Forming images with thermal neutrons

Vanier, P. E.; Forman, L.

doi:10.1117/12.455693

Cited by 15 publications

(12 citation statements)

References 1 publication

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“…Coded aperture imaging of thermal neutron sources has previously been proposed for a number of applications, including warhead counting for treaty verification [1], detecting nuclear smuggling [2], explosives detection [3,4], monitoring stored spent nuclear fuel [5]. In earlier testing of our coded aperture camera, which uses a 2-dimensional He-3 positionsensitive wire chamber and a Cd mask, we used isotopic sources (such as 252 Cf or 241 Am-Be) which continuously emitted fast neutrons that were then thermalized in paraffin.…”

Section: Prior Workmentioning

confidence: 99%

Thermal neutron imaging in an active interrogation environment

Vanier¹

2009

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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 excitation 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.

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Section: Prior Workmentioning

confidence: 99%

Thermal neutron imaging in an active interrogation environment

Vanier¹

2009

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“…The panel focused on both wet and dry storage facilities. One of the suggestions made in the subsequent report [1] was to examine the idea of "fingerprinting" as a means to re-certify the contents of a cask in the event of C/S failure and also as a means of strengthening the C/S regime itself. The general concept relies on identifying cask properties that can be used to uniquely establish a cask ID and that the contents of that cask have not been significantly altered.…”

Section: Introductionmentioning

confidence: 99%

The Feasibility of Cask "Fingerprinting" as a Spent-Fuel, Dry-Storage Cask Safeguards Technique

Ziock¹,

Vanier²,

Forman³

et al. 2005

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This report documents a week-long measurement campaign conducted on six, dry-storage, spentnuclear-fuel storage casks at the Idaho National Laboratory. A gamma-ray imager, a thermalneutron imager and a germanium spectrometer were used to collect data on the casks. The campaign was conducted to examine the feasibility of using the cask radiation signatures as unique identifiers for individual casks as part of a safeguards regime. The results clearly show different morphologies for the various cask types although the signatures are deemed insufficient to uniquely identify individual casks of the same type. Based on results with the germanium spectrometer and differences between thermal neutron images and neutron-dose meters, this result is thought to be due to the limitations of the extant imagers used, rather than of the basic concept. Results indicate that measurements with improved imagers could contain significantly more information. Follow-on measurements with new imagers either currently available as laboratory prototypes or under development are recommended.ii

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“…Brookhaven National Laboratory (BNL) developed a coded aperture thermal neutron imaging device in the late nineties [3]. It consists of a 3 He-filled position sensitive wire chamber L. Forman is with Ion Focus Technology, Miller Place, NY 11764, USA, and a consultant to Brookhaven National Laboratory in a cadmium-lined enclosure.…”

Section: Introductionmentioning

confidence: 99%

“…The detector of the camera is a position-sensitive thermal neutron chamber. The new device is a 3 He-filled ionization chamber, which uses only anode and cathode planes. The anode is composed of an array of individual pads.…”

mentioning

confidence: 99%

A new pad-based neutron detector for stereo coded aperture thermal neutron imaging

Diószegi

Smith

et al. 2014

SPIE Proceedings

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Abstract-A new generation of coded aperture neutron imagers is being developed at Brookhaven National Laboratory. The detector of the camera is a position-sensitive thermal neutron chamber. The new device is a 3 He-filled ionization chamber, which uses only anode and cathode planes. The anode is composed of an array of individual pads. The charge is collected on each of the individual 5x5 mm 2 anode pads, (48x48 in total, corresponding to 24x24 cm 2 sensitive area) and read out by application specific integrated circuits. The new design has several advantages for the coded-aperture applications in the field, compared to the previous generation of wire-grid based neutron detectors. Among these are its rugged design, lighter weight and use of non-flammable stopping gas. The pad-based readout is event by event, thus capable for high count rates, and also to perform data analysis and imaging on an event-by-event basis. The spatial resolution of the detector can be better than the pixel size by using charge sharing between adjacent pads. In this paper we report on the development and performance of the new, prototype pad-based neutron camera, and present the first stereoscopic coded aperture images of thermalized neutron sources.

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Forming images with thermal neutrons

Cited by 15 publications

References 1 publication

Thermal neutron imaging in an active interrogation environment

Thermal neutron imaging in an active interrogation environment

The Feasibility of Cask "Fingerprinting" as a Spent-Fuel, Dry-Storage Cask Safeguards Technique

A new pad-based neutron detector for stereo coded aperture thermal neutron imaging

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