Search

For water radiolysis, conventional simulation methods estimate free radical yields based on the cross-sections. Our results indicated that electron dynamic motion must be further solved to predict the initial yields of hydrated electrons.

To gain insight into complex ion–molecule reactions induced by MeV-energy heavy ion irradiation of condensed matter, we performed a mass spectrometric study of secondary ions emitted from methanol microdroplet surfaces by 2.0 MeV C²⁺. We observed positive and negative secondary ions, including fragments, clusters, and reaction products. We found that a wider variety of negative ions than positive ions (such as C₂H⁻, C₂HO⁻, C₂H₅O⁻, and C₂H₃O₂⁻) were formed. We performed measurements for deuterated methanol (CH₃OD) droplets to identify the hydrogen elimination site of the intermediates involved in the reactions and to reveal the mechanism that generates various negative reaction product ions. Comparing the results of CH₃OD with CH₃OH droplets, we propose that the primary formation mechanism is association reactions of anion and neutral fragments, such as CH₃O⁻ + CO → C₂H₃O₂⁻. Quantum chemical calculations confirmed that the reactions can proceed with no barrier. This study provides new insights into the importance of rapid anion–molecule reactions among fragments as the mechanism that generates complex molecular species in fast heavy-ion-induced reactions.

We report first experimental results on the orientation effect of fast diatomic molecular projectiles on secondary ion emission processes for 3.6-MeV C2+ traversing a self-supporting target of phenylalanine (Phe) film evaporated on a carbon foil. Coincidence measurements were performed on the image of fragments resulting from the Coulomb explosion of C2+ projectiles and the time-of-flight mass spectrometry of secondary ions emitted from the Phe film. We compared the secondary ion yield for C2+ projectiles with parallel and perpendicular orientations to the beam direction. The parallel orientation was found to enhance the secondary ion yield by a factor of approximately 1.1 compared with that for the perpendicular orientation. This enhancement corresponds to an increase in the average charge of Coulomb-exploded fragments. This finding implies that there is a linear correlation between the electronic energy deposition causing secondary ion production and the effective charge number of the incident molecular ions which interact with biomolecular targets.

A Fe-based multi-component alloy, 60Fe-12Cr-10Mn-15Cu-3Mo, which presents higher yield stress than typical stainless steels (such as 304, 316, and 340), was used to investigate the thermal stabilit...

We study morphological changes on the Si surface induced by the C60 ion beam under various irradiation conditions. The fluence and incident energy of the C60 ion beam was 1 × 1016–1 × 1019 ions/m2 and 50 keV–9 MeV, respectively. The beam’s incident angle to the surface normal was 0° or 60°. As a result of the changes in these variables, three types of nanostructures were observed: concave and convex, stringlike, and ripple structures. Structure shapes or sizes varied with changes in the parameters. Almost all cases showed concave and convex structures at an incident angle of 0°. At a 60° incident angle, stringlike or ripple structures were formed. Stringlike structures were formed at higher incident energy, while ripple structures were formed at lower incident energy. We found that both stringlike and ripple structures can form from sputtering and thermal effects. The formation of string structure requires a thicker amorphous layer and the proper balance of sputtering and annealing.

Special Issue: Proceedings of the 19th International Conference on the Physics of Highly Charged Ions (HCI 2018), Caparica, Lisboa, Portugal, 3‐7 September 2018

We present experimental results that show the secondary-ion yield depends on the structure and orientation of incident cluster ions. A beam of carbon-cluster ions ${{\mathrm{C}}_{n}}^{+}$ ($n\ensuremath{\le}4$) with an energy of 0.9 MeV per atom, which were obtained from a tandem electrostatic accelerator, was incident on a glycine target deposited on a carbon foil. The structure and orientation of the cluster ions after passing through the target were determined by the Coulomb explosion imaging method, and the positive secondary ions were simultaneously measured by time-of-flight mass spectrometry. When looking at the orientation dependence of linear structured ${{\mathrm{C}}_{2}}^{+}, {{\mathrm{C}}_{3}}^{+}$, and ${{\mathrm{C}}_{4}}^{+}$ projectiles, parallel orientations with respect to the beam direction were found to enhance the secondary-ion yield compared with perpendicular orientations. Additionally, comparison of the structure dependence of ${{\mathrm{C}}_{3}}^{+}$ and ${{\mathrm{C}}_{4}}^{+}$ projectiles with linear and ring structures showed that the secondary-ion yield was larger for linear structures. Interestingly, there was a clear correlation between the secondary-ion yield and the deposited energy density in the cluster-ion track. The energy density was calculated with electronic stopping power for incident cluster ions using linear-response dielectric theory and the cross section of the track of the incident cluster considering its geometrical structure and orientation. These results suggest that the deposited energy density in the cluster-ion track is a key parameter in the secondary-ion emission process induced by swift cluster-ion impacts.

