Γ-ray Irradiation Research Articles

Physical design of photon-counting mode γ-ray large object radiation imaging system.

The detectors of existing large object radiation imaging systems generally work under current-integration mode and cannot distinguish effective signals of unreacted photons from interfering signals of electronic noise and scattered photons, therefore, resulting in image quality deterioration. This study aims to design a new photon-counting mode γ-ray large object radiation imaging system. Therefore, interfering signals with lower energy than effective signals can be eliminated by energy analysis. In addition, the system enables to work properly even under 30∼300Ci Co-60 intensity. Based on the physical analysis of the system, the design requirements are listed. Following the requirements, the best-performing photon-counting detector based on LYSO and SiPM is used in the system. ZP-SK and (ZP)2-SK filter circuits are designed for Co-60 radiation imaging system with the highest intensity of 100Ci and 300Ci, respectively. Then, a voltage comparator and an FPGA are followed to realize the function of energy analysis and photon counting. The proposed technical solution can improve the Steel Penetration (SP) by at least 60∼70 mmFe compared with the existing current-integration system, which is equivalent to the improvement obtained by increasing the intensity of the radioactive source more than 13 to 20 times. This study demonstrates the advantages of applying the new photon-counting mode γ-ray large object radiation imaging system to improve the radiation image quality and the penetration ability, which will have enormous potential for future applications.

4D printing of shape-changing structures based on IPN epoxy composites formed by UV post-curing and γ-ray radiation

The cross-linking degree is a significant factor affecting the thermodynamic properties of resins, the cross-linking degree of photosensitive resins is limited during Digital Light Procession (DLP) printing. We present a strategy for double networks in epoxy resin to further improve the performances of printed structures via two different processing methods. Epoxy acrylates and polyethylene glycol dimethacrylates crosslink by UV-light radiation forming a light-induced network structure, and epoxy molecules crosslink under γ-ray radiation forming a ray-induced network structure. The two kinds of networks interpenetrate to form the interpenetrating polymer network (IPN). The printed IPN specimens have the characteristics of high Young’s modulus (up to 4.89 GPa) and fracture strain (as high as 30.4 %). The printed flowers and canister reinforced by short glass fibers (GFs) exhibited rapid shape recovery behaviors. The IPN epoxy/GFs composites have good values in manufacturing smart deployable structures, medical devices, and automobile shell parts.

Detailed study of extended γ-ray morphology in the vicinity of the Coma cluster with Fermi Large Area Telescope

ABSTRACT Galaxy clusters can be sources of high-energy (HE) γ-ray radiation due to the efficient acceleration of particles exceeding EeV energies. At present, though, the only candidate for emitting HE γ-rays is the Coma cluster, towards which an excess of γ-ray emission has been detected by the Fermi Large Area Telescope (Fermi-LAT). Using ∼12.3 yr of Fermi-LAT data, we explored the region of the Coma cluster between energies 100 MeV and 1 TeV by detailed spectral and morphological analysis. In the region of the Coma cluster, we detected diffuse γ-ray emission of energies between 100 MeV and 1 TeV with a 5.4σ extension significance and a 68 per cent containment radius of $0.82^{+0.10}_{-0.05}$ degrees derived with a two-dimensional homogeneous disc model. The corresponding γ-ray spectrum extends up to ∼50 GeV, with a power-law index of Γ = 2.23 ± 0.11 and flux of $\mathrm{(3.84\pm 0.67)\times 10^{-12}\, erg\, cm^{-2}\, s^{-1}}$. Using energy arguments we show that point-like sources such as radiogalaxies and star-forming galaxies are unlikely to explain the emission, and more likely, the emission is produced in the Coma cluster. Besides, we also identified three point-like sources in the region. However, because of limited statistics, we could neither exclude nor confirm the contribution of three point-like sources to the total emissions.

Microstructure, luminescence and thermoluminescence of laser-sintered polycrystalline ceramic YAG:Ce scintillators

Y3Al5O12:Ce (YAG:Ce) polycrystalline ceramics with 0.1 and 0.3 mol% Ce substituting for Y were fabricated by laser sintering and characterized in their microstructure, luminescence, thermoluminescence and scintillation in comparison to a single crystal. The polycrystalline ceramics had cubic single crystallographic phase and relative densities of 97 ± 1 and 99 ± 1% for the 0.1 and 0.3 mol% Ce concentrations, respectively. The combined results of attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy and photoluminescence measurements showed the polycrystalline ceramics fabricated by laser sintering to contain a higher level of structural disorder than the single crystal. The consequent broadening of the luminescence bands caused enhanced self-absorption in the polycrystalline ceramics. Radioluminescence (RL) under X-ray excitation, optical transmission and photoluminescence measurements revealed the presence of numerous types of point defects, including F centers, F+ centers/perturbed F+ centers and YAl anti-sites. A detailed investigation of the thermoluminescence of YAG:Ce was executed using different methods and a complex behavior deviating from the first order kinetics mechanism was observed. The scintillation response of the polycrystalline ceramics was evaluated under low energy γ-ray irradiation.

γ-ray Radiation Hardness of CsPbBr3 Single Crystals and Single-Carrier Devices.

The superior environmental stability of all-inorganic metal halide perovskites compared to their organic-inorganic counterparts makes them more promising in practical applications. Here, the stability of an archetypical all-inorganic CsPbBr3 single crystal and its single-carrier devices under 60Co γ-ray irradiation was investigated. The CsPbBr3 single crystal itself shows ostensible hardness as its structural and optical properties present imperceptible changes even with a total ionizing dose of 800 krad. Unexpectedly, the single crystal-based single-carrier devices exhibit apparent dose-dependent hardness. The performance of the hole-only device suffers from more deterioration than the electron-only device under high irradiation doses (>400 krad). Our results reveal that such a discrepancy originates from the different influences of γ-ray irradiation-induced defects on the transport behaviors of holes and electrons in CsPbBr3 single-crystal devices. These findings offer a new understanding of the interaction mechanism between γ-photons and all-inorganic metal halide perovskite-based devices.

Irradiation-Induced Intestinal Injury is Associated With Disorders of Bile Acids Metabolism

Intestinal injury commonly occurs in radiation therapy, but its pathogenesis is not well understood. The relationship between irradiation-induced intestinal injury and bile acids (BAs) metabolism remains elusive. This study intends to clarify the role of BAs metabolism in irradiation-induced intestinal injury and the potential for supplementation with BAs to alleviate this injury. BAs metabolomic analysis of fecal pellets from normal and 12 Gy γ-ray total abdominal irradiation (TAI) treated mice was performed. The effects of a crude bile extract (BAmix) or lithocholic acid (LCA) on mice exposed to 12 Gy γ-ray TAI were determined by analyzing weight loss, colon length, villus length, crypt number, and the expression of leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and yes-associated protein 1 (YAP1). The effects of BAmix or LCA on intestinal organoids after 4 Gy irradiation were analyzed. ELISA assay was applied to test IL-1β, IL-6 and TNF-α levels in mouse intestine. The expression changes of G protein-coupled receptor 1 (TGR5) and YAP1 in the colonic mucosa of patients with radiation-induced intestinal injury were determined by IHC. The relative abundance of secondary BAs was decreased while the relative abundance of primary BAs was increased in irradiated mice, and LCA was the most obvious change. BAmix and LCA alleviated irradiation-induced intestinal injury in a mouse model, as reflected by reduced body weight loss, longer colon, higher villus, more crypts, and increased Lgr5 expression. In intestinal organoids, BAmix and LCA enhanced newborn crypts formation after irradiation. LCA treatment improved the expression of TGR5 and YAP1 in mouse intestinal crypts. LCA has potential to reduce the inflammation levels in irradiated mice. Additionally, the expression levels of TGR5 and YAP1 in the colonic mucosa of patients with radiation enteritis were also significantly decreased. Radiation-induced intestinal injury is associated with disorders of BAs metabolism, and treatment with LCA had a protective effect against radiation-induced intestinal injury in mice by modulating TGR5 and YAP1.

