Effects Of High-energy Irradiation Research Articles

Detecting Exoplanet Transits with the Next Generation of X-Ray Telescopes

Detecting exoplanet transits at X-ray wavelengths would provide a window into the effects of high-energy irradiation on the upper atmospheres of planets. However, stars are relatively dim in the X-ray, making exoplanet transit detections difficult with current X-ray telescopes. To date, only one exoplanet (HD 189733 b) has an X-ray transit detection. In this study, we investigate the capability of future X-ray observatories to detect more exoplanet transits, focusing on both the NewAthena Wide Field Imager instrument and the proposed Advanced X-ray Imaging Satellite (AXIS), which provide more light-collecting power than current instruments. We examined all the transiting exoplanet systems in the NASA Exoplanet Archive and gathered X-ray flux measurements or estimates for each host star. We then predicted the stellar count rates for both AXIS and NewAthena and simulated light curves, using null-hypothesis testing to identify the top 15 transiting planets ranked by potential detection significance. We also evaluate transit detection probabilities when the apparent X-ray radius is enlarged due to atmospheric escape, finding that ≥five of these planetary systems may be detectable on the >4σ level in this scenario. Finally, we note that the assumed host star coronal temperature, which affects the shape of an X-ray transit, can also significantly affect our ability to detect the planet.

Effect of Irradiation (SRFE) on MSM Photodetectors Device

This paper presents the effect of high energy irradiation expose on metal-semiconductor-metal (MSM) photodetectors device. High energy radiation may impact to lattice structure of semiconductor device. The most impact of radiation on MSM device had been studied base on polycrystalline silicon. Based on our research in SRFE process exposed on P-N power device, radiation will interact with device mechanism and structure that change electrical properties of device. However, MSM device show electrical properties change after irradiation exposure process by photocurrent increased around 4 times when compare with non-irradiated.

High energy irradiation effects on silicon photonic passive devices.

In this work, the radiation responses of silicon photonic passive devices built in silicon-on-insulator (SOI) technology are investigated through high energy neutron and 60Co γ-ray irradiation. The wavelengths of both micro-ring resonators (MRRs) and Mach-Zehnder interferometers (MZIs) exhibit blue shifts after high-energy neutron irradiation to a fluence of 1×1012 n/cm2; the blue shift is smaller in MZI devices than in MRRs due to different waveguide widths. Devices with SiO2 upper cladding layer show strong tolerance to irradiation. Neutron irradiation leads to slight changes in the crystal symmetry in the Si cores of the optical devices and accelerated oxidization for devices without SiO2 cladding. A 2-µm top cladding of SiO2 layer significantly improves the radiation tolerance of these passive photonic devices.

Investigation on Molecular Structures of Electron-Beam-Irradiated Low-Density Polyethylene by Rheology Measurements

While the effect of high-energy irradiation on low-density polyethylene (LDPE) has been extensively investigated, the molecular structure changes under different irradiation conditions are less well understood. In this work, we have made systematic investigations on the molecular structure of electron beam irradiated LDPE under various irradiation conditions. The microstructures have been mainly characterized by rheological measurements using small amplitude oscillatory shear (SAOS) and analyzed by a weighted relaxation spectrum and a van Gurp–Palmen plot. It was found that the linear viscoelasticity of LDPE exhibited a strong dependence on the radiation atmosphere due to oxidative degradation in the presence of oxygen. An improved/destroyed network structure could be acquired when LDPE was irradiated in a nitrogen/oxygen environment, as compared with that in air. Differences became more significant when LDPE was irradiated at higher temperature (80 °C) due to the facilitated diffusion of free radicals wi...

Radiation tolerance of nanostructured ZrN coatings against swift heavy ion irradiation

Nano-structured zirconium nitride layers – on Si substrates – of various thicknesses (0.1, 3, 10 and 20μm) were irradiated with 167MeV Xe, 250MeV Kr and 695MeV Bi ions to fluences in the range from 3×1012 to 2.6×1015cm−2 for Xe, 1×1013 to 7.06×1013cm−2 for Kr and 1012 to 1013cm−2 for Bi. The purpose of these irradiation experiments is to simulate the effects of fission fragment bombardment on nanocrystalline ZrN. The irradiated layers where subsequently analysed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nano-indentation hardness testing (NIH) techniques. XRD, TEM and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation.

Effects of gamma and electron beam irradiation on the properties of calendered cord fabrics

The effects of gamma and e-beam irradiation on mechanical and structural properties of nylon 66 (Ny 66), nylon 6 (Ny 6) and poly(ethylene terephthalate) (PET) fabrics used in tyres were investigated. The untreated (greige), treated cords and calendered fabrics were irradiated at different doses. It is found that the effects of high energy irradiation on greige, treated cords and calendered fabrics are similar. No protective effect of compounds used in calendering was observed against radiation-induced oxidative degradation. The deterioration effect of gamma irradiation on mechanical properties is much higher than that of e-beam irradiation for all types of samples. Limiting viscosity numbers of both gamma and e-beam irradiated nylon 6 and nylon 66 cords were found to decrease with increasing dose. It is concluded that PET calendered fabric has higher resistance to ionizing radiation. Ny 6 and Ny 66 calendered fabrics are more sensitive even at low doses. Therefore, the effects of high energy irradiation on tyre cords have to be taken into consideration during tyre design reinforced with particularly Ny fabrics if pre-vulcanization with high energy radiation is to be applied.

The influence of composition of porous copolyester scaffolds on reactions induced by irradiation sterilization

In our previous work regarding radiation sterilization of porous scaffolds we have concluded that the composition and microstructure of the polymer chain are a key factor influencing the degradation reactions occurring upon irradiation. In this work we in contrast reported on the effects of high-energy irradiation on the thermal and mechanical properties. Electron beam (EB)- and γ-irradiation sterilization were used in order to finalize the properties of a series of porous scaffolds comprised of different aliphatic polyester copolymers. The results presented here show that, for both sterilization methods, the crystallinity increased for all copolymers of 1,5-dioxepan-2-one (DXO) and l, l-lactide (LLA) at the minimum sterilization dose. The same was true of the ε-caprolactone (CL)- and LLA-containing copolymers upon EB sterilization, while a reduction in crystallinity were found upon γ-irradiation. As was anticipated, it was shown that crystallinity also is a characteristic of the copolymer influencing the effects of the irradiation-induced reactions. Both the onset temperature and the temperature corresponding to the maximum rate of weight loss increased after irradiation and hence the thermal stability was increased. This is a result of a simultaneous lengthening of the chains by cross-linking reactions and a shortening by random chain-scissions occurring throughout the molecule, which lead to the formation of new endgroups with higher thermal stability. Scaffolds of crystalline polymers retained more of their initial tensile properties after irradiation compared to amorphous materials. The result previously published, showing that the composition was a key factor influencing the degradation reactions occurring upon irradiation, was augmented here.

High energy irradiation effects on AlGaN/GaN HFET devices

The effect of proton, carbon, oxygen and krypton irradiation on AlGaN HFET devices has been studied. Irradiation was performed at 68 and 120 MeV with fluences in the range from 1 × 107 to 1 × 1013 cm−2. Before and after irradiation, dc and pulsed I–V characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured. A thick GaN reference layer was characterized by x-ray diffraction, photoluminescence and Hall measurements before and after irradiation. Proton, carbon and oxygen irradiation show no degradation in devices while krypton irradiation shows a small change at a fluence of 1 × 1010 cm−2 in the device characteristics. The device results are correlated with the thick GaN results.

Effect of gamma irradiation on the properties of tyre cords

Gamma irradiation of high tenacity Nylon 6.6 (Ny 66) and polyester (PET) tyre cords was investigated. The untreated and treated tyre cords with different twist levels were irradiated at different dose rates in air. The effects of irradiation on both Ny 66 and PET cords were not found to be depending on the twist levels of the cords. The changes in the mechanical and thermal properties with absorbed dose at two different dose rates were measured. The mechanical properties were observed to deteriorate with increasing dose for Ny 66 cords, whereas remained almost unchanged for PET cords both in greige and dipped forms. Hot shrinkage value for the greige Ny 66 cords was found to be improved, i.e. decreased. This decrease was much lower for greige PET than Ny 66 cords. It is concluded that PET cord has higher radiation resistance than Ny 66 cord and the effects of high energy irradiation on tyre cords have to be taken into consideration during tyre design if pre-vulcanization with high energy radiation is to be applied.

Effect of γ-irradiation on cotton-cellulose

The effect of high-energy irradiation on cotton-cellulose was studied in inert atmosphere and in the presence of oxygen. A decrease in the degree of polymerization from 1200 to 330 was measured after irradiation with a dose of 15 kGy (dose rate 100 Gy/h) and further gradual decrease was measured when the dose was increased up to 100 kGy. At lower doses a slight increase in crease recovery angle was found as compared to the unirradiated sample. In the FTIR spectra of the same sample the appearance of the absorbance of carbonyl groups (band at 1730–1750 cm−1) was found as a consequence of the oxidative degradation. Cracks on the surface of the fibers were observed by scanning electron microscope on samples irradiated with doses higher than 100 kGy.

Progress in high-energy electron and x-irradiation of insulating dielectrics

The effects of high-energy irradiation on the charging of insulators is reviewed with a viewpoint similar to the seminal work of Professor Bernhard Gross. Recent results relating to insulation breakdown and to insulators in space radiation are more easily explained because of Gross' fundamental studies. A number of important issues remain unsolved, yet the first steps to solutions have been provided by Gross.

