High-energy Heavy-ion Irradiation Research Articles

High-energy heavy ion irradiation of HOPG

Understanding the behavior of the graphite under extreme conditions is very important for its use in applications related to the nuclear technology. In this work, we used atomic force microscopy, scanning tunnelling microscopy, and Raman spectroscopy to study the graphite response to high-energy heavy ions irradiation. On the surface, we found ion tracks after grazing incidence ion irradiation by 23 MeV I, which makes the graphite surface susceptible to this type of irradiation. Within the bulk, no tracks have been found after normal incidence irradiation. However, we show that electronic energy loss plays a role in defect recovery, making graphite below the surface even more stable to the high-energy heavy ion irradiation.

Response of Bilayer and Trilayer Graphene to High-Energy Heavy Ion Irradiation

High-energy heavy ion irradiation is a very useful tool for the nanostructuring of 2D materials because defects can be introduced in a controlled way. This approach is especially attractive for the mass production of graphene nanomembranes when nanopore size and density can easily be tuned by ion irradiation parameters such as ion energy and applied fluence. Therefore, understanding the basic mechanisms in nanopore formation due to high-energy heavy ion impact is of the highest importance. In the present work, we used Raman spectroscopy to investigate the response of bilayer and trilayer graphene to this type of irradiation. Spectra obtained from graphene samples irradiated with 1.8 MeV I, 23 MeV I, 3 MeV Cu, 18 MeV Cu, and 12 MeV Si beams were analysed using the Lucchese model. It was found that the efficiency of damage production scales strongly with nuclear energy loss. Therefore, even for the most energetic 23 MeV I beam, the electronic energy loss does not contribute much to damage formation and ion tracks are unlikely to be formed.

Process design for the manufacturing of soft X-ray gratings in single-crystal diamond by high-energy heavy-ion irradiation

This paper describes in detail a novel manufacturing process for optical gratings suitable for use in the UV and soft X-ray regimes in a single-crystal diamond substrate based on highly focused swift heavy-ion irradiation. This type of grating is extensively used in light source facilities such as synchrotrons or free electron lasers, with ever-increasing demands in terms of thermal loads, depending on beamline operational parameters and architecture. The process proposed in this paper may be a future alternative to current manufacturing techniques, providing the advantage of being applicable to single-crystal diamond substrates, with their unique properties in terms of heat conductivity and radiation hardness. The paper summarizes the physical principle used for the grating patterns produced by swift heavy-ion irradiation and provides full details for the manufacturing process for a specific grating configuration, inspired in one of the beamlines at the ALBA synchrotron light source, while stressing the most challenging points for a potential implementation. Preliminary proof-of-concept experimental results are presented, showing the practical implementation of the methodology proposed herein.

Measured and simulated depth-profiles of fragments induced by 200 MeV/u 40Ar ion beam in copper

This work is a further contribution to our long-term experimental studies of activation- and fragmentation-related effects induced by high-energy heavy-ion irradiation in selected accelerator-construction materials. A stacked-foil copper target consisting of thin foils with different thicknesses was irradiated by 200 MeV/u 40Ar ions. Gamma spectra of the radiation emitted from the activated foils were measured and the nuclides created in the foils as a result of nuclear interaction between the 40Ar ions and the copper target nuclei were identified. The activities of all identified nuclides have been determined from the gamma spectra. The measured activity of each nuclide has been converted to the number of nuclei (of that nuclide) contained in the foil. Finally, the depth-profiles of the induced nuclides, i.e. the number of the induced nuclei as a function of the target depth, have been constructed and analyzed. The measured depth-profiles provide information on physical mechanisms of the high-energy heavy-ion fragmentation. The measured depth-profiles have been also compared with the simulated ones obtained with FLUKA2020. Keeping in mind complexity of the nucleus-nucleus interactions in the broad energy interval, the measured and simulated depth-profiles show a reasonable agreement. However, in some cases, discrepancies between the measured and the simulated depth-profiles have been observed. These cases are presented and discussed in the paper, as they can serve improvement of physical models implemented in the simulation codes.

