NON-STREAMING HIGH-EFFICIENCY PERFORATED SEMICONDUCTOR NEUTRON DETECTORS, METHODS OF MAKING SAME AND MEASURING WAND AND DETECTOR MODULES UTILZING SAME

• US 20090302231A1
• Filed: 03/16/2007
• Published: 12/10/2009
• Est. Priority Date: 03/16/2006
• Status: Active Grant

• Current Assignee: Kansas State University Research Foundation
• Original Assignee: Kansas State University Research Foundation
• Inventors: Shultis, John K., Patterson, Eric L., Bellinger, Steven L., Rice, Blake B., McGregor, Douglas S., Solomon, Clell J., McNeil, Walter J.
• Granted Patent: US 7,855,372 B2
• Time in Patent Office: Days
• US Class Current: 250/390.30
• CPC Class Codes: G01T 3/08 with semiconductor detectors

Abstract

Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

Claims

1. An apparatus for efficiently detecting neutrons, the apparatus comprising:

a particle-detecting first substrate having top and back surfaces and including an array of sinuous fins spaced apart by a corresponding array of sinuous channels at the top surface; and

neutron-responsive material disposed in the array of sinuous channels, the material being responsive to neutrons absorbed thereby for releasing ionizing radiation reaction products wherein the sinuous shape of the fins and channels strengthens the fins and reduces neutron streaming effects whereby the apparatus has a relatively flat and uniform detection efficiency response.

2. The apparatus as claimed in claim 1, wherein the fins and channels are chevron-shaped.

3. The apparatus as claimed in claim 1, wherein the fins and channels are sinusoidal-shaped.

4. The apparatus as claimed in claim 1, wherein the fins and channels are circularly-shaped.

5. The apparatus as claimed in claim 1, further comprising top and back conductive contacts coupled to the first substrate at the top and back surfaces, respectively.

6. The apparatus as claimed in claim 5, wherein the contacts include steering contacts and a collecting contact.

7. The apparatus as claimed in claim 5, wherein the fins have conductive doped regions at the top surface spaced away from the channels and wherein walls which define the channels are coated with an insulating layer to reduce leakage current.

8. The apparatus as claimed in claim 5, wherein the top conductive contacts are Schottky barrier, diffused dopant or metal ohmic contacts.

9. The apparatus as claimed in claim 5, wherein the first substrate has a doped region at the back surface to increase coupling of the back conductive contact to the substrate.

10. The apparatus as claimed in claim 1, wherein the neutron responsive material includes at least one of B or B compounds, Li or Li compounds, Gd or Gd compounds, U or Uranium compounds, Th or Th compounds, and Cd or Cd compounds.

11. The apparatus as claimed in claim 1, further comprising a neutron-responsive layer disposed on the neutron-responsive material disposed in the array of sinuous channels.

12. The apparatus as claimed in claim 1, wherein the first substrate is composed primarily of a semiconductor material.

13. The apparatus as claimed in claim 12, wherein the semiconductor material is silicon, silicon carbide, gallium arsenide, gallium nitride, indium phosphide, cadmium telluride, cadmium-zinc-telluride, gallium phosphide, mercuric iodide, or lead iodide.

14. The apparatus as claimed in claim 1, further comprising a particle-detecting second substrate having neutron-responsive material disposed in cavities of the second substrate and stacked on the first substrate.

15. The apparatus as claimed in claim 14, wherein the neutron-responsive material is also disposed as layers between the substrates.

16. A method for filling perforations which extend into a particle-detecting semiconductor substrate from a top portion of the substrate towards a back portion of the substrate with a neutron-responsive material to form a neutron detector, the method comprising:

evaporating the neutron-responsive material to obtain vaporized neutron-responsive material;

establishing a temperature gradient across the substrate so that the top portion of the substrate is relatively warmer than the relatively cooler back portion of the substrate; and

transporting the vaporized neutron-responsive material to the substrate so that the vaporized neutron-responsive material initially condenses at the relatively cool bottom portion of the substrate rather than the relatively warm top portion of the substrate, wherein the perforations of the substrate are filled from the bottom portion of the substrate up to the top portion of the substrate.

17. The method as claimed in claim 16, wherein the step of transporting is performed with a carrier gas and wherein the method further comprises preventing the carrier gas from flowing completely through the substrate and wherein the method is a static method.

18. The method as claimed in claim 16, wherein the step of transporting is performed with a carrier gas and wherein the method further comprises allowing the carrier gas to flow completely through the substrate and wherein the method is a dynamic method.

19. A measuring wand comprising:

an elongated housing; and

an apparatus for efficiently detecting neutrons mounted within the housing, the apparatus including;

a particle-detecting substrate having top and back surfaces and including an array of sinuous fins spaced apart by a corresponding array of sinuous channels at the top surface; and

neutron-responsive material disposed in the array of sinuous channels, the material being responsive to neutrons absorbed thereby for releasing ionizing radiation reaction products wherein the sinuous shape of the fins and channels strengthens the fins and reduces neutron streaming effects whereby the apparatus has a relatively flat and uniform detection efficiency response.

20. The wand as claimed in claim 19, further comprising a source of electrical power disposed within the housing for powering the wand.

21. The wand as claimed in claim 19, further comprising a gamma ray detector mounted within the housing in line with the apparatus to measure or subtract gamma ray background.

22. The wand as claimed in claim 19, further comprising a readout display mounted on the housing to provide a visual indication of measured radiation.

23. The wand as claimed in claim 19, further comprising manual operable controls mounted on the housing to operate the wand.

24. A detector module for remote neutron sensing, the module comprising:

first apparatus for efficiently detecting neutrons, the apparatus including;

a particle-detecting substrate having top and back surfaces and including an array of sinuous fins spaced apart by a corresponding array of sinuous channels at the top surface; and

neutron-responsive material disposed in the array of sinuous channels, the material being responsive to neutrons absorbed thereby for releasing ionizing radiation reaction products wherein the sinuous shape of the fins and channels strengthens the fins and reduces neutron streaming effects whereby the apparatus has a relatively flat and uniform detection efficiency response; and

means coupled to the first apparatus for determining a radiation unit of measure detected by the first apparatus.

25. The module as claimed in claim 24, further comprising a source of electrical power for powering the module.

26. The module as claimed in claim 24, further comprising a gamma ray detector to measure or subtract gamma ray background.

27. The module as claimed in claim 24, further comprising a readout display to provide a visual indication of measured radiation.

28. The module as claimed in claim 24, further comprising manual operable controls to operate the module.

29. The module as claimed in claim 26, further comprising second apparatus for detecting fast neutrons and at least one of a moderator and shielding to assist the second apparatus in distinguishing between fast and thermal neutrons.

30. The module as claimed in claim 29, wherein the means for determining is also coupled to the second apparatus and the gamma ray detector for determining a dose of fast and thermal neutrons and gamma rays.

31. The module as claimed in claim 24, further comprising a transmitter coupled to the first apparatus to transmit data based on the detected neutrons.

32. The module as claimed in claim 30, further comprising a transmitter coupled to the means for determining for transmitting data based on the dose.

33. The module as claimed in claim 24, further comprising means for determining spatial location of the module.

34. The module as claimed in claim 30, further comprising a transmitter to transmit data based on the detected neutrons and at least one of spectral energy information and detected gamma rays.