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The Practicality of Pulsed Fast Neutron Transmission Spectroscopy for Aviation Security (1999) / Chapter Skim
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2 Principle of Bulk Explosives Detection
Pages 9-12

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From page 9...
... Because x-rays interact primarily with electrons, the attenuation coefficient is strongly correlated with the electron density of the material under investigation (NRC, 1998~. The mechanisms primarily responsible for x-ray attenuation in materials at the x-ray energy ranges typically used by explosives-detection equipment are Compton scattering and photoelectric absorption.
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From page 10...
... Thus, the element identification depends on the broad energy-dependent structures in the cross sections, rather than on the narrow resonances. Because this method measures the energy-dependent neutron attenuation, it is critical that a broad energy neutron source be used.
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From page 11...
... PRINCIPLE OF BULK EXPLOSIVES DETECTION FIGURE 2-la Normalized nitrogen and oxygen distributions determined by PFNTS from the contents of suitcases, with and without explosives. Source: University of Oregon.
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From page 12...
... 12 PULSED FAST NEUTRON TRANSMISSION SPECTROSCOPY FOR AVIATION SECURITY 9 8 7 In ~ 6 m i_ .o 5 In In In o ct 2 o 0.5 ' ' Oxygen , j- , ', ,, , ~ ~ Carbon ~ :~ 1 1 1 1 "' 1 1 2.5 3 1 1.5 2 Energy (MeV) FIGURE 2-2 Total cross section of hydrogen, carbon, nitrogen, and oxygen as a function of energy.
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Key Terms

  • cross section
  • compton scattering
  • detection algorithm
  • inorganic materials
  • photoelectric effect

  • energy resolution
  • attenuation cross
  • organic materials
  • section caused
  • neutron spectrum

  • effective atomic
  • neutron attenuation
  • neutron source
  • five elements
  • physical density

  • geometrical information
  • neutron transmission
  • base set
  • imaging method
  • element identification

  • equipment suitable
  • specifically represented
  • energy dependence
  • temporal width
  • narrow peaks

  • provide discrimination
  • typical pfnts
  • time resolution
  • oregon refers
  • pulsed neutron


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