Neutron detectors comprising boron powder

1. A high-efficiency neutron detector substrate assembly comprising:

a first conductive substrate;

a first layer of a powder material comprising 10 boron, 10 boron carbide or combinations thereof directly deposited on the first conductive substrate;

a second layer of powder material comprising 10 boron, 10 boron carbide or combinations thereof directly deposited on a second side of the first conductive substrate; and

a conductive material in proximity to the first layer of powder material.

2. The substrate assembly of claim 1 , wherein the powder material comprises from about 20% to about 100% of 10 boron, 10 boron carbide or combinations thereof.

3. The substrate assembly of claim 1 , wherein the layer of powder material has an average thickness of from about 1 μm to about 10 μm.

4. The substrate assembly of claim 1 , wherein the powder material comprises particles having an average particle size of from about 0.1 μm to about 10 μm.

5. The substrate assembly of claim 1 , further comprising a first layer of adhesive material in direct contact both with the first side of the first conductive substrate and with the powder material.

6. The substrate assembly of claim 1 , further comprising a second layer of adhesive material in direct contact with both the second side of the first conductive substrate and with the second layer of powder material.

7. The substrate assembly of claim 1 , wherein the conductive material is in the form of one or more wires, a grid, or a plate, and is connectable to a high-voltage source.

8. The substrate assembly of claim 1 , further comprising a gas layer disposed between the first layer of powder material and the conductive material.

9. The substrate assembly of claim 8 , wherein the gas layer comprises a gaseous mixture comprising: C 2 H 6 , CF 4 , and Ar.

10. The substrate assembly of claim 9 , wherein the conductive material comprises a mesh grid.

11. A neutron detector substrate assembly comprising:

a first conductive substrate having two opposing sides, wherein each opposing side is in direct contact with a layer of a powder material comprising 10 boron, 10 boron carbide or combinations thereof and,

at least one additional conductive substrate having two opposing sides, wherein each opposing side is in direct contact with a layer of a powder material comprising 10 boron, 10 boron carbide or combinations thereof wherein two layers of the powder material comprising 10 boron, 10 boron carbide or combinations thereof, which are in direct contact with different substrates, are each in proximity to a conductive material therebetween.

12. The substrate assembly of claim 11 , further comprising a layer of adhesive material in direct contact both with at least one side of one conductive substrate and with at least one layer of the powder material comprising 10 boron, 10 boron carbide or combinations thereof.

13. The substrate assembly of claim 11 , wherein the powder material comprises from about 20% to about 100% of 10 boron, 10 boron carbide or combinations thereof.

14. The substrate assembly of claim 11 , wherein the layer of powder material has an average thickness of from about 1 μm to about 10 μm.

15. The substrate assembly of claim 11 , wherein the powder material comprises particles having an average particle size of from about 0.1 μm to about 10 μm.

16. The substrate assembly of claim 11 , further comprising a gas layer disposed between the first layer of powder material and the conductive material.

17. The substrate assembly of claim 16 , wherein the gas layer comprises a gaseous mixture comprising: C 2 H 6 , CF 4 , and Ar.

18. The substrate assembly of claim 17 , wherein the conductive material comprises a mesh grid.