Radiation Degradation Research Articles

Analysis, Optimization, and Hardware Implementation of Dipole Antenna Array for Wireless Applications

The antenna pattern synthesis is one of the significant problems in the phased array antenna. Pattern synthesis refers to the optimized weight excitation of each antenna element in order to steer the beam electronically without mechanically rotating the antenna. It can be achieved by using a combination of phase shifters and attenuator circuits. In this paper, a 2 by 2 dipole antennas with an RF beamforming circuit has been designed to steer the main beam along the azimuth plane. The main beam coverage from 100° to 140° with a step size of 10° has been successfully optimized using a hybrid of the induced EMF method and a genetic algorithm. The optimization results were compared to the full-wave simulation technique implemented in Empire XCCel. The design is realistically implemented at 2.45 GHz, with both simulation and measurement results shown. The measured reflection coefficient of the phased array antenna is −48 dB at 2.56 GHz. The feasibility of the beam synthesis has been validated successfully with the main beam being steered at 110°. The possibility of a fabrication discrepancy resulting in minor radiation degradation is also discussed in this research. The dipole antenna system with RF beamformer circuit can be applied to indoor positioning systems such as Wi-Fi, wireless local area network (WLAN), and fifth-generation.

Pineapple Fiber Hybrids Prepared by the Fusion of radiation-induced Graft Polymerization and Kabachnik-Fields three-component Reaction (RIGP-KF3CR)

ABSTRACT The fusion of multicomponent reactions and polymer chemistry allows the synthesis of polymeric materials that contain special classes of molecules that are otherwise difficult to produce. In this study, a locally available nonwoven fabric composed of pineapple fibers and polylactic acid (piñatex) was modified by radiation-induced graft polymerization (RIGP) of vanillin methacrylate, a lignin-derived monomer. RIGP yielded organic hybrids made from a natural, renewable, and biodegradable substrate, and surface aldehyde groups from vanillin. The grafted fabric was prepared by gamma pre-irradiation at 50 kGy, exhibiting an increasing degree of grafting with increasing reaction time and monomer concentration. Post-polymerization modification carried out using Kabachnik-Fields three-component reaction (KF3CR) enabled the immobilization of amine and phosphite moieties on the fabric. FTIR, SEM-EDS and XPS analysis of 8 amine and phosphite combinations showed the presence of the corresponding elements and functional groups, indicating successful surface functionalization through RIGP-KF3CR. All modified natural fibers-based fabrics displayed enhanced thermal stability without obvious radiation degradation effects. Synthesized natural fibers contain α-aminophosphonate pendants which may be useful in the selective adsorption and recovery of industry valuable metals.

Impact of Aging Degradation on Heavy-Ion SEU Response of 28-nm UTBB FD-SOI Technology

Integrated circuits (ICs) are a keystone for most critical applications operating in high-level radiation environments, spanning from high-energy nuclear applications up to space applications. The long-term reliability of these applications is essential for safe operation. However, the radiation effects for ICs are commonly investigated using fresh circuits, leaving the coupled effect of radiation and aging degradation unknown. This article investigates the impact of negative bias temperature instability (NBTI) aging degradation mechanism on the heavy-ion single event upset (SEU) radiation susceptibility of 28-nm ultra-thin body and buried oxide (UTBB) fully depleted silicon on insulator (FD-SOI) technology using a custom-designed test vehicle. NBTI aging degradation mechanism has been experimentally proven to increase the SEU sensitivity up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> for 28-nm UTBB FD-SOI flip-flops. A comprehensive framework is presented to analyze the underlying mechanisms for the impact of NBTI, which includes NBTI aging mechanism modeling, SEU SPICE simulation, TCAD irradiation simulation, and Monte-Carlo simulation of radiation effects. The framework offered a quantitative prediction of the effect of NBTI degradation mechanism on the heavy-ion SEU radiation sensitivity.

Review of Radiation-Induced Effects on β-Ga2O3 Materials and Devices

β-Ga2O3 has become an ultimate choice of emerging new-generation material for its wide range of compelling applications in power electronics. In this review, we have explored the available radiations in the atmosphere and the effects of radiation on the β-Ga2O3 material and devices. The focus in this review summarizes various studies covering different radiation such as swift heavy ions, protons, neutrons, electrons, Gamma, and X-rays to understand the radiation-induced effects on the structure and their reliable performance in harsh environments. In addition, we focused on the various pre-existing defects in β-Ga2O3 and the emergence of radiation-induced defects that provoke a severe concern, especially from the device performance point of view. This review presents the irradiation-induced effects on the devices such as high-power devices such as Schottky barrier diodes (SBDs), field-effect transistors (FETs), metal-oxide-semiconductor (MOS) devices, and photodetectors. Some key studies including the changes in carrier concentration with a removal rate, Schottky barrier height (SBH), ideality factor, defect dynamics dielectric damage, interface charge trapping, a thermally activated recovery mechanism for charge carriers at elevated temperature, and diffusion length of minority charge carriers. These reports show that β-Ga2O3-based devices could be deployable for space or high-radiation terrestrial applications. These results provide/suggest a better device design based on the radiation degradation studies in the state-of-the-art β-Ga2O3 devices.

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.

How the Analysis of Archival Data Could Provide Helpful Information About TID Degradation. Case Study: Bipolar Transistors

A critical step of radiation hardness assurance (RHA) for space systems is given by the parts selection in accordance with the observed (or estimated) radiation effects. Although radiation testing is the most decisive way of studying the radiation degradation of electronic components, the increasing use of commercial off-the-shelf (COTS) devices and the challenges posed by <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">NewSpace</i> are pushing the need of finding new approaches to assess the risk associated with radiation environments. This work tries to evaluate if valuable information might be extracted from archival data to carry out this assessment despite the well-known and dramatic lot-to-lot, or even part-to-part, variability for some technologies and the impact of the different test conditions, such as the bias conditions and the dose rate in enhanced low dose rate sensitivity (ELDRS). These factors are briefly analyzed for some examples. A new radiation database is briefly introduced, and some statistical approaches are cited, apart from the analysis herein followed. To finish, a first analysis on three families of bipolar transistors is presented together with the independent results from three external reports, with a good agreement between the experimental results and the expected ones.

Skewness-based characterization of silicon photomultipliers

Characterization of SiPMs is an objective of high importance in almost any research, development, and application of these unique photon detectors. Two decades of characterization method developments resulted in a comprehensive and elegant methodology based on a precisely resolved number of fired SiPM cells or the SiPM spectrum. Spectrum fitting procedures are very sensitive to a proper selection of many initial guess values including parameters of minor importance and happen to be unreliable. Moreover, conventional methods are useless for degraded or unresolved SiPM spectra. This challenge was anticipated for SiPM-based detectors of high-luminosity particle calorimeters where a severe radiation degradation of the SiPMs would co-exist with their acceptable performance. To address it, one can measure a mean and variance of SiPM charge responses relying on a priori known Excess Noise Factor of the SiPM but its stability during SiPM degradation is uncertain. This study proposes and evaluates a new approach for the SiPM characterization based on the first three statistical moments (mean, variance, and skewness) of its charge response including skewness. It assumes the Generalized Poisson distribution of the number of fired cells and provides simple closed-form analytical expressions for the parameter estimation. It allows determining a gain, a number of detected photons, and a probability of correlated events directly from raw data. The skewness-based characterization is anticipated to be especially useful for mass testing and continuous monitoring of SiPMs in large-scale experiments due to its simplicity and robustness. Initial evaluations of the method show promising results.

Thermal and radiation degradation effects on fluoroelastomer destined to gasket applications in nuclear power plants

Thermal and radiation degradation effects on fluoroelastomer destined to gasket applications in nuclear power plants

Evolution of short-term creep strain field near fatigue crack in single crystal Ni-based superalloy measured by digital image correlation

This study measured the variation over time of the creep strain fields around a fatigue crack tip in a single crystal Ni-based superalloy in an open environment at temperatures up to 900 °C using digital image correlation (DIC). A high-temperature DIC measurement system was developed to overcome three difficulties: the degradation of random patterns, thermal radiation, and heat haze. Tension hold was applied to the specimens, and the time evolution of the creep strain fields around the crack tip was measured at different temperatures and under different loading conditions. The proposed DIC system measured the short-term creep strain fields with high reproducibility and reliability, and the strain and strain rate increased as the temperature and hold load increased. To confirm the utility of the measurement results, the stress distribution around the crack tip was calculated using the finite element method (FEM), and the calculation results were validated by comparing the calculated strain to the measurement results. The effect of creep deformation on the fatigue crack propagation (FCP) is discussed.

Exposure of crumb rubber modified bitumen to UV radiation: A waste-based sunscreen for roads

The degradation of asphalt roads due to heat and moisture is well studied, but very little focus has been given to the effects of high energy transmitted by sunlight UV radiations. This study aims to investigate the effect of UV radiations on the chemo-mechanical properties of neat and modified bitumen with different concentrations of crumb rubber and compare it to that of thermal ageing. Samples were aged in the Q-Lab weatherometer for 869 h at 0.89 Wm-2, equivalent to one year of UV radiations energy in the city of Melbourne, Australia, in 2019. Fourier transformation infrared (FTIR) spectroscopy was used for analysing the changes of chemical bonds before and after ageing. It was found that thermal ageing results in the development of carbonyl and sulfoxide oxides while evaporates the volatile components as depicted from the decreasing value of aliphaticity index. On the other hand, UV ageing mainly targets components with bond energy lower than 413 kJ/mol, i.e., C–C, C–O and C–H that usually consist of aliphatic chains of hydrocarbons. The rheological test results revealed that both thermal and UV ageing produce stiffer materials as depicted from the upward shift of the master curves. However, this shift reduces with the increase in CR concentration. All unaged samples were found to lay well below the Glover-Rowe onset damage envelope, however, as the samples underwent thermal ageing, they moved towards the onset damage zone. With the addition of UV ageing, the standard bitumen was only 13.2 kPa away from the ‘onset damage’ threshold while crumb rubber modified bitumen was almost 60 kPa away from the damage zone. Moreover, if neat bitumen is to be modified with 22.5% of CR, it can reduce the damage produced by UV and thermal ageing by approximately 50%, hence showing greater resistance to the thermal and solar radiation degradation.

Identification of radiation degradation products of soluble fraction of silicone foams

It is important to understand the radiation degradation process of silicon foam in radiation aging. Past researches studied the irradiation induced change of mechanical properties. However, the mechanism of micro-degradation is still unclear. In this study, we took a simple pre-treatment of silicone foams with toluene immersion before irradiation. And the results showed that toluene immersion was the key to remove the non-cross-linked oligomers that would interfere with the identification of degradation products. After irradiation, the silicone foams were re-soaked in deuterated toluene solution, and the degradation products were analysed by 1H-NMR, XPS and GPC. The main degradation product of two kinds of silicone foams (methyl vinyl silicone and methyl phenyl silicone) was identified as polysiloxane structures. And the polymerization degree of polysiloxane structures decreased when the irradiation dose increased from 100 kGy to 500 kGy. Theoretical calculations suggested a gradual degradation process, which was in accordance with experiment results.

Gamma radiation modification of cassava starch and its characterization

AbstractRadiation technology has been recognized as a potential tool to modify starches in order to enhance their solubility and enzymatic digestion, hence improving their applicability in food industry. In the present study, the local cassava starch was irradiated under 60Co gamma source with the absorbed dose ranging from 1 to 10 kGy, and the obtained radiation‐modified starches were characterized. The microstructure of the initial cassava starch was not much changed although several starch granules were deformed or even fragmented by gamma irradiation as observed in the scanning electron microscopy images. Water solubility of the irradiated starch was significantly increased, and their viscosity was much reduced by radiation degradation. Gamma radiation broke glycosidic bonds in starch chains into smaller molecules with lower molecular weight, whereby increased the water solubility of cassava starch. Radiation scission also partly decreased the crystallinity of the starches irradiated with dose higher than 5 kGy as indicated in their X‐ray diffraction patterns. The Fourier transform infrared spectra of irradiated starches revealed the reduction in intensities of stretching vibration characterized for OH, CH, and COC groups of starch molecules. Thus, gamma irradiation can be used to modify cassava starch for further applications.