The CLYC-7 scintillator as a fast neutron spectrometer: Pulse-shape discrimination for different neutron-induced reaction channels

The CLYC-7 scintillators (Cs2LiYCl6) are being studied for their capability to detect and discriminate both γ-ray radiation and neutrons in a wide energy range. Different Pulse-Shape Analysis (PSA) techniques were developed to perform this distinction, with excellent results. An intrinsic problem resides in the neutron detection mechanism, which occurs mainly via two nuclear reactions on the chlorine nucleus: 35Cl(n,p)35S and 35Cl(n,α)32P. In the latter, the neutron energy reconstruction turns out to be more difficult, due to the large variety of excited states (and therefore reaction Q values) of 32P. A particular PSA algorithm was investigated to perform this α background rejection, with interesting results in different energy ranges.

Responses of hematopoietic cells after ionizing-irradiation in anemic adult medaka (Oryzias latipes)

Purpose Hematopoietic tissues of vertebrates are highly radiation sensitive and the effects of ionizing radiation on the hematopoiesis have been studied in mammals and teleosts for decades. In this study, radiation responses in the kidney, the main hematopoietic organ in teleosts, were investigated in Japanese medaka (Oryzias latipes), which has been a model animal and a large body of knowledge has been accumulated in radiation biology. Methods Kidney, the main hematopoietic tissue of adult medaka fish, was locally irradiated using proton and carbon ion beams irradiation system of Takasaki Ion Accelerator for Advanced Radiation Application (TIARA), QST, and the effects on peripheral blood cells and histology of the kidney were investigated. Results When only kidneys were locally irradiated with proton or carbon ion beam (15 Gy), the hematopoietic cells in the irradiated kidney and cell density in the peripheral blood decreased 7 days after the irradiation in the same manner as after the whole-body irradiation with γ-rays (15 Gy). These results demonstrate that direct irradiation of the hematopoietic cells in the kidney induced cell death and/or cell cycle arrest and stopped the supply of erythroid cells. Then, the cell density in the peripheral blood recovered to the control level within 4 days and 7 days after the γ-ray and proton beam irradiation (15 Gy), respectively, while the cell density in the peripheral blood did not recover after the carbon ion beam irradiation (15 Gy). The hematopoietic cells in the irradiated kidneys temporarily decreased and recovered to the control level within 21 days after the γ-ray or proton beam irradiation (15 Gy), while it did not recover after the carbon ion beam irradiation (15 Gy). In contrast, the recovery of the cell density in the peripheral blood delayed when anemic medaka were irradiated 1 day after the administration of phenylhydrazine. With and without γ-ray irradiation, a large number of hematopoietic cells was still proliferating in the kidney 7 days after the anemia induction. Conclusions The results obtained strongly suggest that the hematopoietic stem cells in medaka kidney prioritize to proliferate and increase peripheral blood cells to eliminate anemia, even when they are damaged by high-dose irradiation.

Effect of Interleukin-6 Gene Deletion on Radiation-Induced Mouse Hematopoietic Injury and Relative Mechanism

