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Neutron and γ-ray irradiation damages to transistors are found to be non-additive, and this is denoted as the irradiation synergistic effect (ISE). Its mechanism is not well-understood. The recent defect-based model [Song and Wei, ACS Appl. Electron. Mater. 2, 3783 (2020)] for silicon bipolar junction transistors (BJTs) achieves quantitative agreement with experiments, but its assumptions on the defect reactions are unverified. Going beyond the model requires directly representing the effect of γ-ray irradiation in first-principles calculations, which was not feasible previously. In this work, we examine the defect-based model of the ISE by developing a multiscale method for the simulation of the γ-ray irradiation, where the γ-ray-induced electronic excitations are treated explicitly in excited-state first-principles calculations. We find the calculations agree with experiments, and the effect of the γ-ray-induced excitation is significantly different from the effects of defect charge state and temperature. We propose a diffusion-based qualitative explanation of the mechanism of positive/negative ISE in NPN/PNP BJTs in the end. [ABSTRACT FROM AUTHOR]

Radiation-induced property changes in materials originate from the energy transfer from an incoming particle to the existing lattice, displacing atoms. The displaced atoms can cause the formation of extended defects including dislocation loops, voids, or precipitates. The non-equilibrium defects created during damage events determine the extent of these larger defects and are a function of dose rate, material, and temperature. However, these defects are transient and can only be probed indirectly. This work presents direct experimental measurements and evidence of irradiated non-equilibrium vacancy formation, where in situ positron annihilation spectroscopy was used to prove the generation of non-equilibrium defects in silicon. [ABSTRACT FROM AUTHOR]

Purpose: Classical brachytherapy of solid malignant tumors is an invasive procedure which often results in an uneven dose distribution, while requiring surgical removal of sealed radioactive seed sources after a certain period of time. To circumvent these issues, we report the synthesis of intrinsically radiolabeled and gum Arabic glycoprotein functionalized [169Yb]Yb2O3 nanoseeds as a novel nanoscale brachytherapy agent, which could directly be administered via intratumoral injection for tumor therapy. Methods: 169Yb (T½ = 32 days) was produced by neutron irradiation of enriched (15.2% in 168Yb) Yb2O3 target in a nuclear reactor, radiochemically converted to [169Yb]YbCl3 and used for nanoparticle (NP) synthesis. Intrinsically radiolabeled NP were synthesized by controlled hydrolysis of Yb3+ ions in gum Arabic glycoprotein medium. In vivo SPECT/CT imaging, autoradiography, and biodistribution studies were performed after intratumoral injection of radiolabeled NP in B16F10 tumor bearing C57BL/6 mice. Systematic tumor regression studies and histopathological analyses were performed to demonstrate therapeutic efficacy in the same mice model. Results: The nanoformulation was a clear solution having high colloidal and radiochemical stability. Uniform distribution and retention of the radiolabeled nanoformulation in the tumor mass were observed via SPECT/CT imaging and autoradiography studies. In a tumor regression study, tumor growth was significantly arrested with different doses of radiolabeled NP compared to the control and the best treatment effect was observed with ~ 27.8 MBq dose. In histopathological analysis, loss of mitotic cells was apparent in tumor tissue of treated groups, whereas no significant damage in kidney, lungs, and liver tissue morphology was observed. Conclusions: These results hold promise for nanoscale brachytherapy to become a clinically practical treatment modality for unresectable solid cancers. [ABSTRACT FROM AUTHOR]

A point of study in the characterization of additive manufactured (AM) alloys is whether or not AM microstructure responds to external stimuli differently from conventionally manufactured alloys. Samples of Alloy 625, a nickel-based superalloy of interest, were produced by both additive manufacturing and conventional wrought methods. Samples of differing sizes were subjected to one of two different types of neutron fields during irradiation: fast neutron or reactor-spectrum neutron. Vickers microhardness measurements and transmission electron microscope images were used to analyze the differences between samples before and after they were subjected to the neutron fields. Results showed differing responses between the two fabrication methods. [ABSTRACT FROM AUTHOR]

Deuterium-tritium fusion reactions produce energy in the form of 14.1 MeV neutrons, and hence fusion reactor components will be exposed to high energy neutron irradiation while also being subjected to thermal, mechanical and magnetic loads. Exposure to neutron irradiation has numerous consequences, including swelling and dimensional changes, comparable in magnitude to the peak transient thermal deformations occurring in plasma-facing components. Irradiation also dynamically alters the various thermo-mechanical properties, relating temperature, stress and swelling in a strongly non-linear way. Experimental data on the effect of neutron exposure spanning the design parameter space are very sparse and this highlights the relevance of computer simulations. In this study we explore the equivalence between the body force/surface traction approach and the eigenstrain formalism for treating anisotropic irradiation-induced swelling. We find that both commercial and massively parallelised open source software for finite element method (FEM) simulations are suitable for assessing the effect of neutron exposure on the mechanically loaded reactor components. We demonstrate how two primary effects of irradiation, radiation swelling and the degradation of thermal conductivity, affect the distributions of stress and temperature in the divertor of the ITER tokamak. Significant uncertainties characterising the magnitude of swelling and models for treating it suggest that on the basis of the presently available data, only an order of magnitude estimate can be given to the stress developing in reactor components most exposed to irradiation during service. [ABSTRACT FROM AUTHOR]

This paper introduces a novel concept of a TRISO-fueled salt-cooled reactor (TFSCR). The core contains circulating pipes filled with molten salt carrying TRISO particles. The reactor achieves online refueling by slowly circulating the molten salt through the pipeline. The reactor utilizes the same molten salt as the coolant and graphite as the moderator. The reactor design has the characteristics of safety, economy, and nonproliferation. TRISO particles exhibit greater resistance to neutron irradiation, corrosion, oxidation, and high temperatures compared to conventional fuels. A molten salt-cooled reactor can also operate at higher temperatures, consequently enhancing power generation efficiency. Furthermore, lower operating pressures can mitigate the risk of significant damages and loss of coolant caused by accidents, thereby enhancing reactor safety. This paper presents the basic nuclear design of TFSCR under the assumptions concerning the average fuel power density, the volumetric core power density, and the core temperature. At the same time, the feasibility of online refueling and long-life operation was evaluated by fuel burnup calculation. [ABSTRACT FROM AUTHOR]

Autonomous nuclear reactor monitoring is a key aspect of the International Atomic Energy Agency's strategy to ensure nonproliferation treaty compliance. From the rise of small modular reactor technology, decentralized nuclear reactor fleets may strain the capacities of such monitoring and requires new approaches. We demonstrate the superior capabilities of a gamma detection system to monitor the criticality of a zero power nuclear reactor from beyond typical vessel boundaries, offering a powerful alternative to neutron-based systems by providing direct information on fission chain propagation. Using the case example of the research reactor CROCUS, we demonstrate how two bismuth germanate scintillators placed outside the reactor vessel can precisely observe reactor criticality using so called noise methods and provide core status information in seconds. Our results indicate a wide range of applications due to the newly gained geometric flexibility that could find use in fields beyond nuclear safety. [ABSTRACT FROM AUTHOR]

