Pub Date : 2026-01-21DOI: 10.1016/j.nimb.2026.166011
A. Iwase , S. Nishio , F. Hori
An overlapping effect of ion-tracks consisting of defective core areas and shell areas of transient lattice vibration was studied using the Monte Carlo simulation. Under the assumption that pre-existing ion-tracks were annihilated by an overlap with shell areas of newly produced ion-tracks, the resulting two-dimensional distributions and the total fraction of defective areas were predicted as a function of ion-fluence for several core–shell structures of the ion-tracks. To compare the present simulation result with previously reported experimental data, the number densities of ion-tracks were also estimated from the two-dimensional images. The present simulation method will provide a useful clue for understanding nanostructures consisting of defective and non-defective areas as a result of ion-track annihilation due to the inter-track interaction.
{"title":"Annihilation of ion-tracks by inter-track interaction -Monte Carlo simulation-","authors":"A. Iwase , S. Nishio , F. Hori","doi":"10.1016/j.nimb.2026.166011","DOIUrl":"10.1016/j.nimb.2026.166011","url":null,"abstract":"<div><div>An overlapping effect of ion-tracks consisting of defective core areas and shell areas of transient lattice vibration was studied using the Monte Carlo simulation. Under the assumption that pre-existing ion-tracks were annihilated by an overlap with shell areas of newly produced ion-tracks, the resulting two-dimensional distributions and the total fraction of defective areas were predicted as a function of ion-fluence for several core–shell structures of the ion-tracks. To compare the present simulation result with previously reported experimental data, the number densities of ion-tracks were also estimated from the two-dimensional images. The present simulation method will provide a useful clue for understanding nanostructures consisting of defective and non-defective areas as a result of ion-track annihilation due to the inter-track interaction.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166011"},"PeriodicalIF":1.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.nimb.2026.166010
E. Boydaş
This study experimentally and theoretically investigates the gamma-ray and neutron attenuation properties of six zinc-based materials: ZnF2, ZnCl2, ZnO, ZnSO4, ZnCO3, and metallic Zn. Experimental measurements were carried out using an Energy-Dispersive X-Ray Fluorescence (EDXRF) system equipped with a high-purity germanium (HPGe) detector, while theoretical mass attenuation coefficients were obtained from Epixs program for comparison. The samples were irradiated with 59.5 keV photons from Am-241 and Ba-133 sources, as well as with gamma-ray beams of 80.99, 276.39, 302.85, 356.01, and 383.84 keV. A good agreement between experimental and theoretical results was achieved, with relative deviations remaining within a few percent, confirming the reliability and low uncertainty of the measurements. The results demonstrate that zinc-based materials exhibit strong gamma-ray attenuation, particularly at low photon energies dominated by the photoelectric effect. At 59.5 keV, Zn (1.921 cm2/g), ZnCl2 (1.100 cm2/g), ZnF2 (1.261 cm2/g), ZnSO4 (0.996 cm2/g), and ZnCO3 (1.161 cm2/g), with the highest MAC value observed for ZnO (1.672 cm2/g). Compared to ZnSO4, ZnO shows an approximately 68 % higher mass attenuation coefficient at this energy. Among the zinc compounds, ZnO presents the lowest HVL and MFP values, indicating the most efficient gamma-ray shielding, mainly due to its higher density (5.61 g cm−3) and effective atomic number. EABF (gamma-ray absorption buildup factors) and EBF (exposure buildup factors) were also calculated for the energy range 0.015–15 MeV up to a depth of 15 MFP. For most compounds, the differences between EABF and EBF values are limited to a factor of several tens. For photon energies below 0.15 MeV, EABF and EBF values increase as the effective atomic number (Zeff) of the samples decreases.The fast-neutron shielding capability was also evaluated. ZnCO3 exhibits the highest removal cross-section (ΣR) at 0.1312 cm−1, whereas ZnCl2 shows the lowest ΣR value at 0.0636 cm−1. Overall, the study highlights that ZnF2, ZnCl2, ZnO, ZnSO4, ZnCO3, and zinc-based materials are suitable candidates for radiation shielding applications. Zinc compounds offer advantages such as low toxicity, easy availability, and cost-effective production, making them well-suited for applications requiring moderate levels of radiation shielding.
