High-energy Ion Beam Research Articles

Using TRIM-SRIM code simulations to determine defect density produced in HOPG irradiated with high energy heavy ions.

This work is part of the NUMEN Project (NUclear Matrix Elements for Neutrinoless double beta decay), which, among other goals, aims to measure cross-section of double charge exchange reactions (DCE). In the experiments to be carried out at the Laboratori Nazionali del Sud, in Catania, Italy, a target deposited on a carefully chosen backing (substrate) will be irradiated with a high energy ion beam and, importantly, neither the target nor the substrate will be allowed to overheat as this would affect their structures and its properties, which are special for the experiment. Within this context, highly oriented pyrolytic graphite (HOPG) was chosen as a substrate for the deposition of target elements that will be irradiated by ions such as 12C, 18O and 20Ne, with energies ranging from 15 MeV/u to 60 MeV/u. HOPG is considered a semimetal structured in layers, being composed of a stack of graphene sheets with a small and very subtle disorientation (less than 1°), which makes it to approach to a single crystal. With its specific flat hexagonal molecular structure, consisting only of carbon atoms, HOPG has good thermal conductivity in these sheets, making it an excellent candidate as a heat sink. However, for the HOPG to act with thermal energy dissipation functionality during the experiments proposed by the NUMEN project, it is necessary to verify whether possible changes caused by exposure to the radiation beam have a direct or indirect influence on its mechanical and thermal properties. Regarding the thermal conductivity, vacancies produced during irradiation is one of the factors that considerably decrease such property. As the production of vacancies during irradiation is one of the factors that considerably decrease thermal conductivity, in this work it was used the SRIM/TRIM code simulations to investigate the mechanisms of vacancy production in the target plus HOPG backing system. In the simulations, it was considered different types and doses of incident ion beams as well as different target thickness. From the results it was possible to estimated how long a target-HOPG system can be irradiated before the HOPG high heat conductivity property is lost.

Structural and chemical changes in He+ bombarded polymers and related performance properties

The paper presents the effect of He+ ion irradiation of selected polymeric materials: poly(tetrafloroethylene), poly(vinyl chloride), ethylene-propylene-diene monomer rubber, nitrile-butadiene rubber, styrene-butadiene rubber, and natural rubber, on their chemical composition, physical structure, and surface topography. The modification was studied by scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and differential scanning calorimetry. Irradiation with a high-energy ion beam leads to the release of significant amounts of hydrogen from the surface layer, resulting in an increase in cross-linking that manifests itself by shrinkage of the surface layer, which in turn causes significant stresses leading to the formation of a crack pattern on the polymer surface. The development of microroughness is combined with oxidation. Shallow range of the ions makes the modified layer “anchored” in the substrate via bulk macromolecules, assuring its good durability and adhesion to elasto-plastic substrates. Changes in the surface layer were manifested by the modification of functional properties of the polymers. The hardness of the layer subjected to the ion irradiation process increases even up to 10 times. After modification with the ion beam, a significant decrease in frictional forces was also observed, even up to 5–6 times. The microscopic analysis of wear traces confirmed that the wear resistance also significantly increased. However, ion bombardment of polymeric materials caused a reduction in their mechanical strength (despite the range limited to the surface layer of the order of micrometers) and electrical resistance, which has a negative impact on the possibility of using the materials in some applications.

The Damage Analysis for Irradiation Tolerant Spin-Driven Thermoelectric Device Based on Single-Crystalline Y₃Fe₅O₁₂/Pt Heterostructures

Spin-driven thermoelectric (STE) generation based on the combination of the spin Seebeck effect (SSE) and inverse spin Hall effect is an alternative to conventional semiconductor-based thermocouples as it is large scale, low cost, and environment-friendly. The STE device is thought to be radiation hard, making it attractive for space and nuclear technology applications. By using magnetometry, transmission electron microscopy, and the hard X-ray photoemission spectroscopy (HAXPES) measurements, we show that an STE device made of single-crystalline Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> (YIG)/Pt heterostructures has tolerance to irradiation of high-energy heavy ion beams. We used 200 MeV gold ion beams modeling cumulative damages due to fission products emitted from the surface of spent nuclear fuels. By varying the dose level, we confirmed that the thermoelectric and magnetic properties of the single-crystalline YIG/Pt STE device are finite at the ion-irradiation dose up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> ions/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> fluence. In addition, the HAXPES measurements were performed to understand the effects at the interface of YIG/Pt. The HAXPES data suggest that the chemical reaction regarding Fe and O that diminishes the SSE signals is promoted with the increase of the irradiation dose. The understandings of the damage analysis in YIG/Pt are beneficial for developing better STE devices applicable to harsh environmental usages.

Requirements and R&D for detectors at the future Electron–Ion Collider

The Electron–Ion Collider’s (EIC’s) ability to collide high-energy electron beams with high-energy ion beams will provide access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unique access to the spatial and spin structure of gluons and sea-quarks in the proton and light nuclei.The EIC will be an unprecedented collider with luminosities 2–3 orders of magnitude higher than previous e + p colliders over a very wide range of center-of-mass energies, from 20 to 140 GeV, while accommodating highly polarized electron and nucleon beams. Equally demanding are the requirements for the detector(s) that will be needed to carry out the physics program: hermetic coverage in tracking, calorimetry and particle ID within a wide pseudorapidity range, substantial angular and momentum acceptance in the hadron-going direction, as well as high quality hadronic calorimetry among others.This paper gives a brief overview of the detector requirements, current general-purpose detector concepts, and the ongoing EIC detector R&D efforts.

Radiation pressure acceleration of high-quality ion beams using ultrashort laser pulses

The generation of compact, high-energy ion beams is one of the most promising applications of intense laser-matter interactions, but the control of the beam spectral quality remains an outstanding challenge. We show that in radiation pressure acceleration of a thin solid target the onset of electron heating is determined by the growth of the Rayleigh-Taylor-like instability at the front surface and must be controlled to produce ion beams with high spectral quality in the light sail regime. The growth rate of the instability imposes an upper limit on the laser pulse duration and intensity to achieve high spectral beam quality and we demonstrate that under this optimal regime, the maximum peak ion beam energy per nucleon is independent of target density, composition, and laser energy (transverse spot size). Our predictions are validated by two- and three-dimensional particle-in-cell simulations, which indicate that for recent and upcoming experimental facilities using ultrashort ($\lesssim 25$ fs) laser pulses it is possible to produce $100 - 300$ MeV proton beams with $\sim 30\%$ energy spread and high laser-to-proton energy conversion efficiency.

Energy Distribution Functions of Ions Generated by a Circular-type Anode Layer Ion Source

An anode layer ion source, or an ALIS, is classified as a gridless ion source that produces a high-energy ion beam for either surface etching or thin film deposition. In the present work, the energy distribution functions of the ions generated in a circular ALIS were measured using a retarding field energy analyzer (RFA). Consequently, the average density and energy of the ions arriving at the ground surface were determined for the given range of process parameters. The IEDFs show two different groups of ions, namely, a narrow low energy group and a broad high energy group. The low-energy ions are probably generated in the background plasma and accelerated via the cathode sheath adjacent to the RFA. High-energy ions, on the other hand, are possibly generated in the discharge channel and gain an energy of up to 0.7eVanode through the anode sheath. The variations in average ion energies and densities as a function of process conditions could be due to the potential profile between the source and the ground surface.

High energy ion beams from the plasma focus

Instability development in the pinch induces a locally enhanced electric field that accelerates the charged particles to extraordinary high energies. Rapid discharge is the singular state of the ion source confirming high plasma impedance. High energy ion beam is correlated to the electrical discharge parameters and consequently the ion acceleration potential is directly related to the mean ion energy. Multi−MeV ions have been measured by magnetic spectrometry and nuclear activation yield-ratio to obtain the ion energy spectra and critically analyze the ion spectrum. A set of magnetic lens arranged in an optimized coil configuration results in medical grade radioactivity of 0.5GBq for a low energy plasma focus. High energy proton beams enables evaluating the sensitivity of link-board components and the error structure identification, with a significant probability of 0.1perproton.

