Artículos (Física Atómica, Molecular y Nuclear)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10864

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The Lyon Mint in the Roman Tomares Hoard (Seville): Some Considerations on Its Metallic Composition Determined by XRF
(Willey, 2025-06-15) Pliego Vázquez, Ruth; Gómez-Tubio, Blanca María; Alcaide Ramírez, María; Scrivano, Simona; Respaldiza Galisteo, Miguel Ángel; Física Atómica, Molecular y Nuclear; Prehistoria y Arqueología; Física Aplicada III; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla
Selective adsorption of CO2 in TAMOF-1 for the separation of CO2/CH4 gas mixtures
(Nature Research, 2025-04-04) Capelo Avilés, Santiago; Fez Febré, Mabel de; Rodríguez Gómez, Salvador; Cabezas Giménez, Juanjo; Oliveira, Raiana Tomazini de; Gallo Stampino, Irene I.; Galán Mascarós, José Ramón; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Generalitat de Catalunya
TAMOF-1 is a robust, highly porous metal–organic framework built from Cu2+ centers linked by a L-histidine derivative. Thanks to its high porosity and homochirality, TAMOF-1 has shown interesting molecular recognition properties, being able to resolve racemic mixtures of small organic molecules in gas and liquid phases. Now, we have discovered that TAMOF-1 also offers a competitive performance as solid adsorbent for CO2 physisorption, offering promising CO2 adsorption capacity ( > 3.8 mmol g–1) and CO2/CH4 Ideal Adsorbed Solution Theory (IAST) selectivity ( > 40) at ambient conditions. Moreover, the material exhibits favorable adsorption kinetics under dynamic conditions, demonstrating good stability in high-humidity environments and minimal degradation in strongly acidic media. We have identified the key interactions of CO2 within the TAMOF-1 framework by a combination of structural (neutron diffraction), spectroscopic and theoretical analyses which conclude a dual-site adsorption mechanism with the majority of adsorbed CO2 molecules occupying the empty voids in the TAMOF-1 channels without strong, directional supramolecular interactions. This very weak dominant binding opens the possibility of a low energy regeneration process for convenient CO2 purification. These features identify TAMOF-1 as a viable solid-state adsorbent for the realization of affordable biogas upgrading.
Semi-analytical modelling of Pop. III star formation and metallicity evolution - II. Impact on 21 cm power spectrum
(Oxford University Press, 2025-04-30) Ventura, Emanuele M.; Quin, Yuxiang; Sreedhar, Balu; Wyithe, J. Stuart B.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); Junta de Andalucía
Simulating Population (Pop.) III star formation in mini-haloes in a large cosmological simulation is an extremely challenging task but it is crucial to estimate its impact on the 21 cm power spectrum. In this work, we develop a framework within the semi-analytical code meraxes to estimate the radiative backgrounds from Pop. III stars needed for the computation of the 21 cm signal. We computed the 21 cm global signal and power spectrum for different Pop. III models varying star formation efficiency, initial mass function and specific X-ray luminosity per unit of star formation (L /SFR). In all the models considered, we find Pop. III stars have little to no impact on the reionization history but significantly affect the thermal state of the intergalactic medium (IGM) due to the strong injection of X-ray photons from their remnants that heat the neutral IGM at 15. This is reflected not only on the 21 cm sky-averaged global signal during the Cosmic Dawn but also on the 21 cm power spectrum at 10 where models with strong Pop. III X-ray emission have larger power than models with no or mild Pop. III X-ray emission. We estimate observational uncertainties on the power spectrum using 21cmsense and find that models where Pop. III stars have a stronger X-ray emission than Pop. II are distinguishable from models with no or mild Pop. III X-ray emission with 1000 h observations of the upcoming SKA1-low.
