencies of the identified frequency components.
Claim 14
Dependent Claim
92 words
A radiation detector assembly for use in conditions of high vibration, comprising a scintillation crystal; a light sensing device optically coupled to said scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic; and a processor for identifying and monitoring the frequency content of the electronic signal, and providing an indication of wear or failure of the scintillation crystal as a function of the monitored frequency content.
Claim 15
Dependent Claim
92 words
A radiation detector assembly for use in conditions of high vibration, comprising a scintillation crystal; a light sensing device optically coupled to said scintillation crystal and operative to convert photons emitted by said scintillation crystal into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic; and a processor for identifying and monitoring the frequency content of the electronic signal, and providing an indication of wear or failure of the scintillation crystal as a function of the monitored frequency content.
References Cited (Backward Citations)
US4879463A
Cited
US5023450A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-04-27 | 2001-10-27 | 2002-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-04-27 | 2005-10-27 | 2006-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-04-27 | 2009-10-27 | 2010-04-28 | $7700.00 | Window Closed / Lapsed |