Artículos (Física Atómica, Molecular y Nuclear)

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

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M1 dipole strength from projected generator coordinate method calculations in the sd-shell valence space
(American Physical Society, 2025-12-08) Bofos, S.; Martínez-Larraz, J.; Bally, B.; Duguet, T.; Frosini, M.; Rodríguez Frutos, Tomás Raul; Sieja, K.; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; French National Research Agency; Agence Nationale de la Recherche. France
magnetic dipole (M1) radiations, has spurred theoretical efforts to improve on its description. Among the most widely used approaches are the quasiparticle random-phase approximation (QRPA) and its extensions. However, these methods often struggle to reproduce the correct behavior of the M1 strength at the lowest γ energies. An alternative framework, the projected generator coordinate method (PGCM), offers significant advantages over QRPA by restoring broken symmetries and incorporating both vibrational and rotational dynamics within a unified description. Due to these features, PGCM has been proposed as a promising tool to study the low-energy M1 strength function in atomic nuclei. However, comprehensive investigations employing this method are lacking. Purpose: The PGCM is developed and tested in its description of 1+ excited states in even-even nuclei, along with the M1 transitions connecting them to the 0+ ground state. Methods: The PGCM is presently used within the frame of sd-shell valence space calculations based on the USDB shell-model interaction to benchmark its performance against the solutions obtained via exact diagonalization, i.e. results from the latter are considered as “exact” reference results in the present study. The reliability of two different sets of generator coordinates in the PGCM calculations is gauged using 24Mg as a test case. Results: Energies and M1 transition strengths of the lowest excited 1+ states extracted from the PGCM calculation reproduce well the exact results for both sets of collective coordinates. Eventually, PGCM accurately models the exact level density and cumulative B(M1) strength up to about 20 MeV excitation energy in all considered nuclei. Conclusions: The ability of the PGCM to reproduce results from exact diagonalization in the sd valence space is demonstrated for 1+ states and M1 transitions. Future work will need to assess whether the proposed method can be applied systematically and extended to large-scale calculations while maintaining a reasonable computational cost.
Energy deposition by cosmic rays in the molecular cloud using GEANT4 code and voyager I data
(IOP Publishing, 2021-04-26) Tizziani Pazianotto, M.; Pilling, S.; Quesada Molina, José Manuel; Federico, C. A.; Física Atómica, Molecular y Nuclear; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; National Council for Scientific and Technological Development. Brasil
Molecular Clouds (MCs) are exposed to galactic and extragalactic cosmic rays (CR) which trigger several physical and physicochemical changes, including gas and grain heating, and molecular destruction and formation. Here, we present a theoretical model describing the energy delivered by cosmic rays, composed by protons, alphas and electrons taken from Voyager I measurements, into a typical MC with 5,400 solar masses (composed mainly by H with density law of r -1.2 ) and size around 1E6 AU. The calculation was performed employing the Monte Carlo toolkit GEANT4 to obtain the energy deposition per mass from several types of secondary particles (considering nuclear and hadron physics). The results indicate that incoming protons contribute to the most of the energy delivered in the MC in all regions (maximum ~230 MeV/g/s at outer regions of the cloud). Secondary electrons are the second most important component for energy deposition in almost all layers of the MC and can deliver an energy rate of ~130 MeV/g/s in the outer region of the MC. Other cascade particles have their major energy delivery in the central and denser core of the MC. From the temperature model (considering CRs data from Voyager I) we observed i) a small bump in temperature at the distance of 1-2E4 AU from the center; ii) a rapid temperature decrease (roughly 7K) between the outer layer and the second-most outer layer and iii) at distance of 5E4 AU (Av > 10) the gas temperature of MC is below 15 K.
Stochastic resetting with refractory periods: pathway formulation and exact results
(IOP Publishing, 2024-03-19) García Valladares, Gregorio; Gupta, D.; Prados Montaño, Antonio; Plata Ramos, Carlos Alberto; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Junta de Andalucía
We look into the problem of stochastic resetting with refractory periods. The model dynamics comprises diffusive and motionless phases. The diffusive phase ends at random time instants, at which the system is reset to a given position—where the system remains at rest for a random time interval, termed the refractory period. A pathway formulation is introduced to derive exact analytical results for the relevant observables in a broad framework, with the resetting time and the refractory period following arbitrary distributions. For the paradigmatic case of Poissonian distributions of the resetting and refractory times, in general with different characteristic rates, closed-form expressions are obtained that successfully describe the relaxation to the steady state. Finally, we focus on the single-target search problem, in which the survival probability and the mean first passage time to the target can be exactly computed. Therein, we also discuss optimal strategies, which show a non-trivial dependence on the refractory period.
