US6437336B1
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Scintillator crystals and their applications and manufacturing process
Assignee: Luxium Solutions SAS
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Filing: 2000-10-12
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Granted: 2002-08-20
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Expires: 2020-10-12
Abstract
Abstract A monoclinic single crystal with a lutetium pyrosilicate structure is described. The crystal is formed by crystallization from a congruent molten composition of LU 2(1−x) M 2x Si 2 O 7 where LU is lutetium or a lutetium-based alloy which also includes one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and where x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure. The LU alloy should contain greater than about 75 weight percent lutetium. The crystals exhibit excellent and reproducible scintillation response to gamma radiation.
Inventors
- 👤 Damien Pauwels
- 👤 Bruno Viana
- 👤 Andree Kahn-Harari
- 👤 Pieter Dorenbos
- 👤 Carel Wilhelm Eduard Van Eijk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:08
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/208; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/77742
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
83 words
A monoclinic single crystal with a lutetium pyrosilicate structure of the formula LU 2(1−x) M 2x Si 2 O 7 where LU is lutetium or a lutetium-based alloy of one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and where x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure.
Claim 2
Dependent Claim
83 words
A monoclinic single crystal with a lutetium pyrosilicate structure of the formula LU 2(1−x) M 2x Si 2 O 7 where LU is lutetium or a lutetium-based alloy of one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and where x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure.
Claim 3
Dependent Claim
9 words
The crystal of claim 1 wherein LU is lutetium.
Claim 4
Dependent Claim
32 words
The crystal of claim 1 wherein M is cerium, and wherein x is defined by the limiting level of LU substitution with cerium in a monoclinic crystal of the lutetium pyrosilicate structure.
Claim 5
Dependent Claim
18 words
The crystal of claim 1 wherein x is between about 0.01 at % and about 0.5 at %.
Claim 6
Dependent Claim
14 words
The crystal of claim 1 wherein x is less than about 0.2 at %.
Claim 7
Dependent Claim
14 words
The crystal of claim 1 wherein x is less than about 0.1 at %.
Claim 8
Dependent Claim
14 words
The crystal of claim 1 wherein x is greater than about 0.05 at %.
Claim 9
Dependent Claim
18 words
The crystal of claim 1 wherein two dimensions of the crystal are each greater than about 5 mm.
Claim 10
Dependent Claim
18 words
The crystal of claim 1 wherein two dimensions of the crystal are each greater than about 10 mm.
Claim 11
Dependent Claim
45 words
The crystal of claim 1 wherein the crystal lattice parameter a is between about 6.76 and about 6.77 angstroms, b is between about 8.83 and about 8.84 angstroms, c is between about 4.71 and about 4.72 angstroms, and B is between about 101.9° and 102.1°.
Claim 12
Dependent Claim
62 words
The crystal of claim 1 wherein the crystal has a light yield under gamma excitation of greater than about 10,000 photons per MeV, wherein the crystal was obtained by crystallization of a congruent molten composition, and wherein the light yield is within 50% of the light yield of other crystals crystallized in the same manner from congruent melts with the same composition.
Claim 13
Dependent Claim
33 words
The crystal of claim 11 wherein the light yield that is within about 20% of the light yield of other crystals crystallized in the same manner from congruent melts with the same composition.
Claim 14
Dependent Claim
38 words
The crystal of claim 1 wherein LU is a lutetium-based alloy comprising lutetium and one or more of scandium, ytterbium, indium, lanthanum, and gadolinium, and wherein the lutetium-based alloy contains at least about 75 weight percent of lutetium.
Claim 15
Dependent Claim
28 words
The crystal of claim 1 wherein the crystal when excited by gamma radiation emits photons, and wherein the emission of photons decays in less than about 70 nanoseconds.
Claim 16
Dependent Claim
28 words
The crystal of claim 1 wherein the crystal when excited by gamma radiation emits photons, and wherein the emission of photons decays in less than about 50 nanoseconds.
Claim 17
Dependent Claim
28 words
The crystal of claim 1 wherein the crystal when excited by gamma radiation emits photons, and wherein the emission of photons decays in less than about 30 nanoseconds.
Claim 18
Dependent Claim
28 words
The crystal of claim 1 wherein the crystal when excited by gamma radiation emits photons, and wherein the emission of photons decays in less than about 15 nanoseconds.
Claim 19
Dependent Claim
11 words
The crystal of claim 1 wherein M comprises cerium and terbium.