The work investigated the sorption of no-carrier-added 177Lu isolated from neutron-irradiated 176Yb2O3, and carrier-added 177Lu obtained by irradiation of natLu2O3, by commercial and oxidized nanodiamonds (NDs) of various grades from aqueous solutions to identify among them a promising carrier for further research in the field of nuclear medicine. A promising sorbent was found: oxidized NDs of the STP grade (ox-STP); conditions for the fast sorption of lutetium with it in an amount equivalent to 1.2 GBq of no-carrier-added 177Lu were determined, which corresponds to the activity used in therapy. [ABSTRACT FROM AUTHOR]

The assessment of the concentration and distribution of l6N, derived from 16O in the cooling water exposed to neutron irradiation, is essential for ensuring radiation safety during nuclear reactor operation. The imaging method allows for the visualization of the intensity distribution of these l6N by capturing gamma-rays emitted during their decay process. However, the existing gamma camera is exclusively compatible with gamma-rays below 2 MeV. In this paper, a novel gamma camera featuring a thick double-conical penumbra aperture, a pixelated Lu1.8Y0.2SiO5:Ce scintillator array, and a position-sensitive photomultiplier tube is proposed to address this limitation. This innovative design offers a large field of view (FOV) and is suitable for high energy extended gamma source imaging. The optimization of key parameters of the camera was conducted, and a FOV of 60° and an angular resolution of up to 4.57° were achieved. Imaging simulations, including a simplified model of the primary loop of the pressurized-water reactor by GEANT4 code and image reconstruction using the expectation maximum algorithm, demonstrated that the proposed gamma camera could obtain a satisfactory spatial resolution for diagnosing the distribution of 16N in the primary loop of a nuclear reactor. [ABSTRACT FROM AUTHOR]

Ion implanters have extensively been employed to simulate the irradiation effects of neutrons on relevant nuclear materials. In this study, a 50 kV hydrogen–helium mixed ion beam implanter was developed to generate H2+ and He+ ion beams, with a beam current of 20 µA, while keeping the impurity ion content below 2%. The ions are generated by an antenna-type 2.45 GHz electron cyclotron resonance ion source, and the hydrogen-to-helium ion beam ratio was controlled using two gas mass flow controllers to ensure long time stability of the beam current. As a result, the H2+/He+ ratio, beam size, and homogeneity of the beam spot can be maintained at a stable level. The beam line consisted of four Wien filters, a movable dual-slit plate, and an accelerator tube. The experimental results demonstrated successful transport of more than 20 µA of H2+ and He+ ion beams onto the target, with a beam axis deviation of less than 0.5 mm. [ABSTRACT FROM AUTHOR]

This article describes the preparation of 99Mo isotope using the direct nuclear reaction 98Mo(n,γ)99Mo by neutrons of the WWR-K reactor using molybdenum (VI) oxide of natural and enriched composition, according to the isotope 98Mo (98.66%) as a target. The possibility of using enriched 98Mo oxide to produce 99Mo was considered. The estimation of the maximum specific activity of 99Mo was obtained in a comparative manner under the same irradiation conditions at the reactor. [ABSTRACT FROM AUTHOR]

The neutron emission of Mars is known to be produced due to the bombardment of Martian surface by Galactic Cosmic Rays (GCRs). As evidenced by numerical simulation, the intensity of neutron emission on the planetary surface is much larger than that of the neutron emission at the orbital altitude due to multiple reflections of the neutrons emitted from soil by the atmosphere. The code developed for simulations was validated using the experimental data of neutron emission acquired in the Gale crater by the RAD and DAN instruments aboard the NASA's Curiosity rover. Neutron emission was simulated for two Martian areas: the dry Solis Planum territory and the bottom of the Valles Marineris system of canyons, which is thought to be the most wet equatorial spot on Mars. For both areas a strong effect is found, showing a considerable difference between the neutron emission on the surface and at the altitude of a typical orbit. It was also shown that surface emission in these two areas is quite different due to the difference of mass fraction of water in the shallow subsurface. Finally, the seasonal variations of neutron emission in these areas due to the atmospheric seasonal changes are also estimated. • Intensity of neutron emission on the Martian surface is much larger than on the orbit due to presence of atmosphere. • Neutron emission on the surface is simulated for dry Solis Planum and wet Valles Marineris. • The emission at these two areas is different due to the distinction of mass fraction of water in the subsurface. [ABSTRACT FROM AUTHOR]

This Special Topic "Radiation Effects in Materials" is a broad collection of scientific studies addressing the interaction of radiation with condensed matter, a long-standing issue that is relevant for a range of key energy technologies. With the discovery of nuclear fission and its use for energy production, the study and understanding of the effects of radiation on materials got a strong engineering dimension. As noted above, the principle of scintillators is based on the interaction between radiation and matter, and the increasing uses of radiation in our society stimulate the search for better performing materials. [Extracted from the article]

Studies of the radiation tolerance and electrical behavior of gallium nitride (GaN) based devices are important for the next generation of high-power and high-voltage electronics that may be subjected to harsh environments such as nuclear reactor and fusion facilities, particle accelerators, and post-denotation environments. In this work, we study the behavior of Ga-polar and N-polar GaN Schottky diodes before and after exposure to fast and thermal + fast neutrons. Temperature-dependent current–voltage (I–V) and circular transmission line method (CTLM) measurements were used to study the electrical characteristics. A strong reduction in reverse leakage current and an increase in differential resistance in forward bias were observed after neutron irradiation. Thermionic emission (TE), Frenkel–Poole (FP) emission, and Fowler–Nordheim (FN) tunneling models were used to explain the forward and reverse I–V characteristics pre- and post-irradiation. The study confirms that Ga-polar and N-polar GaN Schottky diodes exhibit different electrical responses to fast and thermal neutron irradiations. The reverse bias characteristics of N-polar diodes are less affected after the fast neutron irradiation compared to Ga-polar diodes, while in the forward bias region, the electrical behavior after fast and thermal neutron irradiations is similar in Ga-polar and N-polar diodes. The results indicate that the role of orientation should be considered in the design of GaN-based radiation-tolerant electronics. [ABSTRACT FROM AUTHOR]