To study the effect of interleukin-6 (IL-6) gene deletion on radiation-induced hematopoietic injury in mice and relative mechanism. Before and after whole body 60Co γ-ray irradiation, it was analyzed and compared that the difference of peripheral hemogram, bone marrow hematopoietic stem and progenitor cells conts in IL-6 gene knockout (IL-6-/-) and wild-type (IL-6+/+) mice and serum IL-6 and G-CSF expression levels in above- mentioned mouse were detected. Moreover, 30 days survival rate of IL-6-/- and IL-6+/+ mice after 8.0 Gy γ-ray irradiation were analyzed. IL-6 levels in serum of IL-6+/+ and IL-6-/- mice were respectively (98.95±3.85) pg/ml and (18.36±5.61) pg/ml, which showed a significant statistical differences (P<0.001). There were no significant differences of peripheral blood cell counts and G-CSF level in serum between IL-6+/+ and IL-6-/- mice before irradiation (P>0.05). However, the number of leukocytes, neutrophils, lymphocytes, monocytes, platelets in peripheral blood and G-CSF level in serum of IL-6-/- mice were significantly decreased at 6 h after 8.0 Gy γ-ray irradiation compared with that of IL-6+/+ mice. On days 30 after 8.0 Gy γ-ray irradiation, the survival rate of IL-6+/+ and IL-6-/- mice was 62.5% and 12.5%, and the mean survival time of dead mice was 16.0±1.0 and 10.6±5.3 days, respectively. On days 14 after 6.5 Gy γ-ray irradiation, bone marrow nucleated cells in IL-6+/+ and IL-6-/- mice were respectively (10.0±1.2)×106 and (8.3±2.2)×106 per femur. Compared with IL-6+/+ mice, the proportion of Lin-Sca-1-c-kit+ (LK) in bone marrow of IL-6-/- mice had no significant change (P>0.05), but the proportion of Lin-Sca-1+c-kit+ (LSK) was significantly decreased (P<0.05). IL-6 plays an obvious role in regulating hematopoietic radiation injury, and IL-6 deficiency can inhibit the radiation-induced increase of endogenous G-CSF level in serum, aggravates the damage of mouse hematopoietic stem cells（HSC） and the reduction of mature blood cells in peripheral blood caused by ionizing irradiation, resulting in the shortening of the survival time and significant decrease of the survival rate of mice exposed to lethal dose radiation.

γ-Ray-sensitive motif-driven versatile epoxy thermoset: Highly efficient radiation degradation, intrinsic flame resistance and sustainable synthesis

With the growing awareness of energy consumption and environmental pollution, the development of γ-radiation-degradable technology derived from clean energy is of great concern. However, radiation-induced degradation for thermoset materials is limited because γ-radiation-induced radicals are prone to recombination rather than controlled cleavage. Herein, via introducing the radiation-sensitive groups, phenyl imine conjugated NN bonds, we synthesized a radiation-sensitive epoxy monomer from vanillin (a renewable source) and 4-hydroxybenzhydrazide. The thermoset was formed by crosslinking this bio-based epoxy monomer with our reported hardener bearing phenyl imine conjugated NN bonds. When treated by a stimulus of γ-ray radiation, the resulting epoxy thermoset with high contents of sensitive groups could be efficiently degraded at a dose of 10 kGy. Degradation of the thermosets are realized through the controlled cleavage of phenyl imine conjugated NN bonds. Benefiting from this stable conjugated structural design, the epoxy thermosets exhibit excellent mechanical performance and intrinsic flame resistance with a tensile strength over 70 MPa and a limited oxygen index (LOI) of 35.1 %, which are higher than those of traditional robust thermosets made from bisphenol A. This work not only renders a pioneering paradigm of bio-based γ-ray-degradable thermosets but also develops an effective approach to simplify the manufacturing process of fire-safe thermosets, which significantly enhance the versatility of polymer materials.

Highly efficient γ-ray generation by 10 PW-class lasers irradiating heavy-ion plasmas

10 PW-class lasers irradiating overcritical plasmas in the quantum electrodynamics regime promise to generate ultrabright γ-ray sources in the laboratory. Here using two-dimensional particle-in-cell simulations, we report highly efficient γ-ray generation in the parameter regime of 10 PW-class lasers at an intensity level of 1023 W cm– 2 interaction with heavy-ion plasmas which have large-scale preplasmas. The laser-to-γ-ray (>1 MeV) energy conversion efficiency reaches close to 60% with an above 1014 γ-photons/pulse. The average γ-photon energy is about 14 MeV with the highest photon energy exceeding 1 GeV. The high-energy γ-photons are mainly directed in the forward direction. We also find that plane target geometry is efficient enough for high power γ-ray radiation, which is beneficial for easing the difficulty of complex target manufacturing and alignment in experiments.

Association between exposures to radon and γ-ray radiation and histologic type of lung cancer in Eldorado uranium mining and milling workers from Canada.