Ion beam irradiation of Si induces the formation of fine structures on the surface by sputtering. In this study, the energy dependence of the formed structures was investigated by electron microscopy using fast C60 cluster ion beams. The size of the structures increases with increasing energy.

In this work, we measured and simulated the dissociation of biomolecules in liquid water induced by secondary electrons ejected from water molecules during fast heavy-ion irradiation. We calculated the energy spectra of secondary electrons generated along carbon ion tracks in liquid water in the Bragg peak region. The calculation was done using the Particle and Heavy Ion Transport code System (PHITS) in carbon track structure mode. This mode enables simulation of inelastic collisions along a carbon ion track based on the cross sections considered in the Monte Carlo code KURBUC. To understand the biomolecular dissociation processes in our previous MeV-SIMS experiments with microdroplet targets of glycine solution, we calculated the collision spectra of secondary electrons produced near liquid surfaces using PHITS. Furthermore, we examined the relationship between the secondary electron energy and formation of positive and negative glycine fragments. The results showed that the formation of methylene amine cations is caused by secondary electrons with energies of 13–100 eV. The formation of glycine-related negative ions such as cyanide anion, formate anion, and deprotonated glycine was found to be caused by low-energy (less than 13 eV) secondary electrons. These ions are known products of dissociative electron attachment.

In this study, the recurrent fluorescence of naphthalene ions was investigated using an electrostatic ion beam trap. The number of photons from the recurrent fluorescence on the ${D}_{2}\ensuremath{\rightarrow}{D}_{0}$ transition was measured as a function of time, after the production of naphthalene ions by electron impact. The emission of photons was observed over a time range of approximately 10 ms. The variation in the number of photons for such a long time range could be explained by conducting simulations using previously reported theoretical rate constants of both the fragmentation and the recurrent fluorescence of vibrationally hot naphthalene ions.

In this paper, we performed PIXE analysis of trace elements in freshwater pearls cultured in four different areas: Lake Biwa (Japan), Lake Kasumigaura (Japan), an unidentified lake in China, and Kentucky Lake (USA). We investigated the difference of trace elements contained in the four pearls from different aquaculture environments. The observed trace elements are Mn, Fe, Cu, Zn, and Sr. The major trace elements are Mn, Sr for all the samples. From comparison of the proportions of elements contained, we found the following features: (1) The Kasumigaura pearl has a nucleus with a high Mn/Sr ratio, (2) The Biwako pearl is low in iron content, and (3) The American pearl has high in Fe/Sr, Cu/Sr, and Zn/Sr ratios.

The experimental results are reported on Ni/Si/LiPON/LCO/Pt/Ti and Au/Si/LiPON/LCO/Au batteries prepared on SiN and Al self-supporting films (LiPON = Li3.3PO3.8N0.2, LCO = LiCoO2) which have been in situ measured simultaneously by Transmission ERD and RBS techniques with 5 MeV He+2 ion beam, in order to understand Li transport from positive electrode (LCO) to negative electrode (Si) under charging and over-charging. It has been found on over-charging that for the former battery Li ions over-flowed out of Si reacts with Ni electrode in the follow direction, whereas for the latter battery Li once charged in Si returns back through LiPON to LCO in the counter direction and reacts with Al through intermediate Au. Quite different two transport phenomena of Li on over-charging are discussed in terms of transport process of Li through LiPON, the difference in Fermi energies of the metal electrodes at both sides of LCO/LiPON/Si and in contact potentials of Si with the metal electrodes.

Li depth profiles in Au/Si/LiPON/LCO/Au (LCO = LiCoO2, LiPON = Li3.3PO3.8N0.2) thin films battery under charging condition, prepared on self-supporting Al substrate, have been in situ measured by means of transmission elastic recoil detection (TERD) and Rutherford backscattering spectroscopy (RBS) techniques not only with 5.4 MeV He2+ ion beam without absorber, but also 9 MeV O4+ ion beam with Al absorber. In experiments with 5.4 MeV He2+, well-resolved step-wise TERD spectra have been observed, from which thickness and Li composition of constituent films of the battery are directly estimated. The Li transport from LCO to Si films through LiPON as well as return-back of Li from Si to LCO films and Li leakage into the Al substrate out of the battery system by over-charging under charging condition have been observed in the experiments both 5.4 MeV He2+ and 9 MeV O4+. The latter result indicates that these techniques are applicable to testing degradation of the battery performance by repetition of charging and discharging. Both results are compared in details with each other.

