Composite solid-state scintillators for neutron detection

• US 20050224720A1
• Filed: 04/07/2004
• Published: 10/13/2005
• Est. Priority Date: 04/07/2004
• Status: Active Grant

• Current Assignee: UT-Battelle LLC, UT Research Foundation
• Original Assignee: UT-Battelle LLC
• Inventors: Dai, Sheng, Im, Hee-Jung, Pawel, Michelle D.
• Granted Patent: US 7,105,832 B2
• Time in Patent Office: Days
• US Class Current: 250/390.110
• CPC Class Codes: G01T 1/204 the detector being a liquid
• CPC Class Codes: G01T 3/06 with scintillation detectors

Abstract

Applicant'"'"'s present invention is a composite scintillator for neutron detection comprising a matrix material fabricated from an inorganic sol-gel precursor solution homogeneously doped with a liquid scintillating material and a neutron absorbing material. The neutron absorbing material yields at least one of an electron, a proton, a triton, an alpha particle or a fission fragment when the neutron absorbing material absorbs a neutron. The composite scintillator further comprises a liquid scintillating material in a self-assembled micelle formation homogeneously doped in the matrix material through the formation of surfactant-silica composites. The scintillating material is provided to scintillate when traversed by at least one of an electron, a proton, a triton, an alpha particle or a fission fragment. The scintillating material is configured such that the matrix material surrounds the micelle formation of the scintillating material. The composite scintillator is fabricated and applied as a thin film on substrate surfaces, a coating on optical fibers or as a glass material.

Claims

1. A composite scintillator for neutron detection comprising:

a) a matrix material fabricated from an inorganic sol-gel precursor solution homogeneously doped with a liquid scintillating material and homogeneously doped with a neutron absorbing material, said neutron absorbing material yielding at least one of an electron, a proton, a triton, an alpha particle or a fission fragment when said neutron absorbing material absorbs a neutron; and

b) said liquid scintillating material in a self-assembled micelle formation doped in said matrix material through the formation of surfactant-silica composites, said scintillating material being provided to scintillate when traversed by said at least one of an electron, a proton, a triton, an alpha particle or a fission fragment, said scintillating material being configured such that said matrix material surrounds said micelle formation of said scintillating material.

2. The composite scintillator of claim 1 wherein said neutron absorbing material includes at least one element selected from the group consisting of Li-6, B-10, Gd, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-239, Pu-240, Th-232 and Am-241.

3. The composite scintillator of claim 1 wherein said surfactant-silica composites are polyether-silica composites formed using polyethylene oxides or block copolymers.

4. The composite scintillator of claim 1 wherein said surfactant-silica composites are cation-silica composites formed using cationic surfactants.

5. The composite scintillator of claim 3 wherein said polyethylene oxides include at least one of poly(ethylene glycol)-block-poly(propylene glycol)-block-polyethylene glycols, ethoxylated alkylphenols and alkyl poly(ethylene oxide) oligomeric surfactants.

6. The composite scintillator of claim 3 wherein said block copolymers include poly(styrene-b-ethylene oxide).

7. The composite scintillator of claim 4 wherein said cationic surfactants include quaternary ammonium surfactants and alkylamine surfactants.

8. The composite scintillator of claim 1 being fabricated by homogeneously mixing said liquid scintillating material into a sol-gel precursor solution doped with a neutron absorbing material then being polymerized at room temperature.

9. The composite scintillator of claim 1 wherein said liquid scintillating material comprises at least one nonionic surfactant and further comprises organic fluors in an organic solvent wherein said organic fluors are solubilized into a silica matrix by said nonionic surfactants forming a water-soluble phase in a self-assembled micelle.

10. The composite scintillator of claim 9 wherein said nonionic surfactants include ethoxylated alkylphenols, di(ethylene glycol) butyl ethers and fatty alcoholthoxylates.

11. The composite scintillator of claim 10 wherein said ethoxylated alkylphenols include polyoxyethylene(5)nonylphenyl ethers.

12. The composite scintillator of claim 9 further comprising at least one anionic surfactant.

13. The composite scintillator of claim 12 wherein said anionic surfactant includes R-succinates, R-carboxylates, R-sulfonates, R-sulphates, or R-phosphates, wherein R is alkyl, ethoxylated alkyl, and ethoxylated aryl.

14. The composite scintillator of claim 9 wherein said organic fluors include PPO (2,5-diphenyloxazol)/POPOP (1,4-bis-2-(5-phenyloxazolyl)-benzene), P-terphenyl/POPOP, 1,1,4,4-tetraphenylbutadiene.

15. The composite scintillator of claim 9 wherein said organic solvent is diisopropyinaphthalene, 1-phenyldodecane or 2-ethylnaphthalene.

16. The composite scintillator of claim 1 wherein said composite scintillator is fabricated and applied as a coating to a surface substrate.

17. The composite scintillator of claim 16 wherein said surface substrate includes optical fibers.

18. The composite scintillator of claim 17 wherein said optical fibers are wavelength shifting fibers.

19. The composite scintillator of claim 16 wherein said surface substrate is a surface viewable by an optical emission detecting element to image neutrons.

20. The composite scintillator of claim 16 wherein said surface substrate is an optically clear disk placed in optical communication with a detector.

21. The composite scintillator of claim 1 being positioned relative to at least one detector element sensitive to scintillation light, whereby said detector element produces an electrical signal upon detection of scintillation light resulting from neutron absorption by said neutron absorbing material.

22. The composite scintillator of claim 21 wherein said detector element is selected from the group consisting of a photomultiplier, a silicon photodiode, a charge coupled device, an amorphous silicon screen, a microchannel plate, a channeltron and an avalanche photodiode.

23. The composite scintillator of claim 21 wherein said composite scintillator is coupled to a wavelength shifting fiber wherein said scintillator light occurring within a volume of said composite scintillator is transformed and guided within said wavelength shifting fiber to a detection element of a multianode photomultiplier tube.

24. The composite scintillator of claim 21 wherein said composite scintillator is coupled to a wavelength shifting fiber wherein said scintillator light occurring within a volume of said composite scintillator is transformed and guided within said wavelength shifting fiber to a detection element of an array of avalanche photodiodes.