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This study presents a parallel algorithm for high-dimensional quantum dynamics simulations in poly atomic reactions, integrating distributed- and shared-memory models. The distributions of the wave function and potential energy matrix across message passing interface processes are based on bundled radial and angular dimensions, with implementations featuring either two- or one-sided communication schemes. Using realistic parameters for the H + NH3 reaction, performance assessment reveals linear scalability, exceeding 90% efficiency with up to 600 processors. In addition, owing to the universal and concise structure, the algorithm demonstrates remarkable extensibility to diverse reaction systems, as demonstrated by successes with six-atom and four-atom reactions. This work establishes a robust foundation for high-dimensional dynamics studies, showcasing the algorithm's efficiency, scalability, and adaptability. The algorithm's potential as a valuable tool for unraveling quantum dynamics complexities is underscored, paving the way for future advancements in the field. [ABSTRACT FROM AUTHOR]

Evidence has accumulated for an as-yet unaccounted for source of heat located at shallow depths within the accreted neutron star crust. However, the nature of this heat source is unknown. I demonstrate that the inferred depth of carbon ignition in X-ray superbursts can be used as an additional constraint for the magnitude and depth of shallow heating. The inferred shallow heating properties are relatively insensitive to the assumed crust composition and carbon fusion reaction rate. For low-accretion rates, the results are weakly dependent on the duration of the accretion outburst, so long as accretion has ensued for enough time to replace the ocean down to the superburst ignition depth. For accretion rates at the Eddington rate, results show a stronger dependence on the outburst duration. Consistent with earlier work, it is shown that urca cooling does not impact the calculated superburst ignition depth unless there is some proximity in depth between the heating and cooling sources. [ABSTRACT FROM AUTHOR]

Nuclear reactions are complex, with a large number of possible channels. Understanding how different channels contribute to a given reaction is investigated by perturbing the continuous spectrum. Tools are developed to investigate reaction mechanisms by identifying the contributions from each reaction channel. Cluster decomposition methods, along with the spectral theory of proper subsystem problems, is used to identify the part of the nuclear Hamiltonian responsible for scattering into each channel. The result is an expression of the nuclear Hamiltonian as a sum over all scattering channels of channel Hamiltonians. Each channel Hamiltonian is constructed from solutions of proper subsystem problems. Retaining any subset of channel Hamiltonians results in a truncated Hamiltonian where the scattering wave functions for the retained channels differ from the wave functions of the full Hamiltonian by N-body correlations. The scattering operator for the truncated Hamiltonian satisfies an optical theorem in the retained channels. Because different channel Hamiltonians do not commute, how they interact determines their contribution to the full dynamics. [ABSTRACT FROM AUTHOR]

Recently inaugurated telescopes, such as the MeerKAT radio telescope and the upcoming Rubin Observatory Legacy Survey of Space and Time, will be able to detect millions of transient events in the night sky. Stellar collisions between white dwarfs (WDs) and main-sequence (MS) stars may be detectable among such transients. Simulations will play a key role in characterizing these events and selecting targets for follow-up. We present 3D smoothed particle hydrodynamics models of dynamical interactions between a |$0.6\ {\rm M}_{\odot }$|  WD and 0.3, 0.6, and |$1.2\ {\rm M}_{\odot }$|  MS stars within globular cluster environments. Utilizing a 34-isotope nuclear network, we investigate the energetics, gas morphologies, and mass-loss properties of these collisions for different stellar mass ratios. Our models predict an overabundance of |$^{13}$| C, |$^{15}$| N, and |$^{17}$| O isotopes relative to solar abundances. Moreover, we find that the time-scale of the collisions is too short and maximum temperatures too low for any significant hydrogen burning or triple-alpha reactions to occur. This combined with a negligible production of elements heavier than neon may be key signatures in distinguishing these events from other transient events with similar peak bolometric luminosities (⁠|$\sim\!\! 10^{38}\!\!-\!\!10^{41}$|  erg s |$^{-1}$|⁠). [ABSTRACT FROM AUTHOR]