We have investigated the negative and positive secondary ions emitted from ethanol droplets by 4.0-MeV C3+ impact to reveal the characteristic features of the reaction processes induced by fast heavy ions at the liquid ethanol surface. Analysis of the secondary ions was performed by time-of-flight mass spectrometry for microdroplet targets in a high vacuum environment. Fragment ions, deprotonated cluster ions, and trace amounts of the reaction product ions are observed in the negative secondary ions. The main fragment anions are C2HmO− (m = 1, 3, and 5) and C2H− generated by loss of hydrogen and oxygen atoms. The reaction product anions include deprotonated glycols, larger alcohols, and their dehydrated and dehydrogenated forms generated by secondary reactions between fragments and radicals. Furthermore, C3Hm− (m = 0–2) and C4Hm− (m = 0 and 1) are observed, which could be produced through a plasma state generated in the heavy ion track. Deprotonated ethanol cluster ions, [(EtOH)n − H]−, are observed up to about n = 25. [(EtOH)n − H]− have smaller kinetic energies than the protonated cluster ions (EtOH)nH+. This probably represents the effect of the positive Coulomb potential transiently formed in the ion track. We also discuss the size distributions and structures of the water- and CH2OH-radical-attached ethanol cluster ions.

We study the ion-irradiation-induced deformation of free-standing ultrathin Si wafers with a thickness of 8 [Formula: see text]m. The time-response spectrum of the deformation was measured using a laser displacement meter with a time resolution of 1 ms. The results showed that the deformation appeared during irradiation and disappeared after irradiation. The deformation was composed of a fast deformation with a millisecond time constant and a slow deformation with a second time constant. We performed a model calculation to identify the deformation mechanisms. We found that the fast deformation originated from expansion or shrinkage of crystal lattice caused by beam heating and deduced that the slow deformation resulted from the topological defect formation in Si crystals. The relaxation time of the slow deformation is related to the coordination number of disappeared topological defects. In this experiment, we conclude that the deformation of Si crystals maintains reversible behavior in the formation of topological defects up to the coordination number 5.

A high-entropy alloy (HEA), (CoCrFeNi)95Ti1Nb1Al3, with a tensile strength approximately 60% higher than that of the equiatomic high-entropy alloy CoCrFeNi was developed. The increase in tensile strength results from the formation of Ni, Ti, Nb, and Al-rich precipitates, having a face-centered cubic (FCC) L12 type crystal structure, in the alloy during aging. To investigate the irradiation resistance of this alloy, it was irradiated up to 1.5×1019 ions/m2, corresponding to 1.65 displacements per atom (dpa) at the peak damage, at 300, 573, and 773 K using high-energy 2.5 MeV Fe ions. Applying a slow positron beam, the formation of defect clusters induced by ion irradiation and the thermal stability of defects formed at 300 K were investigated. Vacancy clusters formed after irradiation with 5.0×1018 ions/m2 at 300 K. Irradiation above this fluence at 300 K, and at the same fluence at 573 K did not significantly affect the formation of vacancy clusters. However, no vacancy clusters were formed after irradiation at 5.0×1018 ions/m2 at 773 K. The high-temperatures irradiation of this HEA hinders the formation of vacancy clusters. The irradiation resistance of the (CoCrFeNi)95Ti1Nb1Al3 HEA was excellent.

The radiative lifetimes of Xe3+ ions in the metastable 5s25p3 2P3/2 and 2P1/2 states were measured by using an electrostatic ion beam trap. The lifetimes were obtained by measuring the number of photons emitted during the 2P3/2 → 2D3/2 (447 nm) and 2P1/2 → 4S3/2 (357 nm) forbidden transitions of Xe3+, as a function of the storage time. The storage lifetime of the Xe3+ was simultaneously measured by detecting the Xe ions with changed charge escaping from the trap, which yielded information pertaining to the correction of the collision-induced loss of Xe3+ in the trap. The obtained lifetimes of 7.0 ± 0.2 ms for the 2P3/2 state and 16.6 ± 0.8 ms for the 2P1/2 state were compared with previously reported theoretical and experimental values.

