US3943458A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reducing gain shifts in photomultiplier tubes
Assignee: Energy Research and Development Administration ERDA
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Filing: 1974-10-24
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Granted: 1976-03-09
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Expires: 1994-10-24
Abstract
Abstract A means is provided for reducing gain shifts in multiplier tubes due to varying event count rates. It includes means for limiting the number of cascaded, active dynodes of the multiplier tube to a predetermined number with the last of predetermined number of dynodes being the output terminal of the tube. This output is applied to an amplifier to make up for the gain sacrificed by not totally utilizing all available active stages of the tube. Further reduction is obtained by illuminating the predetermined number of dynodes with a light source of such intensity that noise appearing at the output dynode associated with the illumination is negligible.
Inventors
- 👤 Charles E. Cohn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 02:07
CPC Classifications
H; H01; H01J; H01J43/00; H01J43/04; H01J43/06; H01J43/18; H01J43/20
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
197 words
A device for reducing gain shift in a multiplier tube due to varying event count rates, the multiplier tube having dynodes arrayed in a cascaded series such that with appropriate biasing any dynode of the cascaded series is capable of being responsive to incident electrons directed thereto to emit secondary electrons at a rate amplified from the rate at which incident electrons are applied thereto, the secondary electrons emitted by one dynode being applied as incident electrons to the next consecutive dynode of the cascaded series, with the last dynode of the series being the output terminal, comprising: means coupled to the dynodes for limiting the number of consecutive active dynodes of the cascaded series to a predetermined number by rendering inactive at least one dynode of said cascaded series, with the last of the predetermined number of said consecutive active dynodes being the output terminal of the tube, and an amplifier coupled to said last consecutive active dynode and being responsive to the number of electrons incident on said last consecutive dynode to develop an output signal whose magnitude is proportional to and the amplification of the number of electrons incident on said last consecutive dynode.
Claim 2
Independent Claim
197 words
A device for reducing gain shift in a multiplier tube due to varying event count rates, the multiplier tube having dynodes arrayed in a cascaded series such that with appropriate biasing any dynode of the cascaded series is capable of being responsive to incident electrons directed thereto to emit secondary electrons at a rate amplified from the rate at which incident electrons are applied thereto, the secondary electrons emitted by one dynode being applied as incident electrons to the next consecutive dynode of the cascaded series, with the last dynode of the series being the output terminal, comprising: means coupled to the dynodes for limiting the number of consecutive active dynodes of the cascaded series to a predetermined number by rendering inactive at least one dynode of said cascaded series, with the last of the predetermined number of said consecutive active dynodes being the output terminal of the tube, and an amplifier coupled to said last consecutive active dynode and being responsive to the number of electrons incident on said last consecutive dynode to develop an output signal whose magnitude is proportional to and the amplification of the number of electrons incident on said last consecutive dynode.
Claim 3
Dependent Claim
49 words
The device of claim 1, further including a light source for illuminating said predetermined number of dynodes such that a background noise appearing at the output dynode associated with the illumination of the dynodes by said light source is not more than 10% of all other tube background noise.
Claim 4
Dependent Claim
27 words
The device of claim 2 wherein the multiplier has at least 10 dynodes arrayed in a cascaded series and said predetermined number of active stages is five.
Claim 5
Dependent Claim
16 words
The device of claim 3, wherein said light source is glowing at a dull red glow.
Claim 6
Dependent Claim
30 words
The device of claim 3, wherein said amplifier is a charge sensitive amplifier operated with noise equivalent to an RMS uncertainty of no more than 1000 charges at the input.
References Cited (Backward Citations)
US3015033A
Cited
US3614646A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |