Radiation Resistance Research Articles

Irradiation multi-scale damage and interface effects of 3D braided carbon fiber/epoxy composites subjected to high dose γ-rays

The serious damage caused to 3D braided carbon fiber (CF)/epoxy (EP) composites in high-energy irradiation environments is a pressing research topic that has not yet been reported. This study analyzed the γ-irradiation multi-scale damage of the matrix, interfaces, and near-interface regions in 3D braided CF/EP composites with three different braiding angles (18°, 28°, 38°) at atomic, microscopic, and macroscopic scales. The molecular structure and atomic charge information alterations of epoxy matrix were characterized using soft X-ray absorption spectroscopy (sXAS). When the irradiation dose reached 1000 KGy, the compressive strength of composites decreased by 20.88 %, 18.07 %, and 16.60 %, respectively, with an increase in the braiding angle. Micro-CT observation, along with statistical computing, confirmed that irradiation causes interface damage and increases the defect volume of 3D braided composites. Nanoindentation was used to compare the modulus of carbon fiber, interface, near-interface regions and matrix in irradiated composites and the function of CF/resin interface as an irradiation defect capture site in the irradiation resistance of resin-matrix composites has been newly established. In addition, the mechanism behind the effect of braiding angle on macroscopic properties was also analyzed.

Harnessing ferroic ordering in thin film devices for analog memory and neuromorphic computing applications down to deep cryogenic temperatures

The future computing beyond von Neumann era relies heavily on emerging devices that can extensively harness material and device physics to bring novel functionalities and can perform power-efficient and real time computing for artificial intelligence (AI) tasks. Additionally, brain-like computing demands large scale integration of synapses and neurons in practical circuits that requires the nanotechnology to support this hardware development, and all these should come at an affordable process complexity and cost to bring the solutions close to market rather soon. For bringing AI closer to quantum computing and space technologies, additional requirements are operation at cryogenic temperatures and radiation hardening. Considering all these requirements, nanoelectronic devices utilizing ferroic ordering has emerged as one promising alternative. The current review discusses the basic architectures of spintronic and ferroelectric devices for their integration in neuromorphic and analog memory applications, ferromagnetic and ferroelectric domain structures and control of their dynamics for reliable multibit memory operation, synaptic and neuronal leaky-integrate-and-fire (LIF) functions, concluding with their large-scale integration possibilities, challenges and future research directions.

Carbon-Isovalent Dopant Pairs in Silicon: A Density Functional Theory Study

Carbon (C) is an important isovalent impurity in silicon (Si) that is inadvertently added in the lattice during growth. Germanium (Ge), tin (Sn), and lead (Pb) are isovalent atoms that are added in Si to improve its radiation hardness, which is important for microelectronics in space or radiation environments and near reactors or medical devices. In this work, we have employed density functional theory (DFT) calculations to study the structure and energetics of carbon substitutional-isovalent dopant substitutional CsDs (i.e., CsGes, CsSns and CsPbs) and carbon interstitial-isovalent dopant substitutional CiDs (i.e., CiGes, CiSns and CiPbs) defect pairs in Si. All these defect pairs are predicted to be bound with the larger isovalent atoms, forming stronger pairs with the carbon atoms. It is calculated that the larger the dopant, the more stable the defect pair, whereas the CsDs defects are more bound than the CiDs defects.

Effects of long-term storage on properties of perovskite solar cells

The Japan Aerospace Exploration Agency (JAXA) is planning a Space photovoltaics Demonstration eXperiment (SDX) to reveal the tolerance to the space environment of the next-generation solar cells. One of the next-generation solar cells mounted on SDX is a perovskite solar cell (PSC), which is cost-effective and has the potential for high specific power and radiation tolerance. It is necessary to clarify the long-term stability to analyze the characteristics of PSCs in orbit because SDX will be stored for months before and after launch. Therefore, we conducted three storage tests (in air, nitrogen, and low pressure) using encapsulated PSCs. Their performance was evaluated by Light I–V, Dark I–V, and EQE measurements. As a result, almost no degradation was observed at EOL (after 400 days) under all storage conditions. We found that the encapsulated PSCs mounted on SDX are highly stable. We also found that the slight degradation of Pmax within 4 % was due to an increase in series resistance.

