Neutron Imaging System Research Articles

A freely distributable professional computed tomography system using NICOS

Based on the control system of the ANTARES neutron imaging system at FRM II, we have designed a portable, but professional neutron computed tomography system using the same TANGO device servers and the instrument control system NICOS. We have created a minimalistic setup to control a computed tomography setup using a single control computer that directly connects to a camera detector and interfaces a Raspberry Pi computer with motor control board via a local network. The setup has the full capability of a large instrument controller and can control arbitrary hardware (like professional motor controllers) for which hundreds of free drivers are available. Full schematics for the controller as well as print files for 3D printers for the detector housing and disk or virtual machine images are available for free to allow for the quick implementation of a low-cost, but professional neutron CT system even at very low power research reactors.

Printed circuit heat exchangers and fast neutron radiography

AbstractNon-destructive testing is capable of detecting defects of important components, where a failure could pose a significant hazard and cause severe economic losses. Currently, imaging techniques utilizing gamma or X-ray sources are mainly used and allow to examine of devices ranging in size from units to tens of centimetres, but for industrial-sized large components, these methods usually fail. The utilization of fast neutrons in radiography is a promising alternative, especially for industrial applications. Currently, due to the higher neutron-matter interaction probabilities, most neutron-imaging systems use thermal neutrons originating from research reactors. Due to the intention of on-site inspection of revealing the possible ruptures and failures, this option is not applicable. The paper presents the newly developed neutronic models of printed circuit heat exchangers where the specific ruptures are defined. Next, neutron transport simulations are performed to investigate the different irradiation geometries, various neutron sources, and backfill materials to access the principal detectability of these ruptures in the industrial environment. Finally, conclusions are drawn, and the best backfill material and neutron source are identified in the simplified model.

In Situ Observation of the Decomposition Process of Woodchips in Subcritical- and Supercritical Water by Neutron Imaging

In situ observation of the decomposition process of woodchips (cedar and Quercus acutissima) in subcritical- and supercritical water was performed by neutron imaging experiment. The woodchips and D2O were sealed into a stainless tube, and the tube was heated up to 500 °C by a block heater designed for neutron imaging. The neutron imaging experiment was performed in energy-resolved neutron imaging system (RADEN) of Japan Proton Accelerator Research Complex Material and Life Science Experimental Facility (J-PARC MLF). The decomposition processes of the woodchips in D2O solvent were visualized clearly in time-lapse images. The outside of the woodchips was partially broken at 300 °C. The woodchips have a porous structure at 450 °C, and D2O penetrates the pores. The skeleton of the woodchips remains even at 500 °C. The present study clarified the optimal temperature in the decomposition process to observe the status of the woodchips during the decomposition process. It has an advantage compared with a time-consuming of the batch process. It will be useful for the development of biomass processing technology using high-temperature and high-pressure water.

Combination algorithms applied to source reconstruction for neutron coded images and restoration for incomplete coded images

The neutron emission of compressed capsules filled with fuels in inertial confinement fusion implosions can be measured by neutron imaging systems. Source reconstruction is an important method in coded-aperture imaging. In this paper, we use a combination algorithm to reconstruct the neutron source image. This method can improve the resolution and signal-noise ratio of the reconstructed image. In addition, the ray tracing method is used to obtain the point spread functions of the whole field of view (250 µm), and thus, the system response can be obtained. The edge gray interpolation method is used to restore the missing portion of incomplete coded images. The method can maintain a good performance when the missing-data angle is limited to less than 50°.

The multifunctional neutron imaging system at GPPD: Design, principles and applications

A multifunctional neutron imaging system (MNIS) has been built recently on the day-one instrument general purpose powder diffractometer (GPPD) at the China Spallation Neutron Source (CSNS). The sample position of MNIS is located three meters downstream of the diffraction sample position to maintain good imaging performance without changing the existing layout. MNIS can accommodate several significant neutron imaging technologies, including two-dimensional neutron radiation, three-dimensional computer tomography, neutron Talbot–Lau grating interferometer, and Bragg edge neutron imaging. The system has a largest field of view (FOV) of 6 × 6 cm2 and a best spatial resolution of 25μm by changing the magnification of the optical lens. The wavelength resolution is better than 0.2%. Additionally, MNIS serves as an initial validation for Energy-Resolved Neutron Imaging instrument (ERNI), a dedicated neutron imaging instrument currently under construction at CSNS.