Towards Next-Generation Small-Size Boron Ion Implanting Apparatus

Abstract The article provides a brief insight in the history of ion implantation, paying special attention to boron ion implantation in high purity Germanium crystal, exclusively valuable in the production of highly effective sensors of high-energy radiation to detect photons in the range of megaelectron-volt or higher up to hard X-ray range. There is a need for small user-friendly implanters in response to urgent demand to scale up production of short wave sensors, which are in exclusive demand for various nuclear safety systems worldwide. Particularly, research driven “high tech” small and medium enterprises in Latvia are among the three leading worldwide producers of such sensors and systems. These SME provide instrumentation to the International Atomic Energy Agency, to the government of Singapore, to the government of Japan to facilitate dealing with nuclear waste management caused by the Fukushima disaster, and to the European Space Agency. The challenge is to find technology that allows the use of solid state boron as ion sources instead of its chemical compounds, which create too many technological difficulties in the beam forming process and in most cases are poisonous. The review of existing solutions points towards a possible breakthrough where hollow cathode plasma combined with radiofrequency inductive coupled plasma can be used to produce boron ions from elemental boron in sufficient quantity to form a high energy ion beam close to 100 kV. Based on the review, promising solutions are offered, the first results of relevant analytic and pilot experiments are analysed and the future experimental roadmap is discussed.

Impact of Radiation Quality on Microdosimetry and Chromosome Aberrations for High-Energy (>250 MeV/n) Ions

Studying energy deposition by space radiation at the cellular scale provides insights on health risks to astronauts. Using the Monte Carlo track structure code RITRACKS, and the chromosome aberrations code RITCARD, we performed a modeling study of single-ion energy deposition spectra and chromosome aberrations for high-energy (>250 MeV/n) ion beams with linear energy transfer (LET) varying from 0.22 to 149.2 keV/µm. The calculations were performed using cells irradiated directly by mono-energetic ion beams, and by poly-energetic beams after particle transport in a digital mouse model, representing the radiation exposure of a cell in a tissue. To discriminate events from ion tracks directly traversing the nucleus, to events from δ-electrons emitted by distant ion tracks, we categorized ion contributions to microdosimetry or chromosome aberrations into direct and indirect contributions, respectively. The ions were either ions of the mono-energetic beam or secondary ions created in the digital mouse due to interaction of the beam with tissues. For microdosimetry, the indirect contribution is largely independent of the beam LET and minimally impacted by the beam interactions in mice. In contrast, the direct contribution is strongly dependent on the beam LET and shows increased probabilities of having low and high-energy deposition events when considering beam transport. Regarding chromosome aberrations, the indirect contribution induces a small number of simple exchanges, and a negligible number of complex exchanges. The direct contribution is responsible for most simple and complex exchanges. The complex exchanges are significantly increased for some low-LET ion beams when considering beam transport.

Completion of JT-60SA construction and contribution to ITER

Construction of the JT-60SA tokamak was completed on schedule in March 2020. Manufacture and assembly of all the main tokamak components satisfied technical requirements, including dimensional accuracy and functional performances. Development of the plasma heating systems and diagnostics have also progressed, including the demonstration of the favourable electron cyclotron range of frequency (ECRF) transmission at multiple frequencies and the achievement of long sustainment of a high-energy intense negative ion beam. Development of all the tokamak operation control systems has been completed, together with an improved plasma equilibrium control scheme suitable for superconducting tokamaks including ITER. For preparation of the tokamak operation, plasma discharge scenarios have been established using this advanced equilibrium controller. Individual commissioning of the cryogenic system and the power supply system confirmed that these systems satisfy design requirements including operational schemes contributing directly to ITER, such as active control of heat load fluctuation of the cryoplant, which is essential for dynamic operation in superconducting tokamaks. The integrated commissioning (IC) is started by vacuum pumping of the vacuum vessel and cryostat, and then moved to cool-down of the tokamak and coil excitation tests. Transition to the super-conducting state was confirmed for all the TF, EF and CS coils. The TF coil current successfully reached 25.7 kA, which is the nominal operating current of the TF coil. For this nominal toroidal field of 2.25 T, ECRF was applied and an ECRF plasma was created. The IC was, however, suspended by an incident of over current of one of the superconducting equilibrium field coil and He leakage caused by insufficient voltage holding capability at a terminal joint of the coil. The unique importance of JT-60SA for H-mode and high-β steady-state plasma research has been confirmed using advanced integrated modellings. These experiences of assembly, IC and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.