Titanium-modified austenitic stainless steels (15-15TiSS) are currently used as the fuel cladding material of fast reactors, which are subject to higher radiation damage during their application. In this work, the radiation-induced swelling of 15-15TiSS under a fast reactor neutron and heavy ion irradiation conditions was studied by the rate theory (RT). The simulated swelling properties of 15-15TiSS under fast neutron conditions were calculated initially. The swelling peak, swelling rates, and swelling-related microstructural properties are consistent with the neutron irradiation results, indicating that the selected RT model and material parameters are reasonable. Then, the swelling properties of 15-15TiSS under various damage rates were predicted by changing the radiation damage rates from 1 × 10−6 to 1 × 10−3 dpa/s. It shows that swelling peaks are strongly dependent on temperature and the swelling peaks shift ∼50 °C toward the higher temperature with each order of magnitude increase of defects generation rate. The swelling rates and swelling-related defect evolution at 1 × 10−3 dpa/s (with a swelling peak temperature of 590 °C) are consistent with that under neutron irradiation with 1 × 10−6 dpa/s (with a swelling peak temperature of 460 °C). At length, the RT-predicted heavy ions irradiation results were verified by the previous positron annihilation lifetime spectroscopy results of ions irradiated 15-15TiSS. It indicates that heavy ion irradiation can be used to study the radiation effect of materials under neutron irradiation and should be a feasible technique used in the further screening of radiation-resistant materials. [ABSTRACT FROM AUTHOR]

Irradiation creep is known to be an important process for structural materials in nuclear environments, potentially leading to creep failure at temperatures where thermal creep is generally negligible. While there is a great deal of data for irradiation creep in steels and zirconium alloys in light water reactor conditions, much less is known for first wall materials under fusion energy conditions. Lacking suitable fusion neutron sources for detailed experimentation, modeling, and simulation can help bridge the dose-rate and spectral-effects gap and produce quantifiable expectations for creep deformation of first wall materials under standard fusion conditions. In this paper, we develop a comprehensive model for irradiation creep created from merging a crystal plasticity representation of the dislocation microstructure and a defect evolution simulator that accounts for the entire cluster dimensionality space. Both approaches are linked by way of a climb velocity that captures dislocation-biased defect absorption and a dislocation strengthening term that reflects the accumulation of defect clusters in the system. We carry out our study in Fe under first wall fusion reactor conditions, characterized by a fusion neutron spectrum with average recoil energies of 20 keV and a damage dose rate of ≈ 3 × 10 − 7 dpa/s at temperatures between 300 and 800 K. [ABSTRACT FROM AUTHOR]

An extensive investigation on the microstructural evolution of nanocrystalline–amorphous laminated alloys (NALAs) by molecular dynamics simulations and mechanistic analysis have been conducted to apprehend the interplay of complex phenomena governing structural changes in this alloy under neutron irradiation. It was discovered from the evolution profiles of free volumes, atomic unfilled spaces, and irradiation-induced vacancies that the profound structural response of the NALA was orchestrated by the rapid and spontaneous recovery of free volumes that indicate a self-healing ability in the amorphous zone, while the phenomenon of geometric atomic reconstitution in local structures governs the effective self-healing capacity for annihilated nanocrystal regions. Furthermore, a distinctive, self-migration/diffusion capture dynamics for the annihilation of defects by phase boundaries was discovered as an effective self-healing mechanism in NALAs. These findings will potentially facilitate the development of advanced nuclear materials with high irradiation resistance. [ABSTRACT FROM AUTHOR]

The isotopic shifts of 149Sm–150Sm and 157Gd–158Gd have often been observed in meteorites and lunar surface materials, because they result from the neutron-capture reactions associated with secondary neutrons produced by cosmic-ray irradiation. While the Sm and Gd isotopic shifts can mainly be used for the estimation of thermal neutron fluences that of 167Er–168Er has recently been applied in the estimation of epithermal neutron fluences. The systematic isotopic dataset of Sm, Gd and Er helps us to consider the details of planetary materials' cosmic-ray exposure conditions using the balance of the fluences between thermal and epithermal neutrons. This paper reviews a series of isotopic variations of Sm, Gd, and Er in association with neutron-capture reactions for the application of planetary sciences. As a new attempt and possibility for better understanding the neutron fluence and its energy distribution, the use of Yb isotopic variation is then discussed using two different data sources, namely lunar regolith and the Oklo natural reactors. Finally, the preliminary result for the precise isotopic measurement of Yb is presented from the viewpoint of chemical separation and instrumental improvement. [ABSTRACT FROM AUTHOR]

This work investigates the radiation resistance of high‐performance multi‐component perovskite solar cells (PSCs) for the first time under extreme short‐pulse proton irradiation conditions. The devices are subjected to high‐intensity 170 keV pulsed (150 ns) proton irradiation, with a fluence of up to 1013 p cm−2, corresponding to ≈30 years of operation at low Earth orbit. A complex material characterization of the perovskite active layer and device physics analysis of the PSCs before and after short‐pulse proton irradiation is conducted. The obtained results indicate that the photovoltaic performance of the solar cells experiences a slight deterioration up to 20 % and 50 % following the low 2 × 1012 p cm−2 and high 1 × 1013 p cm−2 proton fluences, respectively, due to increased non‐radiative recombination losses. The findings reveal that multi‐component PSCs are immune even to extreme high‐intense short‐pulse proton irradiation, which exceeds harsh space conditions, including intense coronal ejection events usually associated with solar flares. [ABSTRACT FROM AUTHOR]

L-4-[(10B)]Boronophenylalanine (BPA) is an amino acid analogue with a boron-10 moiety. It is most widely used as a boron carrier in boron neutron capture therapy. In this study, a Bayesian predictive platform of blood boron concentration based on a BPA pharmacokinetic (PK) model was developed. This platform is user-friendly and can predict the individual boron PK and optimal time window for boron neutron capture therapy in a simple way. The present study aimed to establish a PK model of L-4-boronophenylalanine and develop a Bayesian predictive platform for blood boron PKs for user-friendly estimation of boron concentration during neutron irradiation of neutron capture therapy. Whole blood boron concentrations from seven previous reports were graphically extracted and analyzed using the nonlinear mixed-effects modeling (NONMEM) approach. Model robustness was assessed using nonparametric bootstrap and visual predictive check approaches. The visual predictive check indicated that the final PK model is able to adequately predict observed concentrations. The Shiny package was used to input real-time blood boron concentration data, and during the following irradiation session blood boron was estimated with an acceptably short calculation time for the determination of irradiation time. Finally, a user-friendly Bayesian estimation platform for BPA PKs was developed to optimize individualized therapy for patients undergoing BNCT. [ABSTRACT FROM AUTHOR]

ZrN films were irradiated with 2 MeV proton and 91.3 MeV Xe ion. Our aim is to demonstrate the radiation damage tolerance of nanostructured ZrN. Uv–visible spectroscopy revealed localized surface plasmon resonance (LSPR) band at 650 nm of ZrN nanoparticles. After irradiation the LSPR band intensity increases and become larger. The band gap decreases, while Urbach energy increases indicating defect formation. It is found a better crystallinity and no swelling or contraction in the studied fluence range. Therefore, nanostructured ZrN can be used in harsh irradiation environments such as neutron reactors and aerospace without altering its structural and plasmonic properties. [ABSTRACT FROM AUTHOR]