{"title":"The examination of the shielding capabilities of Zn compounds","authors":"E. Boydaş","doi":"10.1016/j.nimb.2026.166010","DOIUrl":"10.1016/j.nimb.2026.166010","url":null,"abstract":"<div><div>This study experimentally and theoretically investigates the gamma-ray and neutron attenuation properties of six zinc-based materials: ZnF<sub>2</sub>, ZnCl<sub>2</sub>, ZnO, ZnSO<sub>4</sub>, ZnCO<sub>3</sub>, and metallic Zn. Experimental measurements were carried out using an Energy-Dispersive X-Ray Fluorescence (EDXRF) system equipped with a high-purity germanium (HPGe) detector, while theoretical mass attenuation coefficients were obtained from Epixs program for comparison. The samples were irradiated with 59.5 keV photons from Am-241 and Ba-133 sources, as well as with gamma-ray beams of 80.99, 276.39, 302.85, 356.01, and 383.84 keV. A good agreement between experimental and theoretical results was achieved, with relative deviations remaining within a few percent, confirming the reliability and low uncertainty of the measurements. The results demonstrate that zinc-based materials exhibit strong gamma-ray attenuation, particularly at low photon energies dominated by the photoelectric effect. At 59.5 keV, Zn (1.921 cm<sup>2</sup>/g), ZnCl<sub>2</sub> (1.100 cm<sup>2</sup>/g), ZnF<sub>2</sub> (1.261 cm<sup>2</sup>/g), ZnSO<sub>4</sub> (0.996 cm<sup>2</sup>/g), and ZnCO<sub>3</sub> (1.161 cm<sup>2</sup>/g), with the highest MAC value observed for ZnO (1.672 cm<sup>2</sup>/g). Compared to ZnSO<sub>4</sub>, ZnO shows an approximately 68 % higher mass attenuation coefficient at this energy. Among the zinc compounds, ZnO presents the lowest HVL and MFP values, indicating the most efficient gamma-ray shielding, mainly due to its higher density (5.61 g cm<sup>−3</sup>) and effective atomic number. EABF (gamma-ray absorption buildup factors) and EBF (exposure buildup factors) were also calculated for the energy range 0.015–15 MeV up to a depth of 15 MFP. For most compounds, the differences between EABF and EBF values are limited to a factor of several tens. For photon energies below 0.15 MeV, EABF and EBF values increase as the effective atomic number (Zeff) of the samples decreases.The fast-neutron shielding capability was also evaluated. ZnCO<sub>3</sub> exhibits the highest removal cross-section (Σ<sub>R</sub>) at 0.1312 cm<sup>−1</sup>, whereas ZnCl<sub>2</sub> shows the lowest Σ<sub>R</sub> value at 0.0636 cm<sup>−1</sup>. Overall, the study highlights that ZnF<sub>2</sub>, ZnCl<sub>2</sub>, ZnO, ZnSO<sub>4</sub>, ZnCO<sub>3</sub>, and zinc-based materials are suitable candidates for radiation shielding applications. Zinc compounds offer advantages such as low toxicity, easy availability, and cost-effective production, making them well-suited for applications requiring moderate levels of radiation shielding.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166010"},"PeriodicalIF":1.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.nimb.2026.166012
Ravikumar Nattudurai , N. Pavithra , R. Deepika , N. Poongodi
This comprehensive study evaluates Carbon-doped Aluminum Oxide (Al2O3:C) as a high-sensitivity thermoluminescent dosimeter for medical and environmental applications. The material’s performance was systematically investigated across gamma (60Co), X-ray (250 kVp), and proton (70 MeV) radiations. Al2O3:C exhibited a characteristic glow peak at 180°C across all radiation types, with excellent linear dose–response from 10 μGy to 1 Gy. The phosphor demonstrated exceptional sensitivity, being 40–50 times more sensitive than conventional TLD-100. Kinetic analysis revealed a trap depth of 1.45 eV, explaining the minimal fading (4% over 30 days) and excellent reusability (CV < 2%). While energy dependence was observed for low-energy X-rays, the material showed consistent performance across radiation modalities. These findings establish Al2O3:C as a superior dosimeter suitable for both environmental monitoring and clinical applications where high sensitivity and reliability are crucial, though energy compensation is needed for low-energy photon fields.