Mo/Zr were added to further improve the mechanical properties of W-Y2O3 alloys, thus improving W ductility due to the addition of Y2O3 nanoparticles. Herein, the effects of minor addition of elemental Mo/Zr and Fe-ion pre-irradiation on D retention in W-Y2O3 alloys were investigated. The maximal fluence of W-1 wt.%Mo-0.25 wt.%Y2O3 and W-0.1 wt.%Zr-0.25 wt.%Y2O3 samples irradiated with 5-keV-energy D2 ions was 1022 D2/m2, and Fe-ion pre-irradiation was performed at ion fluences of up to 4 × 1018 /m2 at the energy of 1 MeV. For both alloys, the D desorption amount increased with increasing D2-ion irradiation fluence, regardless of Fe-ion pre-irradiation. Compared with W-Y2O3, the overall amount of the D desorption increased for both alloys without Fe-ion pre-irradiation. However, it decreased for both alloys with Fe-ion pre-irradiation, when the D2-ion irradiation fluence was 1022 D2/m2. The addition of Mo/Zr prevented the diffusion of D from the surface to the inside of the sample. Therefore, Fe-ion pre-irradiation had a negligible effect on D desorption in the Mo- or Zr-added W-Y2O3 alloys. Changes in the microstructures of the W alloy owing to the addition of minor elements strongly affected the D desorption. The addition of Mo promoted the formation of dislocation loops during the D2-ion irradiation. In contrast, the addition of Zr refined the Y2O3 particles. These defects served as D trapping sites, thereby weakening the pre-irradiation effect of Fe ions.

Change in Li depth profiles of Ti/NbO/LiPON/LMO/Ti and Ti/LMO/LiPON/NbO/Ti (NbO=Nb2O5, LiPON=Li3.3PO3.8N0.2, LMO = LiMn2O4) batteries prepared on Si substrate on one cycle of charging and discharging has been in-situ measured from both Ti/NbO and Ti/LMO sides by ERD (elastic recoil detection analysis) and RBS (Rutherford backscattering spectroscopy) techniques with 9 MeV O+4 ion beam, in order to understand Li transport between NbO to LMO. It is found that on over-charging of the Ti/NbO/LiPON/LMO/Ti battery Li charged in NbO diffuses into top Ti film, but on the Ti/LMO/ LiPON/NbO battery Li does not diffuse into bottom Ti film, but returns back to LMO, reacts with top Ti film and segregates at the Ti surface. The difference in Li transport in both batteries is discussed in terms of the difference in Fermi levels at the interfaces of LMO/Ti and NbO/Ti on the Si substrate.

We have investigated multiple ionization and fragmentation of 1,1,1,2-tetrafluoroethane (CF3–CH2F) in charge-changing collisions with 580-keV C+. By measuring the number of emitted electrons in each collision, we obtained the charge state (r) distribution of multiply ionized CF3–CH2Fr+* ions transiently formed as intermediate states prior to fragmentation. The mean charge states of CF3–CH2Fr+* in single-electron (1e)-capture, 1e-loss, and double-electron-loss collisions were determined to be 1.9, 3.2, and 4.0, respectively. Time-of-flight mass spectra of the product ions from CF3–CH2Fr+* were obtained as a function of r from coincidence measurements with the number of emitted electrons. Production of specific fragment ions and variation of the fragmentation patterns were systematically revealed up to r = 4. For example, it was found that proton emission becomes the dominant decay process from multiply ionized CF3–CH2Fr+. The results also show that coincidence measurements can distinguish ion species with the same mass-to-charge ratio but different charge states. The characteristic features of the fragmentation processes of CF3–CH2Fr+* were investigated by the correlation among the product ions for r ≥ 2. C+ and C2+ fragment ions are emitted to the same side as H+ even at r = 2, reflecting the structural feature of the asymmetric location of the heavier atoms (F) in the molecule.

We measure kinetic energy distributions (KEDs) of product ions from singly and multiply ionized acetylene, C2H2r+∗ (r = 1–4), generated as intermediate states prior to fragmentation in collisions between C2H2 and 0.8 MeV C+ ions, in single-electron capture conditions. The KEDs are systematically obtained as functions of the charge state r by performing coincidence measurements between momentum imaging of the product ions and counting of the number of emitted electrons. The KEDs of the fragment ions exhibit a variety of dependences on r, reflecting the variation of fragmentation dynamics and dominant fragmentation pathways. In particular, the KEDs of C2+ present a characteristic dependence on r because of the different symmetries of charge distributions in three-body fragmentation.

The radiative lifetime of the 3s23p4 1S0 metastable state of Ar2+ was measured using an electrostatic ion beam trap. The lifetime was obtained by measuring the number of photons emitted during the 1S0 → 3P1 magnetic dipole transition of Ar2+ as a function of the storage time. The wavelength of the photons was 311 nm. To correct for the collision-induced loss of Ar2+ ions in the trap, the storage lifetime of the Ar2+ beam was measured simultaneously by detecting Ar neutrals escaping from the trap. The obtained radiative lifetime was 157 ± 19 ms, which was comparable to previously reported theoretical and experimental values.