Prompt gamma rays of terbium emitted after (n,nʹγ) inelastic scattering reactions induced by irradiation of a terbium(III) hexahydrate (TbCl3·6H2O) sample with a beam of fission neutrons were investigated with the instrument FaNGaS (Fast Neutron-induced Gamma-ray Spectrometry) at an angle of 90° between neutron beam and detector. At sample position, the fast-neutron flux was 1.13 × 108 cm−2 s−1 and the neutron beam has an average energy of 2.30 MeV. We identified 124 prompt gamma lines from the 159Tb(n,nʹγ)159Tb reaction. Presence of prompt gamma rays from oxygen and chlorine was used for a concise verification of recently published results. Relative gamma-ray intensities, effective cross sections and fast-neutron spectrum-averaged partial production cross sections of the gamma lines are given including comparisons with available literature data. We found a reasonable agreement and the multitude of unreported lines adds decisive value to nuclear spectroscopy. Additionally, we estimated the detection limit of terbium as 1 mg for a counting time of 12 h. [ABSTRACT FROM AUTHOR]

The article discusses the field of radiation biodosimetry, which involves measuring biological responses to estimate the absorbed radiation dose in exposed humans. The article highlights the current biodosimetry tools used, including prodromal signs/symptoms, hematological analysis, cytogenetics, omics, and physical dosimetry. The special issue contains reviews and research articles on various aspects of biodosimetry, including biomarkers, high-throughput automation, and the need for validation and testing of existing tools. The article also emphasizes the importance of considering confounding factors such as age, sex, and genetic predisposition in dose prediction accuracy. The authors hope that this special issue will inspire further research in the field to protect human safety and health from radiation exposures. [Extracted from the article]

In the case of a radiological or nuclear event, biological dosimetry can be an important tool to support clinical decision-making. During a nuclear event, individuals might be exposed to a mixed field of neutrons and photons. The composition of the field and the neutron energy spectrum influence the degree of damage to the chromosomes. During the transatlantic BALANCE project, an exposure similar to a Hiroshima-like device at a distance of 1.5 km from the epicenter was simulated, and biological dosimetry based on dicentric chromosomes was performed to evaluate the participants ability to discover unknown doses and to test the influence of differences in neutron spectra. In a first step, calibration curves were established by irradiating blood samples with 5 doses in the range of 0–4 Gy at two different facilities in Germany (Physikalisch-Technische Bundesanstalt [PTB]) and the USA (the Columbia IND Neutron Facility [CINF]). The samples were sent to eight participating laboratories from the RENEB network and dicentric chromosomes were scored by each participant. Next, blood samples were irradiated with 4 blind doses in each of the two facilities and sent to the participants to provide dose estimates based on the established calibration curves. Manual and semiautomatic scoring of dicentric chromosomes were evaluated for their applicability to neutron exposures. Moreover, the biological effectiveness of the neutrons from the two irradiation facilities was compared. The calibration curves from samples irradiated at CINF showed a 1.4 times higher biological effectiveness compared to samples irradiated at PTB. For manual scoring of dicentric chromosomes, the doses of the test samples were mostly successfully resolved based on the calibration curves established during the project. For semiautomatic scoring, the dose estimation for the test samples was less successful. Doses >2 Gy in the calibration curves revealed nonlinear associations between dose and dispersion index of the dicentric counts, especially for manual scoring. The differences in the biological effectiveness between the irradiation facilities suggested that the neutron energy spectrum can have a strong impact on the dicentric counts. [ABSTRACT FROM AUTHOR]

At present, to evaluate the service life of space optical materials on the ground, 60Co γ-rays are usually used. However, the irradiation effect of the main space particles (protons, electrons) on materials is obviously different from that of γ-rays, which causes evaluation errors. In this study, the Monte Carlo method was used to study the transportation of 60Co γ-rays, protons, and electrons in the usually used optical materials, silica (SiO2). The number of secondary electrons produced by particles at different energies, and quantities in targets with different thicknesses was obtained, and the dominant effect (ionisation effect) of particles on silica was analysed. Based on the ionisation effect, using the number of secondary electrons as the equivalence parameter, the irradiation effect conversion relation of 60Co γ-rays and particles (protons and electrons) on silica was established, which satisfies Boltzmann's function. This work provides a new life evaluation method for 60Co γ-rays ground irradiation experiments. [ABSTRACT FROM AUTHOR]

The synergistic effects on the 0.18 µm PPD CISs induced by neutron displacement damage and gamma ionization damage are investigated. The typical characterizations of the CISs induced by the neutron displacement damage and gamma ionization damage are presented separately. The CISs are irradiated by reactor neutron beams up to 1 × 1011 n/cm2 (1 MeV neutron equivalent fluence) and 60Co γ-rays up to the total ionizing dose level of 200 krad(Si) with different sequential order. The experimental results show that the mean dark signal increase in the CISs induced by reactor neutron radiation has not been influenced by previous 60Co γ-ray radiation. However, the mean dark signal increase in the CISs induced by 60Co γ-ray radiation has been remarkably influenced by previous reactor neutron radiation. The synergistic effects on the PPD CISs are discussed by combining the experimental results and the TCAD simulation results of radiation damage. [ABSTRACT FROM AUTHOR]

This work describes the straightforward solvothermal microwave irradiation approach utilized to create pure and variable quantities of Fe doped CuO nanoparticles, as well as the experimental methods used to characterize their structural properties. The chemical, physical, and structural features of the nanoparticles were characterized using a wide variety of methods. The crystal structure, lattice properties, and crystallite size of the pure and Fe-doped CuO nanoparticles produced were confirmed by powder X-ray diffraction investigation. Analyzing the produced nanoparticles using Energy Dispersive X-ray Absorptiometry confirmed their atomic percentage and stoichiometry. The band gap and absorption were calculated from the items' measured UV–visible spectra. Photoluminescence tests confirmed the materials' stated green emission. Surface morphology and nanoparticles quality is assessed by SEM. Transmission electron microscopy can assess particle size and dispersion. The temperature dependence of the dielectric characteristics of nanoparticles was studied. It has been shown that CuO nanoparticles, both undoped and Fe-doped possess applications like power generation, circuitry, telecommunication, optical and photovoltaic device. [ABSTRACT FROM AUTHOR]