{"title":"Dosimetric performance evaluation of Al2O3:C across diverse radiation qualities for medical and environmental applications","authors":"Ravikumar Nattudurai , N. Pavithra , R. Deepika , N. Poongodi","doi":"10.1016/j.nimb.2026.166012","DOIUrl":"10.1016/j.nimb.2026.166012","url":null,"abstract":"<div><div>This comprehensive study evaluates Carbon-doped Aluminum Oxide (Al<sub>2</sub>O<sub>3</sub>:C) as a high-sensitivity thermoluminescent dosimeter for medical and environmental applications. The material’s performance was systematically investigated across gamma (<sup>60</sup>Co), X-ray (250 kVp), and proton (70 MeV) radiations. Al<sub>2</sub>O<sub>3</sub>:C exhibited a characteristic glow peak at 180°C across all radiation types, with excellent linear dose–response from 10 μGy to 1 Gy. The phosphor demonstrated exceptional sensitivity, being 40–50 times more sensitive than conventional TLD-100. Kinetic analysis revealed a trap depth of 1.45 eV, explaining the minimal fading (4% over 30 days) and excellent reusability (CV < 2%). While energy dependence was observed for low-energy X-rays, the material showed consistent performance across radiation modalities.<!--> <!-->These findings establish Al<sub>2</sub>O<sub>3</sub>:C as a superior dosimeter suitable for both environmental monitoring and clinical applications where high sensitivity and reliability are crucial, though energy compensation is needed for low-energy photon fields.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166012"},"PeriodicalIF":1.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-18DOI: 10.1016/j.nimb.2026.166009
Kelvin Y. Xie , Digvijay Yadav , Kenneth Cooper , Yu Lu , Jana Howard , Marcus Hansen , Rijul R. Chauhan , JungHun Park , Sunkyung Lee , Yuhyun Park , Andrew Phong , Gi-Dong Sim , Yaqiao Wu , Lin Shao , Michael J. Demkowicz
In this study, we examine a nanocrystalline Ni thin film exposed to high-temperature proton irradiation and compare it with as-deposited and annealed-only counterparts. Despite lacking thermal spikes typical of heavy ions, 400 °C proton irradiation drives pronounced grain growth in select grains, whereas annealing alone yields only modest coarsening. Grain-boundary statistics show fewer low-angle boundaries (10–20°) and more high-angle boundaries (55–60°), consistent with irradiation-enhanced mobility of high-misorientation boundaries. The irradiated films retain a random texture, with no evidence of texture development or sharpening. Mechanisms, such as radiation-enhanced grain boundary diffusion, beam-induced heating, and ion channeling-mediated selective grain growth, are unlikely to be the predominant drivers to explain the resultant microstructure. Instead, we suggest irradiation-induced modifications of grain-boundary structure, including possible complexion transitions, as one plausible explanation for this selective grain growth and retention of random texture. However, additional temperature–dose studies are required to confirm the mechanism.
{"title":"Abnormal grain growth driven by high-temperature proton irradiation in nanocrystalline Ni","authors":"Kelvin Y. Xie , Digvijay Yadav , Kenneth Cooper , Yu Lu , Jana Howard , Marcus Hansen , Rijul R. Chauhan , JungHun Park , Sunkyung Lee , Yuhyun Park , Andrew Phong , Gi-Dong Sim , Yaqiao Wu , Lin Shao , Michael J. Demkowicz","doi":"10.1016/j.nimb.2026.166009","DOIUrl":"10.1016/j.nimb.2026.166009","url":null,"abstract":"<div><div>In this study, we examine a nanocrystalline Ni thin film exposed to high-temperature proton irradiation and compare it with as-deposited and annealed-only counterparts. Despite lacking thermal spikes typical of heavy ions, 400 °C proton irradiation drives pronounced grain growth in select grains, whereas annealing alone yields only modest coarsening. Grain-boundary statistics show fewer low-angle boundaries (10–20°) and more high-angle boundaries (55–60°), consistent with irradiation-enhanced mobility of high-misorientation boundaries. The irradiated films retain a random texture, with no evidence of texture development or sharpening. Mechanisms, such as radiation-enhanced grain boundary diffusion, beam-induced heating, and ion channeling-mediated selective grain growth, are unlikely to be the predominant drivers to explain the resultant microstructure. Instead, we suggest irradiation-induced modifications of grain-boundary structure, including possible complexion transitions, as one plausible explanation for this selective grain growth and retention of random texture. However, additional temperature–dose studies are required to confirm the mechanism.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166009"},"PeriodicalIF":1.4,"publicationDate":"2026-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.nimb.2026.166007
Gaël Simonin , Francesco Mazza-Schuh , David Brasse , Marc Rousseau
Double differential cross-section values for the (p, α) reaction on natural lithium were determined for incident proton energies between 20 MeV and 25 MeV at emission angles between 15° and 55°. A distinct peak corresponding to high-energy α particles was observed in the spectra and the integrated differential cross-section over this peak was evaluated. This cross-section exhibits an angular dependence with a maximum around 45°, as well as an energy dependence where lower proton beam energies result in higher cross-section values. Our results are in good agreement with previous experimental data reported in the literature.