Radiation-Induced Enhancement of Crystallinity in Polymers

Abstract The effects of high-energy irradiation on the structure, properties, and processing of polymers are of considerable scientific and commercial significance and have been reported in several books and review articles [101]. In this massive literature, two of the major radiation-induced changes reported are crosslinking and degradation, sometimes leading to a loss of crystallinity. In fact, in this literature polymers are generally classified as either “crosslinking type” or “chain-scission type.” In the present review we shall not be concerned with radiation-induced crosslinking, although its existence in many polymers is, of course, acknowledged. Nor will our review cover radiation-induced polymerization or grafting. All these topics have already been adequately covered in the extensive radiation literature, such as the references cited above.

Effects of High-Energy Electron Irradiation of Chicken Meat on Salmonella and Aerobic Plate Count

Four experiments were used to determine the effects of high-energy irradiation on the number of aerobic microorganisms and Salmonella on broiler breasts and thighs. Irradiation ranging from 100 to 700 kilorads (krads) was provided by a commercial-scale, electron-beam accelerator. Irradiation of broiler breast and thigh pieces with electron beams at levels of 100, 200, 300, 400, 500, and 600 krads showed that levels as low as 100 krads would eliminate Salmonella. When 33 thighs were tested after irradiation at 200 krads, only one thigh tested presumptive positive. The total number of aerobic organisms was reduced by 2 to 3 log10 cycles at irradiation levels of 100, 200, 300, 400, 500, 600, and 700 krads. Increasing the dose above 100 krads gave little if any additional benefit.

Carbon in Crystalline Silicon

Early measurements are reviewed relating to the solubility. the segregation coefficient, diffusion. Internal precipitation, the infrared absorption and the effect on the lattice parameter of silicon due to substitutional carbon. Interactions with oxygen and group III Impurities are mentioned. A survey is given of the effects of high energy irradiation and heat treatments on both FZ and CZ silicon containing carbon. A rich variety of defects can form, but in general atomic structures have not been determined. The process of site switching from substitutional to interstitial locations which occurs by the selective trapping of self-Interstitials is proving to be invaluable in elucidating the mechanisms of various defect reactions, particularly those Involving oxygen Impurities.

Carbon in Crystalline Silicon

ABSTRACTEarly measurements are reviewed relating to the solubility. the segregation coefficient, diffusion. Internal precipitation, the infrared absorption and the effect on the lattice parameter of silicon due to substitutional carbon. Interactions with oxygen and group III Impurities are mentioned. A survey is given of the effects of high energy irradiation and heat treatments on both FZ and CZ silicon containing carbon. A rich variety of defects can form, but in general atomic structures have not been determined. The process of site switching from substitutional to interstitial locations which occurs by the selective trapping of self-Interstitials is proving to be invaluable in elucidating the mechanisms of various defect reactions, particularly those Involving oxygen Impurities.

Effects of high energy irradiation on polypropylene

AbstractIsotactic polypropylene (Profax) film samples irradiated in the Pennsylvania State University (PSU) reactor at ambient temperatures were examined by solvent extraction and infrared absorption techniques. At low irradiation doses, samples annealed (density = 0.909 g./cc. at 24°C.) prior to irradiation were found to have a lower gel content and a higher concentration of oxidation products than quenched samples (density = 0.899 g./cc. at 24°C.) irradiated under identical conditions. Similar gel fraction results were obtained for electron irradiated samples of polypropylene. These effects are believed to arise from the accumulation of a greater concentration of free macroradicals in the higher density samples. At higher reactor dosages the irradiation effects in the annealed and quenched films appear to be about the same. The gel content as a function of dose was found to be independent of the irradiation intensity level over a twofold range. Irradiations in the PSU reactor were also carried out on high density polyethylene (Marlex 50) pellets at two temperatures, viz., 40 ± 10°C. and 150°C. Irradiation at 150°C. led to a greater gel content at any given dose, a result in agreement with that reported by Lawton, Balwit, and Powell for electron‐irradiated specimens. Nuclear magnetic resonance spectra were obtained for molded annealed samples of partially isotactic polypropylene, irradiated in the Brookhaven reactor, at temperatures of 90–330°K. The observed shifts in the line narrowing process that occur in the 270–330°K. region are explained in terms of the decrease in crystallinity and the increasing density of crosslinks that accompany irradiation.

Effects of high energy irradiation on respiratory enzyme systems

The irradiation sensitivity of the cytochrome system was investigated, using as examples baker's yeast andE. coli. A method is described with which the proportion of reduced cytochrome in cell suspensions could be measured spectrometrically. In contrast to isolated cytochrome, which is easily oxydized by Roentgen rays, the cytochrome of living cells is very stable to Roentgen rays. The electrone transport is not influenced by high energy rays. It is probable that the hydrogen transport is also undisturbed. Only if the cell is so damaged by high doses of rays that every exchange of substances is impossible, i.e. if the cell is dead, is the ferrocytochrome oxydized and perhaps also destroyed. The oxydation is thus a secondary process resulting from death of the cell by rays. It is supposed that the changes in energy metabolism described in the literature, especially the disturbances of oxydative phosphorylation, are also secondary processes.