Several intense energy irradiation testing facilities are functional to study the effects of radiation damage in fusion materials. Tungsten is a potential candidate material to build the plasma-facing armour components of fusion reactors. Therefore, it is vital to estimate the radiation-induced primary damage in the material, particularly due to the large amount of transmutation nuclides produced in the high-energy neutron sources. The basic evaluated nuclear data libraries provide the essential neutron reaction data to estimate the transmutations and their effects during irradiation. However, much of the important high-energy neutron reaction data are often not explicitly provided to directly study their impact on radiation damage. Such inexplicit nuclear reaction data, especially for the transmutation nuclides, can have a significant effect on the estimation of primary radiation damage. A new specific methodology has been developed to unravel information from these inexplicit nuclear reaction data from the basic ENDF-6 libraries and use them with explicit data for estimating the primary radiation damage. The energy distributions of transmuted nuclides (the recoil nuclei in general) and light charged particles produced as a result of several types of neutron–nucleus interactions in tungsten, are quantified using the cross-sections from ENDF / B-VIII.0 and TENDL-2019 basic evaluated nuclear data libraries and their inter-comparisons are carried out. The neutron-induced atomic displacements and heating in tungsten are estimated for irradiations under the fusion and IFMIF-DLi neutron spectra. It shows that the transmutation reactions under these neutron spectra can sometimes contribute more than 50% of the total primary damage, most of which can be from inexplicit nuclear reaction data. Significant differences between the two sources of basic evaluated nuclear data libraries, especially in the production of transmutation nuclides and consequently, in their contributions to damage are observed. The present study helps to illustrate the importance of inexplicit nuclear reaction data and the usefulness of the ENDF-6 libraries for estimating primary radiation damage due to transmutations in plasma-facing materials. [ABSTRACT FROM AUTHOR]

The titanium-stabilized austenitic stainless steel Fe-15Cr-15Ni, which shows enhanced resistance to irradiation swelling compared with more traditional 316Ti, has been selected as a core material for fast reactors. Data on the evolution of irradiation swelling in 15-15Ti steels at very high doses, which cannot be easily achieved by neutron irradiation, are still lacking. In this paper, the swelling behavior of the titanium-modified austenitic stainless steel 15-15Ti was investigated by pre-implantation of He at room temperature followed by Ni-ion irradiation at 580 °C to peak doses of 120, 240 and 400 dpa. Relatively small cavities were observed in the zone of helium implantation, while large cavities appeared in the region near the damage peak. A correction formula for the dpa curve was proposed and applied to samples with large swelling. It was found that the steady-state swelling rate of 15-15Ti remains at ~1%/dpa even at high doses. By comparing the swelling data of the helium-implanted and helium-free regions at same doses, 70 dpa and 122 dpa, the suppression of swelling by excessive helium can be deduced at such doses. [ABSTRACT FROM AUTHOR]

This paper presents the results of studies of the capacitance-voltage characteristics (CVC) of GaAs/In0.53Ga0.47As HEMT before and after neutron irradiation with a fluence of (6.3 ± 1.3) × 1014 cm–2. Based on the experimentally obtained characteristics, the effective electron distribution profiles of the structure are calculated before and after the radiation impact. The effect of radiation defects on the δ-layers of the structure is analyzed. [ABSTRACT FROM AUTHOR]

Cloud and bubble chambers have historically been used for particle detection, capitalizing on supersaturation and superheating, respectively. Here, we present new results from a prototype snowball chamber, in which an incoming particle triggers the crystallization of a purified, supercooled liquid. We demonstrate, for the first time, simulation agreement with our first results from 5 years ago: the higher temperature of the freezing of water and significantly shorter time spent supercooled compared to the control in the presence of a Cf-252 fission neutron source. This is accomplished by combining Geant4 modeling of neutron interactions with the Seitz nucleation model used in superheated bubble chambers, including those seeking dark matter. We explore the possible implications of using this new technology for GeV-scale WIMP searches, especially in terms of spin-dependent proton coupling, and report the first supercooling of WbLS (water-based liquid scintillator). [ABSTRACT FROM AUTHOR]

Fast and high‐linearity detection of fast neutron is vital for special nuclear material seeking, nuclear accident emergency response, nondestructive neutron imaging, and neutron cancer therapy. Neutron scintillators with fast time resolution and linear energy response are indispensable for precisely acquiring the energy and temporal evolution of fast neutron, but none of the conventional neutron scintillators, whether organic, two‐component or inorganic, have performed well in this regard. To address these challenges, it is urgent to develop novel neutron scintillators. Here, 2D hybrid perovskite single crystals (C4H12N)2PbBr4 (BA2PbBr4) successfully combined with fast response time of 2.66 ns and linear energy response to fast neutrons, γ ray, and α particle, is reported. The rapid response time and linear energy response of 2D hybrid perovskite scintillator originate from intensive states density of lead halide frameworks, which are the key fluorescence emitters under neutron irradiation. This effectively suppresses the ionization quenching effect during the fluorescence process. This work represents a milestone in fast neutron detection, demonstrating a new type of neutron scintillator based on 2D hybrid perovskite single crystals with fast and high‐linearity detection characteristics, having great potential in high precision neutron spectrum measurement and nuclear reaction kinetics monitoring. [ABSTRACT FROM AUTHOR]

Faster than expected surface corrosion and a considerable decrease in the 10B areal density of a non-clad Al-B4C neutron absorber were recently reported from surveillance coupons used in a spent fuel pool for about 8 years, which is only approximately one-fifth of the guaranteed service life of the absorber. Such premature degradation was largely attributed to irradiation-assisted corrosion since numerous gas bubbles filled with He and H were discovered in the Al alloy matrix near B4C particles, and naturally 10B(n, α)7Li reactions were designated as the underlying mechanism for the porosification that may have expedited the absorber corrosion. In this study, the levels of radiation damage and He concentration in the micrographs published in recent experimental studies were estimated to design ion beam irradiation experiments having appropriate parameters to emulate the status of neutron-irradiated non-clad Al-B4C absorbers. TRITON, CSAS6, and SDTrimSP were coupled with modifications for the calculation of dpa and He concentration in irradiated neutron absorbers. The simulations yielded 3.74–6.71 dpa and 0.71–1.64 at% of He after 99 months of use and 3.82–8.39 dpa and 0.73–2.08 at% of He after 40 years of use. The simulations also demonstrated that the radiation damage and He concentration have a weak correlation with the particle diameter. In terms of radiation damage, these results are in good agreement with the reported experimental data, indicating that they can be referred to in the experimental design. The calculated He concentrations, however, may warrant modification to include leakage of implanted He atoms through irradiation-induced microcracks in the B4C particles. Because of the high diffusivity of He, full leakage of He from B4C particles to their boundaries with the Al alloy matrix was assumed for further estimations, which revealed that He concentration could be significantly elevated in the Al matrix near B4C particles. [ABSTRACT FROM AUTHOR]