The influence of secondary electrons on radiation damage of biomolecules in water was studied by fast heavy-ion irradiation of biomolecular solutions. Water microdroplets containing the amino acid glycine under vacuum were irradiated by fast carbon projectiles with energies of 0.8–8.0 MeV. A variety of fragments from the droplets were observed by time-of-flight secondary-ion mass spectrometry: methylene amine cation and formate anion originating from the cleavage of C–Cα bonds, cyanide anion generated by cleavage of multiple bonds, and protonated and deprotonated glycine. The dependence of the yield of each fragment on projectile energy was examined; different behavior was observed for positive and negative fragments. Considering that biomolecular fragmentation may be induced by secondary electrons ejected from the water molecules surrounding biomolecules, we calculated the cross section for ejection of secondary electrons from liquid water. We found that the formation of both positive and negative glycine fragment ions correlated with the predicted emission of secondary electrons at different projectile energies. The formation of [Gly–H]− fragments, typical for gas phase dissociative electron attachment to amino acids, is shown to be caused by electrons from the low-energy part of the secondary electron distribution.

Cultured pearls are formed in pearl sacs comprising epithelial cells transplanted into mother-of-pearl. The formation mechanism is complicated and is still not fully understood. Previous studies have shown that the pearl formation is influenced by aquaculture environment and physiological activity of shellfish. The elemental compositions of seawater and freshwater pearls are significantly different. In this work, we used the particle-induced X-ray emission (PIXE) technique to perform elemental analysis of six types of pearls: ordinary and blue Akoya pearls, black-, gold-, and white-lipped oyster pearls, and freshwater Biwako pearl. We investigate the influence of trace elements in aquaculture environments on formation of mother-of-pearl or color. The Mn/Sr or Fe/Sr ratio for the freshwater pearl was found to be significantly higher than that for the seawater pearl. Comparing the sweater pearls, the gold-lipped oyster pearl has high value of Mn/Sr ratio. The Fe/Sr and Cu/Sr ratios for two Akoya pearls harvested from the Sea of Japan are relatively high compared with black-, gold-, and white-lipped oyster pearls from the South Sea.

Fast heavy-ion radiolysis of biomolecules in aqueous solution is investigated for an atomistic understanding of radiation damage to normal cells during heavy-particle beam therapy. The smallest amino acid glycine was used as a model biomaterial. Microjets of aqueous glycine solutions under vacuum were irradiated with 4.0-MeV carbon ions corresponding to energies in the Bragg peak region. To understand the effects of the water environment on molecular damage, the yield of glycine dissociation was measured by secondary ion mass spectroscopy. The yield was significantly reduced relative to gas-phase glycine targets. This implies that the numerous water molecules surrounding a single glycine molecule act as a buffer that suppresses dissociation. This is an environmental effect similar to that observed for other biomolecular cluster targets.

In this study, we carried out the pre-irradiation of a dispersion-strengthened W-2wt.%Y2O3 alloy with good mechanical properties with high-energy Fe-ions instead of neutrons. The effect of this pre-irradiation on the D2 retention behavior of the alloy was investigated. A maximum of 1022 D/m2 was irradiated onto the samples using 5-keV D2 ions, and Fe pre-irradiation was carried out up to an ion fluence of 4 × 1018/m2 with 1 MeV energy. For comparison, commercial pure W was also studied. The Fe-ion pre-irradiation process increased the D2 retention in both pure W and the W–Y2O3 alloy. However, this D2 retention was independent of the pre-irradiation dose. In addition, the formation of He bubbles in the W–Y2O3 alloy caused by the irradiation at 1.8 × 1021 He/m2 and high temperatures of 773, 973, and 1173 K was also investigated. When the irradiation dose exceeded 1.5 × 1020 He/m2, visible He bubbles were formed, and He bubbles grew and void swelling increased with an increase in the irradiation dose. Compared to pure W, the W–Y2O3 alloy showed suppressed void swelling. This can be attributed to the dispersion of vacancies and He atoms due to the He irradiation.