Recent clinical success with metal-based radiopharmaceuticals has sparked an interest in the potential of these drugs for personalized medicine. Although often overlooked, the success and global impact of nuclear medicine is contingent upon the purity and availability of medical isotopes, commonly referred to as radiometals. For nuclear medicine to reach its true potential and change patient lives, novel production and purification techniques that increase inventory of radiometals are desperately needed. This tutorial review serves as a resource for those both new and experienced in nuclear medicine by providing a detailed explanation of the foundations for the production and purification of radiometals, stemming from nuclear physics, analytical chemistry, and so many other fields, all in one document. The fundamental science behind targetry, particle accelerators, nuclear reactors, nuclear reactions, and radiochemical separation are presented in the context of the field. Finally, a summary of the latest breakthroughs and a critical discussion of the threats and future potential of the most utilized radiometals is also included. With greater understanding of the fundamentals, fellow scientists will be able to better interpret the literature, identify knowledge gaps or problems and ultimately invent new production and purification pathways to increase the global availability of medical isotopes. [ABSTRACT FROM AUTHOR]

Context. J-type stars are a subclass of carbon stars that are generally Li-rich, not enriched in s-elements, and have low 12C/13C ratios. They were suggested to be the manufacturers of the pre-solar grains of type AB2 (having low 12C/13C and supersolar 14N/15N). Aims. In this Letter, we investigate the possibility that J-type stars are early asymptotic giant branch (AGB) stars that experienced a proton ingestion event (PIE). Methods. We used the stellar evolution code STAREVOL to compute AGB stellar models with initial masses of 1, 2, and 3M⊙ and metallicities [Fe/H] = − 0.5 and 0.0. We included overshooting above the thermal pulse and used a network of 1160 nuclei coupled to the transport equations. The outputs of these models were compared to observations of J-type stars and AB2 grains. Results. In solar-metallicity AGB stars, PIEs can be triggered if a sufficiently high overshoot is considered. These events lead to low 12C/13C ratios, high Li abundances, and no enrichment in s-elements. We find that the 2 − 3 M⊙ AGB models experiencing a PIE can account for most of the observational features of J-type stars and AB2 grains. The remaining tensions between models and observations are (1) the low 14N/15N ratio of some AB2 grains and of 2 out of 13 J-type stars, (2) the high 26Al/27Al of some AB2 grains, and (3) the J-type stars with A(Li) < 2. Extra mixing mechanisms can alleviate some of these tensions, such as thermohaline or rotation. Conclusions. This work highlights a possible match between AGB stellar models that undergo a PIE and J-type stars and AB2 grains. To account for other types of carbon stars, such as N-type stars, PIEs should only develop in a fraction of solar-metallicity AGB stars. Additional work is needed to assess how the occurrence of PIEs depends on mixing parameters and initial conditions, and therefore to further confirm or exclude the proposed scenario. [ABSTRACT FROM AUTHOR]

Context. Around half of the heavy elements in the Universe are formed through the slow neutron capture (s-) process, which takes place in thermally pulsing asymptotic giant branch (AGB) stars with masses of 1 − 6 M⊙. The nucleosynthetic imprint of the s-process can be studied by observing the material on the surface of binary barium (Ba), carbon (C), CH, and carbon-enhanced metal-poor (CEMP) stars. Aims. We study the s-process by observing the luminous components of binary systems polluted by a previous AGB companion. Our radial velocity (RV) monitoring program establishes an ongoing collection of binary stars exhibiting enrichment in s-process material for the study of elemental abundances, the production of s-process material, and binary mass transfer. Methods. From high-resolution optical spectra, we measured RVs for 350 stars and derived stellar parameters for approximately 150 stars using ATHOS. For a subsample of 24 chemically interesting stars, we refined our atmospheric parameters using ionization and excitation balance with the Xiru program. We used the MOOG code to compute one-dimensional local thermodynamic equilibrium (1D-LTE) abundances of carbon, magnesium, s-process elements (Sr, Y, Zr, Mo, Ba, La, Ce, Nd, Pb), and Eu to investigate neutron capture events and stellar chemical composition. We estimated dynamical stellar masses via orbital optimization using Markov chain Monte Carlo techniques in the ELC program, and we compared our results with low-mass AGB models in the FUll-Network Repository of Updated Isotopic Tables & Yields (FRUITY) database. Results. In our abundance subsample, we find enhancements in s-process material in spectroscopic binaries, a signature of AGB mass transfer. We add the element Mo to the abundance patterns, and for 12 stars we add Pb detections or upper limits, as these are not known in the literature. Computed abundances are in general agreement with the literature. Comparing our abundances to dilution-modified FRUITY yields, we find correlations in s-process enrichment and AGB mass, which are supported by dynamical modeling from RVs. Conclusions. From our high-resolution observations, we expand heavy element abundance patterns and highlight binarity in our chemically interesting systems. We find trends in s-process element enhancement from AGB stars, and agreement between theoretical and dynamically modeled masses. We investigate evolutionary stages for a small subset of our stars. [ABSTRACT FROM AUTHOR]