Resolution enhancement of neutron radiography image using combined SRCNN-POCS method

In this work some post-acquisition image enhancement methods are applied to the case of under-sampled and low-resolution neutron radiography image. The digital neutron imaging system used in this study is a low resolved one; mainly based on an 8 bits CCD camera and a 250μm LiF-ZnS scintillator screen. In this paper, a software solution is proposed to improve the quality of digital neutron radiography images. The suggested method is a combination between the convolution neural network single-image and the projection onto convex sets multi-image super-resolution algorithms (SRCNN-POCS). The results obtained are compared to those by each algorithm separately. The proposed SRCNN-POCS method was found to be more reliable by producing higher quality image than the others tested methods in terms of modulation transfer function, peak-signal-to-noise ratio (PSNR), and structural similarity (SSIM). The visual analysis of the obtained image confirms too the obtained results.

Neutron imaging of inertial confinement fusion implosions.

We review experimental neutron imaging of inertial confinement fusion sources, including the neutron imaging systems that have been used in our measurements at the National Ignition Facility. These systems allow measurements with 10 µm resolution for fusion deuterium-deuterium and deuterium-tritium neutron sources with mean radius up to 400 µm, including measurements of neutrons scattered to lower energy in the remaining cold fuel. These measurements are critical for understanding the fusion burn volume and the three-dimensional effects that can reduce the neutron yields.

Development of a Dual-Modality Gamma-ray/Fast Neutron Imaging System for Air Cargo Inspection

High-energy radiation sources have provided a strong security inspection capability using a non-invasive imaging system. The use of multiple radiation sources in one imaging system can also lead to a more powerful system that can classify various materials compared to using a single radiation source. The Advanced Radiation Technology Institute of Korea Atomic Energy Research Institute has developed an air cargo inspection system using multiple radiation sources such as fast neutrons and gamma-rays to classify the plastics, metals, and organics among various sample materials. The fast neutron beam with an energy of 14.1 MeV, generated using the D-T neutron generator, and the gamma-ray beam with an energy of 6 MeV, generated by an electron linear accelerator, are projected onto the vertically aligned scintillator-based radiation detectors. The neutron and gamma-ray images of a cargo container moved by a motorized linear translation stage are acquired, and the image data processing shows good material classification results. In this paper, we describe a multi-radiation imaging system for air cargo inspection and investigate its material classification capability using various sample materials.

Simulation of a micron resolution capillary liquid scintillation detector for 14 MeV fusion neutrons

Aiming to improve the spatial resolution of a neutron imaging system (NIS) for 14 MeV fusion neutrons, an ideal micron resolution capillary detector filled with a high optical index liquid scintillator was simulated. A threshold for each capillary pixel and a threshold for each cluster were applied to suppress the gamma-induced background. In addition, by using a pattern recognition algorithm and an optimized Hough transform, the accuracy of determining the neutron impinging positions and the dynamic range of this detector were enhanced. For an ideal capillary array detector, the spatial resolution is expected as one capillary size of 20μm. The dynamic range of ∼1000 is reachable while the accuracy of neutron impinging position determination keeps better than 85%. The ionization quenching, light sharing and energy resolution of the detector were applied to the simulated data to understand the capillary array detector.

Fast phase differentiation between liquid–water and ice by pulsed neutron imaging with gated image intensifier

This paper reports on development of pulsed neutron imaging for phase differentiation between liquid–water and ice with introduction of a gated image intensifier. Automotive fuel cells must be operated in a variety of environments, including subzero start-up operations. The precise distribution of liquid–water and/or ice in the fuel cell is critical because gas obstruction by ice has a significant impact on power generation efficiency. While various probes such as electrons, visible light, infrared light, X-ray, and neutron have been used to observe the behavior of H2O in polymer electrolyte fuel cells (PEFCs) under subzero temperatures, neutron imaging is one of the most powerful methods to distinguish ice from liquid–water in the metal cells nondestructively. Previous neutron-imaging systems for phase differentiation between liquid–water and ice, on the other hand, had some issues with temporal resolution, horizontal distribution of neutron wavelength, and field-of-view size. By using energy-selected pulsed neutron imaging with an optical image intensifier, the authors have achieved liquid–water/ice phase identification with a shorter temporal resolution than before with 280 × 280 mm 2, which is roughly the size of commercial PEFCs, and 86 × 86 mm 2 fields of view. The horizontal distribution of neutron wavelength was also sufficiently suppressed.