Probing α-clustering in 9Be via complete fusion and elastic scattering measurements
(Elsevier, 2025-04-03) Kundu, A.; Palit, R; Rodríguez Gallardo, Manuela; Moro Muñoz, Antonio Matías; Dey, P.; Santra, S.; Laskar, Md S. R.; Majumder, C.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear
The intrinsic structure of the 9Be nucleus has been probed by virtue of its influence on reaction dynamics in the 9Be+110Pd collision. Extensive measurements of the complete fusion excitation function have been undertaken across the Coulomb barrier, in conjunction with the measurement of the elastic scattering angular distribution at a few overlapping incident energies. A unified treatment of both processes is carried out by employing 3-body and 4-body Continuum Discretized Coupled Channels calculations, which exclusively cater to the dynamical features of the collision contingent on the low threshold for dissociation of 9Be into either two or three clusters. A synergy between the complete fusion and elastic scattering measurements across different incident energies is attained when the pivotal description of 9Be as α+α+n configuration is invoked. While the elastic scattering angular distribution is observed to be sensitive to the continuum couplings, the fusion excitation function is primarily influenced by the structure of 9Be in its ground state. The α+α+n picture further reveals an absence of above-barrier fusion suppression when compared with the Universal Fusion Function, in contrast to the commonly reported signature for reactions induced by the 9Be projectile.
Divertor shaping with neutral baffling as a solution to the tokamak power exhaust challenge
(Nature Research, 2025-05-23) Verhaegh, Kevin; Harrison, James; Moulton, David; Lipschultz, Bruce; Lonigro, Nicola; Osborne, Nick; Lingyan, Xiang; The EUROfusion Tokamak Exploitation Team; The MAST Upgrade Team; Ayllón Guerola, Juan Manuel; Cruz Zabala, Diego José; Domínguez-Palacios Durán, Jesús José; Doyle, Scott James; Galdón Quiroga, Joaquín; García Muñoz, Manuel; Hidalgo Salaverri, Javier; Van Vuuren, Anton Jansen; Mancini, Alessio; McKay, Kiera Anne; Oyola Domínguez, Pablo; Rivero Rodríguez, Juan Francisco; Romero Madrid, Carlos Francisco; Rueda Rueda, José; Toscano Jiménez, Manuel; Velarde Gallardo, Lina; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación; Engineering and Physical Sciences Research Council (UK); US Department of Energy; European Union (UE)
Exhausting power from the hot fusion core to the plasma-facing components is one fusion energy’s biggest challenges. The MAST Upgrade tokamak uniquely integrates strong containment of neutrals within the exhaust area (divertor) with extreme divertor shaping capability. By systematically altering the divertor shape, this study shows the strongest evidence to date to our knowledge that long-legged divertors with a high magnetic field gradient (total flux expansion) deliver key power exhaust benefits without adversely impacting the hot fusion core. These benefits are already achieved with relatively modest geometry adjustments that are more feasible to integrate in reactor designs. Benefits include reduced target heat loads and improved access to, and stability of, a neutral gas buffer that ‘shields’ the target and enhances power exhaust (detachment). Analysis and model comparisons shows these benefits are obtained by combining multiple shaping aspects: long-legged divertors have expanded plasma-neutral interaction volume that drive reductions in particle and power loads, while total flux expansion enhances detachment access and stability. Containing the neutrals in the exhaust area with physical structures further augments these shaping benefits. These results demonstrate strategic variation in the divertor geometry and magnetic topology is a potential solution to one of fusion’s power exhaust challenge.
Impact of amplitude and phase damping noise on quantum reinforcement learning: challenges and opportunities
(Springer Nature, 2025-07-04) Olivera Atencio, María Laura; Lamata Manuel, Lucas; Casado Pascual, Jesús; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Ministerio de Hacienda. España; Junta de Andalucía
Quantum machine learning (QML) is an emerging field with significant potential, yet it remains highly susceptible to noise, which poses a major challenge to its practical implementation. While various noise mitigation strategies have been proposed to enhance algorithmic performance, the impact of noise is not fully understood. In this work, we investigate the effects of amplitude and phase damping noise on a quantum reinforcement learning algorithm. Through analytical and numerical analysis, we assess how these noise sources influence the learning process and overall performance. Our findings contribute to a deeper understanding of the role of noise in quantum learning algorithms and suggest that, rather than being purely detrimental, unavoidable noise may present opportunities to enhance QML processes.
