skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thermal neutron imaging in an active interrogation environment

Abstract

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probingmore » with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
Doe/Office Of Nonproliferation & National Security
OSTI Identifier:
970434
Report Number(s):
BNL-90269-2009
R&D Project: 2011-BNL-NC001-BUDG; TRN: US1000782
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Technical Report
Resource Relation:
Related Information: Twentieth International Conference. AIP Conference
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 43 PARTICLE ACCELERATORS; ACCELERATORS; DELAYED NEUTRONS; DETECTION; EXCITATION; FAST NEUTRONS; FISSION; FISSION PRODUCTS; FISSIONABLE MATERIALS; HEAVY METALS; IONIZING RADIATIONS; NEUTRON FLUX; NEUTRONS; PHOTONS; SHAPE; TARGETS; THERMAL NEUTRONS; neutron; imaging; thermalization; helium-3; wire chamber; position-sensitive; coded aperture

Citation Formats

Vanier,P.E., and Forman, L., and Norman, D.R.. Thermal neutron imaging in an active interrogation environment. United States: N. p., 2009. Web. doi:10.2172/970434.
Copy to clipboard
Vanier,P.E., & Forman, L., and Norman, D.R.. Thermal neutron imaging in an active interrogation environment. United States. doi:10.2172/970434.
Copy to clipboard
Vanier,P.E., and Forman, L., and Norman, D.R.. Tue . "Thermal neutron imaging in an active interrogation environment". United States. doi:10.2172/970434. https://www.osti.gov/servlets/purl/970434.
Copy to clipboard
@article{osti_970434,
title = {Thermal neutron imaging in an active interrogation environment},
author = {Vanier,P.E. and Forman, L., and Norman, D.R.},
abstractNote = {We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.},
doi = {10.2172/970434},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 10 00:00:00 EDT 2009},
month = {Tue Mar 10 00:00:00 EDT 2009}
}
Copy to clipboard
Technical Report:
View Technical Report
DOI:  10.2172/970434
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

  • ; ; ; ...
    Gain an in-depth understanding of the role of quark flavor.

  • ; ; - AIP Conference Proceedings
    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutron-emitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons canmore » be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.« less

  • ; ;
    The portable active interrogation assay system for light water reactor fuel assemblies is described. Methods for its calibration and use are given and results of several tests are presented that indicate the results to be expected from the instrument.

  • ;
    The Nuclear Materials Identification System (NMIS) at Oak Ridge National Laboratory (ORNL), although primarily designed for analyzing special nuclear material, is capable of identifying nonradiological materials with a wide range of measurement techniques. This report demonstrates four different measurement methods, complementary to fast-neutron imaging, which can be used for material identification: DT transmission, DT scattering, californium transmission, and active time-tagged gamma spectroscopy. Each of the four techniques was used to evaluate how these methods can be used to identify four materials: aluminum, polyethylene, graphite, and G-10 epoxy. While such measurements have been performed individually in the past, in this project,more » all four measurements were performed on the same set of materials. The results of these measurements agree well with predicted results. In particular, the results of the active gamma spectroscopy measurements demonstrate the technique's applicability in a future version of NMIS which will incorporate passive and active gamma-ray spectroscopy. This system, designated as a fieldable NMIS (FNMIS), is under development by the US Department of Energy Office of Nuclear Verification.« less

  • ; ; ; ...
    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems bothmore » with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).« less