BackgroundThe authors assessed the association between radon decay products (RDP) exposure and histologic types of incident lung cancer in a cohort of 16,752 (91.6% male) Eldorado uranium workers who were first employed from 1932 to 1980 and were followed through 1969–1999.MethodsSubstantially revised identifying information and RDP exposures were obtained on workers from the Port Radium and Beaverlodge uranium mines and from the Port Hope radium and uranium refinery and processing facility in Canada. Poisson regression was conducted using the National Research Council's Biological Effects of Ionizing Radiation (BEIR) VI–type models to estimate the risks of lung cancer by histologic type from RDP exposures and γ‐ray doses.ResultsLung cancer incidence was significantly higher in workers compared with the general Canadian male population. Radiation risks of lung cancer for all histologic types (n = 594; 34% squamous cell, 16% small cell, 17% adenocarcinoma) increased with increasing RDP exposure, with no indication of curvature in the dose response (excess relative risk per 100 working level months = 0.61; 95% confidence interval, 0.39–0.91). Radiation risks did not differ by histologic type (p = .144). The best‐fitting BEIR VI–type model included adjustments for the significant modifying effects of time since exposure, exposure rate, and attained age. The addition of γ‐ray doses to the model with RDP exposures improved the model fit, but the risk estimates remained unchanged.ConclusionsThe first analysis of radiation risks of lung cancer histologic types in the Eldorado cohort supported the use of BEIR VI–type models to predict the future risk of histologic types of lung cancer from past and current RDP exposures.Lay summary Lung cancer survival depends strongly on the cell type of lung cancer.The best survival rates are for patients who have the adenocarcinoma type.This study included 16,752 Eldorado uranium workers who were exposed to radon and γ‐ray radiation during 1932–1980, were alive in 1969, and were followed for the development of new lung cancer during 1969–1999.One third of all lung cancers were of the squamous cell type, whereas the adenocarcinoma and small cell types accounted for less than 20% each.Radiation risks of lung cancer among men increased significantly with increasing radon exposure for all cell types, with the highest risks estimated for small cell and squamous cell lung cancers.

Study on irradiation effect of insulating materials for fusion superconducting magnets -interlaminar shear strength at liquid helium temperature-

Insulating materials for superconducting magnets of fusion reactors are not only exposed to electromagnetic forces at cryogenic temperatures, but also to neutrons and γ-rays which are secondary radiation generated by nuclear fusion reactions. Hence, insulating materials are required to keep high radiation resistance, high mechanical strength and high insulation performance even at cryogenic temperatures. To evaluate the physical properties of insulating materials at cryogenic temperatures, most of the previous studies have been conducted in liquid nitrogen. However, it has been pointed out that the molecular motion freezing between liquid nitrogen temperature and liquid helium temperature may cause changes in mechanical properties. In this study, the experiments were conducted in liquid helium, which is closer to the actual environment of ITER, to evaluate the temperature dependence of irradiation effects. Interlaminar shear strength (ILSS) was measured at room temperature (RT), liquid nitrogen temperature (LNT), and liquid helium temperature (LHeT) after γ-ray irradiation of glass reinforced plastics (GFRP) made of epoxy resin. As a result, in the unirradiated samples, ILSS was maximum at LNT, whereas in the samples irradiated at 5 and 10 MGy, ILSS was maximum at LHeT. It was considered that the change in molecular structure caused by γ-ray irradiation led to stress relaxation phenomena even at LHeT in the irradiated samples.