The application of hydrogen flooding was recently shown to be a simple and effective approach for improved layer differentiation and interface determination during secondary ion mass spectrometry (SIMS) depth profiling of thin films, as well as an approach with potential in the field of quantitative SIMS analyses. To study the effects of hydrogen further, flooding of H2 molecules was compared to reactions with atomic H on samples of pure metals and their alloys. H2 was introduced into the analytical chamber via a capillary, which was heated to approximately 2200 K to achieve dissociation. Dissociation of H2 up to 30% resulted in a significant increase in the intensity of the metal hydride cluster secondary ions originating from the metallic samples. Comparison of the time scales of possible processes provided insight into the mechanism of hydride cluster secondary ion formation. Cluster ions presumably form during the recombination of the atoms and molecules from the sample and atoms and molecules adsorbed from the gas. This process occurs on the surface or just above it during the sputtering process. These findings coincide with those of previous mechanistic and computational studies. [ABSTRACT FROM AUTHOR]

Atmospheric traces of radioactive xenon can be a strong indicator for underground nuclear fission reactions. 131mXe, 133Xe, 133mXe and 135Xe are the primary gaseous isotopes/isomers currently used to identify and classify nuclear events. During decay, each of these radioactive species produces a unique beta-gamma energy spectra, which can be measured using beta-gamma coincidence counting. Current operational Xe beta-gamma spectrum analysis software relies on Region of Interest (ROI) counting (Bowyer et al. in J Environ Radioact 59(2):139–151, 2002). This algorithm occasionally produces mismeasurements, especially when quantifying meta-stable isomers, due to overlapping ROIs and shifts in detector calibration in fielded systems over time (Ringbom and Axelsson in Appl Radiat Isot 156:108950, 2020). In an attempt to better de-convolve overlapping isotope spectra we have developed a technique that applies a supervised neural-network implemented in TensorFlow with Keras to classify and quantify the isotopes and mixtures of isomers based on their beta-gamma spectra—similar to image recognition. From this, we have improved upon the false-positive rate for classification and regression models, however challenges remain with dealing with differing detector energy calibrations and with estimating measurement uncertainty. [ABSTRACT FROM AUTHOR]

47Sc is a theranostic radionuclide under the spotlight of the scientific community thanks to its potential for SPECT imaging and therapeutic applications. This work presents the recent measurements of proton-induced nuclear reaction cross-sections aimed at 47Sc production using enriched 48Ti, 49Ti and 50Ti targets from 23 up to 70 MeV. Since the co-production of contaminant isotopes is a key issue, and 46Sc is the main one having a longer half-life than 47Sc, the 48/49/50Ti(p,x)47Sc and 46Sc cross sections are presented and compared with the scarce literature data and TALYS estimations. [ABSTRACT FROM AUTHOR]

We study the contribution of various astrophysical events asymptotic giant branch (AGB stars, core collapse and thermonuclear supernovae, neutron star mergers, and collapsars) to the abundances of elements both up to and heavier than the iron peak in a Local Group dwarf irregular galaxy, Wolf–Lundmark–Melotte (WLM). Its star formation history has been recently determined by observations with the JWST , and we use it to estimate the occurrence of the astrophysical sources. The rates of the gas accretion and the outflow are roughly determined based on the stellar metallicity distribution, the oxygen abundance of H  ii regions, and the gas fraction. As discussed in the literature, the difference in time-scales on which the astrophysical events release the nucleosynthesis products is seen in the occurrence of the events and the evolution of abundance ratios. WLM has an extended star formation history and massive stars are recently and currently formed. Thus, the contribution of rotating massive stars through the weak s-process appears in the abundance ratios of light trans-iron elements to iron at later time of the evolution. [ABSTRACT FROM AUTHOR]

