# US 7,608,201 B2 · Scintillator material based on rare earth with a reduced nuclear background

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- Number: US 7,608,201 B2
- Document ID: US7608201B2
- Status: Granted
- Kind: B2
- Application number: 11/578,379
- Filed: 2005-04-12
- Published: 2007-10-18
- Granted: 2009-10-27
- Earliest claimed: 2004-04-14
- Assignees: Saint-Gobain Cristaux Et Detecteurs
- Inventors: Alain Iltis
- Web page: https://patentgrep.com/patent/US7608201B2

## CPC

- C30B 11/00: Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method (C30B13/00, C30B15/00, C30B17/00, C30B19/00 take precedence; under a protective fluid C30B27/00)
- C30B 15/00: Single-crystal growth by pulling from a melt, e.g. Czochralski method (under a protective fluid C30B27/00)
- C30B 29/12: Halides
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR

## Abstract

Inorganic scintillator material of formula AnLnpX(3p+n) in which has a very low nuclear background noise and is particularly suitable as a detector scintillator for coating weight or thickness measurements, in the fields of nuclear medicine, physics, chemistry and oil exploration, and for the detection of dangerous or illicit materials.

## Claims

### Claim 1

An inorganic scintillator material of formula AnLnpX(3p+n) wherein Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of F, Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb-and Cs, 0≦n ≦2p, and p is greater than or equal to 1, wherein the content of daughter elements of uranium and thorium in the material is in an amount which results in activity resulting from alpha radiation from these elements to be less than 0.7 Bq/cc.

### Claim 2 (depends on 1)

The material of claim 1 having the formula AnLnp−xLn′xX(3p+n) wherein Ln is one or a mixture of rare earths chosen from the group consisting of Y, La, Gd, and Lu, Ln′ is Ce or Pr, and 0.01 ≦x <1.

### Claim 3 (depends on 2)

The material of claim 2, wherein x ranges from 0.01 to 0.9.

### Claim 4 (depends on 2)

The material of claim 2 wherein Ln is La and Ln′ is Ce.

### Claim 5 (depends on 1)

The material of claim 1 wherein n is zero.

### Claim 6 (depends on 1)

The material of claim 1 wherein X is a mixture of Cl and Br.

### Claim 7 (depends on 1)

The material of claim 1 wherein X is a mixture of Br and I.

### Claim 8 (depends on 1)

The material of claim 1 wherein said material is a single crystal.

### Claim 9 (depends on 8)

The material of claim 8 wherein said material has a volume of at least 10 cm3.

### Claim 10 (depends on 8)

The material of claim 8 wherein said material has a volume of at least 200 cm3.

### Claim 11 (depends on 1)

The material claim 1 wherein said material is synthesized from rare-earth salts from ionic South China ores.

### Claim 12 (depends on 1)

The material of claim 1 wherein the rare-earth salts used to synthesize said material have undergone a purification process intended to extract the daughter elements of uranium and thorium therefrom.

### Claim 13 (depends on 1)

The material of claim 1 wherein said material includes daughter elements of uranium and thorium.

### Claim 14 (depends on 1)

A process for preparing the material claim 1, comprising
1) melting a Ln salt and
2) growing at least one crystal from the melted Ln salt,
wherein the Ln salt is obtained from a Ln source raw material is an Ln oxide, wherein the daughter elements of uranium and thorium in the material are in an amount which results in activity resulting from the alpha radiation from these elements of less than 0.7 Bq/cc.

### Claim 15 (depends on 1)

A detector comprising a the scintillator material of claim 1.

### Claim 16 (depends on 2)

The material of claim 2 wherein n is 0.

### Claim 17 (depends on 2)

The material of claim 2 wherein X is a mixture of Cl and Br.

### Claim 18 (depends on 2)

The material of claim 2 wherein X is a mixture of Br and I.

### Claim 19 (depends on 2)

The material of claim 2 wherein said material is a single crystal.

### Claim 20 (depends on 19)

The material of claim 19 wherein said material has a volume of at least 10 cm3.

### Claim 21 (depends on 19)

The material of claim 19 wherein said material has a volume of at least 200 cm3.

### Claim 22 (depends on 2)

The material of claim 2 wherein said material is synthesized from rare-earth salts from ionic South China ores.

### Claim 23 (depends on 2)

The material of claim 2 wherein the rare-earth salts used to synthesize-said material have undergone a purification process intended to extract the daughter elements of uranium and thorium there from.

### Claim 24 (depends on 2)

The material of claim 2 wherein said material includes daughter elements of uranium and thorium.

### Claim 25 (depends on 2)

A process for preparing the material of claim 2, comprising
1) melting Ln and Ln′ salts and
2) growing at least one crystal from the melted Ln and Ln′ salts,
wherein the Ln and Ln′ salts are obtained from Ln and Ln′ source raw materials that are Ln and Ln′ oxides, wherein the daughter elements of uranium and thorium in the materials are in an amount which results in activity resulting from alpha radiation from these elements of less than 0.7 Bq/cc.

### Claim 26 (depends on 2)

A detector comprising the scintilator material of claim 2.

### Claim 27 (depends on 4)

The material of claim 4 wherein n is 0.

### Claim 28 (depends on 4)

The material of claim 4 wherein X is a mixture of Cl and Br.

### Claim 29 (depends on 4)

The material of claim 4 wherein X is a mixture of Br and I.

### Claim 30 (depends on 4)

The material of claim 4 wherein said material is a single crystal.

### Claim 31 (depends on 30)

The material of claim 30 wherein said material has a volume of at least 10 cm3.

### Claim 32 (depends on 30)

The material of claim 30 wherein said material has a volume of at least 200 cm3.

### Claim 33 (depends on 4)

The material of claim 4 wherein said material is synthesized from rare-earth salts from ionic South China ores.

### Claim 34 (depends on 4)

The material of claim 4 wherein the rare-earth salts used to synthesize said material have undergone a purification process intended to extract the daughter elements of uranium and thorium there from.

### Claim 35 (depends on 4)

The material of claim 4 wherein said material includes daughter elements of uranium and thorium.

### Claim 36 (depends on 4)

A process for preparing the material of claim 4, comprising
1) melting La and Ce salts and
2) growing at least one crystal from the melted La and Ce salts,
wherein the La and Ce salts are obtained from La and Ce source raw materials that are La and Ce oxides, wherein the daughter elements of uranium and thorium in the materials are in an amount which results in activity resulting from alpha radiation from these elements of less than 0.7 Bq/cc.

### Claim 37 (depends on 4)

A detector comprising the scintillator material of claim 4.

### Claim 38 (depends on 1)

A process for preparing the material of claim 1, comprising synthesizing the material from raw materials comprising an Ln oxide which includes daughter elements of uranium of thorium in a sufficiently low quantity for the material to have an activity resulting from the alpha radiation from these elements of less than 0.7 Bq/cc.