Using a fast-neutron spectrometer system to candle luggage for hidden explosives

Harlan W. Lefevre; R. J. Rasmussen; Michael S. Chmelik; R. M. S. Schofield; G. E. Sieger; Jack C. Overley

doi:10.1117/12.267901

27 February 1997 Using a fast-neutron spectrometer system to candle luggage for hidden explosives

Harlan W. Lefevre, R. J. Rasmussen, Michael S. Chmelik, R. M. S. Schofield, G. E. Sieger, Jack C. Overley

Proceedings Volume 2867, International Conference Neutrons in Research and Industry; (1997) https://doi.org/10.1117/12.267901
Event: Fifth International Conference on Applications of Nuclear Techniques: Neutrons in Research and Industry, 1996, Crete, Greece

Abstract

A continuous spectrum of neutron switch energies up to 8.2 MeV is produced by a 4.2-MeV nanosecond-pulsed deuteron beam slowing down in a thick beryllium target. The spectrum form the locally shielded target is collimated to a horizontal fan-beam and delivered to a row of 16, 6-cm square plastic scintillators located 4 m from the neutron source. The scintillators are coupled to 12-stage photomultiplier tubes, constant-fraction discriminators, time-to-amplitude converters, analog-to-digital converters, and digital memories. Unattenuated neutron-source spectra and background spectra ar recorded. Luggage is stepped through the fan beam by an automated lift located 2 m from the neutron source. Transmission spectra are measured, and are transferred to a computer while the location is advanced one pixel width. As the next set of spectra is being measured, the computer calculates neutron attenuations for the previous set, deconvolutes attenuations into projected elemental number densities, and determines the explosive likelihood for each pixel. With a time-averaged deuteron beam current o 1(mu) A, a suitcase 60-cm long can be automatically imaged in 1600s. We will suggest that time can be reduced to 8s or less with straight-forward improvements. The following paper describes the explosives recognition algorithm and presents the results of teste with explosives.

Citation Download Citation

Harlan W. Lefevre, R. J. Rasmussen, Michael S. Chmelik, R. M. S. Schofield, G. E. Sieger, and Jack C. Overley "Using a fast-neutron spectrometer system to candle luggage for hidden explosives", Proc. SPIE 2867, International Conference Neutrons in Research and Industry, (27 February 1997); https://doi.org/10.1117/12.267901

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