Hardening and ductility loss of RAFM steel CLF-1 irradiated with high-energy heavy ions

Irradiation induced hardening and ductility loss of a Chinese reduced-activation ferritic / martensitic steel CLF-1 is evaluated by utilizing the high-energy heavy ion irradiation and the subsequent miniature specimen test technique. Specimens were irradiated with high energy 14N6+ and 56Fe17+ ions supplied by a cyclotron to generate a quasi uniform atomic displacement damage plateau from surface to a depth about 25 μm. Three successively increasing damage levels (0.05, 0.1 and 0.2 dpa) were approached at a low temperature around 223 K. The small punch test at room temperature showed that the ductility loss can be observed at the lowest damage level and increases with the increasing damage level, similar to the variation trend of yield stress with irradiation dose. The TEM observation revealed that the average size and number density of irradiation-induced defect clusters also increased with displacement damage. Assuming that the hardening is caused by the self-interstitial-type dislocation loops, an estimation by combining the numerical calculation of the number density / mean diameter of dislocation loops with the dispersion barrier hardening model yields a similar dose dependence of the irradiation hardening.

High-Energy Heavy Ion Irradiation of Al2O3, MgO and CaF2.

High-energy heavy ion irradiation can produce permanent damage in the target material if the density of deposited energy surpasses a material-dependent threshold value. It is known that this threshold can be lowered in the vicinity of the surface or in the presence of defects. In the present study, we established threshold values for Al2O3, MgO and CaF2 under the above-mentioned conditions, and found those values to be much lower than expected. By means of atomic force microscopy and Rutherford backscattering spectrometry in channelling mode, we present evidence that ion beams with values of 3 MeV O and 5 MeV Si, despite the low density of deposited energy along the ion trajectory, can modify the structure of investigated materials. The obtained results should be relevant for radiation hardness studies because, during high-energy ion irradiation, unexpected damage build-up can occur under similar conditions.

Synergistic effects assessment between nuclear damage and electronic energy dissipation in LiTaO3 under heavy ion irradiation using optical waveguides properties and the irradiation angle of incidence

High energy heavy ion irradiation has been performed in LiTaO3 in a broad set of experimental conditions to study the synergistic effects in the damage generation between the nuclear and the electronic energy loss mechanisms. Optical waveguides have been fabricated in LiTaO3, using 20–25 MeV F and 40 MeV Si ions, and their refractive index profiles were used as a very accurate method for the in-depth damage profile determination and its correlation with the energy loss curves. In-situ optical reflectance of low energy irradiations (500 keV F and 300 keV Si ions) has been performed to estimate the nuclear damage kinetics of the buried regions of the high energy irradiations that are not optically accessible with the optical waveguide characterization in the fluence regime when the electronic damage is intense. The angle of incidence has been varied to enhance the damage and further ascertain the existence of a synergistic mechanism.

Irradiation resistance of chromium coatings for ATFC in the temperature range 300–550°C

Within the accident tolerant fuel cladding (ATFC) concept, chromium coatings appear to be promising for protecting zirconium alloys from high temperature oxidation. The effects of high energy heavy ion irradiation in the temperature range of 300–550°C on the structure of chromium coatings deposited on Zr-based (E110) alloy substrate by the cathodic arc evaporation method were studied. Isotropic growth of the grain size in chromium coatings from the initial 250 nm to 476 nm at 550°C is caused by irradiation with 1.4 MeV argon ions to the dose of 25 displacements per atom (dpa). Maximum swelling up to 1.6 % was observed under the irradiation temperature of 500°C.

Effect of high-energy heavy-ion irradiation on electromechanical coupling factor of piezoelectric lead zirconate titanate

The variation of the electromechanical coupling factor of lead zirconate titanate (PZT) was studied using a piezoelectric PZT disk exposed to a 400 MeV/n xenon beam. The resonant and antiresonant frequencies were measured in pairs by an impedance analyzer in situ manner. A systematic behavior of the pairs resulted in a decrease of the coupling factor. It was found that the coupling factor linearly decreased with increasing integrated beam energy incident on the PZT disk while its surface temperature was equilibrium at room temperature. We discuss a possible PZT-based radiation detector for practical use in a high-radiation field.