{"title":"Measurement of the (p, α) reaction cross-section on natural lithium for production of high-energy α beam","authors":"Gaël Simonin , Francesco Mazza-Schuh , David Brasse , Marc Rousseau","doi":"10.1016/j.nimb.2026.166007","DOIUrl":"10.1016/j.nimb.2026.166007","url":null,"abstract":"<div><div>Double differential cross-section values for the (p, α) reaction on natural lithium were determined for incident proton energies between 20 MeV and 25 MeV at emission angles between 15° and 55°. A distinct peak corresponding to high-energy α particles was observed in the spectra and the integrated differential cross-section over this peak was evaluated. This cross-section exhibits an angular dependence with a maximum around 45°, as well as an energy dependence where lower proton beam energies result in higher cross-section values. Our results are in good agreement with previous experimental data reported in the literature.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166007"},"PeriodicalIF":1.4,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electronic devices in space are susceptible to single-event effects (SEEs) induced by energetic particles. SEEs induced by low-energy protons and low linear energy transfer (LET) particles have become a serious concern as device sizes decrease. Electrostatic accelerators are well-suited to the study of device responses in the low-LET region due to their ability to provide a wide variety of ion species, a broad energy range, and precise energy control. It is essential to precisely control the incident ion beam energy and intensity when evaluating SEE cross-sections in the low-LET region. SEE tests require beam fluxes down to 102 particles/cm2/s, below the detection limit of conventional Faraday cups. We developed a beam current monitor and energy calibration techniques for SEE testing using a 1 MV electrostatic tandem accelerator. The beam monitor combined with a ZnS(Ag) scintillator was calibrated using a Faraday cup and a passivated implanted planar silicon (PIPS) detector. The dynamic range is 102–109 particles/cm2/s, and the accuracy is ±30 %. Beam energy calibration was first performed by adjusting the terminal voltage using nuclear reaction methods. Subsequently, beam irradiation into the PIPS detector allowed direct measurement of beam energy. The measured energies were in good agreement with those obtained from a PIPS detector calibrated using an Am-241 source, confirming the validity of the direct calibration approach. We thus offer a stable experimental platform for low-LET SEE studies, expanding the applications of electrostatic accelerators that test space electronic devices.