Multi-technique computational assessment of fluoride uptake in enamel using PIGE, NEXAFS, and Raman spectroscopy
(2025-05-12) Pessanha, Sofia; Fortes, António; Lopes, Marta B.; Guilherme Buzanich, Ana; Ortega-Feliú, Inés; Respaldiza Galisteo, Miguel Ángel; Gómez-Tubio, Blanca María; Silveira, João; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Fundação para a Ciência e a Tecnologia. Portugal
The uptake of fluoride in the enamel matrix is an effective strategy to prevent demineralization and caries formation. In this study a comprehensive methodology is developed to evaluate and understand the uptake of fluoride in human enamel. Twenty-six healthy anterior teeth were sectioned in half; one half remained untreated, while the other was treated with 50 mg mL−1 NaF (equivalent to 22.6 mg of fluoride) through three 1-minute applications over a 12-day period, following the manufacturer's guidelines. Fluoride uptake was quantified with particle-induced gamma-ray emission (PIGE), revealing an average increase of 160% in treated samples. The formation of calcium fluoride (CaF2) and fluorapatite-like structures was confirmed through near edge X-ray absorption fine structure (NEXAFS) analysis. Due to the absence of reference spectra for hydroxyapatite, fluorapatite, and calcium fluoride, finite difference method near edge structure (FDMNES) simulations were employed to computationally model the fluorine K-edge and the Ca L-edge spectra. Density functional theory (DFT) and time-dependent DFT (TDDFT) approaches were applied to enhance spectral accuracy, enabling a refined comparison with experimental data. To establish a rapid and laboratory-based screening technique, Raman microscopy was used to analyze fluoride-treated and untreated samples. Spectral data were evaluated using both full-spectrum analysis and specific spectral features, including band intensity, full-width at half maximum (FWHM) of Raman peaks, and phosphate symmetric stretching depolarization ratios. Furthermore, machine learning algorithms were applied to classify treated and untreated enamel samples. The random forest classifier demonstrated strong predictive performance, successfully distinguishing fluoride-treated samples. This methodological approach provides an effective framework for analyzing fluoride uptake in enamel, potentially guiding future preventive dentistry strategies.
Neutron capture measurements for s-process nucleosynthesis: A review about CERN n_TOF developments and contributions
(Springer, 2025-05-19) Domingo Pardo, César; The n_TOF Collaboration; Bartolomé, J.; Cortés Giraldo, Miguel Antonio; Guerrero Sánchez, Carlos; Lerendegui Marco, Jorge; Pavón Rodríguez, J. A.; Pérez Maroto, Pablo; Quesada Molina, José Manuel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
This article presents a review about the main CERN n_TOF contributions to the field of neutron-capture experiments of interest for s-process nucleosynthesis studies over the last 25 years, with a special focus on the measurement of radioactive isotopes. A few recent capture experiments on stable isotopes of astrophysical interest are also discussed. Results on s-process branching nuclei are appropriate to illustrate how advances in detection systems and upgrades in the facility have enabled increasingly challenging experiments and, as a consequence, have led to a better understanding and modeling of the s-process mechanism of nucleosynthesis. New endeavors combining radioactive-ion beams from ISOLDE for the production of radioisotopically pure samples for activation experiments at the new NEAR facility at n_TOF are briefly discussed. On the basis of these new exciting results, also current limitations of state-of-the-art TOF and activation techniques will be depicted, thereby showing the pressing need for further upgrades and enhancements on both facilities and detection systems. A brief account of the potential technique based on inverse kinematics for direct neutron-capture measurements is also presented.