Effect of acid-treatment on the activated carbon of Ru/AC catalysts for catalytic decomposition of hydroxylamine nitrate and hydrazine nitrate

Two types of 5 %wt Ru/AC catalysts were prepared using carbon carriers treated with 5 mol L−1 HNO3 and 5 mol L−1 HCl by the impregnation method, respectively. The catalysts were characterized by N2 physical adsorption, XRD, XPS, SEM, TEM and ICP-AES. The catalytic activity and stability of the catalysts for the decomposition of hydroxylamine nitrate (HAN) and hydrazine nitrate (HN) was evaluated. The results demonstrated that both catalysts exhibited complete decomposition of HAN and HN under moderate reaction conditions (70–90 ℃), displaying similar activities. And the catalysts treated with hydrochloric acid exhibited better stability and can be reused 128 cycles. Furthermore, the experimental results on various parameters indicate that an increase in temperature and nitric acid concentration leads to a reduction in reaction time. The catalytic performance of Ru/AC catalyst remains unchanged after 20 cycles under radioactive conditions, exhibiting exceptional radiation resistance.

Anomalous exchange bias behavior of NiFe/NiO bilayers induced by high-energy Xe+ ion irradiation

The alteration of the microstructure and magnetic performance of an exchange bias system, induced by ion irradiation, adversely affects the practical application of spintronic/storage devices in extreme environments. Here, we report systematically the correlation between static and dynamic magnetism and microstructure changes in NiFe/NiO exchange-biased bilayers after high-energy Xe+ ion irradiation. The effect of cascade collision induced by irradiation on exchange bias is studied through Monte Carlo simulations. It is distinguished from the traditional modification caused by keV-level ion irradiation. At low doses, the transition from amorphous to recrystallization occurs in the NiFe layer and the anomalous exchange bias behavior is induced. A step-like structure appears in the magnetic hysteresis loop and the step gradually shifts downward as the dose increases. At high doses, the exchange bias effect is suppressed due to the disordered antiferromagnetic moment caused by heat accumulation during cascade collision, which significantly decreases the thermal stability of the sample by 5–6 times. In addition, the non-monotonic evolution of high-frequency magnetic properties is observed with increasing irradiation doses. This work provides important foundational data for designing future spintronic/memory devices to enhance radiation tolerance and stability.

Revealing the critical role of vanadium in radiation damage of tungsten-based alloys

Refractory tungsten-based medium- and high-entropy alloys form a promising class of strong, heat- and radiation-resistant materials for nuclear applications. Here, we systematically explore the radiation tolerance of Mo–Nb–Ta–V–W alloys using molecular dynamics simulations and a machine-learned interatomic potential. Going from pure W to W-based equiatomic binaries, ternaries, quaternary, and the quinary high-entropy alloy, we simulate the radiation damage accumulation up to 0.4–0.8 dpa through cumulative collision cascades. We find that the radiation damage and evolution are controlled by a combination of cascade-induced clustering, the balance in migration of vacancies and interstitials, and defect cluster binding energies. These mechanisms are strongly influenced by atom size, among which vanadium as the smallest atom is decisive. In pure W and alloys without V, the microstructure is characterised by large and growing interstitial dislocation loops. In stark contrast, in alloys containing V, vacancy dislocation loops are formed directly in collision cascades and the balanced migration rate of vacancies and interstitials promotes recombination and prevents growth of interstitial loops. The atom size differences also lead to clear segregation, with small atoms (V) in interstitial clusters and larger atoms (Ta, Nb) segregating around vacancy clusters. Furthermore, the small cluster sizes, formation of vacancy loops, segregation, and balanced migration in V-containing alloys lead to low swelling and an exceptionally efficient defect annealing compared to pure W and V-free alloys. Our results highlight WTaV as a promising low-activation material, where almost 90% of defects are annealed at 2000 K during 5 ns compared to <20% in pure W.

Long-Range Influence of Cr on the Stacking Fault Energy of Cr-Containing Concentrated Solid-Solution Alloys

Single-phase concentrated solid-solution alloys (CSAs) have exhibited excellent mechanical and radiation tolerance properties, making them potential candidate materials for nuclear applications. These excellent properties are closely related to dislocation movements, which depend on the stacking fault energies (SFEs). In CSAs, SFEs show large fluctuations due to variations in the local atomic environments in the vicinity of the stacking faults. In this work, first-principle calculations were performed to investigate the origin of the fluctuations in the SFEs of the widely studied CSA, NiCoCr, which show a very wide distribution from about −200 mJ/m2 to 60 mJ/m2. Compared to the common understanding that only atoms in close proximity to the stacking fault influence the SFEs in pure metals and dilute alloys, charge redistribution can be observed in several nearby planes of the stacking fault in NiCoCr, indicating that atoms several atomic layers away from stacking fault also contribute to the SFEs. Our analysis shows that Cr plays a major role in the large fluctuation in the SFEs of NiCoCr based on both electronic and magnetic responses. The flexible electronic structure of Cr facilitates easier charge transfer with Cr in several nearby atomic planes near the stacking fault, leading to significant changes in the d-electron number, orbital occupation number, and magnetic moments of Cr.

