Lithium based scintillators for neutron detection
View Patent ↗A neutron scintillator composite (NSC) is made of a neutron scintillator and a binder. The neutron scintillator of the composite has the formula Li y MgBr y+2 , where y=2, 4 or 6 and may further comprise cerium as a scintillation activator. The binder of the composite has an index of refraction substantially identical to that of the neutron scintillator. The neutron scintillator and binder are mixed into a solid or semi-solid neutron scintillator composite having sufficient flowability for molding into a shaped article, such as a neutron sensing element of a radiation detector. The neutron scintillator composite collects and channels photons through the material itself and into a photosensing element optically coupled to the composite. Because the indices of refraction for both the neutron scintillator and the binder are substantially identical, scattering at the scintillator-binder interface(s) is minimized, thereby producing transmission efficiencies that approach single crystals.
1. A neutron scintillator composite, comprising:
a neutron scintillator of the formula Li y MgBr y+2 , where y=2, 4 or 6; and
a binder having an index of refraction that is substantially identical to an index of refraction of the neutron scintillator.
2. The composite of claim 1 , wherein the neutron scintillator incorporates a scintillation activator.
3. The composite of claim 2 , wherein the scintillation activator comprises cerium.
4. The composite of claim 3 , wherein the neutron scintillator has the formula Li y Mg 1−x Ce x Br y+2 where 0≦x<1 and y=2, 4 or 6.
5. The composite of claim 3 , wherein the neutron scintillator is Li 6 Mg 1−x Ce x Br 8 , where 0≦x<1.
6. The composite of claim 3 , wherein the neutron scintillator is Li 4 Mg 1−x Ce x Br 6 , where 0≦x<1.
7. The composite of claim 3 , wherein the neutron scintillator is Li 2 Mg 1−x Ce x Br 4 , where 0≦x<1.
8. The composite of claim 1 , wherein the binder is selected from a thermoplastic resin and a thermoset resin.
9. The composite of claim 1 , wherein the binder is selected from the group consisting of acrylate-based resin, epoxy resin, polycarbonate resin, and combinations thereof.
10. The composite of claim 1 , wherein the neutron scintillator composite has sufficient flowability to be formed into a shaped article.
11. A method for making a neutron scintillator composite comprising:
mixing (a) a neutron scintillator of formula Li y MgBr y+2 , where y=2, 4 or 6
and (b) a binder.
12. The method of claim 11 , wherein the neutron scintillator further comprises a scintillation activator.
13. The method of claim 11 , wherein the scintillation activator is cerium.
14. The method of claim 11 , wherein the neutron scintillator has the formula
Li y Mg 1−x Ce x Br y+2 , where 0≦x<1 and y=2, 4 or 6.
15. The method of claim 11 , wherein the binder comprises a thermoplastic resin or a thermoset resin.
16. The method of claim 11 , wherein the binder is selected from the group consisting of acrylate-based resin, epoxy resin, polycarbonate resin, and combinations thereof.
17. The method of claim 11 , wherein the binder provides the neutron scintillator composite with sufficient flowability to be formed into a shaped article.
18. An article comprising the neutron scintillator composite of claim 1 .
19. The article of claim 18 , wherein the article is a radiation detector comprising the neutron scintillator composite of claim 1 optically coupled to a photosensor.
20. The radiation detector of claim 19 , wherein the neutron scintillator composite forms a neutron sensing element of the radiation detector, wherein photons emitted within the neutron sensing element are collected and channeled through the neutron sensing element and into a photosensing element.
21. A method for making a neutron scintillator composite, the method comprising mixing a Ce-containing neutron scintillator of the formula Li y MgBr y+2 , where y=2, 4 or 6 and a binder having an index of refraction that is substantially identical to an index of refraction of the neutron scintillator.
22. The method of claim 21 , wherein the amount of neutron scintillator present in the composite is about 5% to about 60% by weight.
23. The method of claim 21 , wherein the amount of neutron scintillator present in the composite is about 10% to about 30% by weight.
24. The method of claim 21 , wherein the amount of neutron scintillator present in the composite is about 15% to about 20% by weight.
25. The method of claim 21 , wherein the amount of neutron scintillator present in the composite is about 5% to about 30% by volume.
26. The method of claim 21 , wherein the Ce-containing neutron scintillator of formula Li y MgBr y+2 , where y=2, 4 or 6 is prepared by:
(a) combining stoichiometric amounts of LiBr, MgBr2 and CeBr3 to obtain a mixture;
(b) grinding the mixture to obtain a fine powder;
(c) heating the powder to a temperature of about 600° C. to about 800° C. to obtain the neutron scintillator.
27. The method of claim 26 , wherein said heating step is performed in an environment essentially free of moisture and air.