Material discrimination using scattering and stopping of muons and electrons

Patent metadata

Field	Value
Publication number	US-9841530-B2
Application number	US-201514822825-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Aug 11, 2014
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

In one aspect, a process for characterizing a range of materials based on the scattering and stopping of incident cosmic ray charged particles passing through each material includes: determining a scattering metric and a stopping metric for each material within the range of materials exposed to cosmic ray charged particles; computing a ratio of the scattering metric to the stopping metric to obtain a scattering-to-stopping ratio for each material within the range of materials for the material; and establishing a scattering-stopping relationship for the range of materials based on the determined pairs of the scattering-to-stopping ratio and the associated scattering metric for the range of materials.

First claim

What is claimed are techniques and structures as described and shown, including:

1. A method for characterizing a range of materials based on scattering and stopping of incident cosmic ray charged particles passing through each material, the method comprising:
for a given material within the range of materials:
creating a volume of interest (VOI) of the material;
determining a scattering metric of cosmic ray charged particles interacting with the VOI to represent a first set of cosmic ray charged particles entering and exiting the VOI;
determining a stopping metric of cosmic ray charged particles interacting with the VOI to represent a second set of cosmic ray charged particles entering and stopping inside the VOI; and
computing a ratio of the scattering metric to the stopping metric to obtain a scattering-to-stopping ratio for the material; and

establishing a scattering-stopping relationship of cosmic ray particles for the range of materials based on the determined pairs of the scattering-to-stopping ratio and the associated scattering metric for the range of materials.

2. The method of claim 1 , wherein establishing the scattering-stopping relationship includes obtaining a relationship between the scattering-to-stopping ratio and the scattering metric.

3. The method of claim 1 , wherein the obtained relationship between the scattering-to-stopping ratio and the scattering metric is substantially linear over the range of materials, and wherein a greater scattering-to-stopping ratio corresponds to a greater density of the associated material.

4. The method of claim 1 , wherein determining the scattering metric includes:
obtaining a set of scattering angles for the first set of cosmic ray charged particles;
computing an average scattering angle of the set of scattering angles;
determining an average momentum of the incident cosmic ray charged particles; and
determining the scattering metric based on the average scattering angle and the average momentum.

5. The method of claim 4 , wherein determining the scattering metric includes normalizing the scattering metric by a thickness of the VOI of the material.

6. The method of claim 1 , wherein determining the stopping metric includes:
obtaining a raw stopping number of a set of cosmic ray charged particles entering and stopping inside the VOI;
obtaining a scattering number of a set of cosmic ray charged particles entering and exiting the VOI; and
determining the stopping metric by normalizing the raw stopping number by the scattering number to compensate for undetected scattered cosmic ray particles.

7. The method of claim 6 , wherein determining the stopping metric includes normalizing the stopping metric by a thickness of the VOI of the material.

8. The method of claim 6 , wherein determining the stopping metric includes multiplying the stopping metric by an average momentum of the incident cosmic ray charged particles.

9. The method of claim 1 , wherein the cosmic ray charged particles include at least one of cosmic ray muons or cosmic ray electrons.

10. The method of claim 9 , wherein the cosmic ray muons are used to characterize metals in the range of materials having densities great than density of aluminum.

11. The method of claim 10 , wherein the characterized metals include special nuclear materials (SNM).

12. The method of claim 11 , wherein the SNM includes uranium, plutonium or another fissile material used to manufacture nuclear weapons.

13. The method of claim 12 , wherein the characterized metals include metals of commercial interests, wherein the metals of commercial interests include one of silver, gold or platinum.

14. The method of claim 9 , wherein the cosmic ray electrons are used to characterize materials in the range of materials having densities substantially equal to or less than density of aluminum.

15. A method for identifying the material of a volume of interest (VOI) exposed to cosmic ray particles, the method comprising:
determining a scattering metric of cosmic ray charged particles interacting with the VOI to represent a first set of cosmic ray particles entering and exiting the VOI;
determining a stopping metric of cosmic ray charged particles interacting with the VOI to represent a second set of cosmic ray charged particles entering and stopping inside the VOI;
computing a ratio of the scattering metric to the stopping metric to obtain a scattering-to-stopping ratio for the VOI; and
comparing the determined pair of scattering-to-stopping ratio and the scattering metric against an established relationship between the scattering-to-stopping-ratio and the scattering metric for a range of known materials to determine whether the material of the VOI matches a material in the range of known materials.

16. The method of claim 15 , wherein determining the scattering metric includes:
obtaining a set of scattering angles for the first set of cosmic ray charged particles;
computing an average scattering angle of the set of scattering angles;
determining an average momentum of the incident cosmic ray charged particles; and
determining the scattering metric based on the average scattering angle and the average momentum.

17. The method of claim 16 , wherein determining the scattering metric includes normalizing the scattering metric by a thickness of the VOI.

18. The method of claim 15 , wherein determining the stopping metric includes:
obtaining a raw stopping number of a set of cosmic ray charged particles entering and stopping inside the VOI;
obtaining a scattering number of a set of cosmic ray charged particles entering and exiting the VOI; and
determining the stopping metric by normalizing the raw stopping number by the scattering number to compensate for the undetected scattered cosmic ray charged particles.

19. The method of claim 18 , wherein determining the stopping metric includes normalizing the stopping metric by a thickness of the VOI.

20. The method of claim 18 , wherein determining the stopping metric includes multiplying the stopping metric by an average momentum of the incident cosmic ray charged particles.

21. The method of claim 15 , wherein the cosmic ray charged particles include cosmic ray muons and cosmic ray electrons.

22. The method of claim 21 , wherein the cosmic ray muons are used to detect the VOI for target metals having densities great than density of aluminum.

23. The method of claim 22 , wherein the target metals include special nuclear materials (SNM).

24. The method of claim 23 , wherein the SNM includes uranium, plutonium or another fissile material used to manufacture nuclear weapons.

25. The method of claim 22 wherein the target metals include metals of commercial interests, wherein the metals of commercial interest includes one of silver, gold or platinum.

26. The method of claim 21 , wherein the cosmic ray electrons are used to detect the VOI for target metals having densities substantially equal to or less than the density of aluminum.

27. The method of claim 21 , wherein after identifying the material of the VOI, the method further comprises inferring a thickness of the VOI based on an established relationship between the scattering-to-stopping-ratio and a normalized stopping metric per unit thickness for the range of known materials.

28. A cosmic ray based detection system comprising:
a position sensitive incoming cosm

Assignees

• Decision Sciences Int Corp

Inventors

• Blanpied Gary
• Kumar Sankaran
• Dorroh Dustin
• Morgan Craig

Classifications

• G01V5/0091

  Physics · mapped topic

• G01N23/08

  Physics · mapped topic

• G01N23/20083

  by using a combination of at least two measurements at least one being a transmission measurement and one a scatter measurement · CPC title

• G01N2223/419

  computed tomograph · CPC title

• G01V5/0016

  Physics · mapped topic