# US 2012/0061580 A1 · Neutron detector having enhanced absorption and bifurcated detection elements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2012/0061580 A1 - Document ID: US20120061580A1 - Status: Published application - Kind: A1 - Application number: 12/880,505 - Filed: 2010-09-13 - Published: 2012-03-15 - Earliest claimed: 2010-09-13 - Assignees: PartTec, Ltd. - Inventors: Craig R. Kline; Herschel Ellis Workman - Web page: https://patentgrep.com/patent/US20120061580A1 ## CPC - G01T 3/06: with scintillation detectors - G01T 1/20: with scintillation detectors - G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00) ## Abstract A neutron detection system includes a neutron scintillator having a thickness greater than an optimal thickness and less than twice the optimal thickness. The system includes a first layer of wavelength shifting fiber optic elements positioned on a first side of the neutron scintillator. Adjacent fibers of the first layer pass light to distinct photo-multiplication devices. The system further includes a second layer of wavelength shifting fiber optic elements positioned on a second side of the neutron scintillator. Adjacent fibers of the second layer pass light to distinct photo-multiplication devices. The two layers may share photo-multiplication devices or use different sets of photo-multiplication devices. The system includes a controller that distinguishes a neutron radiation event from a gamma radiation event in response to electronic signals from the distinct photo-multiplication devices. ## Claims ### Claim 1 An apparatus, comprising: a neutron scintillator; a first wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator; a second wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator and further positioned parallel and in optical proximity to the first fiber optic element along at least a portion of the neutron scintillator; a first photo-multiplication device optically coupled to the first fiber optic element; a second photo-multiplication device optically coupled to the second fiber optic element; and a controller structured to: interpret a first electronic signal from the first photo-multiplication device; interpret a second electronic signal from the second photo-multiplication device; and distinguish a neutron radiation event from a gamma radiation event in response to the first electronic signal and the second electronic signal. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the second fiber optic element is positioned within three fiber diameters of the first fiber optic element on a first side of the neutron scintillator. ### Claim 3 (depends on 1, 2) The apparatus of claim 2 claim 1, further comprising: the neutron scintillator having a thickness between 0.5 and 1.0 mm, inclusive; a third wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator on a second side of the neutron scintillator; and a fourth wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator on the second side and further positioned parallel and in optical proximity to the third fiber optic element along at least a portion of the neutron scintillator. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the third fiber optic element and the fourth fiber optic element are optically coupled to distinct photo-multiplication devices, and wherein the controller is further structured to distinguish the neutron radiation event from the gamma radiation event in response to distinct electronic signals from the distinct photo-multiplication devices. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising: the neutron scintillator having a thickness between 1.0× and 2.0×, inclusive, wherein X comprises an optimal scintillator thickness; wherein the first and second fiber optic elements are positioned on a first side of the neutron scintillator; a third wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator on a second side of the neutron scintillator; and a fourth wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator and further positioned parallel to and in optical proximity to the third fiber optic element along at least a portion of the neutron scintillator. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the third fiber optic element and the fourth fiber optic element are optically coupled to distinct photo-multiplication devices, and wherein the controller is further structured to distinguish the neutron radiation event from the gamma radiation event in response to distinct electronic signals from the distinct photo-multiplication devices. ### Claim 7 (depends on 5) The apparatus of claim 5, wherein the optimal scintillator thickness comprises a thickness value between: a maximum thickness value comprising a thickness value providing a greatest neutron absorption value at a minimum photon emission quantity threshold; and a minimum thickness comprising a thickness value providing a greatest photon emission quantity at a minimum neutron absorption value threshold. ### Claim 8 A system, comprising: a neutron scintillator comprising a sheet of neutron absorptive material having a thickness greater than 1.0×, wherein × comprises an optimal scintillator thickness; a first layer of wavelength shifting fiber optic elements in optical proximity to the neutron scintillator on a first side of the neutron scintillator, wherein alternating fibers of the first layer are optically coupled to distinct photo-multiplication devices; a second layer of wavelength shifting fiber optic elements in optical proximity to the neutron scintillator on a second side of the neutron scintillator, wherein alternating fibers of the second layer are optically coupled to distinct photo-multiplication devices; and a controller structured to