Ionoluminescence of LiF and Al 2 O 3 crystals under high-energy heavy ion irradiation

Ionoluminescence of LiF and Al 2 O 3 crystals under high-energy heavy ion irradiation

Surface modification by high-energy heavy-ion irradiation in various crystalline ZnO facets.

Self-assembled surface nanoscale structures on various ZnO facets are excellent templates for the deposition of semiconductor quantum dots and manipulation with surface optical transparency. In this work, we have modified the surface of c-, m- and a-plane ZnO single-crystals by high-energy W-ion irradiation with an energy of 27 MeV to observe the aspects of surface morphology on the optical properties. We kept ion fluences in the range from 5 × 109 cm-2 to 5 × 1011 cm-2 using the mode of single-ion implantation and the overlapping impact mode to see the effect of various regimes on surface modification. Rutherford backscattering spectroscopy in the channeling mode (RBS-C) and Raman spectroscopy have identified a slightly growing Zn-sublattice disorder in the irradiated samples with a more significant enhancement for the highest irradiation fluence. Simultaneously, the strong suppression of the main Raman modes and the propagation of the modes corresponding to polar Zn-O vibrations indicate disorder mainly in the O-sublattice in non-polar facets. The surface morphology, analysed by atomic force microscopy (AFM), shows significant changes after ion irradiation. The c- and a-plane ZnO exhibit the formation of small grains on the surface. The m-plane ZnO forms a sponge-like surface for lower fluences and grains for the highest fluence. The surface roughness itself increases with the irradiation fluence as shown by AFM measurement as well as spectroscopic ellipsometry (SE) analysis. The damage caused by high-energy irradiation leads to non-radiative processes and suppression of the near-band-edge peak as well as the deep-level emission peak in the photoluminescence spectra. Furthermore, the refraction index n and the extinction coefficient k of irradiated samples, determined by SE, have features corresponding to the particular exciton states blurred and are slightly lower in the optical bandgap region especially for the polar c-plane ZnO facet.

Interface improvement of epitaxial 4H-SiC based Schottky didoes by selective heavy ion irradiation

This work reports selective high-energy heavy ions irradiation for improving the interfacial properties of epitaxial SiC-based Schottky barrier diode (SBD). Ni/4H-nSiC(0001) SBDs have been fabricated and irradiated using 200 MeV silver ions at a fluence of 1 × 1012 ions/cm2 in selective and in blanket ways under same experimental conditions. Electrical performance of the blanket way-irradiated SBD was found almost destroyed. In stark contrast, barrier height is enhanced from 1.16 eV to 1.41 eV and ideality factor reduced from 1.81 to 1.76 in selectively irradiated SBD. Moreover, interface trap/defect states density has been reduced from 1.56 × 1013 eV−1 cm−2 to 6.47 × 1012 eV−1 cm−2 after selective irradiation of SBD. Role of heavy ions irradiation-induced electronic excitations in refinement of atomic-scale interfacial defects/disorders of the SBD and, hence, modification in its electrical performance has been discussed. Photoluminescence studies are also performed to get insight into the measured device performance.

Evaluation Method of Heavy-Ion-Induced Single-Event Upset in 3D-Stacked SRAMs

The interaction of radiation with three-dimensional (3D) electronic devices can be determined through the detection of single-event effects (SEU). In this study, we propose a method for the evaluation of SEUs in 3D static random-access memories (SRAMs) induced by heavy-ion irradiation. The cross-sections (CSs) of different tiers, as a function of the linear energy transfer (LET) under high, medium, and low energy heavy-ion irradiation, were obtained through Monte Carlo simulations. The simulation results revealed that the maximum value of the CS was obtained under the medium-energy heavy-ion penetration, and the effect of penetration range of heavy ions was observed in different tiers of 3D-stacked devices. The underlying physical mechanisms of charge collection under different heavy-ion energies were discussed. Thereafter, we proposed an equation of the critical heavy-ion range that can be used to obtain the worst CS curve was proposed. Considering both the LET spectra and flux of galactic cosmic ray (GCR) and the variation in the heavy-ion Bragg peak values with the atomic number, we proposed a heavy-ion irradiation test guidance for 3D-stacked devices. In addition, the effectiveness of this method was verified through simulations of the three-tier vertically stacked SRAM and the ultrahigh-energy heavy-ion irradiation experiment of the two-tier vertically stacked SRAM. this study provides a theoretical framework for the detection of SEUs induced by heavy-ion irradiation in 3D-integrated devices.