The injuries of spleen and intestinal immune system induced by 2-Gy 60Co γ-ray whole-body irradiation

Purpose The aim of the present study was to investigate the injuries of spleen and intestinal immune system induced by 2 Gy 60Co γ ray in mice. Materials and methods A total of 120 Balb/c mice were randomly divided into two groups: blank control (Ctrl) and model (IR). The IR mice were exposed to a single dose of total body irradiation (2 Gy, dose rate: 1 Gy/min) and sacrificed on 1st, 3rd, 7th, 14th and 21st day after irradiation. The indicators including general observations and body weight, the changes in peripheral hemogram, spleen index, histopathology examination and lymphocyte subsets of spleen. As well as the count and subsets of lymphocyte in gut-associated lymphoid tissue. Results Compared with the Ctrl group, the body weight, spleen index, peripheral blood cell and splenocyte amounts, intraepithelial lymphocytes number decreased significantly after exposure, accompanied by a notable decreased count of lymphocytes in Peyer’s patch and mesenteric lymph nodes. Moreover, ionizing radiation also broke the balance of CD4+/CD8+ and increased the Treg proportion in spleen, which then triggered immune imbalance and immunosuppression. In general, the spleen injuries occurred on 1st day after exposure, worse on 3rd day, and were relieved on 7th day. The intestinal immune injuries were observed on 1st day, and attenuated on 3rd day. On 21st day after exposure, the spleen volume and index have returned to normal, except for the distribution of lymphocyte subpopulations. Furthermore, all indicators of gut-associated lymphoid tissue, except for mesenteric lymph nodes lymphocyte count, had returned to normal levels on 21st day. Conclusion In conclusion, our data showed the injuries of spleen and intestinal immune system induced by 2 Gy 60Co γ ray whole-body irradiation. These findings may provide the bases for further radiation protection in the immunity.

Integrity of the ECM Influences the Bone Regenerative Property of ECM/Dicalcium Phosphate Composite Scaffolds.

Due to the limitation of clinical autologous bone supply and other issues, the development of bone regeneration materials is still a hot topic. Natural tissue-derived bone repair materials have good biocompatibility and degradability, but their structure and properties are likely to be adversely affected during terminal sterilization. In this study, a composite scaffold consisting of the acellular extracellular matrix and dicalcium phosphate (ECM/DCP) was fabricated and terminally sterilized by γ-ray irradiation. In addition, the ECM/DCP scaffold was saturated with water and was also sterilized by γ-ray irradiation (RX-ECM/DCP). Results showed that the triple helix structure of collagen was better maintained in RX-ECM/DCP than in ECM/DCP. The thermal stability of RX-DCP/ECM was much better than that of ECP/ECM. The in vitro and in vivo performances of both types of scaffolds were also evaluated. The RX-ECM/DCP scaffold exhibited better in vitro bioactivity than that of the ECM/DCP scaffold as evidenced by more mineral formation in the simulated body fluid. In addition, RX-ECM/DCP also induced more effective bone regeneration than the ECM/DCP scaffold did in a rat calvarial defect model. Results sufficiently demonstrated that the addition of water to the scaffold could protect the structure of the ECM/DCP scaffold from being damaged by γ-ray irradiation during the terminal sterilization process. In summary, this study demonstrated a means to protect the ECM structure, which in turn led to the improvement of bone regenerative properties of the materials during γ-ray irradiation of ECM-based bone repair materials.

Preparation of Fe3O4-doped magnetic graphene aerogels via radiation method in ethanol-H2O solution

The γ-ray irradiation method has been successfully used to prepare Fe3O4-Doped Graphene Aerogels(GA-Fe3O4-ethanol) in Ethanol-H2O solution. Electron microscopy and X-ray powder diffraction (XRD) techniques show that the graphene oxide was successfully reduced and showed a porous structure while Fe3O4 Nanoparticles are stably loaded on graphene. The material showed good adsorption stability in the process of repeatedly absorbing the organic solvent. At the same time, in the process of adsorbing organic solvents, it was noticed that the material has a certain elasticity in the organic phase, which is rarely seen in many other aerogel materials.