How target distributions shape optimal stochastic resetting
(American Physical Society, 2026-02-05) García Valladares, Gregorio; Prados Montaño, Antonio; Manacorda, Alessandro; Plata Ramos, Carlos Alberto; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (EU); Junta de Andalucía; Ministerio de Hacienda y Función Pública. España
We investigate the search of a target with a given spatial distribution in a finite one-dimensional domain. The searcher follows Brownian dynamics and is always reset to its initial position when reaching the boundaries of the domain (boundary resetting). In addition, the searcher may be reset to its initial position from any internal point of the domain (bulk resetting). Specifically, we look for the optimal strategy for bulk resetting, i.e., the spatially dependent bulk resetting rate that minimizes the average search time. The best search strategy exhibits a second-order transition from vanishing to nonvanishing bulk resetting when varying the target distribution. The obtained mathematical criteria are further analyzed for different monoparametric families of distributions, which sheds light on the properties that control the optimal strategy for bulk resetting. Our work paves new research lines in the study of search processes, emphasizing the relevance of the target distribution for optimal search strategies, and identifies a successful framework to address these questions.
Overview of the MAST Upgrade physics programme: testing novel concepts at low aspect ratio to inform future devices
(IOP Publishing, 2026) Harrison, J.R.; Aboutaleb, A.; Aljunid, M.; Allan, S.Y.; Allan, R.; Alli, A.; Cano Megías, Pilar; Galdón Quiroga, Joaquín; Rivero Rodríguez, Juan Francisco; Viezzer, Eleonora; Ingeniería Energética; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; European Union (UE)
The research programme performed on the Mega Amp Spherical Tokamak (MAST) Upgrade experiment has made significant advances in developing the physics understanding of low aspect ratio tokamaks in support of the operation of ITER and design of fusion powerplants. High performance plasma scenarios have been developed to facilitate a broad programme of experiments, in which confinement is constrained by the presence of m/n = 2/1 modes that cause substantial losses of fast ions. The onset of these modes coincides with the q = 2 surface residing in a local minimum in the toroidal current density profile. The maximum electron temperature at the pedestal top, Te,ped is limited with gas fuelling to ∼350 eV to maintain regular ELMs; higher Te,ped results in a transition to a non-stationary ELM-free regime. The operational space of spherical tokamaks has been expanded into small and ELM-free regimes. Strong shaping of the last closed flux surface can induce a transition from large to small ELMs, and ELM suppression with resonant magnetic perturbations has been observed for the first time in a low aspect ratio tokamak. Negative triangularity shaping has induced a transition from ELMy H-mode to a high-performance L-mode regime for the first time in a low aspect ratio tokamak. In studies of fast ion confinement, losses of fast particles due to Global Alfvén Eigenmodes have been identified. Interactions between fast ions generated by off-axis neutral beam injection and thermal neutrals can result in significant losses of fast ions. Experiments with on- and off-axis neutral beam injection exhibit a flux pumping mechanism, where the central safety factor is held to ∼1 in the absence of sawteeth. In studies of pedestal physics, it has been found that elevated main chamber neutral pressures result in an increase in the electron density and reduction in the temperature at the pedestal top. Advances in understanding plasma exhaust include the integration of a high-performance plasma core with detached outer divertors in the X-point target configuration. A newly commissioned lower divertor cryopump reduces the lower divertor neutral pressure by up to 50%, with minimal effect on the main chamber or upper divertor. New measurements and SOLPS-ITER simulations emphasise the importance of plasma–neutral interactions on divertor detachment in the conditions accessible in experiments. Real-time control of the ionisation front location in both divertor chambers independently has been demonstrated in double null experiments, enabled by the tightly baffled divertor chambers.
Nuclear reaction dynamics in 12 C + 119 Sn collisions
(American Physical Society, 2025-03-18) Martinis, L. M.; Gasques, L. R.; Fernández García, Juan Pablo; Scarduelli, V.; González Álvarez, Marcos Aurelio; Chamon, L. C.; Hatano, W. A. Y.; Chaves, J. K. L.; Cessel, G. P.; Garrido Gómez, Lucas; Física Atómica, Molecular y Nuclear; Fondo para la Investigación Científica y Tecnológica. Argentina; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico. Brasil; Ministerio de Economía y Competitividad (MINECO). España; European Union (UE); Junta de Andalucía; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
First Experimental Microdosimetry Maps in Low-Energy Cyclotron Proton Beams
(IEEE, 2025-06-26) Riera Llobet, Carla; Ibáñez García, Paula Beatriz; Fleta Corral, María Celeste; Jiménez Ramos, María del Carmen; García López, Francisco Javier; Bachiller Perea, Diana; Guardiola Salmerón, Consuelo; Física Atómica, Molecular y Nuclear; Física Aplicada II; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Consejo Superior de Investigaciones Científicas (CSIC)
This work presents the first findings of microdosimetry measurements covering 12 cm ×0.4 mm of sensitive area on low-energy proton beams (3–14 MeV) of the cyclotron at the National Center of Accelerators (CNA, Spain) with clinical-equivalent fluence rates (∼107protons⋅cm−2⋅s−1) . Sensors are arrays of silicon-based 3D-microdetectors ( 20 μm thickness, 25 μm diameter) that were manufactured at the National Microelectronics Centre (IMB-CNM, CSIC) in Spain. Microdosimetry spectra were recorded at several proton energies both individually and in dual irradiation mode. Tool for particle simulation-based Monte-Carlo simulations recreating the experimental configuration were also performed to compare with the experimental data. A good agreement was found between the simulated and the experimental spectra. The experimental y¯f values in silicon covered from ( 6±1 ) to ( 17.4±0.5 ) keVμm−1 . To the best of our knowledge, this is the largest radiation sensitive surface covered with microdosimeters so far.