Tardigrades: A Glimpse into the Molecular Shields Against Radiation

Tardigrades, often colloquially known as water bears, are microscopic extremophiles renowned for their extraordinary ability to withstand harsh environmental conditions, including extreme radiation. This editorial synthesizes recent research examining the mechanisms underlying tardigrades' radiation resistance, which not only enhances our understanding of biological survival extremes but also paves the way for innovative advancements in radioprotection applicable in medical sciences, space exploration, and synthetic biology.

Increasing the radiation-induced cytotoxicity by silver nanoparticles and docetaxel in prostate cancer cells.

Radiation therapy is utilized for treatment of localized prostate cancer. Nevertheless, cancerous cells frequently develop radiation resistance. While higher radiation doses have not always been effective, radiosensitizers have been extensively studied for their ability to enhance the cytotoxic effects of radiation.So, this study aims to evaluate the possible radiosensitization effects of docetaxel (DTX) and silver nanoparticles (SNP) in LNCaP cells. The cytotoxic effects of DTX, SNP and2Gy of X-Ray radiation treatments were assessed in human LNCaP cell line using the MTT test after 24 h. Moreover, the effects of DTX, SNP and radiation on Epidermal growth factor (EGF), Caspase 3, inducible nitric oxide synthase and E-cadherin gene expression were analyzed using the Real-time PCR method. The level of Hydrogen peroxide (H2O2), an oxidative stress marker, was also detected 24h after various single and combined treatments. The combinations of SNP (in low toxic concentration) and/or DTX (0.25× IC50 and 0.5 × IC50 concentrations for triple and double combinations respectively) with radiation induced significant cytotoxicity in LNCaP cells in comparison to monotherapies. These cytotoxic effects were associated with the downregulation of EGF mRNA. Additionally, H2O2 levels increased after Radiation + SNP + DTX triple combination and double combinations including Radiation + SNP and Radiation + DTX versus single treatments. The triple combination treatment also increased Caspase 3 and and E-cadherin mRNA levels in compared to single treatments in LNCaP cells. Our results indicate that the combination of SNP and DTX with radiation induces significant anti-cancer effects. Upregulation of Caspase 3 and E-cadherin gene expression, and decreased mRNA expression level of EGF may be exerted specifically by use of this combination versus single treatments.

Effect of H+ pre-irradiation on irradiation hardening and microstructure evolution of FeCoCrNiAl0.3 alloy with He2+ irradiation

FeCoCrNiAlx-based high entropy alloys (HEAs) exhibit excellent high-temperature strength, good radiation tolerance and corrosion resistance. However, studies on light-ion irradiation damage are relatively lacking. The influence of hydrogen and helium effect on HEAs deserves further study, given their complex interaction during different sequence irradiation at different irradiation conditions. In the present study, FeCoCrNiAl0.3 HEA was irradiated under two different modes at 723 K, one is single He2+ and the other is pre-iradiation of H+ followed by He2+. Microstructure evolution and irradiation hardening were studied by transmission electron microscopy and nanoindentation technique. There is no distinct difference of the irradiation hardening rate between sequential H+-He2+ and single He2+ irradiated samples. A large number of irradiation-induced nano-defects were observed after pre-irradiation of H+, which act as sinks to trap the subsequent helium atoms in the H+-He2+ irradiated sample. Fine helium bubbles and dislocation loops with high density dispersed in both irradiated samples. Compared with single He2+ irradiation, pre-irradiation of H+ resulted in a decrease in bubble density and an increase in loop density in H+-He2+ irradiated sample, but had little effect on their size. It is speculated that the critical concentration of bubble formation originating from H-He-V clusters is supposed to be higher than that of HeV clusters at elevated temperatures in FeCoCrNiAl0.3 alloy, leading to the aggregation and redistribution of He atoms at the H-He-V clusters rather than the formation of stable bubble nucleus after succeeding He2+ irradiation. The influence of pre-irradiation of H+ on FeCoCrNiAl0.3 alloy on the formation of helium bubbles and the relationship between bubble, loop and irradiation hardening are discussed.

