Method for obtaining information about a radiation source or a material interacting with a radiation source and a measurement setup for performing the method

• US 9,651,505 B2
• Filed: 06/23/2010
• Issued: 05/16/2017
• Est. Priority Date: 06/23/2010
• Status: Active Grant

• Current Assignee: Arktis Radiation Detectors Ltd.
• Original Assignee: Arktis Radiation Detectors Ltd.
• Inventors: Chandrasekharan, Rico, Davatz, Giovanna, Howard, Alexander
• Primary Examiner(s): Henson, Mischita
• Application Number:
  US13/806,150
• Publication Number:
  US 20130204578A1
• Time in Patent Office: 2,519 Days
• CPC Class Codes: G01N 23/06 and measuring the absorption
• CPC Class Codes: G01T 3/00 Measuring neutron radiation G01T5/00 takes precedence
• CPC Class Codes: G01V 5/20 Detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects
• CPC Class Codes: G06F 17/18 for evaluating statistical data , e.g. average values, frequency distributions, probability functions, regression analysis forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04

Abstract

A method for obtaining information about an unknown neutron source or an unknown material interacting with a known neutron source comprises the steps of: (a) providing a radiation detector capable of delivering a neutron energy information allowing the production of response histogram(s) as a function of neutron energy, (b) measuring with said radiation detector neutrons being emitted from said unknown neutron source or from said unknown material, (c) deriving from said measured neutrons a neutron energy spectrum, especially in form of a histogram, (d) normalizing said energy spectrum or histogram relative to a parameter or set of parameters derived from the measurement of a different variable, (e) comparing said normalized energy spectrum or histogram with known energy spectra or histograms, and (f) drawing conclusions on the basis of said comparison about the nature of the unknown neutron source or unknown material.

Claims

1. A method for obtaining information about a radiation source or a material interacting with radiation from a radiation source, said method comprising:

providing a detector capable of detecting both neutrons and electromagnetic radiation, the detector comprising separate outputs for a neutron energy spectrum of measured neutrons and for an intensity of electromagnetic radiation;

providing a normalization device comprising two separate inputs, a first input for the neutron energy spectrum and a second input for the electromagnetic radiation, and a single output for a normalized energy spectrum;

providing a database comprising a previously measured or simulated energy spectrum;

providing a comparing device with two separate inputs, a first input for the normalized energy spectrum and a second input of the energy spectrum from the database, and a single output for information obtained from comparing the normalized energy spectrum with the energy spectrum from the database;

measuring with the detector neutrons being emitted from the radiation source or from a material interacting with radiation from a radiation source;

deriving a neutron energy spectrum from the measured neutrons;

measuring an intensity of electromagnetic radiation within a predetermined energy range of the electromagnetic radiation;

deriving a parameter or a set of parameters used for normalization from the measurement of intensity of electromagnetic radiation, thereby introducing an energy dependence into the normalization;

normalizing the neutron energy spectrum relative to the parameter or set of parameters;

comparing the normalized energy spectrum with the previously measured or simulated energy spectrum from the database; and

outputting the information obtained from comparing the normalized energy spectrum with the energy spectrum from the database to an output device.

2. The method according to claim 1, wherein comparing the normalized energy spectrum with the previously measured or simulated energy spectrum from the database is performed automatically by the comparing device.

3. The method according to claim 1, wherein the electromagnetic radiation comprises one or more of gamma, infrared, visible, and UV radiation.

4. The method according to claim 1, wherein the detector is a radiation detector based on He-3, He-4, Ar-40, Xe-131 or an organic scintillation material.

5. The method according to claim 1, wherein said radiation source comprises a plurality of different radiation sources, and the information gained is used to reject or subtract one or more of said plurality of different radiation sources, to thereby achieve higher sensitivity for the remaining sources of radiation.

6. The method according to claim 1, wherein said radiation source or said material comprises a nuclear material.

7. The method according to claim 1, further comprising using the information obtained from comparing the normalized energy spectrum with the energy spectrum from the database for drawing conclusions about the nature of the radiation source or material.

8. The method according to claim 1, wherein normalizing the neutron energy spectrum relative to the parameter or set of parameters comprises using one or more of a spectral deconvolution, template matching, fitting and/or extrapolation to higher or lower energies based on a set of plausible assumptions.

9. The method according to claim 1, wherein the output information is used for diagnostic purposes in processes involving nuclear fission or fusion.

10. The method according to claim 3, wherein the parameter or set of parameters used for normalization is derived from at least one measurement of gamma radiation, and there is a gamma source independent of the radiation source.

11. The method according to claim 1, wherein the output information includes classifying the radiation source as being an industrial source, an alpha-n neutron source, a fission source, a cosmic source, an ambient source, or a specific isotope.

12. The method according to claim 1, wherein the radiation source emits coincident particles including neutrons, gammas or fission fragments from fission decays, and said coincident particles are measured to assess the Poissonian character of said neutron source.

13. The method according to claim 1, wherein said material is placed between the radiation source and the radiation detector, such that the material moderates the neutron radiation.

14. The method according to claim 1, wherein said material scatters radiation from the radiation source into the radiation detector.

15. The method according to claim 1, wherein a gamma and neutron radiation source as well as gamma and neutron detectors are used, and the information from the detectors is used to gain information regarding an object between the source and the detector or in a position where radiation from the source passes through the object prior to arriving at the detector, and the output information is based on comparing a ratio of detected neutron to detected gamma radiation as a function of energy.

16. A measurement setup for performing the method according to claim 1, comprising:

the detector for detecting both neutrons and electromagnetic radiation, the detector comprising separate outputs for a neutron energy spectrum of the measured neutrons and for an intensity of electromagnetic radiation, the detector being capable of detecting both fast neutron radiation and gamma radiation;

the normalization device for normalizing the neutron energy spectrum by means of the gamma count rate or total count rate as the sum of gamma count rate and other count rates delivered by the detector, the normalization device comprising two separate inputs, a first input for the neutron energy spectrum and a second input for the electromagnetic radiation and a single output for a normalized energy spectrum; and

the comparing device for comparing the normalized neutron energy spectrum with the previously measured or simulated energy spectrum from the database, the comparing device comprising two separate inputs, a first input for the normalized energy spectrum and a second input of the energy spectrum from the database, and a single output for information obtained from comparing the normalized energy spectrum with the energy spectrum from the database.

17. The measurement setup according to claim 16, wherein the detector uses the scintillation of a noble gas as a detecting means.

18. The measurement setup according to claim 16, wherein the database is connected to the comparing device.

19. The method according to claim 7, wherein drawing conclusions about the nature of the radiation source or material is based, at least in part, on information in a form of timing or directional information.