{"title":"Calibration of an electrostatic accelerator for single-event-effects tests","authors":"Sho Toyama, Naoki Shibanuma, Takumi Matsumoto, Yuki Otsuka, Ayumi Nakatsuma, Kyoka Maruta, Misako Miwa, Wataru Kada, Shigeo Matsuyama","doi":"10.1016/j.nimb.2026.166006","DOIUrl":"10.1016/j.nimb.2026.166006","url":null,"abstract":"<div><div>Electronic devices in space are susceptible to single-event effects (SEEs) induced by energetic particles. SEEs induced by low-energy protons and low linear energy transfer (LET) particles have become a serious concern as device sizes decrease. Electrostatic accelerators are well-suited to the study of device responses in the low-LET region due to their ability to provide a wide variety of ion species, a broad energy range, and precise energy control. It is essential to precisely control the incident ion beam energy and intensity when evaluating SEE cross-sections in the low-LET region. SEE tests require beam fluxes down to 10<sup>2</sup> particles/cm<sup>2</sup>/s, below the detection limit of conventional Faraday cups. We developed a beam current monitor and energy calibration techniques for SEE testing using a 1 MV electrostatic tandem accelerator. The beam monitor combined with a ZnS(Ag) scintillator was calibrated using a Faraday cup and a passivated implanted planar silicon (PIPS) detector. The dynamic range is 10<sup>2</sup>–10<sup>9</sup> particles/cm<sup>2</sup>/s, and the accuracy is ±30 %. Beam energy calibration was first performed by adjusting the terminal voltage using nuclear reaction methods. Subsequently, beam irradiation into the PIPS detector allowed direct measurement of beam energy. The measured energies were in good agreement with those obtained from a PIPS detector calibrated using an Am-241 source, confirming the validity of the direct calibration approach. We thus offer a stable experimental platform for low-LET SEE studies, expanding the applications of electrostatic accelerators that test space electronic devices.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166006"},"PeriodicalIF":1.4,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.nimb.2026.166005
N. Catarino , E. Alves , L.C. Alves , J. Flora , M. Peres , R.C. Silva , N.P. Barradas
The accuracy of IBA experiments depends on many factors, of which counting statistics is often the least important. The nuclear data used in the data analysis have a direct influence in the results obtained with IBA experiments. Sometimes, the uncertainty in scattering cross sections or in stopping powers is taken as a systematic uncertainty. However, in techniques such as RBS, given the signal superposition of different elements, the uncertainty in the stopping power may have a non-linear effect in the uncertainty of the depth profiles obtained. The experimental database is sparse for some elemental targets, as is the case for many rare earths. We previously developed a method for stopping power determination based on measuring bulk spectra. We report on the application of the method to the determination of the stopping power of 4He and 1H in the rare earths Sc, Gd and Yb, using beam energies from 1 to 2.1 MeV.
{"title":"Stopping power determination of 4He and 1H in Sc, Gd and Yb using a bulk sample method","authors":"N. Catarino , E. Alves , L.C. Alves , J. Flora , M. Peres , R.C. Silva , N.P. Barradas","doi":"10.1016/j.nimb.2026.166005","DOIUrl":"10.1016/j.nimb.2026.166005","url":null,"abstract":"<div><div>The accuracy of IBA experiments depends on many factors, of which counting statistics is often the least important. The nuclear data used in the data analysis have a direct influence in the results obtained with IBA experiments. Sometimes, the uncertainty in scattering cross sections or in stopping powers is taken as a systematic uncertainty. However, in techniques such as RBS, given the signal superposition of different elements, the uncertainty in the stopping power may have a non-linear effect in the uncertainty of the depth profiles obtained. The experimental database is sparse for some elemental targets, as is the case for many rare earths. We previously developed a method for stopping power determination based on measuring bulk spectra. We report on the application of the method to the determination of the stopping power of <sup>4</sup>He and <sup>1</sup>H in the rare earths Sc, Gd and Yb, using beam energies from 1 to 2.1 MeV.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166005"},"PeriodicalIF":1.4,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Groundwater on small carbonate islands is a vital but vulnerable freshwater resource. Understanding these groundwater dynamics is important for sustainable management, particularly where freshwater lenses overlie seawater in highly permeable carbonate aquifers. This study focuses on the aquifer system in eastern Tongatapu, Tonga. We conducted a multi-tracer survey at 14 sites, based on three field campaigns in November 2023, July 2024, and November 2024. Our study aim is to identify groundwater origins, characterize freshwater-seawater mixing, and clarify the controls on groundwater flow and residence time. Radiocarbon (Δ14C) of dissolved inorganic carbon (DIC) stable water isotopes (δ18O and δD), major elements (Ca, Mg, K), and field parameters were measured. Salinity ranged from 0.8‰ in cave and tap water to 33.6‰ in seawater, δ18O from -5.66 to +1.22‰, and Δ14C from -170 to +31‰. δ18O–δD values define a tight linear trend between an isotopically depleted, low-salinity freshwater lens and enriched seawater. This indicates a dominant two-component mixing framework, while major element compositions reflect carbonate dissolution along groundwater flow paths. Δ14C shows the largest variability and increases systematically with salinity, major element concentrations, and δ18O–δD, consistent with mixing between 14C-depleted groundwater and near-modern seawater. At several coastal sites, Δ14C values shifted more than 150‰ between seasons, while salinity remained close to seawater values, revealing transient discharge of older groundwater that is not resolved by conventional tracers. In contrast, other coastal sites retained persistently near-modern Δ14C and stable hydrochemistry, indicating weak connection to the freshwater lens. These results demonstrate that the coastal aquifer is heterogeneous and dynamic, and that Δ14C provides a sensitive relative tracer of the contribution of older groundwater and groundwater–seawater mixing. They further imply that vulnerability assessments for Tongatapu and similar carbonate islands should incorporate dynamic tracers such as Δ14C with conventional hydrochemical monitoring to support robust, site-specific management under changing climate and water demand.