The present study deals with the development and characterization of Mo-35Ti-10Si and Mo-35Ti-10Si-2B (wt.%) alloy for ultra-high temperature applications beyond the temperature limit of existing super alloys. The microstructural characterization using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), electron back scattered diffraction (EBSD), x-ray diffraction (XRD) revealed that the Mo-35Ti-10Si-2B alloy was consisted of three phases, namely, (Mo, Ti)ss, (Mo, Ti)5SiB2 and (Ti, Mo)5Si3; whereas, Mo-35Ti-10Si alloy was found to be consisting of (Mo, Ti)ss, and (Mo,Ti)3Si phases. Since quantification of boron is difficult by EDS, Particle Induced Gamma-ray Emission (PIGE), a nuclear reaction analysis technique was used for chemical composition analysis of boron. The oxidation behavior of the Mo-35Ti-10Si-2B alloy in the temperature regime of 825-1250 °C was studied in detail and compared with boron-free Mo-35Ti-10Si alloy. Mo-35Ti-10Si-2B alloy exhibited superior oxidation behavior at intermediate temperatures of 825 °C, and excellent oxidation resistance at higher temperatures between 1000 and 1250 °C due to the formation of the protective borosilica and double oxide layers (TiO2 and duplex borosilica-TiO2), respectively. High-temperature oxidation mechanisms were discussed using detailed microstructural cross section analysis of the oxidized alloy samples. The micro-mechanical behavior of constitutive phases of the Mo-35Ti-10Si-2B alloy were studied by microhardness, nano-indentation and micropillar compression testing. The micropillar compression of (Mo, Ti)ss phase showed fairly ductile behavior with the evidence of activation of dislocation in the form of slip lines revealed through the post-deformation fractography. Deformation studies of (Mo, Ti)5SiB2 and (Ti, Mo)5Si3 phases were also carried out which showed large strain bursts indicating possibility of activation of dislocation activities even at room temperatures imparting low level of ductility. [ABSTRACT FROM AUTHOR]

Asymptotic normalization coefficients (ANC) are important nuclear characteristics. This paper discusses a method for determining ANC values from experimental data on differential cross-sections of nuclear transfer reactions. The method is based on the use of the analytic continuation of these cross-sections to the pole point of the reaction amplitude with respect to the variable cosθ, where θ is the center-of-mass scattering angle. The method under consideration is used to determine the ANC for the channel 17O(1/2+; 0.871MeV) →16O(0+; 0MeV) +n from the data on the 16O(0+; 0MeV)(d,p)17O (1/2+; 0.871MeV) reaction. When determining the ANC, the corrections caused by the Coulomb interaction in the initial, final and intermediate states of the reaction were taken into account. It is shown that these corrections have a great impact on the extracted ANC value. [ABSTRACT FROM AUTHOR]

The interest in terbium radionuclides, which can be used in nuclear medicine, has increased tremendously over the last decade. Several research studies have shown the potential of four terbium radionuclides 149,152,155,161Tb both for cancer diagnosis as well as therapy. The comparison of 161Tb and 177Lu showed 161Tb as the preferred candidate not only for standard radiotherapy, but also for the treatment of minimal residual disease. Nevertheless, among the terbium sisters, currently, only 161Tb has an established production protocol where its nocarrier-added form is obtained via neutron irradiation of enriched 160Gd targets. The other terbium radioisotopes face challenges related to production capacity and production yield, which currently restricts their use in nuclear medicine. The purpose of this review is to report on recent research on the production and separation of terbium sisters and to assess the prospects for upscaling their production for nuclear medicine applications. [ABSTRACT FROM AUTHOR]