The formation processes of secondary ions in liquid materials were studied for methanol microdroplets bombarded by carbon ions with incident energies of 0.4–4.0 MeV, where the corresponding electronic stopping power ranged 300–800 eV nm−1. Positive and negative secondary ions including molecular fragments, methanol clusters, and reaction products were investigated, and each ion yield was examined as a function of electronic stopping power Se. We observed different Se-dependence on the emission yields between positive and negative ions. For positive cluster ions [(CH3OH)n + H]+ (n = 2−10), the yield nonlinearly increases and follows the power-law Seα with α = 3. For negative secondary ions, the value of α varies according to secondary ion species or ion mass: α ≈ 0 for fragments with small mass (CH−, CH2−, and OH−), α = 0.5–1.5 for reaction products with medium mass(C2−, C2H−, C2HO−, and C2H5O−), and α = 1.2−1.5 for clusters with large mass [(CH3OH)n – H]− (n = 1−25). The latter finding implies that the value of α is a quantity related to the electronic energy density depending on the distance from the ion trajectory.

The migrations of lithium (Li) as well as hydrogen (H) in multi-layers thin films of Au/LiCoO2 (thickness: approximately 42 nm/80 nm), deposited onto one face of Li1.4Ti2Si0.4P2.6O12-AlPO4 (LATP) substrates, were dynamically observed with electric charging as well as isochronal annealing in vacuum by combining elastic recoil detection (ERD) analysis with Rutherford backscattering spectrometry (RBS)with 9.0-MeV O4+ ion-probe beams. The ERD spectra clearly revealed that Li atoms of approximately 9.4 at% migrated from the LiCoO2 surface to the LiCoO2/LATP interface with H absorption by a charge of approximately 0.48 e/cm2, which the acquiredvoltage was1.65 V. In addition, the diffusion of Li atoms to the LATP bulk occurred with H release by isochronal annealing at only 323 K for 10 min.The presence of H significantly influences the Li+ ion conduction for the Li-battery systems., The 23rd International Conference on the Application of Accelerators in Research and Industry - CAARI 2014

The elastic scattering cross-sections for α particles from nitrogen at a scattering angle of 83.6° were measured in the energy range of 2.0–5.4 MeV, and the nitrogen recoil cross-sections at a recoil angle of 40° were derived from the scattering cross-sections. Simultaneous measurements of scattering cross-sections at a scattering angle of 165° were also performed to validate the measurements. The obtained recoil cross-section data are essential for the quantitative examination of nitrogen through time-of-flight elastic recoil detection analysis with He beams.

Li Depth profiles at the interfaces of capacitors of Cu/LiPON/Cu and Al/LiPON/Al prepared on buffer Ti layer /SiO2 glass and Au/LATP/Au (LiPON = Li3.3PO3.8N0.2, LATP = Li3.1Al0.84Ti1.16Ge1.27P1.73O12) under biasing bottom metal against top metal at earth potential have been in-situ measured by means of elastic recoil detection analysis (ERD) and Rutherford backscattering spectrometry (RBS) techniques. Li has been found to be enriched near the interface with electrode biased negatively, while it is depleted near that biased positively. The Li depth profile in electrolyte has been theoretically calculated, taking into account the transport faction of Li ions, based on hopping diffusion model of Li ions under potential gradient. It is shown that the Li depth profile calculated as a solution of diffusion equation at steady state agrees qualitatively well with the experimental ones and the transport fraction of Li ions in electrolyte is less than unity.

Li depth profiles in Au/LCO/mixed LATP-LAGP/Pt battery (mixed LATP-LAGP (LATP/LAGP) = Li1+X+YAlYTi2−YGeXP3−XO12, LCO = LiCoO2) under discharging by biasing Pt to Au at earth potential, have been measured from both Au and Pt surfaces by means of reflection elastic recoil detection (ERD) and Rutherford backscattering spectrometry (RBS) techniques with 9 MeV O4+ ions. Ge and Ti compositions of a mixed LATP-LAGP electrolyte and thickness of LCO were determined from RBS spectrum for the as-prepared specimen, where Y and X in LATP were estimated to be 0.84 and 1.27, respectively. On charging at 2.4 V for 25 min, Li composition in LCO measured from the Au surface by ERD was reduced down to ~0.3 and hereafter on discharging at 0.5 V for 25 min the composition was not enriched, but contrary was further reduced to 0.2. However, by successive discharging at 1.0, 1.5 and 2.2 V for 50 min the composition was enriched. On the other hand, it was found from the Pt surface that Li charged in the electrolyte near Pt by biasing at 2.4 V for 20 min was reduced by discharging at 1.0 V for 20 min. By further discharging for 20 min Li was not reduced, but contrary was enriched. Both anomalous transports of Li under discharging are discussed in terms of diffusion of Li atoms in the counter direction to the biasing which is caused by the transport fraction of Li ions in the electrolyte less than unity.