distinguish a neutron radiation event from a gamma radiation event in response to electronic signals from the distinct photo-multiplication devices. ### Claim 9 (depends on 8) The system of claim 8, wherein the neutron scintillator further comprises a thickness less than or equal to 2.0×. ### Claim 10 (depends on 8) The system of claim 8, wherein a first set of the alternating fibers from the first layer and a second set of the alternating fibers from the second layer are optically coupled to a first one of the distinct photo-multiplication devices, and wherein a third set of the alternating fibers from the first layer and a fourth set of the alternating fibers from the second layer are optically coupled to a second one of the distinct photo-multiplication devices. ### Claim 11 (depends on 10) The system of claim 10, wherein the controller is further structured to determine a radiation event as a neutron radiation event in response to a simultaneous signal response from each of the distinct photo-multiplication devices. ### Claim 12 (depends on 8) The system of claim 8, wherein each of the alternating fibers are mirrored at an end of each fiber, and wherein each of the distinct photo-multiplication devices are optically coupled to the alternating fibers at an opposite end of each fiber. ### Claim 13 (depends on 12) The system of claim 12, further comprising a neutron detector having a housing defining the neutron scintillator, the alternating fibers, the distinct photo-multiplication devices, and the controller, the housing further comprising a power input and a neutron reporting output. ### Claim 14 (depends on 13) The system of claim 13, wherein the neutron detector is a portable neutron detector weighing less than 35 kg (77 lbs.). ### Claim 15 (depends on 14) The system of claim 14, wherein the neutron scintillator comprises one of 6Li and 10B, and wherein the neutron scintillator has a thickness between 0.6 mm and 1.0 mm, inclusive. ### Claim 16 (depends on 14) The system of claim 14, wherein the neutron scintillator comprises one of 6Li and 10B, and wherein the neutron scintillator has a thickness greater than 0.6 mm. ### Claim 17 (depends on 14) The system of claim 14, wherein the neutron scintillator comprises 6LiF:ZnS/Ag, and wherein the neutron scintillator has a thickness between 0.6 mm and 1.0 mm, inclusive. ### Claim 18 (depends on 14) The system of claim 14, wherein the neutron scintillator comprises one of a P47 phosphor and (6LiF:Y2SiO5:Ce). ### Claim 19 (depends on 14) The system of claim 14, wherein the housing comprises a polyethylene moderator. ### Claim 20 (depends on 14) The system of claim 14 wherein each of the distinct photo-multiplication devices comprise a photomultiplier diode. ### Claim 21 (depends on 8) The system of claim 8, further comprising a cylindrical shield defining a moderator positioned in proximity to the neutron scintillator, the cylindrical shield having an open end and comprising a material that blocks neutrons from reaching the moderator except through the open end. ### Claim 22 (depends on 21) The system of claim 21, wherein the cylindrical shield comprises at least one neutron absorbing material selected from the neutron absorbing materials consisting of gadolinium, boron, and lithium. ### Claim 23 (depends on 21) The system of claim 21, further comprising the moderator formed as a cylinder disposed in the cylindrical shield, and wherein the neutron scintillator at least partially surrounds the moderator. ### Claim 24 (depends on 9) The system of claim 9, further comprising a second neutron scintillator comprising a sheet of neutron absorptive material having a thickness greater than 1.0× and less than or equal to 2.0×; a third layer of wavelength shifting fiber optic elements in optical proximity to the second neutron scintillator on a first side of the second neutron scintillator, wherein alternating fibers of the third layer are optically coupled to distinct photo-multiplication devices; and a fourth layer of wavelength shifting fiber optic elements in optical proximity to the second neutron scintillator on a second side of the second neutron scintillator, wherein alternating fibers of the fourth layer are optically coupled to distinct photo-multiplication devices. ### Claim 25 A method, comprising: providing a neutron detection platform comprising a neutron scintillator, a first wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator, a second wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator and further positioned parallel to and in optical proximity to the first fiber optic element along at least a portion of the neutron scintillator, a first photo-multiplication device that provides a first electronic signal and a second photo-multiplication device that provides a second electronic signal, the first photo-multiplication device optically coupled to the first fiber optic element and the second photo-multiplication device optically coupled to the second fiber optic element; interpreting the first electronic signal and the second electronic signal; and determining that a neutron radiation event has occurred in response to the first electronic signal and the second electronic signal simultaneously exceeding a first threshold amplitude deviation. ### Claim 26 (depends on 25) The method of claim 25, wherein the determining is further in response to the first electronic signal and the second electronic signal simultaneously exceeding the first threshold amplitude deviation for a second threshold amount of time. ### Claim 27 (depends on 26) The method of claim 26, wherein the second threshold amount of time comprises 100 nano-seconds. ### Claim 28 (depends on 26) The method of claim 26, wherein the