Irradiation hardening of pure vanadium and vanadium alloys due to helium ion implantation and displacement damage

Pure V and V–5Cr–5Ti were irradiated by He and high-energy heavy ions to various doses. Nanoindentation was used to characterize the hardness change induced by ion irradiation. Under high-energy heavy ions irradiation, the hardness of pure V increased rapidly and saturated at very low damage level (0.03 dpa), the hardness of V–5Cr–5Ti increased slowly and tended to saturate at the damage higher than 0.4 dpa. In contrast to high-energy heavy-ion irradiation, more significant hardening occurred in both pure V and V–5Cr–5Ti under He ion irradiation. The significant hardening induced by He ion irradiation at the low dose was probably from the coarsening of dislocation loops due to the existence of He atoms in materials. TEM results revealed that He bubbles with high density have been formed in V–5Cr–5Ti at the high dose. The estimation based on the dispersion barrier hardening model suggested that He bubbles exhibited as weak obstacles due to the limitation of size, the major contribution to hardening was considered to be from dislocation loops.

Thermal conductivity measurement of the interaction layer between UMo and Al produced by high-energy heavy ion irradiation

Here, we report the first direct thermal conductivity measurement results for Al–UMo interaction layer (IL), which is typically observed in UMo/Al dispersion fuel plates under irradiation. The investigated IL was formed by irradiating Al coated UMo substrate using 80 MeV iodine ions at 180∘C up to 3.03×1017 ions/cm2 fluence. Microstructural characterization indicated that the induced IL is amorphous with an approximately (U0.8,Mo0.2)Al5.3 stoichiometry, which is similar to that formed under in-pile irradiation. Focused ion beam (FIB) was used to prepare nine specimens of various lengths from the IL that could be suspended across a microfabricated device for thermal conductivity measurement. The measured thermal conductivity values of the IL were significantly lower than the values for both the original UMo fuel and the Al. The successful measurement of the Al–UMo IL provides valuable information for the development and qualification of UMo/Al dispersion fuels for research and test reactor conversion applications, and further demonstrates the promising capabilities of utilizing the suspended bridge method in nuclear fuel research.

Effects of high energy heavy ion irradiation on resistive switches

Resistive switches have great potential in aerospace application due to their excellent radiation resistibility. It is important to study the effect of radiation on resistive switches. In this work, we use Ta5+ with an energy of 125 MeV to irradiate the Cu/Ta2O5/Pt devices. Here, fresh devices are irradiated by 108 and 109 ions/cm2 Ta5+, respectively. The devices exhibit high radiation resistibility under an irradiation dosage of 108 ions/cm2. However, the operating voltage was changed from 5 ~ −2 V to 2 ~ −1.5 V under a dosage of 109 ions/cm2. High energy heavy ion irradiation can controllably modify the density of defects or pores in resistive layer, reduce the barrier height of the redox reaction and achieve rapid migration of large amounts of ions. Moreover, the defects or pores generated by irradiation will provide growth paths for preventing conductive filaments from random growth and adjust the size of conductive filaments, making them more likely be in a stable state with the lowest energy and increasing the retention to be more than 8 × 104 s under a current compliance of 100 μA.