Fe ion irradiation-induced defects in F82H model alloys were studied using positron annihilation lifetime measurements. Irradiation was performed with an accelerating voltage of 6.0 MeV to a dose of 22 dpa at 593 K. In addition, a comparative study was conducted with results from our previous neutron irradiation measurements for F82H model alloys. The results showed an apparent decrease of the mobility of interstitial clusters in Fe by addition of Cr. This finding supports the configuration model of Cr on void swelling resistance in Fe–Cr alloys. A remarkable delay of defect structural evolution was also observed by ion irradiation compared to neutron irradiation because of a high damage rate.

By combining elastic recoil detection (ERD) analysis with Rutherford backscattering spectrometry (RBS) using 9.0-MeV oxygen-ion (O4+) probe beams from a tandem accelerator, we simultaneously investigated the distributions of lithium (Li), hydrogen (H), cobalt (Co), and platinum (Pt) in 20 nm Pt/260 nm LiCoO2 multi-layer thin films acting as the positive electrode in a solid-state Li+ ion battery and, deposited on Li1.4Ti2Si0.4P2.6O12–AlPO4 (LATP) substrates by using pulsed laser deposition. Measurement of the ERD and RBS spectra revealed the effects of Pt deposition on the hydrogen absorption characteristics of the LiCoO2 thin films, with segregation of Co to the surface as a catalyst. We speculate from the results that the presence of H in the LiCoO2 thin films has a marked influence on Li+ ion conduction in Li-battery systems.

Characteristics of irradiation-induced hydrogen trapping in tungsten were investigated by observing deuterium concentration profiles under continuous deuterium plasma exposure. Tungsten samples called A3 and A4 were 1.5-MeV W irradiated with an average of 0.63 and 4.2 dpa, respectively, and another sample called A5 was 5.0-MeV W irradiated with 54 dpa. Results show that traps were produced around 500 K, a recovery stage of interstitials, and were suggested to migrate from the damaged region to greater depths within the samples. The number of traps significantly increases with displacement at low dpa and then gradually increases around 0.1 dpa. Traps are effectively produced at high temperature irradiation. The trapping energy of 0.70 eV in A3 and A4 is the same as He- and H- irradiated samples. These traps are likely point-defect-like sites that accompany interstitial clusters such as dislocation loops.

We studied the grain size dependence of the defect evolution that occurred in a nanocrystalline (NC) Ni and its coarse-grained counterpart under irradiation. The vacancy defects produced during irradiation were investigated via in situ observations of the positron annihilation Doppler broadening spectra. The annihilation line-shape parameter S was measured under beam-on (during irradiation) and beam-off (after irradiation) conditions. We found that different variations in S were observed depending on the grain size; for the coarse-grained specimen, the S measured under beam-on conditions was larger than that observed under beam-off conditions, while for the NC specimen, the S value remained unchanged under beam-on and beam-off conditions. The former result indicated that the vacancy concentration was enhanced during irradiation, due to transient vacancy production. The latter result may imply that defect accumulation was strongly suppressed under irradiation. We also studied the flux dependence of the radiation damage effects for the NC specimen, using high-flux He ions in the flux range of 1.2 × 10 13 –6 × 10 14 ions/(cm 2 s). A slight flux dependence was observed, which was due to microstructural changes at the intersections of the crystallite interfaces under the highest flux irradiation studied.

We apply the capillary beam-focusing method for the C 60 fullerene projectiles in the velocity range between 0.14 and 0.2 a.u. We study the C 60 transmission properties through two different types of capillaries: (1) borosilicate glass microcapillary with an outlet diameter of 5.5 μm, and (2) Al 2 O 3 multi-capillary foil with a pore size of about 70 nm and a high aspect ratio of about 750. We measured the transmitted particle composition by using the electrostatic deflection method combined with the microchannel plate imaging technique. For the experiments with the single microcapillary, the main transmission component is found to be primary C 60 beams that are focused in the area equal to the capillary outlet diameter. Minor components are charge-exchanged C 60 ions and charged or neutral fragments (fullerene-like C 60-2 m and small C n particles), and their fractions decrease with decreasing the projectile velocity. It is concluded that the C 60 transmission fraction is considerably high for both types of the capillaries in the present velocity range.

