Charged particle scanners

Patent metadata

Field	Value
Publication number	US-11152190-B2
Application number	US-202016853529-A
Country	US
Kind code	B2
Filing date	Apr 20, 2020
Priority date	Apr 18, 2019
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

A volume interrogation system can use an accelerated beam of charged particles to interrogate objects using charged-particle attenuation and scattering tomography to screen items such as electronic devices, packages, baggage, industrial products, or food products for the presence of materials of interest inside. The apparatus, systems, and methods in this patent document can be employed in checkpoint applications to scan items. Such checkpoint applications can include border crossings, mass transit terminals (subways, buses, railways, ferries, etc.), and government and private-sector facilities.

First claim

What is claimed is:

1. A scanner for interrogating contents of a volume comprising:
an accelerator structured to generate a beam of charged particles;
a chamber located in a path of the beam of charged particles to receive the beam of charged particles;
a beam distribution system located in the chamber to receive the beam of charged particles and structured to distribute the beam of charged particles over a range of incidence angles and positions;
a scan-volume stage located in a path of the beam of charged particles from the chamber, the scan-volume stage configured to support an object to be scanned, and the scan-volume stage operable to move the object relative to the beam of charged particles;
a first particle tracking detector located relative to the scan-volume stage to receive charged particles that transit through the object and to measure position and direction of the charged particles that transit through the object while allowing the charged particles to pass through;
a calorimeter located relative to the first particle tracking detector to receive the charged particles from the first particle tracking detector and to measure the received charged particles to represent energy of the charged particles received by the first particle tracking detector; and
a processor communicably coupled to the first particle tracking detector and the calorimeter to process information from the first particle tracking detector and the calorimeter to yield an estimate of a spatial map of atomic number and density of the object.

2. The scanner of claim 1 , wherein the beam distribution system further comprises:
a bend magnet structured to receive the charged particles from the accelerator and structured to orient the electrons toward the object under inspection; and
a plurality of scattering foils to receive the charged particles from the bend magnet, wherein the plurality of scattering foils distribute the beam of charged particles over the range of incidence angles.

3. The scanner of claim 1 , wherein the first particle tracking detector comprises two or more layers of charged particle detectors with each layer being perpendicular to at least one other layer and each layer including a plurality of charged particle detectors parallel to each other and structured to convert deposited energy from at least some of the charged particles into electrical current.

4. The scanner of claim 3 , wherein the charged particle detectors comprise scintillating fibers coupled with silicon photomultiplier sensors.

5. The scanner of claim 1 , further comprising:
a second particle tracking detector located relative to the scan-volume stage and opposite to the first particle tracking detector system,
wherein the second particle tracking detector structured to receive and measure position and direction of the charged particles before the charged particles transit though the object while allowing the charged particles to pass through, and
wherein the second particle tracking detector is communicably coupled to the processor to send information to the processor.

6. The scanner of claim 5 , wherein the second particle tracking detector comprises two or more layers of charged particle detectors with each layer being perpendicular to at least one other layer and each layer including a plurality of charged particle detectors parallel to each other and structured to convert deposited energy from at least some of the charged particles into electrical current.

7. The scanner of claim 6 , wherein the charged particle detectors comprise scintillating fibers coupled to silicon photomultiplier sensors.

8. The scanner of claim 1 , wherein the scan-volume stage is a conveyor belt.

9. The scanner of claim 1 , wherein the beam of charged particles include electrons.

10. The scanner of claim 1 , wherein the atomic number is an average atomic number of materials associated with or included in the object.

11. The scanner of claim 1 ,
wherein the calorimeter includes a scintillator coupled to a photomultiplier tube (PMT),
wherein the scintillator is structured to converted the charged particles from the first particle tracking detector into photons,
wherein the PMT is structured to convert the photons to electrical current, and
wherein the energy of the charged particles received by the first particle tracking detector is based on the electrical current.

12. A method of operating a scanner for interrogating contents of a volume, the method comprising:
generating a beam of charged particles;
distributing the beam of charged particles over a range of incidence angles and positions to enter an object to be scanned;
detecting positions and directions of the charged particles that exit the object; and
generating an estimate of a spatial map of the atomic number and the density of the object based on at least the positions and the directions of the charged particles that exit the object.

13. The method of claim 12 , further comprising:
moving the object to be scanned through the range of incidence angles and the positions of the beam of charged particles that enter the object.

14. The method of claim 12 , wherein the distributing comprises adjusting the beam of charged particles from a horizontal orientation received from a source of the beam of charged particles to a vertical orientation that enables the beam of charged particles to be directed towards the object to be scanned.

15. The method of claim 12 , further comprising:
determining scatter angles of the charged particles using at least the positions and the directions of the charged particles that exit the object, wherein the atomic number and the density of the object are proportional to the scatter angles.

16. The method of claim 15 , further comprising:
detecting positions and directions of the beam of charged particles before the beam of charged particles enter the object, wherein the scatter angles are determined based on the positions of the beam of charged particles before the beam of charged particles enter the object and based on the positions of the charged particles that exit the object.

17. The method of claim 12 , further comprising:
measuring energy of the charged particles that exit the object;
determining energy loss of the charged particles based on the measured energy and an energy of the beam of charged particles that enter the object; and
determining an estimate of the density of a part of the object along a path of the beam of charged particles based on the energy loss, wherein the density of the part of the object is proportional to the energy loss.

18. The method of claim 12 , wherein the beam of charged particles includes electrons.

19. The method of claim 12 , wherein the atomic number is an average atomic number of materials associated with or included in the object.

20. The method of claim 12 , wherein the spatial map is a three-dimensional (3D) reconstruction of the object.

Assignees

• Decision Sciences Int Corp

Inventors

• Penny Robert D
• Sossong Michael James
• Steiger Matthew
• Lee Young K

Classifications

• H01J2237/24495

  Signal processing, e.g. mixing of two or more signals · CPC title

• H01J2237/2443

  Scintillation detectors · CPC title

• H01J2237/2446

  Position sensitive detectors · CPC title

• H01J37/1475

  magnetic · CPC title

• H01J2237/2445

  Photon detectors for X-rays, light, e.g. photomultipliers · CPC title