Evaluation of AES depth profiles with serious artefacts in C/W multilayers

Ion beam mixing was applied to produce tungsten carbide nano-layers in C/W nano-multilayer structures, which was studied by Auger electron spectroscopy depth profiling. The destructive AES depth profiling caused serious artefacts such as tungsten-carbide production at the interfaces, even when choosing the optimal sputter removal conditions. Here we show that ion mixing due to the AES depth profiling could be described by TRIDYN simulation, and compound formation could be also estimated by introducing a simple model. Thus, despite the serious artefact production the original pristine depth distribution could be reconstructed. This evaluation method has been checked on C/W layer systems containing tungsten-carbide enrichment in the interface region (due to high energy ion beam mixing); the true in-depth distribution could be reconstructed. It has been found also that with increasing carbide formation the artefact production decreases allowing the use the AES depth profiling without reconstruction.

Laboratory Simulation of Solar Wind Interaction With Lunar Magnetic Anomalies

AbstractMagnetic anomalies on the surface of the Moon interact with the solar wind plasma flow, resulting in both magnetic and electrostatic deflection/reflection of charged particles. Consequently, surface charging in these regions differs from regions without magnetic fields. Using the Colorado Solar Wind Experiment facility, this interaction is investigated with high‐energy flowing plasmas (100–800 eV beam ions) that are incident upon a magnetic dipole embedded beneath an insulating surface. The dipole moment is perpendicular to the surface. The plasma potential distribution is measured above the surface using an emissive probe. In the dipole lobe regions the surface is charged to significantly higher positive potentials by the un‐magnetized ion beam impinging on the surface while the electrons remain excluded by the magnetic field. At low ion beam energies the results agree with these expectations as the surface potential follows the ion beam energy. However, at high beam energies, the surface potentials in the electron‐shielded lobe regions remain significantly lower than the expected magnitude. Surprisingly, electrons are detected in the shielded regions by a Langmuir probe. A test particle simulation indicates that secondary electrons induced by the high energy ion beams impinging on the surface can enter the shielded regions, thus lowering the surface potential.

Vacuum System Optimization for EAST Neutral Beam Injector

The neutral beam injector (NBI) generates a high-energy ion beam and neutralizes it, and then relies on drift transmission to inject the formed neutral beam into the fusion plasma to increase the plasma temperature and drive the plasma current. In order to better cooperate with the Experimental Advanced Superconductive Tokamak (EAST), part of the Chinese major national scientific and technological infrastructure, in carrying out long-pulse high-parameter physics experiments of 400 s and above, this paper considers the optimization of the current design and operation of the NBI beam line with a pulse width of 100 s. Based on an upgraded and optimized NBI vacuum chamber and the structure of the beam-line components, the gas-source characteristics under the layout design of the NBI system are analyzed and an NBI vacuum system that meets relevant needs is designed. Using Molflow software to simulate the transport process of gas molecules in the vacuum chamber, the pressure gradient in the vacuum chamber and the heat-load distribution of the low-temperature condensation surface are obtained. The results show that when the NBI system is dynamically balanced, the pressure of each vacuum chamber section is lower than the set value, thus meeting the performance requirements for the NBI vacuum system and providing a basis for subsequent implementation of the NBI vacuum system upgrade using engineering.