Vibrational spectroscopic detection of radiation-induced structural changes in Chironomus hemoglobin

PurposeChironomus hemoglobin is known to exhibit higher gamma radiation resistance compared to human hemoglobin. In the present study, we have introduced a sensitive method to analyze radiation-induced alterations in Chironomus hemoglobin using Vibrational spectroscopy and further highlighting its potential for monitoring radiotoxicity in aquatic environments. Materials and methodsVibrational spectroscopic methods such as Raman and FT-IR spectroscopy were used to capture the distinctive chemical signature of Chironomus hemoglobin (ChHb) under both in vitro and in vivo conditions. Any radiation dose-dependent shifts could be analyzed Human hemoglobin (HuHb) as standard reference. ResultsDistinctive Raman peak detected at 930 cm-1 in (ChHb) was attributed to C–N stretching in the heterocyclic ring surrounding the iron atom, preventing heme degradation even after exposure to 2400 Gy dose. In contrast, for (HuHb), the transition from deoxy-hemoglobin to met-hemoglobin at 1210 cm-1 indicated a disruption in oxygen binding after exposure to 1200 Gy dose. Furthermore, while ChHb exhibited a consistent peak at 1652 cm-1 in FT-IR analysis, HuHb on the other hand, suffered damage after gamma irradiation. ConclusionThe findings suggest that vibrational spectroscopic methods hold significant potential as a sensitive tool for detecting radiation-induced molecular alterations and damages. Chironomus hemoglobin, with its robust interaction of the pyrrole ring with Fe, serves as a reliable bioindicator molecule to detect radiation damage using vibrational spectroscopic method.

Quantum dots may improve space laser communications by tolerating harsh radiation conditions

Bolstering semiconductor laser diodes’ radiation hardness can facilitate their application in harsh environments like space or nuclear power plants.

Current relation between Durante-Conheim theory and radiation resistance. Commentary on “Embryonic stem cell-like subpopulations are present within Schwannoma”

Current relation between Durante-Conheim theory and radiation resistance. Commentary on “Embryonic stem cell-like subpopulations are present within Schwannoma”

A new cold cooling system using krypton for the future upgrade of the LHC after the long shutdown 4 (LS4)

Future silicon detectors for High Energy Physics Experiments will require operation at lower temperatures to cope with radiation damage of the sensors and consequent increase of the dark current, beyond the limit of the current CO2 evaporative cooling system. This, together with many other requirements such as mass minimization and high radiation hardness, pushes the need of a new advanced cooling technology. The new coolant shall be able to approach ultra-low temperatures below −60 °C, withstand high radiation levels while having cooling lines diameters comparable to the currently achieved with the CO2 technology. Among different natural working fluids, krypton appears as a promising coolant for the thermal management of future detectors in high-irradiated environments. The thermodynamic properties of krypton do not allow the use of a pumped loop cycle but rather impose a need of a novel cooling technology. A new ejector-supported krypton cycle is presented, highlighting the cycle dynamics involved due to the different temperature levels normally encountered during the detector lifetime.

Spatially-resolved cluster dynamics modeling of irradiation growth

We develop here a spatially resolved, three-dimensional continuum model coupling cluster dynamics (SR-CD) and crystal plasticity to investigate irradiation growth in zirconium. The model uses scale separation to divide the population of the irradiation cluster into mobile and immobile families. Small interstitial and vacancy clusters are modeled using anisotropic reaction–diffusion equations. Among the immobile clusters, an atomistically-informed vacancy cluster to vacancy loop transition is taken into account. The coupling between the evolution equation of CD and the plastic deformation of the material is two-fold, with stress-informed bias factors and local inelastic strains computed from the evolution of the evolving cluster population. The numerical implementation of the model utilizes the finite element method to analyze both single-crystal and polycrystalline samples. The growth strains that are computed align well with the experimental data provided by Carpenter for single-crystal Zr. Furthermore, the transformation of a vacancy cluster into a complete vacancy loop, occurring at a size of 14 nm, is in agreement with experimental observations and atomistic simulations. The density, size, and growth rate of the dislocation loops, denoted as 〈c〉 and 〈a〉, also exhibit good agreement with transmission electron microscopy (TEM) analysis of irradiated Zr and its alloys. Our findings demonstrate that there is a spatial correlation between the growth of these dislocation loops and growth strains, significantly influenced by the crystal size. To explain the expansion of the 〈a〉 axis and the contraction of the 〈c〉 axis in irradiated Zr, it is necessary to consider the diffusion anisotropy difference (DAD) of mobile interstitial species. We show that the PWR Kearns parameters, specifically fr = 0.63, ft = 0.32, fa = 0.05, confer enhanced irradiation resistance to Zr along the principal directions when compared to single crystals. Additionally, reducing the grain size to nanograins further enhances the resistance to irradiation-induced growth, particularly along the direction with the highest volume fraction of basal poles [0001].