Boron Neutron Capture Therapy (BNCT) is a radiotherapy technique based on the enrichment of tumour cells with suitable 10-boron concentration and on subsequent neutron irradiation. Low-energy neutron irradiation produces a localized deposition of radiation dose caused by boron neutron capture reactions. Boron is vehiculated into tumour cells via proper borated formulations, able to accumulate in the malignancy more than in normal tissues. The neutron capture releases two high-LET charged particles (i.e., an alpha particle and a lithium ion), losing their energy in a distance comparable to the average dimension of one cell. Thus BNCT is selective at the cell level and characterized by high biological effectiveness. As the radiation field is due to the interaction of neutrons with the components of biological tissues and with boron, the dosimetry requires a formalism to express the absorbed dose into photon-equivalent units. This work analyzes a clinical case of an adenoid cystic carcinoma treated with carbon-ion radiotherapy (CIRT), located close to optic nerve and deep-seated as a practical example of how to apply the formalism of BNCT photon isoeffective dose and how to evaluate the BNCT dose distribution against CIRT. The example allows presenting different dosimetrical and radiobiological quantities and drawing conclusions on the potential of BNCT stemming on the clinical result of the CIRT. The patient received CIRT with a dose constraint on the optic nerve, affecting the peripheral part of the Planning Target Volume (PTV). After the treatment, the tumour recurred in this low-dose region. BNCT was simulated for the primary tumour, with the goal to calculate the dose distribution in isoeffective units and a Tumour Control Probability (TCP) to be compared with the one of the original treatment. BNCT was then evaluated for the recurrence in the underdosed region which was not optimally covered by charged particles due to the proximity of the optic nerve. Finally, a combined treatment consisting in BNCT and carbon ion therapy was considered to show the consistency and the potential of the model. For the primary tumour, the photon isoeffective dose distribution due to BNCT was evaluated and the resulted TCP was higher than that obtained for the CIRT. The formalism produced values that are consistent with those of carbon-ion. For the recurrence, BNCT dosimetry produces a similar TCP than that of primary tumour. A combined treatment was finally simulated, showing a TCP comparable to the BNCT-alone with overall dosimetric advantage in the most peripheral parts of the treatment volume. Isoeffective dose formalism is a robust tool to analyze BNCT dosimetry and to compare it with the photon-equivalent dose calculated for carbon-ion treatment. This study introduces for the first time the possibility to combine the dosimetry obtained by two different treatment modalities, showing the potential of exploiting the cellular targeting of BNCT combined with the precision of charged particles in delivering an homogeneous dose distribution in deep-seated tumours. [ABSTRACT FROM AUTHOR]

Boron Neutron Capture Therapy (BNCT) is a radiotherapy technique based on the enrichment of tumour cells with suitable 10-boron concentration and on subsequent neutron irradiation. Low-energy neutron irradiation produces a localized deposition of radiation dose caused by boron neutron capture reactions. Boron is vehiculated into tumour cells via proper borated formulations, able to accumulate in the malignancy more than in normal tissues. The neutron capture releases two high-LET charged particles (i.e., an alpha particle and a lithium ion), losing their energy in a distance comparable to the average dimension of one cell. Thus BNCT is selective at the cell level and characterized by high biological effectiveness. As the radiation field is due to the interaction of neutrons with the components of biological tissues and with boron, the dosimetry requires a formalism to express the absorbed dose into photon-equivalent units. This work analyzes a clinical case of an adenoid cystic carcinoma treated with carbon-ion radiotherapy (CIRT), located close to optic nerve and deep-seated as a practical example of how to apply the formalism of BNCT photon isoeffective dose and how to evaluate the BNCT dose distribution against CIRT. The example allows presenting different dosimetrical and radiobiological quantities and drawing conclusions on the potential of BNCT stemming on the clinical result of the CIRT. The patient received CIRT with a dose constraint on the optic nerve, affecting the peripheral part of the Planning Target Volume (PTV). After the treatment, the tumour recurred in this low-dose region. BNCT was simulated for the primary tumour, with the goal to calculate the dose distribution in isoeffective units and a Tumour Control Probability (TCP) to be compared with the one of the original treatment. BNCT was then evaluated for the recurrence in the underdosed region which was not optimally covered by charged particles due to the proximity of the optic nerve. Finally, a combined treatment consisting in BNCT and carbon ion therapy was considered to show the consistency and the potential of the model. For the primary tumour, the photon isoeffective dose distribution due to BNCT was evaluated and the resulted TCP was higher than that obtained for the CIRT. The formalism produced values that are consistent with those of carbon-ion. For the recurrence, BNCT dosimetry produces a similar TCP than that of primary tumour. A combined treatment was finally simulated, showing a TCP comparable to the BNCT-alone with overall dosimetric advantage in the most peripheral parts of the treatment volume. Isoeffective dose formalism is a robust tool to analyze BNCT dosimetry and to compare it with the photon-equivalent dose calculated for carbon-ion treatment. This study introduces for the first time the possibility to combine the dosimetry obtained by two different treatment modalities, showing the potential of exploiting the cellular targeting of BNCT combined with the precision of charged particles in delivering an homogeneous dose distribution in deep-seated tumours. [ABSTRACT FROM AUTHOR]

The imaging heavy ion beam probe (i-HIBP) diagnostic has been successfully commissioned at ASDEX Upgrade. The i-HIBP injects a primary neutral beam into the plasma, where it is ionized, leading to a fan of secondary (charged) beams. These are deflected by the magnetic field of the tokamak and collected by a scintillator detector, generating a strike-line light pattern that encodes information on the density, electrostatic potential, and magnetic field of the plasma edge. The first measurements have been made, demonstrating the proof-of-principle of this diagnostic technique. A primary beam of 85/87Rb has been used with energies ranging between 60 and 72 keV and extracted currents up to 1.5 mA. The first signals have been obtained in experiments covering a wide range of parameter spaces, with plasma currents (Ip) between 0.2 and 0.8 MA and on-axis toroidal magnetic field (Bt) between 1.9 and 2.7 T. Low densities appear to be critical for the performance of the diagnostic, as signals are typically observed only when the line integrated density is below 2.0–3.0 × 1019 m−2 in the central interferometer chord, depending on the plasma shape. The strike line moves as expected when Ip is ramped, indicating that current measurements are possible. Additionally, clear dynamics in the intensity of the strike line are often observed, which might be linked to changes in the edge profile structure. However, the signal-to-background ratio of the signals is hampered by stray light, and the image guide degradation is due to neutron irradiation. Finally, simulations have been carried out to investigate the sensitivity of the expected signals to plasma density and temperature. The results are in qualitative agreement with the experimental observations, suggesting that the diagnostic is almost insensitive to fluctuations in the temperature profile, while the signal level is highly determined by the density profile due to the beam attenuation. [ABSTRACT FROM AUTHOR]