Ion Mobility and Segregation in Seed Surfaces Subjected to Cold Plasma Treatments
(American Chemical Society, 2025-02-24) Perea Brenes, Álvaro; Ruiz Pino, Natalia; Yubero, Francisco; Garcia, José Luis; Rodríguez González-Elipe, Agustín; Gómez Ramírez, Ana María; Prados Montaño, Antonio; López Santos, Carmen; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Universidad de Sevilla; Junta de Andalucía
Plasma treatment of seeds is an efficient procedure to accelerate germination, to improve initial stages of plant growth, and for protection against pathogen infection. Most studies relate these beneficial effects with biochemical modifications affecting the metabolism and genetic growth factors of seeds and young plants. Using barley seeds, in this work, we investigate the redistribution of ions in the seed surface upon their treatment with cold air plasmas. In addition, we investigate the effect of plasma in the lixiviation of ions through the seeds’ hull when they are immersed in water. Ion redistribution in the outer layers of air plasmatreated seeds has been experimentally determined through X-ray photoelectron spectroscopy analysis in combination with in-depth chemical profiling with gas cluster ion beams. The results show that in the shallowest layers of the seed hull (at least up to a depth of ∼100 nm) there is an enrichment of K+ and Ca2+ ions, in addition to changes in the O/C and N/C atomic ratios. These data have been confirmed by the electron microscopy/fluorescence analysis of seed cuts. Observations have been accounted for by a Monte Carlo model, simulating the electrostatic interactions that develop between the negative charge accumulated at the seed surface due to the interaction with the plasma sheath and the positive ions existing in the interior. Furthermore, it is shown that upon water immersion of plasma-treated seeds mobilized ions tend to lixiviate more efficiently than in pristine seeds. The detection of a significant concentration of NO3− anions in the water has been attributed to a secondary reaction of nitrogen species incorporated into the seeds during plasma exposure with reactive oxygen species formed on their surface during this treatment. The implications of these findings for the improvement of the germination capacity of seeds are discussed.
Forecasting constraints on the high-z IGM thermal state from the Lyman-α forest flux autocorrelation function
(Oxford University Press, 2025-05-08) Wolfson, Molly; Hennawi, Joseph F.; Davies, Frederick B.; Lukic, Zarija; Oñorbe Bernis, José; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; National Energy Research Scientific Computing Center National Energy Research Scientific Computing Center (NERSC) U. S.
The autocorrelation function of the Lyman-α (Ly α) forest flux from high-z quasars probes the small-scale structure of the intergalactic medium (IGM). The thermal state of the IGM, determined by the physics of reionization, sets the small-scale power observed in the Ly α forest. To explore the sensitivity of the autocorrelation function to the IGM’s thermal state, we compute the autocorrelation function from a cosmological hydrodynamical simulation with an instantaneous reionization model and 135 post-processed thermal states. Using mock data sets of 20 quasars, we forecast constraints on T0 and γ , which characterize the post-processed IGM thermalstate, at 5.4 ≤ z ≤ 6. While this model simplifiesthe IGM’sthermalstate, itserves as a key firststep in assessing future observational prospects. We also perform an inference test on mocks and re-weight out posterior distributions to guarantee that they exhibit statistically correct behaviour. At z = 5.4, we find that an idealized data set constrains T0 to 59 per cent and γ to 16 per cent at the 1σ equivalent confidence level. To explore more realistic, non-instantaneous reionization scenarios, we analyse four models combining temperature and ultraviolet background (UVB) fluctuations at z = 5.8. We find that mock data generated from a model with both temperature and UVB fluctuations can rule out a model with only temperature fluctuations at the > 1σ level 73.9 per cent of the time.
Evaluating quenching in cosmological simulations of galaxy formation with spectral covariance in the optical window
(Oxford University Press, 2025-04-03) Sharbaf, Z.; Ferreras, I.; Negri, Andrea; Angthopo, J.; Vecchia, C. dalla; Lahav, O.; Somerville, Rachel S.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
Cosmological hydrodynamical simulations provide valuable insights on galaxy evolution when coupled with observational data. Comparisons with real galaxies are typically performed via scaling relations of the observables. Here, we follow an alternative approach based on the spectral covariance in a model-independent way. We build upon previous work by Sharbaf et al. that studied the covariance of high-quality SDSS (Sloan Digital Sky Survey) continuum-subtracted spectra in a relatively narrow range of velocity dispersion (⁠ km s ⁠). Here, the same analysis is applied to synthetic data from the eagle and IllustrisTNG100 simulations, to assess the ability of these runs to mimic real galaxies. The real and simulated spectra are consistent regarding spectral covariance, although with subtle differences that can inform the implementation of subgrid physics. Spectral fitting done a posteriori on stacks segregated with respect to latent space reveals that the first principal component (PC1) is predominantly influenced by the stellar age distribution, with an underlying age–metallicity degeneracy. Good agreement is found regarding star formation prescriptions but there is disagreement with active galactic nucleus (AGN) feedback, that also affects the subset of quiescent galaxies. We show a substantial difference in the implementation of the AGN subgrid prescriptions, regarding central black hole seeding, that could lead to the mismatch. Differences are manifest between these two simulations in the star formation histories stacked with respect to latent space. We emphasize that this methodology only relies on the spectral covariance to assess whether simulations provide a true representation of galaxy formation.
Energetic particle physics: Chapter 7 of the special issue: on the path to tokamak burning plasma operation
(2025-03-24) Salewski, M.; Spong, D. A.; Aleynikov, P.; Bilato, R.; Breizman, B. N.; Briguglio, S.; García Muñoz, Manuel; Pinches, S. D.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE)
We review the physics of energetic particles (EPs) in magnetically confined burning fusion plasmas with focus on advances since the last update of the ITER Physics Basis (Fasoli et al 2007 Nucl. Fusion 47 S264). Topics include basic EP physics, EP generation, diagnostics of EPs and instabilities, the interaction of EPs and thermal plasma instabilities, EP-driven instabilities, energetic particle modes (EPMs), and turbulence, linear and nonlinear stability and simulation of EP-driven instabilities and EPMs, 3D effects, scenario optimization strategies based on EP phase-space control, EPs in reduced field scenarios in ITER before DT, and the physics of runaway electrons. We describe the simulation and modeling of EPs in fusion plasmas, including instability drive and damping as well as EP transport, with a range of approaches from first-principles to reduced models, including gyrokinetic simulations, kinetic-MHD models, gyrofluid models, reduced models, and semi-analytical approaches.
Comparing 3He content in magnetron sputtered and implanted targets for nuclear studies
(Springer, 2025-05-25) Pilotto, E,; Ferrer Fernández, Francisco Javier; Akhmadaliev, S.; Fernández, A.; Gadea, A.; Camacho, J.; Valiente Dobón, J. J.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); Agencia Estatal de Investigación. España; Generalitat Valenciana
3He targets are a valuable tool in nuclear physics, particularly for studying nuclear structure and dynamics via direct reactions in inverse kinematics. However, they are often prone to degradation under intense beam irradiation and have insufficient 3He content for use with lowintensity exotic beams. In a recent AGATA experiment at LNL, designed to study the astrophysically relevant lifetime of a 15O excited state, two types of 3He targets were tested. One was produced using ion implantation and the other with a novel magnetron sputtering technique, in both cases on Au substrates. Following irradiation with a stable 16O beam, they were characterized using Nuclear Reaction Analysis (NRA) and Elastic Recoil Detection Analysis (ERDA). Results demonstrated that, under the here used fabrication conditions, sputtered targets present a higher 3He content, while implanted ones exhibit thinner profiles. This highlights the possibilities and complementarity of these targets, suggesting their tailored use for future experimental campaigns.
A hypervalent metal MOF catalyst as an avenue to go beyond heterogeneous Fenton-like processes for organic contaminant removal in water
(Royal Society of Chemistry, 2025-05-01) Santos Juanes, Lucas; Rodríguez Sánchez, Noelia; Rodríguez Gómez, Salvador; Núñez, Nuria O.; Arqués, Antonio; Ruiz-Salvador, A. Rabdel; Ballesteros, Menta; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España
Metal–organic frameworks (MOFs) have recently been proposed as a plausible solution to the pressing issue of water scarcity and as a means of remediating contaminated water bodies. In light-assisted water treatment, they have so far only been exploited via the hydroxyl radical route, through Fenton-like processes. A new avenue is introduced here by the biomimetic conceptual design of MOF bearing hypervalent metal atoms for photocatalytic water treatment. We report a zeolitic imidazole framework (ZIF) material doped with iron (Fe-ZIF-7-III; UPO-4) synthesized via a novel mild treatment to stabilize photoactive hypervalent ferryl ions for the first time in a MOF for water treatment. The successful synthesis of the 2D material and the adequate incorporation of iron into the structure were demonstrated using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). A simulation study analyzed the structure and stability of the Fe-ZIF-7-III material as well as the involvement of ferryl ions in the photo-Fenton-type process. Furthermore, the calculated band gap of this material shows its viability for use in photocatalysis using sunlight. This was confirmed by evaluating the photodegradation of caffeine, a model pollutant in water, without the assistance of hydroxyl radicals as indicated by a scavenger test. The recyclability test revealed that Fe-ZIF-7-III could be used continuously with effective catalytic activity, thus opening the door to the field of studying hypervalent metal MOFs not yet explored in water treatment.
On the stability conditions of a stationary argon plasma at atmospheric-pressure conditions
(1995-05-01) Gordillo Vázquez, Francisco José; Cotrino Bautista, José; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Dirección General de Investigación Científica y Técnica (DGICYT). España
The stability of the general analytical solutions of a collisional-radiative model, for nonequilibrium, partially ionized, steady-state argon plasma, is examined. The model includes three atomic energy levels: the ground level, one excited level, and the continuum. A Maxwellian electron distribution function is also assumed. This model was previously considered by Braun and Kunc [Phys. Fluids 30, 67 1 (1987)]. All the rates for collisional-radiative processes and diffusion losses are expressed as analytical functions. The model is solved for the electron and excited atom densities in two plasma regimes, with and without diffusion losses. Transitions between these two possibilities are also discussed.
Gas temperature equation in a high-frequency argon plasma column at low pressures
(American Institute of Physics, 2002-01) Palmero Acebedo, Alberto; Cotrino Bautista, José; Barranco Quero, Ángel; Rodríguez González-Elipe, Agustín; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Comisión Interministerial de Ciencia y Tecnología (CICYT). España; European Union (UE)
Using a collisional-radiative model and taking into account an energy balance equation in a surface-wave-produced and -sustained argon plasma, it is possible to obtain the dependence of the gas temperature on the plasma parameters. If only heat conduction and radiative losses are considered for the neutral system, as well as the interaction with the electrons, the plasma parameters that determine the gas temperature will be the elastic absorbed power per electron and the electron number density. In a first approximation the axial dependence of the neutral gas temperature can be considered lineal with the product of these two parameters.
Collisional radiative model of an argon atmospheric capillary surface-wave discharge
(American Institute of Physics, 2004-11-03) Yanguas Gil, A.; Cotrino Bautista, José; Rodríguez González-Elipe, Agustín; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Dirección General de Investigación Científica y Técnica (DGICYT). España
The characteristics of a microwave surface-wave sustained plasma operated at atmospheric pressure in an open-ended dielectric tube are investigated theoretically as a first step in the development of a self-consistent model for these discharges. The plasma column is sustained in flowing argon. A surface-wave discharge that fills the whole radial cross section of the discharge tube is considered. With experimental electron temperature profiles [García et al., Spectrochim. Acta, Part B 55, 1733 (2000)] the numerical model is used to test the validity of the different approximations and to study the influence of the different kinetic processes and power loss mechanisms on the discharge.