{"title":"Groundwater dynamics of eastern Tongatapu Island, Tonga: Insights from radiocarbon and hydrochemical tracers","authors":"Naoto Fukuyo , Geoffrey Clark , Shoko Hirabayashi , Toshihiro Miyajima , Yusuke Yokoyama","doi":"10.1016/j.nimb.2025.165980","DOIUrl":"10.1016/j.nimb.2025.165980","url":null,"abstract":"<div><div>Groundwater on small carbonate islands is a vital but vulnerable freshwater resource. Understanding these groundwater dynamics is important for sustainable management, particularly where freshwater lenses overlie seawater in highly permeable carbonate aquifers. This study focuses on the aquifer system in eastern Tongatapu, Tonga. We conducted a multi-tracer survey at 14 sites, based on three field campaigns in November 2023, July 2024, and November 2024. Our study aim is to identify groundwater origins, characterize freshwater-seawater mixing, and clarify the controls on groundwater flow and residence time. Radiocarbon (Δ<sup>14</sup>C) of dissolved inorganic carbon (DIC) stable water isotopes (δ<sup>18</sup>O and δD), major elements (Ca, Mg, K), and field parameters were measured. Salinity ranged from 0.8‰ in cave and tap water to 33.6‰ in seawater, δ<sup>18</sup>O from -5.66 to +1.22‰, and Δ<sup>14</sup>C from -170 to +31‰. δ<sup>18</sup>O–δD values define a tight linear trend between an isotopically depleted, low-salinity freshwater lens and enriched seawater. This indicates a dominant two-component mixing framework, while major element compositions reflect carbonate dissolution along groundwater flow paths. Δ<sup>14</sup>C shows the largest variability and increases systematically with salinity, major element concentrations, and δ<sup>18</sup>O–δD, consistent with mixing between <sup>14</sup>C-depleted groundwater and near-modern seawater. At several coastal sites, Δ<sup>14</sup>C values shifted more than 150‰ between seasons, while salinity remained close to seawater values, revealing transient discharge of older groundwater that is not resolved by conventional tracers. In contrast, other coastal sites retained persistently near-modern Δ<sup>14</sup>C and stable hydrochemistry, indicating weak connection to the freshwater lens. These results demonstrate that the coastal aquifer is heterogeneous and dynamic, and that Δ<sup>14</sup>C provides a sensitive relative tracer of the contribution of older groundwater and groundwater–seawater mixing. They further imply that vulnerability assessments for Tongatapu and similar carbonate islands should incorporate dynamic tracers such as Δ<sup>14</sup>C with conventional hydrochemical monitoring to support robust, site-specific management under changing climate and water demand.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 165980"},"PeriodicalIF":1.4,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1016/j.nimb.2025.165999
Xuan Feng, Yunliang Song, Yuwei Ma, Bowen Li
Accurate interatomic potentials are critical for reliable simulations of ion–solid interactions. In this work, we present a systematic development of interatomic potentials for hydrogen–metal systems based on density functional theory (DFT) calculations. Pairwise potential energy curves for H–Ag, H–Cu, and H–Au were computed and fitted to both the Ziegler–Biersack–Littmark (ZBL) and Morse potential forms. The fitted potentials were implemented into the RustBCA binary collision approximation code to simulate hydrogen stopping powers. Comparison with SRIM and experimental values shows that the Morse-based potentials yield improved consistency across a range of incident energies. In addition, we present theoretical interatomic potential predictions for Sn–H2, Gd–H2 and Bi–H2 systems, highlighting their potential use in future modeling of extreme ultraviolet lithography and Blue-X under hydrogen irradiation. Our results demonstrate that Morse-fitted DFT potentials provide a more accurate and transferable framework than traditional ZBL-based models for simulating hydrogen interactions with metallic targets.