Inhaled amifostine for the prevention of radiation-induced lung injury

ObjectiveTo alleviate radiation-induced lung injury and prevent the related pneumonitis and pulmonary fibrosis by inhaled amifostine (AMI). Methods15 ​Gy 60Co γ-ray irradiation was performed on the thoracic area of rats once to establish the radiation injury model. AMI was intraperitoneally (i.p.) injected or intratracheally (i.t.) administered to the rats 30 ​min pre-irradiation. The protective effects of the two AMI administration manners were compared in the aspects of hematopoietic system, lung edema, and histopathological examination, and the mechanisms were explored. ResultsCompared to i.p. AMI, i.t. AMI remarkably alleviated radiation-induced lung injury and prevented consequent pneumonitis or pulmonary fibrosis. Specifically, i.t. AMI notably protected white blood cells and platelets, reduced the lung wet/dry weight ratio, and decreased collagen volume fractions compared to the model group (P ​< ​0.05), while i.p. AMI showed no significant difference with the model group (P ​> ​0.05). The high therapeutic efficiency of i.t. AMI was related to its high antioxidation and anti-inflammation effects with downregulation of pro-inflammatory cytokines, the enhanced superoxide dismutase activity, the low levels of malondialdehyde and total proteins. ConclusionInhaled AMI is a promising medicine for preventing radiation-induced lung injury, including pneumonitis and pulmonary fibrosis.

Radiation-hardened silicon photonic passive devices on a 3 µm waveguide platform under gamma and proton irradiation.

Silicon photonics is considered to be an ideal solution as optical interconnect in radiation environments. Our previous study has demonstrated experimentally that radiation responses of device are related to waveguide size, and devices with thick top silicon waveguide layers are expected to be less sensitive to irradiation. Here, we design radiation-resistant arrayed waveguide gratings and Mach-Zehnder interferometers based on silicon-on-insulator with 3 µm-thick silicon optical waveguide platform. The devices are exposed to 60Co γ-ray irradiation up to 41 Mrad(Si) and 170-keV proton irradiation with total fluences from 1×1013 to 1×1016 p/cm2 to evaluate performance after irradiation. The results show that these devices can function well and have potential application in harsh radiation environments.

Study on Irradiation Effect of Insulating Materials for Fusion Superconducting Magnet: Effect of Low-temperature Irradiation

The purpose of this study is to investigate the change in dielectric performance in the direction of parallel to layers due to the difference in γ-ray irradiation temperature, irradiation atmosphere, and absorbed dose. γ-ray was irradiated using a 60Co source at room temperature, in liquid nitrogen, and in liquid nitrogen temperature gas atmosphere in the absorbed doses of 0, 5, and 10 MGy, respectively, and the dielectric breakdown tests were conducted at room temperature using a high-voltage breakdown tester. To investigate the mechanism of the change in dielectric strength, the density and electron spin resonance (ESR) measurements of the specimens were carried out. After irradiation at room temperature, the dielectric strength increased slightly with the increase in the absorbed dose. The reason for this may be that the molecular density increased due to the promotion of cross-linking reaction by recombination of molecules and reaction of unreacted epoxy groups by γ-ray irradiation. After irradiation in liquid nitrogen, the dielectric strength decreased significantly at 10 MGy, while after irradiation in liquid nitrogen temperature gas atmosphere, the dielectric strength slightly decreased with the increase in absorbed dose. These results suggest that, at low temperature, the freezing of molecular motion limits the movement of radicals generated by irradiation, and that the decomposition reaction is dominant against the crosslinking reaction.

H2 production from the radiolysis of aqueous suspensions of ZnO nanoparticles by 5.5 MeV He2+ ions

The effects of ion beam irradiation on aqueous suspensions of metal oxides has received relatively little attention compared to γ-ray irradiation despite being a highly prevalent process in spent nuclear fuel storage and reprocessing. This is partly due to the difficulties associated with homogeneously irradiating condensed-phase matter using α-particles. Here, we report experimental yields of H2 from the 5.5 MeV He2+ ion irradiation of aqueous suspensions of ZnO nanoparticles. The obtained results are compared to our previously measured results for the γ-radiolysis of the same system. The amount of H2 increases linearly with adsorbed dose for all studied concentrations. The measured yields are of the same order of magnitude as those observed for pure water, but decrease with increasing water content. Overall, the yields follow a similar trend to those observed for γ-ray radiolysis.