Measurement of the Yb 176 (n,γ) cross section at the n_TOF facility at CERN
(American Physical Society, 2024-12-27) García Infantes, F.; Praena, J.; Casanovas-Hoste, A.; Henkelmann, R.; Köster, U.; Aberle, O.; Cortés Giraldo, Miguel Antonio; Guerrero Sánchez, Carlos; Lerendegui Marco, Jorge; Pérez Maroto, Pablo; Pavón Rodríguez, J. A.; Quesada Molina, José Manuel; Žugec, P.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España
Background: The 176Yb(n, γ ) 177Yb → 177Lu reaction is of interest in nuclear medicine as it is the preferred production route for 177Lu. This radioisotope has seen a very fast growth of usage in nuclear medicine in recent years due to its outstanding properties. New data on this reaction could provide useful information for production at new facilities. Purpose: We aim to resolve resonances in the 176Yb(n, γ ) 177Yb reaction for the first time. Previous capture measurement provided data at thermal point and encompassed integral measurements in the range from 3 keV to 1 MeV, where three time-of-flight measurements are available, but with low resolution to resolve the resonances. Transmission measurements from the 1970s resolved and analyzed some resonances. Method: We measure the neutron capture cross section of 176Yb(n, γ ) 177Yb by means of the time-of-flight technique at the Experimental Area 1 of the n_TOF facility at CERN using an enriched 176Yb2 O3 sample and an array of four C6D6 liquid scintillation detectors. Results: We have resolved 164 resonances up to 21 keV, including 96 new ones. We also provide new capture experimental data from 90 eV to 3 keV, and we extend the resolved resonance region up to 21 keV. In addition, resonance decay widths, γ and n, are provided for all resonances together with resonance energies. Conclusions: The 176Yb(n, γ ) 177Yb reaction has been measured, providing resonance parameters for the first time from a few eV to 21 keV. The analysis of the resonances has been carried out and compared with previous works and existing libraries, revealing discrepancies due to the new information on γ parameters. Our results are consistent with the n parameters obtained in transmission measurements.
Measurement of the Se 78 (n,γ) Se 79 cross section up to 600 keV at the n_TOF facility at CERN
(American Physical Society, 2024-12-17) Sosnin, N. V.; Lederer-Woods, C.; Garg, R.; Battino, U.; Cristallo, S.; Dietz, M.; Cortés Giraldo, Miguel Antonio; Guerrero Sánchez, Carlos; Lerendegui Marco, Jorge; Quesada Molina, José Manuel; Sabaté Gilarte, Marta; Žugec, P.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Gobierno de United Kingdom; European Union (UE); Gobierno de la República Checa; Gobierno de Polonia
The 78Se(n, γ ) 79Se cross section has a high impact on the abundances of 78Se produced during the slow neutron capture process (s process) in massive stars. A measurement of the 78Se radiative neutron capture cross section has been performed at the Neutron Time-of-Flight facility at CERN using a set of liquid scintillation detectors that have been optimized for a low sensitivity to neutrons. We present resonance capture kernels up to 70 keV and cross section from 70 to 600 keV. Maxwellian-averaged cross section (MACS) values were calculated for stellar temperatures between kT = 5 and 100 keV, with uncertainties between 4.6% and 5.8%. The new MACS values result in substantial decreases of 20–30% of 78Se abundances produced in the s process in massive stars and AGB stars. Massive stars are now predicted to produce subsolar 78Se / 76Se ratios, which is expected since 76Se is an s-only isotope, while solar 78Se abundances have also contributions from other nucleosynthesis processes.
Efficient computation of the magnetic field created by a toroidal volumetric current of convex cross section with application to the study of the magnetic confinement in tokamaks
(Elsevier, 2025-08) Camacho Aguilar, Miguel; Rodríguez Boix, Rafael; Cruz Zabala, Diego José; Galdón Quiroga, Joaquín; Ayllón Guerola, Juan Manuel; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE); European Research Council (ERC)
In this paper we present an efficient approach for the numerical computation of the static vector potential and the poloidal magnetic field of a toroidal volumetric current with arbitrary convex cross section. The standard integral expressions for both the vector potential and the magnetic field include singularities that have a deleterious effect in the computation of these integrals. In order to handle these singularities, we first introduce a change of variables to polar coordinates with origin at the observation point that makes it possible to remove the singularities of the integrands thanks to the Jacobian factor. Then, two different numerical integration methods are applied to the resulting integrals: Ma-Rokhlin-Wandzura quadrature rules and the double exponential quadrature rule. Both methods efficiently handle the singularities in the derivative of the integrand for the integrals of the vector potential and the magnetic field, and the advantages and disadvantages of each method are discussed. The results obtained for the vector potential and magnetic field are validated by comparing with closed-form results existing for the vector potential and magnetic field of a circular loop and an infinite cylinder, and good agreement is found. Then, the magnetic field code is used to model the plasma toroidal current in a tokamak nuclear fusion reactor, and it is shown that the combined magnetic field of the plasma current and that of the poloidal and toroidal coils leads to magnetic confinement of the charged particles existing in the plasma.

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