Nanoscale Gd2O2S:Tb Scintillators for High-Resolution Fluorescent Imaging of Cold Neutrons

Cold neutron has a strong ability to penetrate metal materials and identify light elements, making it an ideal nondestructive testing technique for detecting cracks, bubbles, or other defects in metals. However, the low imaging resolution and detection efficiency of scintillators limit the application of cold neutron technology in imaging. The particle size and luminescence properties of scintillator materials have an important influence on the spatial resolution and detection efficiency of cold neutron radiography. Here, we report a series of NaF-doped Gd2O2S:Tb3+ (NaF-d-GOS:Tb) scintillators with adjustable particle size, which were prepared through a two-step method of solution precipitation followed by solid-phase vulcanization calcination. It was found that the NaF-d-GOS:Tb scintillators showed the highest quantum yield, reaching up to 62.94%. They were applied to fabricating cold neutron ultrathin screens. The resolution can reach 12 μm in the cold neutron imaging system. These NaF-d-GOS:Tb scintillators with excellent fluorescence facilitate the development of nondestructive testing techniques based on cold neutron imaging.

Design of the scintillator imaging lens for the neutron imaging system at the 100 kJ-level laser facility.

Deuterium-tritium neutron yield has reached up to about 1013 at the 100 kJ-level laser facility, which makes measurement of neutron emission images possible with the neutron imaging system. There are two methods to collect neutron images from the scintillator array, optical fiber taper and the lens system. Here, we report a design of the lens system for the neutron imaging system at the 100 kJ-level laser facility. The lens system, which consists of a nine-element collecting lens, with a spatial resolution of 20 µm and a light-collection efficiency of 5.9% has been designed.

The neutron imaging system for inertial confinement fusion at the 100 kilo-Joule laser facility

The neutron imaging system based on the penumbral aperture for the inertial confinement fusion research at the 100 kilo-Joule laser facility has been developed. The aperture has been designed with a geometric model and fabricated by machining one half double-tapered cylinder into each of two tungsten slabs. The aperture is mounted into a box which helps to precisely fix two slabs to form a biconic-shaped aperture. The neutron image recording system has been constructed with a capillary-array neutron image detector, and tested with the static accelerator neutron source. The spatial resolution of neutron image detector can be within 1.1 mm. The preliminary results of neutron imaging system in the exploding pusher target experiment at the 100 kilo-Joule laser facility have been presented.

Simultaneous neutron and gamma imaging system for real time range and dose monitoring in Hadron Therapy and nuclear security applications

GN-Vision is a novel dual γ-ray and neutron imaging system, which aims at imaging, simultaneously to the prompt gammas, the spatial origin of the slow and thermal neutron dose (<100 eV) generated during hadron therapy treatments. The proposed device can also be of interest for industrial applications as well as in nuclear security. The GN-Vision system has been designed following the technical developments of the iTED detector, an array of high efficiency Compton cameras intended for neutron-capture experiments, in which γ-ray energies span up to 5-6 MeV, similar to the energies encountered in hadron therapy. This manuscript presents the evolution of the i-TED detector towards the GN-Vision system and the first conceptual study of the simultaneous neutron and γ-ray imaging capability. Last, it reviews the status of the development and first results of the promising performance of this device for PG imaging in proton therapy, based on MC simulations.

Characterization of a collimated neutron imager for low-rate fast neutron imaging

Spatial localization of special nuclear materials (SNM) via their neutron signatures amidst background requires knowledge of the background neutron environment or a means of separating a source from background based on low amounts of information. This requirement has created the need for characterizing the spatial distribution of the cosmogenic neutron background. Neutron scatter cameras have been developed and optimized for rapid detection of high activity sources, but have low imaging efficiency, making it difficult to use them to characterize low rate diffuse sources, such as the neutron background. The Low Intensity Neutron Imaging System (LINIS) is a collimated neutron imager that has been designed and optimized for imaging diffuse cosmogenic neutron background in the energy range of 0.5−15 MeV. LINIS operates using 16 liquid scintillation detectors shielded by ultra-high molecular weight polyethylene cylindrical collimators in a staggered orientation and rotates to 7 discrete positions, giving it roughly 2π sensitivity. LINIS has been characterized using (α,n) and fission neutron sources using two imaging techniques for neutron source localization, simple backprojection and Maximum Likelihood Expectation Maximization.

Preface to the Special Issue on Signal Processing, Data Acquisition and Front-end Systems for Radiation Detection and Measurements

This special issue of the Journal of Signal Processing Systems focuses on advancement of signal processing and data-acquisition for radiation detection and measurements. The seven articles cover diverse topics within the scope of radiation detection ranging from understanding of fundamental fission process, instrumentation, and application of radiation interaction (e.g., tomography and imaging). The articles focus on signal processing for fission spectrometer, neutron and gamma-ray computed tomography and artificial intelligence methods, dynamic neutron imaging system, pulse-pileup correction in x-ray spectroscopy and calibration methods in radiation measurement.

Characterization and Implementation of A Dynamic Neutron Imaging System at the PULSTAR Reactor

Characterization and Implementation of A Dynamic Neutron Imaging System at the PULSTAR Reactor

TENIS — ThErmal Neutron Imaging System for use in BNCT

A thermal neutron flux measurement tool with two perpendicular sets of plastic scintillator arrays was designed and simulated (Ghal-Eh and Green, 2016) with the MCNPX code (Version 2.6.0, with ENDF/B-VII cross section library (ENDF, 2011)). The proposed system aimed to provide a thermal neutron map based on the detection of 2.22 MeV gamma-rays resulting from 1H(nth, γ)2D reactions. In the present work, using Monte Carlo code FLUKA and its scintillation light transport capability, several important upgrades were carried out to include the light transport modeling in the response of plastic scintillators, analyze the cross-talk phenomenon, optimize the system geometry, and also provide a new approach in thermal neutron image reconstruction. The results showed that the last two cases played a significant role in improving the longitudinal profile of thermal neutron flux.

Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Samples were examined using a superconducting (Nb) neutron imaging system employing a delay-line technique which in previous studies was shown to have high spatial resolution. We found excellent correspondence between neutron transmission and scanning electron microscope (SEM) images of Gd islands with sizes between 15 and 130 μm which were thermally-sprayed onto a Si substrate. Neutron transmission images could be used to identify tiny voids in a thermally-sprayed continuous Gd2O3 film on a Si substrate which could not be seen in SEM images. We also found that neutron transmission images revealed pattern formations, mosaic features and co-existing dendritic phases in Wood’s metal samples with constituent elements Bi, Pb, Sn and Cd. These results demonstrate the merits of the current-biased kinetic inductance detector (CB-KID) system for practical studies in materials science. Moreover, we found that operating the detector at a more optimal temperature (7.9 K) appreciably improved the effective detection efficiency when compared to previous studies conducted at 4 K. This is because the effective size of hot-spots in the superconducting meanderline planes increases with temperature, which makes particle detections more likely.

No-reference quality assessment for neutron radiographic image based on a deep bilinear convolutional neural network

Neutron imaging (NI) has been widely employed in non-destructive investigations. Since the image quality assessment (IQA) method can be beneficial in reflecting the performance of imaging systems and image processing algorithms, we propose a proof-of-concept IQA method for the NI system based on a deep bilinear convolutional neural network (CNN) framework with two designed datasets. Due to the lack of neutron IQA database, different levels of authentic distortion induced by NI are first simulated on the natural and neutron radiographic images to generate the pre-training and fine-tuning datasets, respectively. Then, the gradient magnitude similarity deviation (GMSD) algorithm and transfer learning method are respectively employed to label the above datasets and optimize the prediction performance. Experimental results demonstrate that the proposed method can maintain good consistency with human perception in predicting the quality scores of both the authentic and enhanced neutron radiographic images.