US3898466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for measuring neutron flux
Assignee: Mitsubishi Electric Corp
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Filing: 1973-08-03
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Granted: 1975-08-05
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Expires: 1993-08-03
Abstract
Abstract The disclosed device comprises a gamma ray-compensated ionization chamber for producing a first output current caused from the irradiation with a neutron flux and gamma rays and a second output current substantially caused from the gamma rays alone. The second output current is amplified by an adjustable gain current amplifier having a wide dynamic range and then the second output current amplified is substracted from the first output current. The difference current provides a measure of the neutron flux. The amplifier has its amplification factor adjusted so as to increase the gamma compensation effect.
Inventors
- 👤 Katsuhiko Kawashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:44
CPC Classifications
G; G01; G01T; G01T3/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
167 words
A device for measuring a neutron flux, comprising, in combination, a biased gamma ray compensated ionization chamber including first means responsive in use to both a neutron flux and gamma rays to produce a first output current having components representative of the neutron flux and the gamma ray flux, and second means responsive to the gamma rays but substantially non-responsive to the neutron flux to produce a second output current representative of the gamma ray flux; a variable gain current amplifier connected to said second means of said ionization chamber to amplify said second output current to equal the component of the first output current representative of the gamma ray flux, a coupling circuit connected to both said first means of said ionization chamber and said current amplifier to provide a difference current equal to the difference between the first output current and the amplified second output current, and measuring means connected to said coupling circuit to determine the neutron flux by measuring the difference current .
Claim 2
Independent Claim
167 words
A device for measuring a neutron flux, comprising, in combination, a biased gamma ray compensated ionization chamber including first means responsive in use to both a neutron flux and gamma rays to produce a first output current having components representative of the neutron flux and the gamma ray flux, and second means responsive to the gamma rays but substantially non-responsive to the neutron flux to produce a second output current representative of the gamma ray flux; a variable gain current amplifier connected to said second means of said ionization chamber to amplify said second output current to equal the component of the first output current representative of the gamma ray flux, a coupling circuit connected to both said first means of said ionization chamber and said current amplifier to provide a difference current equal to the difference between the first output current and the amplified second output current, and measuring means connected to said coupling circuit to determine the neutron flux by measuring the difference current .
Claim 3
Dependent Claim
68 words
A device for measuring a neutron flux as claimed in claim 1, wherein said ionization chamber includes a first, a second and a third electrode plate disposed in spaced parallel relationship therein, said second plate being disposed between said first and third plates, said first means comprising in combination said first and second electrode plates, and said second means comprising in combination said second and third electrode plates.
Claim 4
Dependent Claim
52 words
A device for measuring a neutron flux as claimed in claim 2, wherein a source of direct current voltage is connected to said second electrode plate whereby said first output current flows between said first and second electrode plates and said second output current flows between said second and third electrode plates.
Claim 5
Dependent Claim
60 words
A device for measuring a neutron flux as claimed in claim 1, wherein said current amplifier includes a logarithmic amplifier for logarithmically amplifying said second output current, and an antilogarithmic conversion circuit connected to said loGarithmic amplifier circuit to convert the logarithmically amplified current to a current linearly proportional to said output current which is supplied to said coupling circuit.
Claim 6
Dependent Claim
33 words
A device for measuring a neutron flux as claimed in claim 4, wherein said current amplifier includes a gain control circuit having a variable resistor for adjusting the gain of said current amplifier.
Claim 7
Dependent Claim
29 words
A device for measuring a neutron flux as claimed in claim 5, wherein said gain control circuit comprises means to adjust a biasing voltage applied to said antilogarithmic circuit.
Claim 8
Dependent Claim
32 words
A device for measuring a neutron flux as claimed in claim 4, wherein said gain control circuit includes a temperature compensation resistor having a magnitude of resistance proportional to an absolute temperature.
Claim 9
Dependent Claim
119 words
In combination: a. a gamma ray compensated ionization chamber having means for developing in use a first signal having a component representative of a neutron flux incident thereon and a component representative of a gamma ray flux incident thereon and developing in use a second signal representative of only the gamma ray flux; b. means receptive of said second signal for developing an amplified second signal substantially equal to the component of said first signal representative of the gamma ray flux; and c. means receptive of said first signal and the amplified second signal for developing a difference signal representative of only the neutron flux and equal to the difference between said first signal and said amplified second signal.
Claim 10
Dependent Claim
119 words
In combination: a. a gamma ray compensated ionization chamber having means for developing in use a first signal having a component representative of a neutron flux incident thereon and a component representative of a gamma ray flux incident thereon and developing in use a second signal representative of only the gamma ray flux; b. means receptive of said second signal for developing an amplified second signal substantially equal to the component of said first signal representative of the gamma ray flux; and c. means receptive of said first signal and the amplified second signal for developing a difference signal representative of only the neutron flux and equal to the difference between said first signal and said amplified second signal.
Claim 11
Dependent Claim
32 words
In a combination according to claim 8 wherein said compensated ionization chamber having means for developing in use the first and second signals comprises means for developing electrical first and second signals.
Claim 12
Dependent Claim
21 words
In a combination according to claim 9 wherein said means for developing said amplified second signal comprises a variable gain amplifier.
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) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |