A Fast Neutron Radiography System Using a High Yield Portable DT Neutron Source

Abstract

Resolution measurements were made using 14.1 MeV neutrons from a high-yield, portable DT neutron generator and a neutron camera based on a scintillation screen viewed by a digital camera. Resolution measurements were made using a custom-built, plastic, USAF-1951 resolution chart, of dimensions 125 × 98 × 25.4 mm3, and by calculating the modulation transfer function from the edge-spread function from edges of plastic and steel objects. A portable neutron generator with a yield of 3 × 109 n/s (DT) and a spot size of 1.5 mm was used to irradiate the object with neutrons for 10 min. The neutron camera, based on a 6LiF/ZnS:Cu-doped polypropylene scintillation screen and digital camera was placed at a distance of 140 cm, and produced an image with a spatial resolution of 0.35 cycles per millimeter.

Tritium-titanium target degradation due to deuterium irradiation for DT neutron production

“…The validation of evaluated nuclear cross-section data, investigation of the effects of 14.1 MeV energy neutrons on the fusion reactor components, and tritium breeding capabilities of various breeding blankets require the 14.1 MeV neutron sources at laboratories [8,9]. These 14.1 MeV neutrons are also very useful in medical radioisotope production, fundamental nuclear physics experiments, fast neutron detector development, and neutron imaging tool developments [10][11][12]. Tritium-titanium targets are among such commercially available targets [13][14][15][16] that are used to produce the 14.1 MeV energy neutrons through the 2 H( 3 H,n) 4 He reaction at various laboratories [9,10,17,18].…”

Scalable Detector Design for a High-Resolution Fast-Neutron Radiography Panel

“…Williams et al [17], Bishnoi et al [18], and Wang et al [15] have developed neutron radiography systems using D-T neutron generators. Williams et al resolved an image at 2.85 line pairs per millimeter with a 2-mm-thick scintillator screen, a neutron flux of 4×10 7 n/s, and an exposure time between 4 and 5 hours [17]. Thin scintillator screens offer high spatial resolution, but require longer irradiation times due to the lower interaction efficiency.…”

“…Williams et al and Wang et al used lithium-doped zinc sulfide [17] and undoped zinc sulfide [15] as the scintillating material in their respective systems. Both of these scintillators rely on neutron absorption as the primary mode for generating light.…”

“…Systems that rely on this method will fundamentally require longer acquisition times for D-T neutrons compared to systems that use a scattering-based scintillator like plastic. Bishnoi et al, which used BC400 plastic, achieved an acquisition time on the order of minutes [18] compared to the hours needed in the other systems [17] [15]. It is well understood that using a scattering-based scintillator has a significant advantage when developing highly efficient fast-neutron imaging systems.…”

“…This research effort has developed a fast-neutron radiography system that can achieve spatial resolutions close to that of camera and mirror systems [17][18] [15] while still achieving the portability of larger pixelated block detector systems [19]. In addition to this, the system has been designed to be tileable so that the user has the ability to scale in detection area as large as desired.…”