Patent Number: 047568666
Section: claims

1. Nitrogen concentration detection apparatus useful for the detection of nitrogen concentration in an article containing suspect nitrogen comprising: a source of x-ray energy exceeding 30.64 MeV, said x-rays causing the following reaction EQU .sup.14 N(gamma, 2n).sup.12 N  in nitrogen in said article but having insufficient energy to cause a significant reaction .sup.16 O(gamma, n.sup.3 H).sup.12 N, said significant reaction being that which would interfere with .sup.12 N production desired from interaction with .sup.14 N;  at least two gamma ray detectors aligned near the path of said generated x-ray for detecting the 511 keV annihilation gamma radiation produced by the reaction of .sup.14 N(gamma, 2n).sup.12 N; and  means for conveying said article proximate said x-ray source and said gamma ray detectors.  providing an x-ray source having x-rays exceeding 30.64 MeV in the range sufficient to cause a significant reaction EQU .sup.14 N(gamma, 2n).sup.12 N  but insufficient to cause a significant reaction  .sup.16 O(gamma, n.sup.3 H).sup.12 N, said significant reaction being that which would interfere with .sup.12 N production desired from interaction with .sup.14 N;  irradiating a suspect article to determine the presence of nitrogen with radiation sufficient to cause the reaction .sup.14 N(gamma, 2n).sup.12 N where gamma is x-radiation, and n is a neutron;  detecting delayed annihilation radiation from said .sup.14 N(gamma, 2n).sup.12 N in the range of 511 keV on opposite sides of said articles for simultaneous scintillation events; and  moving said article and beam relative to one another to quantitatively map said article in three dimensions, relative to its nitrogen content.  a high energy electron source having an output electron beam in the order of 35 MeV;  a target for said high energy electron source to produce x-radiation in the range exceeding 30.64 MeV;  deflection magnets adjacent said target for deflecting the electron beam of said microtron to cause said electron beam to scan;  a conveyer suitable to transport an article containing suspect nitrogen through the path of said electron beam scan; and  a stack of scintillation detectors for detecting the 511 keV annihilation gamma radiation produced by the reaction .sup.14 N(gamma, 2n).sup.12 N where:  gamma is x-radiation;  n is a neutron; and  .sup.14 N and .sup.12 N are isotopes of nitrogen.  a source of x-ray energy exceeding 30.64 MeV, said x-rays causing the following reaction EQU .sup.14 N(gamma, 2n).sup.12 N  in nitrogen in said article but having insufficient energy to cause a significant reaction .sup.16 O(gamma,n.sup.3 H).sup.12 N; said significant reaction being that which would interfere with .sup.12 N production derived from interaction with .sup.14 N  means for conveying along a conveyor path said article by said scanning x-ray beam; and,  means for scanning said source of x-rays across said article and said conveyor path;  first and second linear arrays of annihilation radiation detectors aligned parallel to the path of said generated x-rays for detecting the 511 keV annihilation gamma radiation produced by the reaction of N(gamma, 2n).sup.12 N, one array disposed on one side of a said conveyor path and the other array disposed on the opposite side of said conveyor path whereby a tomographic plot of the nitrogen in said articles can be made. 2. The apparatus of claim 1 and wherein the x-ray energy source has an energy level of less than 40 MeV. 3. The apparatus of claim 1 and including means for scanning said x-rays from said x-ray energy source. 4. The apparatus of claim 1 and including two linear arrays of gamma ray detectors aligned parallel to the path of said generated x-rays, one array disposed on one side of said article and the other detector disposed on the opposite side of said article to give a three-dimensional tomographic image of the nitrogen content of the article. 5. A method of scanning a series of conveyed articles for randomly placed nitrogen concentrations in the order of 20% to 30% by weight comprising the steps of: 6. The method of claim 5 and wherein said moving step includes conveying said article. 7. Method of claim 5 and wherein said mapping includes pulsating said x-radiation incident upon said article and examining said article for 11 milliseconds after each pulsation for said reaction. 8. Nitrogen concentration detection apparatus comprising in combination: 9. The apparatus of claim 8 and wherein said high energy electron source has an energy level less than 40 MeV. 10. The apparatus of claim 1 and wherein said source of x-rays is an electrom beam from a microtron or linear accelerator impacting a heavy element target. 11. The apparatus of claim 8 and including first and second stacks of solid state detectors on opposite sides of said conveyor. 12. Nitrogen concentration detection apparatus useful for the tomographic mapping of nitrogen concentrations in an article containing suspect nitrogen comprising: