Gamma and neutron radiation detector

1. A sensing element activated by radiation for use with a photosensor comprising:

a first scintillator activated by gamma radiation; and

a neutron sensing layer comprising a second scintillator activated by neutron radiation;

wherein one scintillator is coupled directly to the photo sensor and the other scintillator is coupled to the photosensor through wavelength-shifting material.

2. The sensing element of claim 1 wherein the first scintillator activated by gamma radiation comprises Ce 3+ activated [La(Cl,Br,I) 3 ].

3. The sensing element of claim 1 wherein the first scintillator activated by gamma radiation comprises a lanthanum halide based material.

4. The sensing element of claim 3 wherein the lanthanum halide based material comprises a cerium-doped lanthanum halide.

5. The sensing element of claim 1 wherein the second scintillator comprises ZnS(Ag)—LiF.

6. The sensing element of claim 1 wherein the second scintillator comprises ZnS(Ag)—LiF; and

the first scintillator comprises a cerium-doped lanthanum halide.

7. The sensing element of claim 1 wherein the first scintillator activated by gamma radiation is from the group consisting of:

Ce 3+ activated compositions, CsLnO(Cl,Br,I) 2 (Ln=rare earth, Y,La), NaBaLaBr 6 , BaGdCl 5 , (Cs,Rb)Ba 2 Br 5 ; members of the elpasolite family of materials, LnCl 3 -LnBr 3 -LnI 3 solid solution (Ln=La,and Y), CeCl 3 —CeBr 3 —CeI 3 solid solutions, A 2 LnX 5 :Ce 3+ (A=K,Rb,Cs; Ln=La, Y (X=Cl,Br,I) family of materials; MCl 2 -MBr 2 solid solutions (M=Ca,Sr,Ba), and ABX 3 where A=Cs, Rb, K, B=Ca, Sr, Ba, Mg, Cd, X=Cl, Br, I.

8. The sensing element of claim 1 wherein the second scintillator comprises an enriched lithium containing material.

9. The sensing element of claim 8 wherein the second scintillator comprises an enriched lithium containing material from the group consisting of: LiI, LiYSiO4, LiBaF3, and Li-based glasses.

10. The sensing element of claim 1 wherein the second scintillator comprises a lithium containing material.

11. The sensing element of claim 1 wherein the second scintillator comprises borosilicate glass.

12. The sensing element of claim 1 , wherein the wavelength-shifting material comprises wavelength-shifting fibers.

13. A radiation detector allowing both gamma and neutron detection comprising:

a radiation sensing element comprising a gamma radiation sensing first scintillator and a neutron sensing second scintillator; and

a photosensor;

wherein one scintillator is coupled directly to the photo sensor and the other scintillator is coupled to the photosensor through wavelength-shifting material.

14. The radiation detector of claim 13 wherein the first scintillator is a lanthanum halide based material.

15. The radiation detector of claim 13 wherein the second scintillator emits light in the range of 300-500 nm.

16. The radiation detector of claim 13 wherein the second scintillator is structured not to excite the first scintillator and is also not excitable by the first scintillator.

17. The radiation detector of claim 13 wherein the second scintillator comprises a 6LiF/ZnS:Ag composite.

18. The radiation detector of claim 13 wherein the detector is a hand-held or portable detector.

19. The radiation detector of claim 13 wherein the first scintillator activated by gamma radiation comprises Ce 3+ activated [La(Cl,Br,I) 3 ].

20. The radiation detector of claim 13 wherein the first scintillator and the second scintillator are optically connected such that the light from one scintillator passes through the other.

21. The radiation detector of claim 13 wherein the first scintillator and the second scintillator are optically separated.

22. The radiation detector of claim 13 , wherein the wavelength-shifting material comprises wavelength-shifting fibers.

23. The radiation detector of claim 13 further comprising:

a moderating material to thermalize the neutrons before detection in order to increase detection efficiency.

24. The radiation detector of claim 13 wherein the second scintillator has a primarily speed distinct from that of the first scintillator.

25. The radiation detector of claim 13 wherein the first scintillator for sensing gamma radiation is from the group consisting of:

Ce 3+ activated compositions, CsLnO(Cl,Br,I) 2 (Ln=rare earth, Y,La), NaBaLaBr 6 , BaGdCl 5 , (Cs,Rb)Ba 2 Br 5 ; members of the elpasolite family of materials, LnCl 3 -LnBr 3 -LnI 3 solid solution (Ln=La, and Y), CeCl 3 —CeBr 3 —CeI 3 solid solutions, A 2 LnX 5 :Ce 3+ (A=K,Rb,Cs; Ln=La, Y (X=Cl,Br,I) family of materials; MCl 2 -MBr 2 solid solutions (M=Ca,Sr,Ba), and ABX 3 where A=Cs, Rb, K, B=Ca, Sr, Ba, Mg, Cd, X=Cl, Br, I.

26. The radiation detector of claim 13 wherein the second scintillator comprises an enriched lithium containing material.

27. The radiation detector of claim 26 wherein the second scintillator comprises an enriched lithium containing material from the group consisting of: LiI, LiYSiO4, LiBaF3, and Li-based glasses.

28. The radiation detector of claim 13 wherein the second scintillator comprises a lithium containing material.

29. The radiation detector of claim 13 wherein the second scintillator comprises borosilicate glass.

30. A radiation detector allowing both gamma and neutron detection comprising:

a radiation sensing element comprising a gamma radiation sensing first scintillator and a neutron sensing second scintillator;

a photosensor; and

a photodiode;

wherein the photodiode is used for both reading the second scintillator for neutrons and for direct detection of low energy gamma rays, and the detector is structured with pulse-shape discrimination capability to discriminate between low energy gamma rays and neutrons.

31. A radiation detector allowing both gamma and neutron detection comprising:

a radiation sensing element comprising a gamma radiation sensing first scintillator and a neutron sensing second scintillator; and

a photosensor;

wherein the first scintillator is an inner cylinder that is coupled directly to the photosensor and the second scintillator is an outer cylinder that is coupled to multiple wavelength-shifting optical fibers which are arranged in an inter-leaving helix pattern and connected on both ends to the photosensor.