Multiphysics simulation of a superconducting bolometer working in a portable cryostat

We present the characterization and the numerical simulation of a high-temperature superconducting bolometer based on an YBa2Cu3O7-x (YBCO) film, which is patterned in serpentine elements and selectively modified by means of micro-collimated high-energy heavy-ion irradiation. The local irradiation of YBCO yields to a controlled reduction of the critical temperature and of the critical current, but the resistance versus temperature slope is preserved near Tc. In this way, only the irradiated part of the YBCO films is used for detecting infrared radiation, while the pristine one serves for electro-thermal feedback. The bolometer has been engineered in a portable cryostat, which is equipped with an optical window for suitably filtering the spectrum of the incoming electromagnetic radiation. The optimization of the cryostat has been performed with modelling by finite element method of the whole apparatus, along with simulations of the bolometer response.

Investigating the latent reliability degradation of partially depleted SOI devices induced by high-energy heavy ions irradiation

Through electrical stress and annealing experiments performed on irradiated partially depleted SOI MOS devices, high-energy heavy ions induced defects in the gate oxide are shown to affect insulation character and the long time reliability of the devices. A decrease of the time-dependent dielectric breakdown (TDDB) lifetime and an increase of the radiation-induced leakage current (RILC) were observed after irradiation at the nominal operating irradiation bias. But then, the RILC was completely removable using isochronal annealing experiment, while the TDDB lifetime did not increase back to its initial value. We interpreted these results and degeneration mechanisms in terms of the neutral electrons traps and morphological oxide defects induced by high-energy heavy ions, which may be meaningful to evaluate the reliability of the devices used in the radiation environment.

Interaction between Al and atomic layer deposited (ALD) ZrN under high-energy heavy ion irradiation

Uranium-molybdenum (U-Mo) particles dispersed in an aluminum matrix is the most promising candidate fuel to convert high-power research and test reactors in Europe from using high-enriched to using low-enriched fuel. However, chemical interaction between the U-Mo and the Al matrix leads to undesirable fuel behavior. Zirconium nitride (ZrN) is used as a diffusion barrier between the U-Mo fuel particles and the Al matrix. To understand the potential microstructural evolution of ZrN during irradiation, a high-energy heavy ion (84 MeV Xe) irradiation experiment was performed on atomic layer deposited (ALD) nanocrystalline ZrN deposited on an Al plate. A fluence of 1.86×1017 ions/cm2, or 90.3 dpa was reached during this experiment. Both analytic transmission electron microscopy (TEM) and synchrotron microbeam X-ray diffraction (μXRD) techniques were utilized to investigate the kinetics of radiation-induced grain growth of ZrN at various radiation doses based on the Williamson-Hall analyses. The grain growth kinetics can be described by a power law expression, Dn−D0n=Kϕ, with n = 5.1. The Al-ZrN interaction products (Al3Zr and AlN) created by radiation-induced ballistic mixing/radiation-enhanced diffusion and their corresponding formation mechanism were determined from electron diffraction and elemental composition analysis. These experimental results were confirmed by first principle thermodynamic density functional theory (DFT) calculations. The results from this ion irradiation study were also compared to in-pile irradiation data from physical vapor deposited (PVD) ZrN samples for a comprehensive evaluation of the interaction between Al and ZrN and its influence on diffusion barrier performance.

A small‐scale investigation process for the Clostridium acetobutylicum production of butanol using high‐energy carbon heavy ion irradiation

Applied heavy ion irradiation technology and butanol industrial practices as a whole have been used as a strategy for the development of an attractive alternative to petroleum-based fuels. Clostridium acetobutylicum (C. acetobutylicum) strains are well documented as fermentation strains for the production of biobutanol. However, it has been reported that solvent production inhibits the growth of these strains, and the accumulation of acetate also inhibits biomass synthesis, rendering the production of butanol from acetone-butanol-ethanol (ABE) fermentation processes economically challenging. In this manuscript, we propose the use of high-energy carbon heavy ion irradiation from the Heavy Ion Research Facility in Lanzhou (HIRFL) to obtain a culture with an increased butanol yield. Our findings suggest that the use of a high-energy 12C6+ heavy ion irradiation dose of 45 Gy with an energy of 135AMeV and ion pulses/levels of 106-108 favours ABE solvent production in an irradiated strain compared with the non-irradiated strain. The strategy reported in this manuscript may contribute to the development of a cost-effective butanol fermentation process that is competitive with similar fermentation processes.