Claim 20
Dependent Claim
127 words
A process for manufacturing scintillator crystals comprising: supplying a lutetium-containing reactant, a silica-containing reactant, and a cerium-containing reactant; melting the reactants at a temperature below about 2200° C. to form a congruent molten composition; and crystallizing a crystal from the congruent molten composition, wherein the crystal has the composition LU 2(1−x) M 2x Si 2 O 7 in a lutetium pyrosilicate structure, where LU is lutetium or a lutetium-based alloy which also includes one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and wherein x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure.
Claim 21
Dependent Claim
127 words
A process for manufacturing scintillator crystals comprising: supplying a lutetium-containing reactant, a silica-containing reactant, and a cerium-containing reactant; melting the reactants at a temperature below about 2200° C. to form a congruent molten composition; and crystallizing a crystal from the congruent molten composition, wherein the crystal has the composition LU 2(1−x) M 2x Si 2 O 7 in a lutetium pyrosilicate structure, where LU is lutetium or a lutetium-based alloy which also includes one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and wherein x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure.
Claim 22
Dependent Claim
44 words
The process of claim 19 wherein the lutetium-containing reactant is lutetium oxide powder, the silica-containing reactant is silica powder, and the cerium-containing reactant is cerium oxide, and wherein the reactants melt at a temperature below about 2100° C. to form a congruent molten composition.
Claim 23
Dependent Claim
22 words
The process of claim 19 wherein the reactants melt at a temperature below about 2000° C. to form a congruent molten composition.
Claim 24
Dependent Claim
22 words
The process of claim 19 wherein the reactants melt at a temperature below about 1900° C. to form a congruent molten composition.
Claim 25
Dependent Claim
44 words
The process of claim 19 further comprising pretreating the supplied reactants by heating the reactants to a temperature of at least about 1500° C. under an atmosphere comprising a vacuum of at least about 30 millimeters of mercury pressure, or an atmosphere comprising argon.
Claim 26
Dependent Claim
25 words
The process of claim 19 further comprising annealing the composition under an atmosphere comprising molecular hydrogen for a period of at least about 30 minutes.
Claim 27
Dependent Claim
22 words
The process of claim 19 wherein the crystallizing the crystal from the congruent molten composition is completed by the floating zone technique.
Claim 28
Dependent Claim
21 words
The process of claim 19 wherein the crystallizing the crystal from the congruent molten composition is completed by the Czochralski method.
Claim 29
Dependent Claim
33 words
The process of claim 19 wherein the single crystals produced from the same congruent molten compositions have a relative variation in light yield under excitation from a gamma ray of less than 50%.
Claim 30
Dependent Claim
17 words
A monoclinic scintillator crystal of the lutetium pyrosilicate structure obtained by the process of claim 19 .
Claim 31
Dependent Claim
122 words
A radiation detector for detecting gamma-rays and/or X-rays, comprising: a scintillator consisting of a transparent monoclinic single crystal of the composition LU 2(1−x) M 2x Si 2 O 7 , where LU is lutetium or a lutetium-based alloy which also includes one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and wherein x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure; and photodetector optically coupled to the scintillator in order to produce an electrical signal in response to the emission of a light pulse produced by the scintillator.
Claim 32
Dependent Claim
122 words
A radiation detector for detecting gamma-rays and/or X-rays, comprising: a scintillator consisting of a transparent monoclinic single crystal of the composition LU 2(1−x) M 2x Si 2 O 7 , where LU is lutetium or a lutetium-based alloy which also includes one or more of scandium, ytterbium, indium, lanthanum, and gadolinium; where M is cerium or cerium partially substituted with one or more of the elements of the lanthanide family excluding lutetium; and wherein x is defined by the limiting level of LU substitution with M in a monoclinic crystal of the lutetium pyrosilicate structure; and photodetector optically coupled to the scintillator in order to produce an electrical signal in response to the emission of a light pulse produced by the scintillator.
Claim 33
Dependent Claim
10 words
The radiation detector of claim 29 wherein LU is lutetium.
Claim 34
Dependent Claim
19 words
The radiation detector of claim 30 wherein M is cerium, and wherein x is less than 0.5 at %.
Claim 35
Dependent Claim
12 words
The detector of claim 29 operably connected to a nuclear medicine machine.
Claim 36
Dependent Claim
12 words
The detector of claim 29 operably connected to a well logging tool.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2005-08-19 | 2006-02-18 | 2006-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-08-19 | 2010-02-18 | 2010-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-08-19 | 2014-02-18 | 2014-08-20 | $7700.00 | Window Closed / Lapsed |