Mechanical properties of amorphous SiCN films deposited by ion-beam-assisted deposition

This study discusses the fabrication of amorphous silicon carbon nitride (a-SiCN) films by ion-beam-assisted deposition (IBAD) and investigates their hardness and frictional properties. The a-SiCN films are deposited by IBAD via electron beam evaporation of graphite and Si under simultaneous nitrogen ion-beam bombardment at acceleration voltages of 0–15 kV. The a-SiCN films are deposited at acceleration voltages of 0, 0.2, 10, and 15 kV. The films are not deposited via nitrogen ion-beam irradiation at 0.5 or 1.0 kV. The a-SiCN films deposited at 0, 0.2 and 15 kV are primarily composed of C. However, the a-SiCN films deposited at 10 kV are primarily composed of Si. The chemical bond of the a-SiCN films, measured via X-ray photoelectron spectroscopic analysis, is dominant in the CC bonds in the C1s spectra. The a-SiCN film deposited at 0 kV demonstrates a hardness value of 19.5 GPa, whereas the a-SiCN films deposited at 0.2, 10 and 15 kV exhibit hardness values in the range of 25–34 GPa. The hardness of the a-SiCN films depended on the ion beam acceleration voltages. The friction coefficient of the a-SiCN film with a high CC bond content against a steel ball is as low as 0.07. In summary, the a-SiCN films deposited with a high-energy ion beam of 15 kV exhibit a high hardness level and a low friction coefficient.

Defects engineering and enhancement in optical and structural properties of 2D-MoS2 thin films by high energy ion beam irradiation

Transition metal dichalcogenides (TMDs) like molybdenum disulfide (MoS2) have extra-ordinary physical and chemical peculiarities which can be additionally modified by ion beam irradiation. In the present work, we illustrate the tailoring of MoS2 thin films by employing ion beam irradiation. Silicon ion beam with 100 MeV energy was used to have an apparent impact on structural, morphological and optical properties of MoS2 thin films. Sputtered MoS2 films were irradiated with 100 MeV Si8+ ion beam with a fluence of 1E13 ions/cm2. The X-ray diffraction (XRD) technique validates the structural analysis of MoS2 films with hexagonal phase and reduction in the crystallinity is observed after irradiation owing to the generation of defects by high energy ion beam irradiation. MoS2 thin films display Raman modes at ⁓378 cm−1 and ⁓411 cm−1 corresponding to the one molybdenum atom and two sulfur atoms of the same layer vibrates in the converse in-plane and out-of-plane direction respectively. Intensity of Raman peaks is reduced after the employment of ion beam irradiation. Slight reduction in transmittance is observed after irradiation. The intensity of broad PL emission spectra observed at 360 nm showed the enhancement in PL intensity after ion beam irradiation. Rutherford backscattering spectroscopy (RBS) substantiated the presence of molybdenum (Mo) and sulfur (S) elements and 440 nm thickness of the samples. The investigation of the thickness and atomic fraction of the specimen was also governed by simulating the RBS spectrum using SIMNRA software. To demonstrate the changes occur in grain size and surface roughness parameters in ion irradiated and pristine MoS2 thin films were analyzed by AFM (atomic force microscopy). The alterations of binding energy of Mo 3d and S 2p region of MoS2 pristine and ion irradiated thin films were analyzed by X-ray photoelectron spectroscopy (XPS).

Preparation strategy for statistically significant micrometer-sized particle systems suitable for correlative 3D imaging workflows on the example of X-ray microtomography

The characterization of multidimensional particle property distributions through computed tomography requires an adapted sample preparation strategy. This strategy should both generate as many spatially separated particles as possible in the smallest achievable volumes and also enable mechanically and vacuum-stable samples that are suitable for correlative measurement, for example with high-energy ion beam methods. In the present study an epoxy-based method is presented that minimizes the negative influence of particle sedimentation by adding very low X-ray absorbing graphite nanoparticles as spacer. A machine learning-based method is presented to discretize the particle system. Results are compared with data from 2D SEM validation measurements and data of a previous study.