RADIATION DAMAGE TO BERYLLIUM UNDER LOW-TEMPERATURE NEUTRON IRADIATION

In this work, to assess the radiation damage of beryllium under low-temperature neutron irradiation, samples from beryllium grade TShG-200 with an oxide phase concentration of about 1 wt % were studied, which were kept in the IVG.1M research reactor for a long time and were irradiated to fluences 0.8–4·1020 neut./cm2. Also, unirradiated original witness samples of the same brand were tested to compare the results.The aim was to establish the level of radiation degradation of beryllium samples during their tests in the IVG.1M reactor. Mechanical tests for three-point bending and tension were performed to determine the strength of beryllium samples, and their microhardness was also measured. To determine the degree of swelling of the beryllium samples their densities were measured by the method of hydrostatic weighing in the medium of distilled water.According to the results of short-term bending and tensile tests, it was found that the beryllium material after reactor irradiation softens in the range of 9.3–16.7%. And the results of measuring the microhardness showed an increase of up to 23%. Density results did not reveal swelling of the samples after low-temperature neutron irradiation.After mechanical tests, special studies of fractures and microstructural analysis were carried out, which did not reveal noticeable changes in the microstructure of beryllium after irradiation.

Analysis of I-V characteristics of Si diodes irradiated with short-range ions

Radiation degradation of Si ion detectors becomes critical for the experiments at new facilities giving the beam intensity increase up to 105 times. The study is focused on the impact of heavily damaged Bragg peak region (BPR) at the ion range end on the bulk current of Si sensors irradiated with 53.4 MeV 40Ar ions in the fluence range (1-4)·10^9 ion/cm2. It is shown that taking into account only the generation current component is insufficient to explain the experimental I-V curves. Simulating I-V characteristics and the electric field profiles demonstrated arising of a built-in junction in the BPR, which controls hole diffusion at voltages below full depletion voltage. Contribution of this component to the total diode current enabled the agreement between experimental and simulated I-V curves. Keywords: silicon sensors, radiation degradation, current-voltage characteristic, carrier diffusion.

Analysis of I-V characteristics of Si diodes irradiated with short-range ions

Radiation degradation of Si ion detectors becomes critical for the experiments at new facilities giving the beam intensity increase up to 10^5 times. The study is focused on the impact of heavily damaged Bragg peak region (BPR) at the ion range end on the bulk current of Si sensors irradiated with 53.4 MeV ^40Ar ions in the fluence range (1 ‒ 4)x10^9 ion/cm^2. It is shown that taking into account only the generation current component is insufficient to explain the experimental I-V curves. Simulating I-V characteristics and the electric field profiles demonstrated arising of a built-in junction in the BPR, which controls hole diffusion at voltages below full depletion voltage. Contribution of this component to the total diode current enabled the agreement between experimental and simulated I-V curves.

Ultrafast multi-shot ablation and defect generation in monolayer transition metal dichalcogenides

Transition metal dichalcogenides are known to possess large optical nonlinearities, and driving these materials at high intensities is desirable for many applications. Understanding their optical responses under repetitive intense excitation is essential to improve the performance limit of these strong-field devices and to achieve efficient laser patterning. Here, we report the incubation study of monolayer MoS2 and WS2 induced by 160 fs, 800 nm pulses in air to examine how their ablation threshold scales with the number of admitted laser pulses. Both materials were shown to outperform graphene and most bulk materials; specifically, MoS2 is as resistant to radiation degradation as the best of the bulk thin films with a record fast saturation. Our modeling provides convincing evidence that the small reduction in threshold and fast saturation of MoS2 originate from its excellent bonding integrity against radiation-induced softening. Sub-ablation damages, in the form of vacancies, strain, lattice disorder, and nanovoids, were revealed by transmission electron microscopy, photoluminescence, Raman, and second harmonic generation studies, which were attributed to the observed incubation in 2D materials. For the first time, a sub-ablation damage threshold is identified for monolayer MoS2 to be 78% of the single-shot ablation threshold, below which MoS2 remains intact for many laser pulses. Our results firmly establish MoS2 as a robust material for strong-field devices and for high-throughput laser patterning.

