US3789227A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Environmental dosimeter of the thermo-luminescent type
Assignee: United States Atomic Energy Commission
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Filing: 1973-05-18
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Granted: 1974-01-29
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Expires: 1993-05-18
Abstract
Abstract A dosimeter for accurately monitoring normally low-energy radiation includes thermoluminescent CaF phosphors enclosed within a tantalum capsule. The tantalum acts as a filter to weaken the measured dose due to photons having energies below about 0.2 MeV. Tantalum end caps are maintained on the capsule body by a polyolefin sheath formed from heat-contractable tubing. After exposing the dosimeter to environmental radiation, it is placed in a shielded chamber for about 24 hours and subsequently annealed at about 80*C. to release radiation energy accumulated in low-temperature traps. The dosimeter is then disassembled and the phosphors photometrically read at temperatures about 80*C. to determine the absorbed radiation dose.
Inventors
- 👤 F Eichner
- 👤 L Kocher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:13
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/02; G01T1/10; G01T1/11
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
30 words
The dosimeter of claim 1 wherein said capsule includes a tubular portion with end closures, and wherein heat-contractable means are provided to secure said end closures onto said tubular portion.
Claim 2
Dependent Claim
92 words
The dosimeter of claim 2 wherein said heat-contractable means comprises a polyolefin sheath disposed in a shrink fit with onE end of said sheath positioned flush with a first end closure of said capsule, and the opposite end of said sheath overlapping the opposite end and a second end closure of said capsule, said overlapping end of said sheath being radially contracted to tightly fit over said second end closure, and further comprises a removable polyolefin cap snugly disposed over the flush end of said polyolefin sheath and said first end closure.
Claim 3
Dependent Claim
30 words
The dosimeter of claim 1 wherein said phosphor is maintained at a coaxial location within said capsule by the interposition of foamed material to envelop said phosphor within said capsule.
Claim 4
Dependent Claim
12 words
The dosimeter of claim 4 wherein said foamed material is polyurethane foam.
Claim 5
Dependent Claim
18 words
The dosimeter of claim 1 wherein said capsule walls include a tantalum thickness of 250 to 300 microns.
Claim 6
Dependent Claim
56 words
A method of determining absorbed radiation dose in the dosimeter of claim 1 comprising: A. maintaining said capsule with phosphor within a totally enclosed, radiation-shielded chamber for about 24 hours; B. annealing said phosphor at about 80*C. for about 20 minutes; and C. photometrically reading said phosphor for sustained radiation at termperatures between 80*C. and 260*C.
Claim 7
Independent Claim
60 words
A method of determining environmental radiation dose with a dosimeter including a CaF2 thermoluminescent phosphor comprising: A. exposing said dosimeter to environmental radiation; B. maintaining said dosimeter within a totally-enclosed, radiation-shielded chamber for about 24 hours; C. annealing said phosphor at about 80*C. for about 20 minutes; and D. photometrically reading said phosphor for sustained radiation at temperatures above 80*C.
Claim 8
Dependent Claim
30 words
The method of claim 8 wherein said thermoluminescent phosphor is preannealed at 400*C. for about 1 hour and maintained at 100*C. for about 2 hours prior to said radiation exposure.
References Cited (Backward Citations)
US3229097A
Cited
US3555277A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |