Combined Photoneutron And X Ray Interrogation Of Containers For Nuclear Materials

Journal Article · Wed Jun 01 00:00:00 EDT 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3586190· OSTI ID:21513447

Gozani, Tsahi; Shaw, Timothy; King, Michael J; Stevenson, John; Elsalim, Mashal; Brown, Craig; Condron, Cathie ^[1]

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1. Rapiscan Laboratories, Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)

Effective cargo inspection systems for nuclear material detection require good penetration by the interrogating radiation, generation of a sufficient number of fissions, and strong and penetrating detection signatures. Inspection systems need also to be sensitive over a wide range of cargo types and densities encountered in daily commerce. Thus they need to be effective with highly hydrogenous cargo, where neutron attenuation is a major limitation, as well as with dense metallic cargo, where x-ray penetration is low. A system that interrogates cargo with both neutrons and x-rays can, in principle, achieve high performance over the widest range of cargos. Moreover, utilizing strong prompt-neutron ({approx}3 per fission) and delayed-gamma ray ({approx}7 per fission) signatures further strengthens the detection sensitivity across all cargo types. The complementary nature of x-rays and neutrons, used as both probing radiation and detection signatures, alleviates the need to employ exceedingly strong sources, which would otherwise be required to achieve adequate performance across all cargo types, if only one type of radiation probe were employed. A system based on the above principles, employing a commercially-available 9 MV linac was developed and designed. Neutrons are produced simultaneously with x-rays by the photonuclear interaction of the x-ray beam with a suitable converter. A total neutron yield on the order of 10{sup 11} n/s is achieved with an average electron beam current of 100 {mu}A. If fissionable material is present, fissions are produced both by the high-energy x-ray beam and by the photoneutrons. Photofission and neutron fission dominate in hydrogenous and metallic cargos, respectively. Neutron-capture gamma rays provide information on the cargo composition. The prompt neutrons resulting from fission are detected by two independent detector systems: by very efficient Differential Die Away Analysis (DDAA) detectors, and by direct detection of neutrons with energies higher than 3 MeV using a recently developed fluorine-based threshold activation detector (TAD). The delayed gamma-ray signals are measured with high efficiency with the same TAD and with additional lower-cost plastic scintillators.

• OSTI ID: 21513447
• Journal Information: AIP Conference Proceedings, Vol. 1336, Issue 1; Conference: CAARI 2010: 21. International Conference on the Application of Accelerators in Research and Industry, Fort Worth, TX (United States), 8-13 Aug 2010; Other Information: DOI: 10.1063/1.3586190; (c) 2011 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPES AND RADIATION SOURCES
ACTIVATION DETECTORS
CAPTURE
CARGO
CONTAINERS
DENSITY
ELECTRON BEAMS
FISSIONABLE MATERIALS
FLUORINE
GAMMA RADIATION
LINEAR ACCELERATORS
MEV RANGE 01-10
NEUTRON REACTIONS
PHOTOFISSION
PHOTONEUTRONS
PLASTIC SCINTILLATORS
POSITION SENSITIVE DETECTORS
PROMPT NEUTRONS
X RADIATION
ACCELERATORS
BARYON REACTIONS
BARYONS
BEAMS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
FERMIONS
FISSION
FISSION NEUTRONS
HADRON REACTIONS
HADRONS
HALOGENS
IONIZING RADIATIONS
LEPTON BEAMS
MATERIALS
MEASURING INSTRUMENTS
MEV RANGE
NEUTRON DETECTORS
NEUTRONS
NONMETALS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEONS
PARTICLE BEAMS
PHOSPHORS
PHOTONUCLEAR REACTIONS
PHOTONUCLEONS
PHYSICAL PROPERTIES
RADIATION DETECTORS
RADIATIONS