High performance neutron detector with near zero gamma cross talk

• US 8,330,115 B2
• Filed: 02/25/2010
• Issued: 12/11/2012
• Est. Priority Date: 12/01/2005
• Status: Expired due to Fees

• Current Assignee: Advanced Measurement Technology, Inc. (Ametek Incorporated)
• Original Assignee: Innovative American Technology, Inc.
• Inventors: Frank, David L.
• Primary Examiner(s): Labaze, Edwyn
• Application Number:
  US12/713,014
• Publication Number:
  US 20100294943A1
• Time in Patent Office: 1,020 Days
• Field of Search: 250/390, 250366-369, 250/336.1, 250/360.1, 250/359.1, 250/390.01, 250/359
• US Class Current: 250/390.01
• CPC Class Codes: G01T 3/06 with scintillation detectors

Abstract

A scintillator system is provided to detect the presence of fissile material and radioactive material. One or more neutron detectors include scintillator material, and are optically coupled to one or more wavelength shifting fiber optic light guide media that extend from the scintillator material to guide light from the scintillator material to a photosensor. An electrical output of the photosensor is connected to an input of a pre-amp circuit designed to provide an optimum pulse shape for each of neutron pulses and gamma pulses in the detector signals. Scintillator material as neutron detector elements can be spatially distributed with interposed moderator material. Individual neutron detectors can be spatially distributed with interposed moderator material. Detectors and moderators can be arranged in a V-shape or a corrugated configuration.

Claims

1. A scintillation neutron detector system, comprising:

at least one neutron detector comprising at least one detector element comprising scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the scintillation material of the at least one detector element for coupling light photons emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal;

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector, wherein the at least one neutron detector comprises a plurality of detector elements comprising scintillation material and that are arranged in a plurality of layers with moderator material interposed between individual detector elements of the plurality of detector elements.

2. The scintillation neutron detector system of claim 1, wherein the at least one neutron detector comprises a plurality of neutron detectors that are arranged in at least one of the following:

a V-shape configuration; and

a corrugated configuration.

3. The scintillation neutron detector system of claim 1, wherein the at least one neutron detector comprises a plurality of neutron detectors that are arranged to substantially surround a moderator block.

4. The scintillation neutron detector system of claim 1, wherein the optical input of the photosensor is optically coupled to the scintillation material of the at least one detector element by at least one light guide medium that optically couples light emitted from the scintillation material to the optical input of the photosensor.

5. The scintillation neutron detector system of claim 4, wherein the at least one light guide medium comprises wavelength shifting material coupled with light guide medium at the scintillation material, that optically couples light emitted from the scintillation material to the optical input of the photosensor.

6. The scintillation neutron detector system of claim 4, wherein the at least one light guide medium comprises wavelength shifting fibers that optically couple light emitted from the scintillation material to the optical input of the photosensor.

7. A scintillation neutron detector system, comprising:

at least one neutron detector comprising at least one detector element comprising scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the scintillation material of the at least one detector element for coupling light photons emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal;

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector, wherein the at least one neutron detector comprises a plurality of detector elements comprising scintillation material and that are spatially distributed with moderator material interposed between individual spatially distributed detector elements.

8. The scintillation neutron detector system of claim 7, wherein the plurality of detector elements comprising scintillation material are spatially distributed with moderator material interposed between individual spatially distributed detector element layers.

9. The scintillation neutron detector system of claim 7, wherein the plurality of detector elements comprising scintillation material are spatially distributed with moderator material interposed between individual spatially distributed detector elements arranged in at least one layer.

10. A scintillation neutron detector system, comprising:

at least one neutron detector comprising at least one detector element comprising scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the scintillation material of the at least one detector element for coupling light photons emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal;

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector, wherein the at least one neutron detector comprises a plurality of neutron detectors that are spatially distributed with moderator material interposed between individual spatially distributed neutron detectors.

11. The scintillation neutron detector system of claim 10, wherein at least one neutron detector of the plurality of neutron detectors, comprises a plurality of detector elements comprising scintillation material and that are spatially distributed with moderator material interposed between individual spatially distributed detector elements.

12. A scintillation neutron detector system, comprising:

at least one neutron detector comprising at least one detector element comprising scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the scintillation material of the at least one detector element for coupling light photons emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal;

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector, and further comprising;

a plurality of optical fibers surrounded by scintillation material and arranged in a plurality of layers with optical fibers in one layer being staggered arrangement relative to optical fibers of an adjacent layer, the plurality of optical fibers optically coupling the scintillation material to the optical input of the photosensor, for coupling the light photons emitted as one or more light pulses from the scintillation material to the optical input of the photosensor through the plurality of optical fibers.

13. A neutron detector system, comprising:

a plurality of neutron detectors, each detector comprising a plurality of spatially distributed detector elements interposed with moderator material, each detector element comprising scintillation material that includes any one or more of 6LiF, Li6, and Li3, and mixed with one or more phosphor materials in a binder medium, individual detectors of the plurality of neutron detectors being interposed with at least two inches thick of moderator material;

a plurality of wavelength shifting optical fibers distributed in the scintillation material to optimally receive and guide light photons emitted as one or more light pulses from the scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the plurality of wavelength shifting optical fibers that guide light emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal; and

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector.

14. A neutron detector, comprising:

a plurality of detector elements interposed with moderator material, each detector element comprising scintillation material that includes any one or more of 6LiF, Li6, and Li3, and mixed with one or more phosphor materials in a binder medium, a pair of individual detector elements of the plurality of detector elements being interposed with moderator material from about 0.25 inches up to about 3 inches thick;

a plurality of wavelength shifting optical fibers distributed in the scintillation material to optimally receive and guide light photons emitted as one or more light pulses from the scintillation material;

a photosensor having an optical input and an electrical signal output, the optical input being optically coupled to the plurality of wavelength shifting optical fibers that guide light emitted as one or more light pulses from the scintillation material to the optical input of the photosensor, in response to neutron particles interacting with the scintillation material, and the electrical signal output providing an electrical sensor signal comprising one or more electrical pulses corresponding to the one or more light pulses from the scintillation material;

an amplifier sensor circuit having an amplifier signal input, that is electrically coupled to the electrical signal output of the photosensor, and an output, the amplifier sensor circuit being configured to provide at its output an electrical amplifier signal having an optimum electrical signal pulse shape for each of the one or more electrical pulses of the electrical sensor signal; and

an analog to digital converter having an input electrically coupled to the output of the amplifier sensor circuit, and an output for providing a digital sensor signal corresponding to the electrical amplifier signal; and

digital signal processing circuits, having an input electrically coupled to the output of the analog to digital converter, for performing pulse shape differentiation on the digital sensor signal based on one or more neutron signal shape filters and one or more gamma signal shape filters that are applied to the digital sensor signal to reduce, eliminate, or separate gamma pulse signal detection from neutron pulse signal detection by the at least one neutron detector.