Background: Radiopharmaceutical therapy (RPT) uses radionuclides that decay via one of three therapeutically relevant decay modes (alpha, beta, and internal conversion (IC) / Auger electron (AE) emission) to deliver short range, highly damaging radiation inside of diseased cells, maintaining localized dose distribution and sparing healthy cells. Antimony-119 (119Sb, t1/2 = 38.19 h, EC = 100%) is one such IC/AE emitting radionuclide, previously limited to in silico computational investigation due to barriers in production, chemical separation, and chelation. A theranostic (therapeutic/diagnostic) pair can be formed with 119Sb's radioisotopic imaging analogue 117Sb (t1/2 = 2.80 h, Eγ = 158.6 keV, Iγ = 85.9%, β+ = 262.4 keV, Iβ+ = 1.81%). Results: Within, we report techniques for sustainable and cost-effective production of pre-clinical quality and quantity, radionuclidically pure 119Sb and 117Sb, novel low energy photon measurement techniques for 119Sb activity determination, and physical yields for various tin target isotopic enrichments and thicknesses using (p, n) and (d, n) nuclear reactions. Additionally, we present a two-column separation providing a radioantimony yield of 73.1% ± 6.9% (N = 3) and tin separation factor of (6.8 ± 5.5) x 105 (N = 3). Apparent molar activity measurements for deuteron produced 117Sb using the chelator TREN-CAM were measured at 42.4 ± 25 MBq 117Sb/µmol (1.14 ± 0.68 mCi/µmol), and we recovered enriched 119Sn target material at a recycling efficiency of 80.2% ± 5.5% (N = 6) with losses of 11.6 mg ± 0.8 mg (N = 6) per production. Conclusion: We report significant steps in overcoming barriers in 119Sb production, chemical isolation and purification, enriched target material recycling, and chelation, helping promote accessibility and application of this promising therapeutic radionuclide. We describe a method for 119Sb activity measurement using its low energy gamma (23.87 keV), negating the need for attenuation correction. Finally, we report the largest yet-measured 119Sb production yields using proton and deuteron irradiation of natural and enriched targets and radioisotopic purity > 99.8% at end of purification. [ABSTRACT FROM AUTHOR]

Bi-based materials can retain massive amounts of sodium ions through alloying and conversion reactions, resulting in excellent theoretical capacity. However, during the sodiation/desodiation process, there is always a significant volume change in the alloying reaction. In this work, TiO2-coated hexagonal-phase topological insulator (TI) Bi2Te3 composites grown on carbon cloth (CC) were prepared using a solvothermal reaction and an atomic layer deposition process (TiO2/Bi2Te3/CC) as anode materials for sodium-ion batteries without the need for a binder. Compared to the pure Bi2Te3 electrode, the optimized TiO2/Bi2Te3/CC composite exhibits a superior specific capacity of 450 mA h g−1, a high rate performance of 0.1 A g−1, and a high cycling stability of 100 cycles due to the inherent properties of TIs, contributed by the effective TiO2 cladding layer and large interfacial spacing of Bi2Te3. The enhanced reversible capacitance, rate capability, and cycling performances can be attributed to the heterointerfaces and excellent mechanical properties of TiO2, which balance the electronic structure of the building blocks and inhibit the detaching of Bi2Te3 due to large internal stresses. The amorphous TiO2/Bi2Te3/CC composite was treated in a tubular furnace to obtain crystalline TiO2/Bi2Te3/CC, and the electrochemical performance of the heterostructures formed by the TiO2 coating layer with different properties was compared. This work demonstrates the enormous potential for enhancing the sodium-ion storage capabilities of alloy electrode materials by constructing heterostructures. [ABSTRACT FROM AUTHOR]

Precisely controlling the microstructure of supported metal catalysts and regulating metal‐support interactions at the atomic level are essential for achieving highly efficient heterogeneous catalysts. Strong metal‐support interaction (SMSI) not only stabilizes metal nanoparticles and improves their resistance to sintering but also modulates the electrical interaction between metal species and the support, optimizing the catalytic activity and selectivity. Therefore, understating the formation mechanism of SMSI and its dynamic evolution during the chemical reaction at the atomic scale is crucial for guiding the structural design and performance optimization of supported metal catalysts. Recent advancements in in situ transmission electron microscopy (TEM) have shed new light on these complex phenomena, providing deeper insights into the SMSI dynamics. Here, the research progress of in situ TEM investigation on SMSI in heterogeneous catalysis is systematically reviewed, focusing on the formation dynamics, structural evolution during the catalytic reactions, and regulation methods of SMSI. The significant advantages of in situ TEM technologies for SMSI research are also highlighted. Moreover, the challenges and probable development paths of in situ TEM studies on the SMSI are also provided. [ABSTRACT FROM AUTHOR]

