An automated fast neutron computed tomography instrument with on-line focusing for non-destructive evaluation

• Published in: Review of scientific instruments 2022-11, Vol.93 (11), p.113702-113702
• Main Authors: Bisbee, M. G., Oksuz, I., VanZile, M. P., Cherepy, N. J., Cao, L. R.
• Format: Article
• Language: English
• Subjects: Automation; Cameras; Charge coupled devices; Computed tomography; Control equipment; Fast neutrons; Graphical user interface; Image acquisition; Knife-edge; Lenses; Neutron flux; Neutrons; Nondestructive testing; Scintillation counters; Software; Spatial resolution; Thermal imaging; Thermal neutrons; Toluene; Tomography
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/5.0091032

A fast neutron tomography imaging instrument has been designed, built, and tested at The Ohio State University 500 kW Research Reactor on a fast neutron beamline with a peak neutron flux ≈5.4 × 107 n·cm−2·s−1 at 1.6 MeV median neutron energy. The instrument and beamline are also configurable for thermal neutron imaging. The imaging apparatus is composed of a lens coupled, water-cooled Electron Multiplying Charge Coupled Device camera, a front-surface mirror, and a high light yield plastic Polyvinyl toluene scintillator. The instrument sits on a mobile cart. A total of 5 motion-control stages are built into the system for XYZ and rotational degrees of freedom for sample positioning; the fifth stage fine tunes the focal distance between the camera and the scintillator to achieve on-line focusing. A Python code with a user-friendly graphical user interface controls the fully automated image acquisition, not requiring user interaction, yet facilitating tracking of the image acquisition. A complete fast neutron computed tomography dataset with 360 projections requires less than 3 h, with 30 s per projection. On-line focusing is accomplished with a commercial, off-the-shelf, dielectrically actuated liquid lens. Finally, tomographic reconstructions are visualized using the Livermore Tomography Tools software package. The effective pixel size (width and height) is ≈0.1058 mm, yielding a minimum voxel size of 0.1058 × 0.1058 × 0.1058 mm3, and produces a spatial resolution of 231 μm when calculated from knife-edge measurements.