Study of Radiation Embitterment and Degradation Processes of Li2ZrO3 Ceramic under Irradiation with Swift Heavy Ions

The work is devoted to the study of radiation damage and subsequent swelling processes of the surface layer of Li2ZrO3 ceramics under irradiation with heavy Xe22+ ions, depending on the accumulation of the radiation dose. The samples under study were obtained using a mechanochemical synthesis method. The samples were irradiated with heavy Xe22+ ions with an energy of 230 MeV at irradiation fluences of 1011–1016 ion/cm2. The choice of ion types is due to the possibility of simulating the radiation damage accumulation processes as a result of the implantation of Xe22+ ions and subsequent atomic displacements. It was found that, at irradiation doses above 5 × 1014 ion/cm2, point defects accumulate, which leads to a disordering of the surface layer and a subsequent decrease in the strength and hardness of ceramics. At the same time, the main process influencing the decrease in resistance to radiation damage is the crystal structure swelling as a result of the accumulation of defects and disordering of the crystal lattice.

Semi-insulating GaAs detectors degraded by 8 MeV electrons up to 1500 kGy

Radiation degradation of semi-insulating GaAs detectors by 8 MeV electrons up to doses of 1500 kGy is studied in this paper. The influence of irradiation on GaAs material parameters and on spectrometric and electrical properties of fabricated detectors is evaluated. The detector material was degraded before contact preparation, which ensured separation of radiation degradation solely to the bulk material, excluding the contact degradation. The positron annihilation lifetime spectroscopy (PALS) was involved to characterize the substrate material together with galvanometric measurements. Radiation-induced mono-vacancies were clearly identified by PALS in the irradiated materials with increasing concentration up to 2.8 × 1016 cm−3 at maximal applied dose. In correlation with defect concentration the electron Hall mobility decreased with dose down to 3270 cm2 V−1 s−1 and resistivity increased up to 5.22 × 108 Ω cm at 1500 kGy. The bulk material properties influenced the parameters of fabricated detectors. The detectors lost their current blocking behaviour at 1000 kGy according to current-voltage measurements. The charge collection efficiency during alpha-particle and gamma ray measurements almost exponentially decreased with applied dose from initial 40% down to 5% at 1500 kGy in the case of alpha spectrometry and from 48% to 12% at 500 kGy for gamma spectrometry.

Prediction of radiation degradation of Si detectors irradiated by relativistic ions of different masses

The presented paper is focused around radiation damage of silicon material under the different ions irradiation. The ion total energy range is 0.7 GeV for 7Li to 208 GeV for 208Pb. The results of TRIM modeling for the set of six ions are presented. The extracted information about vacancy production allows making first assumptions of the Si degradation dependence on mass and energy of the incident ion.

Effect of binder-aggregate ratio on the mechanical and functional properties of porous polyurethane cement mixture

ABSTRACT Polyurethane mixtures are regarded as novel polymer pavement materials that can overcome the shortcomings of poor mechanical properties and loose particles of open-graded friction course (OGFC). Owing to its high strength after curing, polyurethane binder improves the mechanical connection at the aggregate-aggregate contact point, which effectively enhances the service performance of permeable pavement. However, the relationship between the binder content and the mechanical and functional properties of polyurethane mixture has not clearly understood yet. The objective of this study is to investigate the influence of the binder-aggregate ratio on the mechanical and functional properties using laboratory tests. Firstly, the effect of binder content on the mechanical properties of the mixture is examined by Marshall stability test, uniaxial compression test, and bending beam test. Secondly, the functional properties of the mixtures are characterised by Cantabro test, permeability test, computed tomography, and particle clogging test. Finally, the durability of the mixtures is characterised by hydrolysis resistance test and ultraviolet radiation degradation test. The results reveal that the content of binder has a significant impact on the mechanical and functional properties of the mixture. It is necessary to maintain a balance between the mechanical and functional properties.