Chemical evolution models predict a gradual build-up of 13C in the Universe, based on empirical nuclear reaction rates and assumptions on the properties of stellar populations. However, old metal-poor stars within the Galaxy contain more 13C than is predicted, suggesting that further refinements to the models are necessary. Gas at high-redshift provides important supplementary information at metallicities |$-2\lesssim \left[{\rm Fe/H}\right]\lesssim -1$|⁠ , for which there are only a few measurements in the Galaxy. We obtained new, high-quality, VLT/ESPRESSO observations of the QSO B1331 |$+$| 170 and used them to measure 12C/13C in the damped Lyman- |$\alpha$| system (DLA) at |$z_{\rm abs}=1.776$|⁠ , with |$\left[{\rm Fe/H}\right]$| = −1.27. ai-vpfit , an artificial intelligence tool based on genetic algorithms and guided by a spectroscopic information criterion, was used to explore different possible kinematic structures of the carbon gas. Three hundred independent ai-vpfit models of the absorption system were produced using pre-set 12C/13C values, ranging from 4 to 500. Our results show that |${\rm ^{12}C / ^{13}C}=28.5^{+51.5}_{-10.4}$|⁠ , suggesting a possibility of 13C production at low metallicity. [ABSTRACT FROM AUTHOR]

Featured Application: This research presents a novel image reconstruction method for Boron Neutron Capture Therapy (BNCT)-Single Photon Emission Computed Tomography (SPECT) using Bayesian estimation with limited view-angle projection data. The method aims to address the inherent challenges in BNCT-SPECT imaging where conventional algorithms struggle with incomplete data from restricted projection angles. By improving the image accuracy under such conditions, this technique has potential applications in clinical settings, where accurate tumor localization and dose distribution are critical for the success of BNCT treatments. This method could lead to enhanced treatment planning and monitoring, ultimately improving patient outcomes. Boron Neutron Capture Therapy (BNCT) is an emerging radiation treatment for cancer, and its challenges are being explored. Systems capable of capturing real-time observations of this treatment's effectiveness, particularly BNCT-SPECT methods that measure gamma rays emitted instantaneously from outside the body during nuclear reactions and that reconstruct images using Single Photon Emission Computed Tomography (SPECT) techniques, remain unavailable. BNCT-SPECT development is hindered by two main factors, the first being the projection angle. Unlike conventional SPECT, the projection angle range which is achievable by rotating a detector array cannot exceed approximately 90 degrees. Consequently, Fourier-based image reconstruction methods, requiring projections from at least 180 degrees, do not apply to BNCT-SPECT. The second limitation is the measurement time. Given these challenges, we developed a new sequential approximation image reconstruction method using Bayesian estimation, which is effective under the stringent BNCT-SPECT conditions. We also compared the proposed method with the existing Maximum Likelihood-Expectation Maximization (ML-EM) image reconstruction method. Numerical experiments were conducted by obtaining BNCT-SPECT projection data from true images and reconstructing images using both the proposed and ML-EM methods from the resulting sinograms. Performance comparisons were conducted using a dedicated program applying Bayesian estimation and this showed promise as a new image reconstruction method useful under BNCT-SPECT conditions. [ABSTRACT FROM AUTHOR]

Fusion is inherently safer than fission due to the absence of nuclear chain reactions. However, operating fusion power plants will not be risk free. There will still be numerous hazards that will need careful management in order to safely build, operate and ultimately decommission a fusion power plant. Ensuring a robust safety demonstration that covers all radiological and non-radiological hazards is therefore vitally important for the future permissioning and consenting of fusion power plants. The safety case for the STEP prototype plant will be developed in line with a set of safety philosophies, safety functional requirements and design safety principles to ensure that the safety case production process is consistent and robust. This article is part of the theme issue 'Delivering Fusion Energy – The Spherical Tokamak for Energy Production (STEP)'. [ABSTRACT FROM AUTHOR]