second threshold amount of time comprises 200 nano-seconds. ### Claim 29 (depends on 26) The method of claim 26, wherein the second threshold amount of time comprises 550 nano-seconds. ### Claim 30 (depends on 25) The method of claim 25, wherein the first threshold amplitude deviation is at least 10 times a noise level amplitude deviation. ### Claim 31 (depends on 25) The method of claim 25, further comprising determining an optimal thickness for the neutron scintillator, wherein the providing further comprises providing the first and second fiber optic elements on a first side of the neutron scintillator, providing the neutron scintillator having a thickness greater than the optimal thickness and less than twice the optimal thickness, the method further comprising providing a third wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator on a second side of the neutron scintillator and a fourth wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator and further positioned parallel to and in optical proximity to the third fiber optic element along at least a portion of the neutron scintillator. ### Claim 32 An apparatus, comprising: a photo detection module structured to interpret a first electronic signal provided by a first photo-multiplication device optically coupled to a first wavelength shifting fiber optic element positioned in optical proximity to a neutron scintillator and to interpret a second electronic signal provided by a second photo-multiplication device optically coupled to a second wavelength shifting fiber optic element positioned in optical proximity to the neutron scintillator and further positioned parallel to and in optical proximity to the first fiber optic element along at least a portion of the neutron scintillator; a radiation discrimination module structured to determine that a neutron radiation event has occurred in response to the first electronic signal and the second electronic signal simultaneously exceeding a first threshold amplitude deviation; and a neutron notification module structured to provide a neutron indication signal to an output device in response to the determining that the neutron radiation event has occurred. ### Claim 33 (depends on 32) The apparatus of claim 32, wherein the radiation discrimination module is further structured to determine that a gamma radiation event has occurred in response to only one of the first electronic signal and the second electronic signal exceeding the first threshold amplitude deviation. ### Claim 34 (depends on 32) The apparatus of claim 32, wherein the radiation discrimination module is further structured to determine the neutron radiation event has occurred in response to the first electronic signal and the second electronic signal simultaneously exceeding the first threshold amplitude deviation for a second threshold amount of time. ### Claim 35 A neutron detection system, comprising: a neutron scintillator comprising at least one neutron absorption material; a plurality of wavelength shifting fiber optic elements positioned in optical proximity to the neutron scintillator, wherein adjacent fiber optic elements are optically coupled to distinct photo-multiplication devices; and means for distinguishing a neutron radiation event from a gamma radiation event. ### Claim 36 (depends on 35) The neutron detection system of claim 35, wherein the at least one neutron absorption material comprises a material selected from the materials consisting of 6Li, 10B, P47 phosphor, and (6LiF:Y2SiO5:Ce). ### Claim 37 (depends on 35) The neutron detection system of claim 35, wherein the plurality of wavelength shifting fiber optic elements comprise a first layer of wavelength shifting fiber optic in optical elements positioned in proximity to the neutron scintillator on a first side of the neutron scintillator, and a second layer of wavelength shifting fiber optic elements positioned in optical proximity to the neutron scintillator on a second side of the neutron scintillator. ### Claim 38 (depends on 35) The neutron detection system of claim 35, further comprising means for directional detection of the neutron radiation event. ### Claim 39 (depends on 35) The neutron detection system of claim 35, wherein the distinct photo-multiplication devices comprise photomultiplier diodes. ### Claim 40 (depends on 39) The neutron detection system of claim 39, wherein a ratio of wavelength shifting fiber optic elements to distinct photo-multiplication devices comprises 9:1. ### Claim 41 (depends on 39) The neutron detection system of claim 39, wherein a ratio of wavelength shifting fiber optic elements to distinct photo-multiplication devices comprises a value between 1:1 and 9:1, inclusive. ### Claim 42 (depends on 35) The neutron detection system of claim 35, wherein a ratio of wavelength shifting fiber optic elements to distinct photo-multiplication devices comprises a value between 2:1 and 40:1, inclusive. ### Claim 43 (depends on 35) The neutron detection system of claim 35, wherein a ratio of wavelength shifting fiber optic elements to distinct photo-multiplication devices comprises a value between 9:1 and 100:1, inclusive. ### Claim 44 (depends on 35) The neutron detection system of claim 35, further comprising a second neutron scintillator comprising at least one neutron absorption material; a second plurality of wavelength shifting fiber optic elements positioned in optical proximity to the second neutron scintillator, wherein adjacent fiber optic elements are optically coupled to distinct photo-multiplication devices; and wherein at least a portion of the first neutron scintillator and the second neutron scintillator comprise one of parallel planes and parallel curviplanar structures.