Background: Boron‐containing compounds, such as 4‐borono‐phenylalanine (BPA) are used as drugs for cancer treatment in the framework of Boron Neutron Capture Therapy (BNCT). Neutron irradiation of boron‐rich compounds delivered to cancer cells triggers nuclear reactions that destroy cancer cells. Purpose: We provide a modeling of the thermal neutron cross section of BPA, a drug used in Boron Neutron Capture Therapy (BNCT), to quantify the competing contributions of boron absorption against hydrogen scattering, for optimizing BNCT by minimizing the latter. Methods: We perform the experimental determination of the total neutron scattering cross section of BPA at thermal and epithermal neutron energies using neutron transmission measurements. We isolate the contribution related to the incoherent scattering by hydrogen atoms as a function of the neutron energy by means of the Average Functional Group Approximation, and we calculate the probability for a neutron of being absorbed as a function of the neutron energy both for BPA and for its variants where either one or all four aromatic hydrogen atoms are substituted by 19F, and both for the samples with natural occurrence or enriched concentration of 10B. Results: While referring to the already available literature for in vivo use of fluorinated BPA, we show that fluorine‐rich variants of BPA increase the probability of neutrons being captured by the molecule. As the higher absorption efficiency of fluorinated BPA does not depend on whether the molecule is used in vivo or not, our results are promising for the higher efficiency of the boron neutron capture treatment. Conclusions: Our results suggest a new advantage using fluorinated compounds for BNCT, in their optimized interaction with neutrons, in addition to their already known capability to be used for monitoring and pharmacokinetics studies using 19F‐Nuclear Magnetic Resonance or in 18F‐Positron Emission Tomography. [ABSTRACT FROM AUTHOR]

Purpose: We developed a 4‐dimensional dynamic dose (4DDD) calculation model for proton pencil beam scanning (PBS). This model incorporates the spill start time for all energies and uses the remaining irradiated spot time model instead of irradiated spot time logs. This study aimed to validate the calculation accuracy of a log file‐based 4DDD model by comparing it with dose measurements performed under free‐breathing conditions, thereby serving as an alternative approach to the conventional log file‐based system. Methods: Three cubic verification plans were created using a heterogeneous block phantom; these plans were created using 10 phase 4D‐CT datasets of the phantom. The CIRS dynamic platform was used to simulate motion with amplitudes of 2.5, 3.75, and 5.0 mm. These plans consisted of eight‐ and two‐layered rescanning techniques. The lateral profiles were measured using a 2D ionization chamber array (2D‐array) and EBT3 Gafchromic films at four starting phases, including three sinusoidal curves (periods of 3, 4, and 6 s) and a representative patient curve during actual treatment. 4DDDs were calculated using in‐house scripting that assigned a time stamp to each spot and performed dose accumulation using deformable image registration. Furthermore, to evaluate the impact of parameter selection on our 4DDD model calculations, simulations were performed assuming a ±10% change in irradiation time stamp (0.8 ± 0.08 s) and spot scan speed. We evaluated the 2D gamma index and the absolute point doses between the calculated values and the measurements. Results: The 2D‐array measurements revealed that the gamma scores for the static plans (no motion) and 4DDD plans exceeded 97.5% and 93.9% at 3%/3 mm, respectively. The average gamma score of the 4DDD plans was at least 96.1%. When using EBT3 films, the gamma scores of the 4DDD model exceeded 92.4% and 98.7% at 2%/2 mm and 3%/3 mm, respectively. Regarding the 4DDD point dose differences, more than 95% of the dose regions exhibited discrepancies within ±5.0% for 97.7% of the total points across all plans. The spot time assignment accuracy of our 4DDD model was acceptable even with ±10% sensitivity. However, the accuracy of the scan speed, when varied within ±10% sensitivity, was not acceptable (minimum gamma scores of 82.6% and maximum dose difference of 12.9%). Conclusions: Our 4DDD calculations under free‐breathing conditions using amplitudes of less than 5.0 mm were in good agreement with the measurements regardless of the starting phases, breathing curve patterns (between 3 and 6 s periods), and varying numbers of layered rescanning. The proposed system allows us to evaluate actual irradiated doses in various breathing periods, amplitudes, and starting phases, even on PBS machines without the ability to record spot logs. [ABSTRACT FROM AUTHOR]

This study investigates the broad-energy-spectrum reactor-neutron irradiation effects on the electrical characteristics of Ni/β-Ga2O3 Schottky barrier diodes (SBDs), where the irradiated neutron fluence was up to 1 × 1016 cm−2. On the one hand, the high neutron fluence of 1016 cm−2 resulted in a reduction in forward current density by two orders of magnitude and an extremely high on-resistance property due to the radiation-generated considerable series resistance in the SBD. On the other hand, the irradiation brought little influence on the Ni/β-Ga2O3 Schottky contact, since the extracted ideality factor and barrier height from temperature-dependent current–voltage (I–V–T) characteristics showed no significant changes after the radiation. Moreover, the capacitance–voltage (C–V) characterization revealed that the net carrier density in the β-Ga2O3 material was only reduced by 25% at the neutron fluence of 1015 cm−2 but a significant reduction by 2–3 orders at 1016 cm−2. Within the neutron fluence range of 2 × 1014 cm−2 up to 1016 cm−2, the carrier removal rates trended to be saturated with the increased fluences, following an exponential regular. In addition, the C–V measurement on the 1016 cm−2 irradiated sample exhibited an obvious frequency dispersion, and the extracted carrier distribution was not uniform. [ABSTRACT FROM AUTHOR]

Molybdenum is used as plasma-facing material in tokamaks and as material for plasma optical diagnostics mirrors. Harsh conditions of neutron irradiation, exposure to hydrogen isotopes and helium ions, and high operating temperatures result in degradation of the molybdenum surface and ultimately limit their lifetime in a fusion power plant. In the current paper, intake and subsequent thermal release of deuterium from self-irradiated by high energy (1 MeV) ions molybdenum as a function of irradiation dose are investigated. Several characteristic temperature regions where deuterium release takes place are identified and attributed to trapping of deuterium in intrinsic and radiation-induced microstructure defects. This attribution is further validated by molecular dynamics modeling, which confirms that increase and saturation of vacancy concentration found in simulations follows increase and saturation of experimentally determined deuterium content. Deuterium inventory and vacancy content saturate at a damage level of around 0.2 dpa (displacement per atom), similar to recent modeling and experimental studies of iron and tungsten. Reflectivity measurements of irradiated molybdenum show that it is only slightly affected by damage up to 1 dpa. [ABSTRACT FROM AUTHOR]