We study the transmission properties of fast cluster ions (Cn+ (n = 2–4) with velocities ranging from 0.89 to 1.79 a.u.) through a single tapered capillary with an outlet diameter of 13.7 μm. We investigate the projectile-velocity dependence of the transmission fraction from the measurements of transmitted particle energy spectra. It is found that the non-fragmentation fraction of C2+ projectiles increases with decreasing velocity, indicating that fragmentation occurs mainly via close collisions with the surfaces of the capillary wall. For Cn+ (n = 2–4) ions with the same incident velocity, the cluster-size dependence of the non-fragmentation fraction shows even–odd alternation, implying that the fraction includes contributions from stable clusters surviving the grazing scattering process at the capillary surface. We also find that the angular distribution of transmitted particles is narrower for cluster projectiles compared with atomic projectiles.

The positron beam technique has been widely used as a detection tool for vacancy-type defects in solids, especially defects induced by ion irradiation/implantation that are localized near the surface. To extend this technique to other applications, we constructed unique in situ positron beam measurement equipment combined with an ion beam irradiation chamber. This equipment enables us to measure positron beam Doppler broadening during or immediately after irradiation without any sample handling. With this equipment, defect accumulation and evolution in iron and nickel were investigated at room temperature. In addition, the defect accumulation and annealing process was investigated at temperature below stage III to reveal vacancy configurations after cascade, without any thermal migration after the cascade cooling. In this paper, we summarize these results and discuss ideas for future study.

Measurements of thermal diffusivity and positron annihilation lifetime were performed on neutron- and 30 MeV electron-irradiated ceramics. Thermal diffusivity of heavily neutron-irradiated ceramics decreased to a very low level and the difference between specimens was small. Positron annihilation lifetime of these specimens also showed a distinct change; however, the difference between specimens was also small. Accordingly, in this study, electron irradiation was performed to 0.01–0.02 dpa via the 30 MeV KURRI-Linac. The electron-irradiated specimens also showed obvious degradation in thermal diffusivity and an increment in positron annihilation lifetime, and it was clarified that positron annihilation lifetime showed some correlation with thermal diffusivity.

Experimental study on tritium retention in tungsten was conducted, in which samples were irradiated with MeV-energy H or He ions and deuterium concentration profiles were subsequently observed under deuterium-plasma exposure conditions. The results showed that the deuterium concentration was significantly increased by irradiation at 573 K due to production of hydrogen traps while it was not under irradiation below 400 K. In the latter case, however, the concentration was increased when the sample was heated around 550 K. The trap was considered to be a kind of interstitial defects and grown at 550 - 600 K from irradiation defects. Once produced, the trap was stable at least 710 K.

We have constructed and made available atomic and molecular (AM) numerical databases on collision processes such as electron‐impact excitation and ionization, recombination and charge transfer of atoms and molecules relevant for plasma physics, fusion research, astrophysics, applied‐science plasma, and other related areas. The retrievable data is freely accessible via the internet. We also work on atomic data evaluation and constructing collisional‐radiative models for spectroscopic plasma diagnostics. Recently we have worked on Fe ions and W ions theoretically and experimentally. The atomic data and collisional‐radiative models for these ions are examined and applied to laboratory plasmas. A visible M1 transition of W26+ ion is identified at 389.41 nm by EBIT experiments and theoretical calculations. We have small non‐retrievable databases in addition to our main database. Recently we evaluated photo‐absorption cross sections for 9 atoms and 23 molecules and we present them as a new database. We establis...

The effect of fast cluster irradiation on the formation of fibrous structures is investigated for single crystal GaSb surfaces irradiated by Cun+ ions (n = 1–3) with an energy of 0.4 MeV/atom at ion fluences up to 5 × 1015 cm−2. We study the cluster size dependence on the growth of fibrous network structures. With increasing cluster size, the shape of the fiber changed from rod-like to spherical. To quantitatively evaluate this cluster effect, a fiber diameter d in rod or spherical portion is examined as a function of ion fluence Φ and cluster size n. We find that the fiber diameter nonlinearly increases and follows the relation d∝nα×Φ, with α≈2. This evidently implies that the amount of defects generated by n-sized cluster bombardments varies as n2 for n≤3. Cluster ion irradiation enhances the defect generation owing to the overlap between cascades of individual cluster constituents and is therefore effective for the growth of nanofibers.

Cross sections for the stopping of swift protons in liquid water have been measured for the first time by using a liquid water jet target of 50 μm in diameter. The energy loss spectra of incident 2.0 MeV protons were measured at scattering angles of 5.0–50 mrad. Experimental energy loss spectra have been successfully reproduced by Monte Carlo simulation calculations (GEANT4.9.1.p02 toolkit) by taking account of multiple scattering of projectile ions inside the liquid water target. The present stopping cross sections are found to be considerably smaller than other standard stopping power data, revealing e.g. about 11% deviation from those of SRIM2003.