{"title":"DFT-based interatomic potentials for hydrogen–metal systems: Improved stopping power modeling","authors":"Xuan Feng, Yunliang Song, Yuwei Ma, Bowen Li","doi":"10.1016/j.nimb.2025.165999","DOIUrl":"10.1016/j.nimb.2025.165999","url":null,"abstract":"<div><div>Accurate interatomic potentials are critical for reliable simulations of ion–solid interactions. In this work, we present a systematic development of interatomic potentials for hydrogen–metal systems based on density functional theory (DFT) calculations. Pairwise potential energy curves for H–Ag, H–Cu, and H–Au were computed and fitted to both the Ziegler–Biersack–Littmark (ZBL) and Morse potential forms. The fitted potentials were implemented into the RustBCA binary collision approximation code to simulate hydrogen stopping powers. Comparison with SRIM and experimental values shows that the Morse-based potentials yield improved consistency across a range of incident energies. In addition, we present theoretical interatomic potential predictions for Sn–H<sub>2</sub>, Gd–H<sub>2</sub> and Bi–H<sub>2</sub> systems, highlighting their potential use in future modeling of extreme ultraviolet lithography and Blue-X under hydrogen irradiation. Our results demonstrate that Morse-fitted DFT potentials provide a more accurate and transferable framework than traditional ZBL-based models for simulating hydrogen interactions with metallic targets.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 165999"},"PeriodicalIF":1.4,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1016/j.nimb.2026.166004
Ernest Ejeh , Faith Ochai-Ejeh , David Aladese , Morgan Madhuku
In this study, we investigate individual L-shell X-ray production cross sections of selected high-Z elements bismuth (Bi), gold (Au), and silver (Ag) induced by heavy ion bombardment. Measurements were performed for the Ll, Lα, Lβ, and Lγ lines corresponding to transitions within the L-subshells using carbon ions in the energy range of 12 MeV to 16 MeV. This work forms part of an ongoing investigation aimed at improving the understanding of ion-atom interaction mechanisms involving carbon, oxygen, and proton projectiles. X-ray spectra were collected and analysed to obtain individual X-ray production cross sections, and the results were compared to theoretical predictions from the ECPSSR model and the ECPSSR with United Atom correction (ECPSSR + UA). Overall, good agreement was generally observed between experimental results and ECPSSR + UA model, which performed better than the standard ECPSSR model, as expected.
{"title":"Ion-induced L-shell X-rays in heavy elements: measurement and modelling using carbon ions","authors":"Ernest Ejeh , Faith Ochai-Ejeh , David Aladese , Morgan Madhuku","doi":"10.1016/j.nimb.2026.166004","DOIUrl":"10.1016/j.nimb.2026.166004","url":null,"abstract":"<div><div>In this study, we investigate individual L-shell X-ray production cross sections of selected high-Z elements bismuth (Bi), gold (Au), and silver (Ag) induced by heavy ion bombardment. Measurements were performed for the L<sub>l</sub>, L<sub>α</sub>, L<sub>β</sub>, and L<sub>γ</sub> lines corresponding to transitions within the L-subshells using carbon ions in the energy range of 12 MeV to 16 MeV. This work forms part of an ongoing investigation aimed at improving the understanding of ion-atom interaction mechanisms involving carbon, oxygen, and proton projectiles. X-ray spectra were collected and analysed to obtain individual X-ray production cross sections, and the results were compared to theoretical predictions from the ECPSSR model and the ECPSSR with United Atom correction (ECPSSR + UA). Overall, good agreement was generally observed between experimental results and ECPSSR + UA model, which performed better than the standard ECPSSR model, as expected.</div></div>","PeriodicalId":19380,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms","volume":"572 ","pages":"Article 166004"},"PeriodicalIF":1.4,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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