One of the challenges of multi-recycled Pu, to be used to produce MOx fuel, lies in its isotopic composition. Further recycling enriches the isotopy toward 238Pu, 240Pu, and 241Pu, which have much higher specific activities than the 239Pu isotope, meaning that those fuels are subjected to strong self-irradiation, provoking defect accumulation in the (U,Pu)O2 crystal lattice. A combination of three different techniques, XRD, EPMA, and RS (x-ray diffraction, electron probe micro-analysis, and Raman spectroscopy, respectively) was implemented to characterize a particular self-irradiated, 238Pu, 240Pu, and 241Pu-enriched MIMAS (MIcronized-MASter blend)-type MOx fuel sample, which had been stored for 15 years at room temperature under an inert atmosphere, to maximize irradiation effects. For comparison purposes, a specimen from the same batch was submitted to a thermal treatment and was completely analyzed in the two months following this treatment. Two of these methods (EPMA and RS) were used in their imaging mode. In particular, four spectral characteristics could be extracted from the Raman spectra. However, because of the inherent heterogeneity of this particular MOx material, the results had to be analyzed in part in a rather statistical way. This combination of techniques first allowed for determining the local Pu content. Then, the effects of self-irradiation were analyzed in terms of lattice parameter swelling, defect injection, and resonant scattering. The merits and uncertainties associated with these methods are discussed in terms of macro- and/or micro-strains. Finally, the Raman spectroscopy of (U,Pu)O2, in the 0%–40% range, was revisited in part, in an indirect way, however. [ABSTRACT FROM AUTHOR]

Nitride ceramics have been investigated for different applications in the nuclear industry, such as space nuclear power, fusion reactor diagnostics and plasma heating, inert matrix fuels, and accident tolerant fuels. Although thermal conductivity remains one of the most important properties to track following irradiation, traditional techniques such as laser flash and xenon flash are limited to bulk sample characterization, which requires lengthy and cost-consuming neutron irradiation. This work used spatial domain thermoreflectance (SDTR) for the micrometer-scale measurement of thermal conductivity in 15 MeV Ni ion-irradiated silicon nitride and zirconium nitride from 1 to 50 dpa and 300 to 700 °C. The SDTR-measured unirradiated thermal conductivity was found to be consistent with the published data on bulk samples. Electrically conductive ZrN exhibits modest reduction after irradiation which is minimal at the highest irradiation temperatures. In electrically insulating Si3N4, the reduction is more significant and unlike ZrN, the reduction remains significant even at a higher irradiation temperature. The thermal resistance evolution following irradiation was compared with lattice swelling, which was determined using grazing incidence x-ray diffraction, and radiation-induced defects were observed using transmission electron microscopy. A saturation value was observed between 15 and 50 dpa for thermal conductivity degradation in both nitride ceramics and a direct correlation with high-temperature defect recombination was observed, as well as the potential presence of additional carrier scattering mechanisms. [ABSTRACT FROM AUTHOR]

This study presents a new model for point-defect modification in III-V-N alloys through first-principle calculations and several validation experiments conducted in our previous study, which explain the enhanced crystallinity of III-V-N alloys caused by proton irradiation and rapid thermal annealing (RTA). Validation experiments clarified that the conversion efficiency of the GaAsPN solar cell increased after proton irradiation followed by RTA, whereas that of the GaP solar cell decreased after the same process. Thus, the improved crystallinity of the GaAsPN alloy by this process is attributed to the decrease in nitrogen-related point defects in the crystal. The detailed annihilation mechanism of the nitrogen-related point defect was then studied using first-principle calculations demonstrating that the representative nitrogen-related point defects can change to a lower-energy state when a vacancy forms at its neighboring group V site, leading to the annihilation of the defects. It was concluded that vacancies created by proton irradiation enhance the annihilation of nitrogen-related point defects. [ABSTRACT FROM AUTHOR]

Nanoindentation of ion-irradiated materials has attracted much interest as a tool envisaged to derive the dose dependence of bulk-equivalent hardness from small samples. A major challenge arises from the steep damage gradient in the thin ion-irradiated layer and its unavoidable interplay with the indentation size effect. The present study relies on a number of choices aimed at simplifying the interpretation of the results and strengthening the conclusions. The studied alloys are two ferritic Fe-9Cr model alloys differing in controlled amounts of Ni, Si, and P known to enhance irradiation hardening. Both ion-irradiated (5 MeV Fe2+ ions) and neutron-irradiated samples along with the unirradiated references were investigated using Berkovich tips. According to the collaborative nature of the study, tests were conducted in two different laboratories using different equipment. A generalized Nix–Gao approach was applied to derive the bulk-equivalent hardness and characteristic length scale parameters for the homogeneous unirradiated and neutron-irradiated samples. Comparison with Vickers hardness indicates a 6% overestimation of the bulk-equivalent hardness as compared to the ideal correlation. For the case of ion irradiation, a first model assumes a homogeneous irradiated layer on a homogeneous substrate, while a second model explicitly takes into account the damage gradient. The first model was combined with both the original and the generalized Nix–Gao relation. We have found that the results revealed for Fe-9Cr vs Fe-9Cr-NiSiP are compatible with expectations based upon known irradiation-induced microstructures. The bulk-equivalent hardness derived for ion-irradiated samples reasonably agrees with the observation for neutron-irradiated samples. [ABSTRACT FROM AUTHOR]

Investigation of intrinsic defects such as gallium vacancies (VGa) and their interactions with extrinsic defects like Fe in β-Ga2O3 is crucial for the development of devices. Photoinduced electron paramagnetic resonance (photo-EPR) experiments are performed at room temperature and 30 K by illuminating neutron irradiated Fe-doped and unintentionally doped β-Ga2O3 crystals with LEDs from 0.7 to 4.7 eV, and interactions between VGa and other defects such as Fe are investigated. 30 K measurements indicate small photoinduced changes in the amount of V Ga 2 − , but the photothreshold suggests little or no interaction with Fe. Rather, the decrease of V Ga 2 − is accompanied by the emergence of self-trapped holes (STHs), indicating that the stability of the STH is critical to the V Ga 2 − optical transition. We suggest the decrease of V Ga 2 − is due to excitation of electrons from valence band maximum to the defect. The resulting hole is captured at an oxygen atom to form STH. By performing a systematic photo-EPR study of gallium vacancies, we show that the intrinsic defect, VGa, does not interact with extrinsic defects, Fe or Ir. Instead, VGa contributes to the stability of the STH. [ABSTRACT FROM AUTHOR]

Boron neutron capture therapy (BNCT) is a promising modality for cancer treatment because of its minimal invasiveness. To maximize the therapeutic benefits of BNCT, the development of efficient platforms for the delivery of boron agents is indispensable. Here, carborane‐integrated immunoliposomes were prepared via an exchanging reaction to achieve HER‐2‐targeted BNCT. The conjugation of an anti‐HER‐2 antibody to carborane‐integrated liposomes successfully endowed these liposomes with targeting properties toward HER‐2‐overexpressing human ovarian cancer cells (SK‐OV3); the resulting BNCT activity toward SK‐OV3 cells obtained using the current immunoliposomal system was 14‐fold that of the l‐BPA/fructose complex, which is a clinically available boron agent. Moreover, the growth of spheroids treated with this system followed by thermal neutron irradiation was significantly suppressed compared with treatment with the l‐BPA/fructose complex. [ABSTRACT FROM AUTHOR]