Fracture Toughness, Radiation Hardness, and Processibility of Polymers for Superconducting Magnets.

High fracture toughness at cryogenic temperature and radiation hardness can be conflicting requirements for the resins for the impregnation of superconducting magnet coils. The fracture toughness of different epoxy-resin systems at room temperature (RT) and at 77 K was measured, and their toughness was compared with that determined for a polyurethane, polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Among the epoxy resins tested in this study, the MY750 system has the highest 77 K fracture toughness of KIC = 4.6 MPa√m, which is comparable to the KIC of PMMA, which also exhibits linear elastic behaviour and unstable crack propagation. The polyurethane system tested has a much higher 77 K toughness than the epoxy resins, approaching the toughness of PC, which is known as one of the toughest polymer materials. CTD101K is the least performing in terms of fracture toughness. Despite this, it is used for the impregnation of large Nb3Sn coils for its good processing capabilities and relatively high radiation resistance. In this study, the fracture toughness of CTD101K was improved by adding the polyglycol flexibiliser Araldite DY040 as a fourth component. The different epoxy-resin systems were exposed to proton and gamma doses up to 38 MGy, and it was found that adding the DY040 flexibiliser to the CTD101K system did not significantly change the irradiation-induced ageing behaviour. The viscosity evolution of the uncured resin mix is not significantly changed when adding the DY040 flexibiliser, and at the processing temperature of 60 °C, the viscosity remains below 200 cP for more than 24 h. Therefore, the new resin referred to as POLAB Mix is now used for the impregnation of superconducting magnet coils.

Design of polarity hardening SRAM for mitigating single event multiple node upsets

With technology scaling down, the charge sharing among multiple nodes has becoming significant, making Single Event Multiple Node Upsets (SEMNUs) has become one of the major concern in memory cell designs. In this paper, a design of polarity hardening memory cell (PH_14T) is proposed for mitigating Single Event Multiple Node Upsets (SEMNUs). Through the 3D TCAD mixed-mode simulation established that the high robustness against SEU and SEMNUs of the PH_14T cell. Additionally, Cadence Spectre simulation results demonstrated that the proposed PH_14T cell has smaller write access time, lower power consumption, and highest critical charge compared to radiation-hardened cells. Monte Carlo simulation further confirmed the high radiation tolerance and high reliability of the proposed cell against SNU and DNU.

Effect of Graphite on Radiation Resistance and Oxygen Shielding Properties of EPDM Composites: Insights from Experiment and Molecular Simulation

Effect of Graphite on Radiation Resistance and Oxygen Shielding Properties of EPDM Composites: Insights from Experiment and Molecular Simulation

Quad-module characterization with the MALTA monolithic pixel chip

The MALTA silicon pixel detector combines a depleted monolithic active pixel sensor (DMAPS) with a fully asynchronous front-end and readout. It features a high granularity pixel matrix with a 36.4 μm symmetric pixel pitch, low power consumption of <1 μW/pixel and low material budget with detector thicknesses as little as 50 μm. It achieves a radiation hardness to 100MRad TID and more than 1 × 10E15 1 MeV neq/cm2 with a time resolution of <2 ns (Pernegger et al., 2023).In order to cover large sensitive areas efficiently with a minimum of power and data connections the development of modules, comprising of up to 4 MALTA detectors, is studied.This contribution presents the beam test performance of parallel and serial powered MALTA 4-chip modules in an effort to characterize the sensor’s chip-to-chip data and power transmission and prepare the production of a first prototype of an ultra-light weight 4-chip module on a flexible circuit with next generation MALTA2 sensors.