A Concept for Reconstruction of the Capsulated Microchip Structure Using Its Interaction with High-Energy Ion Beams of the NICA Accelerator Complex

A Concept for Reconstruction of the Capsulated Microchip Structure Using Its Interaction with High-Energy Ion Beams of the NICA Accelerator Complex

Large enhancement of magnetic moment in nitridated CeFe12

Due to success of desired doping, ion implantation has been widely used for semiconductor processing. In this work, we used nitrogen ion implantation to enhance magnetism in CeFe12 epitaxial thin films. To optimize nitrogen contents in CeFe12 and minimize the damage caused by the high-energy ion beam, we varied the thickness of the capping Mo layer. The saturation magnetization increased nearly 25% by nitrogen ion implantation into CeFe12 thin film. This phenomenon is explained by density functional theory calculations and confirmed by the magnetic resonance technique. The ion implantation and design strategy can be used for light-ion implantation into lattices to modulate magnetic, optical, and electrical properties.

High energy (MeV) ion beam induced modifications in Al2O3-ZnO multilayers thin films grown by ALD and enhancement in photoluminescence, optical and structural properties

Atomic Layer Deposition (ALD) is employed for the growth of nanometric conformal layers on distinct substrates. In the present work, we demonstrated the attainable consequences on the examination of optical and structural peculiarities of pristine and SHI (swift heavy ions) irradiated ultrathin multilayer samples of Al2O3-ZnO fabricated on glass and silicon substrates using the technique based on ALD. Multilayer Al2O3-ZnO specimens were irradiated with 100 MeV SHI in the fluence range of 1E12 to 5E13 ions/cm2. For a better conception of the impact of ion beam irradiation with high energy on structural parameters like strain, dislocation density, crystallite size was demonstrated by X-Ray Diffraction (XRD). The coefficient of absorption was used to demonstrate the changes that occur in optical bandgap, urbach energy, skin depth and optical density with the function of ion fluence. Photoluminescence (PL) spectra were investigated at room temperature to comprehend the mechanism of changes in peak shifting and intensity of broad and strong emission luminescence spectra at excitation wavelengths of 300 nm were noteworthy. To evaluate the thickness, crystalline quality and quantitative composition of the elements Rutherford Backscattering Spectroscopy (RBS) employing utilizing the He2+ with high energy was used and reported. Regulation of optical peculiarities through swift heavy ion beam irradiation explores extensive opportunities for Al2O3-ZnO multilayer nanofabrication in optoelectronics domain.

Identification and characterization of inheritable structural variations induced by ion beam radiations in rice.

High energy ion beams are effective physical mutagens for mutation induction in plants. Due to their high linear energy transfer (LET) property, they are known to generate single nucleotide variations (SNVs) and insertion/deletions (InDels, <50 bp) as well as structural variations (SVs). However, due to the technical difficulties to identify SVs, studies on ion beam induced SVs by genome sequencing have so far been limited in numbers and inadequate in nature, and knowledge of SVs is scarce with regards to their characteristics. In the present study, we identified and validated SVs in six M4 plants (designated as Ar_50, Ar_100, C_150, C_200, Ne_50 and Ne_100 according to ion beam types and irradiation doses), two each induced by argon (40Ar18+), carbon (12C6+) and neon (20Ne10+) ion beams and performed in depth analyses of their characteristics. In total, 22 SVs were identified and validated, consisting of 11 deletions, 1 duplication, and 4 intra-chromosomal and 6 inter-chromosomal translocations. There were several SVs larger than 1 kbp. The SVs were distributed across the whole genome with an aggregation with SNVs and InDels only in the Ne_50 mutants. An enrichment of a 11-bp wide G-rich DNA motif 'GAAGGWGGRGG' was identified around the SV breakpoints. Three mechanisms might be involved in the SV formation, i.e., the expansion of tandem repeats, transposable element insertion, and non-allelic homologous recombination. Put together, the present study provides a preliminary view of SVs induced by Ar, C and Ne ion beam radiations, and as a pilot study, it contributes to our understanding of how SVs might form after ion beam irradiation in rice.