The effect of baryons on the positions and velocities of satellite galaxies in the MTNG simulation
(EDP Sciences, 2026-03-18) Contreras Hantke, Sergio Antonio; Angulo, Raúl Esteban; Bose, Sownak; Hadzhiyska, Boryana; Hernquist, Lars; Maion, Francisco; Pakmor, Rüdiger; Springel, Volker; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE)
Mock galaxy catalogues are often constructed from dark-matter-only simulations based on the galaxy–halo connection. Although modern mocks can reproduce galaxy clustering to some extent, the absence of baryons affects the spatial and kinematic distributions of galaxies in ways that remain insufficiently quantified. We compare the positions and velocities of satellite galaxies in the MTNG hydrodynamic simulation – a state-of-the-art cosmological hydrodynamic run – with those in its dark-matter-only counterpart, assessing how baryonic effects influence galaxy clustering and contrasting them with the impact of galaxy selection, i.e. the dependence of clustering on sample definition. We introduce a new method to track subhaloes using the merger trees of the simulations, which enables us to match systems even when their positions at z = 0 differ. We then compute positional and velocity offsets as functions of halo mass and distance from the halo centre, and use these to construct a subhalo catalogue from the dark-matter-only simulation that reproduces the galaxy distribution in the hydrodynamic run. Satellites in the hydrodynamic simulation lie 3–4% closer to halo centres than in the dark-matter-only case, with an offset that is nearly constant with halo mass and increases towards smaller radii. Satellite velocities are also systematically higher in the dark-matter-only run, with differences that grow towards lower halo masses and radii. At scales of 0.1 h−1 Mpc, these spatial and kinematic differences produce 10–20% variations in clustering amplitude – corresponding to 1–3σ assuming DESI-like errors – though the impact decreases at larger scales. We repeat the analysis in zoom-in simulations with varied physical models and find consistent trends. These baryonic effects are relevant for cosmological and lensing analyses and should be accounted for when building high-fidelity mocks. However, they remain smaller than the differences introduced by galaxy selection, which thus represents the dominant source of uncertainty when constructing mocks based on observable quantities.
Eikonal calculation of (p,3p) cross sections for neutron-rich nuclei
(American Physical Society, 2002-06-24) Gómez Ramos, Mario; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
In this work, I present the first, to my knowledge, theoretical description of two-proton removal reactions with proton target (p, 3p) for medium-mass nuclei at intermediate energies and present cross sections for the different bound states of the residual nucleus with two fewer protons. The description of the reaction assumes two sequential “quasifree” collisions between the target and removed protons and considers eikonal propagation in between. The formalism is applied to the reactions 12C(p, 3p)10Be, 28Mg(p, 3p)26Ne and 54Ca(p, 3p)52Ar, finding reasonable agreement to ex-perimental data for the 12C target and an overestimation of a factor ≈ 3 for the more neutron-rich and 54Ca, which is similar to the results found in two-proton knockout experiments with 9Be and 12C targets.
Elastic scattering of 10B + 119Sn: optical model analysis at energies around the Coulomb barrier
(IOP Publishing, 2025-07-25) Hatano, W. A. Y.; Gasques, L. R.; Scarduelli, V.; Chamon, L. C.; Chaves, J. K. L.; Martinis, L.; Cessel, G.P.; González Álvarez, Marcos Aurelio; Fernández García, Juan Pablo; Garrido Gómez, Lucas; Física Atómica, Molecular y Nuclear; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. Brasil; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico. Brasil; Ministerio de Economía y Competitividad (MINECO). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; National Science Foundation (NSF). United States
This work investigates the elastic scattering of 10B on 119Sn at several energies around the Coulomb barrier. The experimental angular distributions are analyzed within the optical model framework using two different nuclear interactions: the São Paulo potential (SPP) and its updated version, SPP2. The analysis shows that SPP2 provides a better overall description of the data, with the main differences between the two interactions stemming from the matter density adopted for the 10B projectile. The optical potentials obtained in this study are expected to serve as a reliable starting point for describing cross sections of other reaction channels for this system with in the coupled-channel formalism.
Commissioning of the Power Supplies and Coils of the SMART Tokamak
(Institute of Electrical and Electronics Engineers (IEEE), 2026-06) Vicente Torres, P.; Sánchez Gamino, Juan; Cruz Zabala, Diego José; Salas Suárez-Barcena, Jesús; Erena Guardia, Diego; Peña Arévalo, David; Márquez Alcaide, Abraham; León Galván, José Ignacio; Garcia Muñoz, Cristina; Física Atómica, Molecular y Nuclear; Ingeniería Electrónica; Ingeniería Mecánica y Fabricación; European Union (UE)
The small aspect ratio tokamak (SMART) is a spherical tokamak (ST) that ffers unique capabilities for studying the potential of negative triangularity. It has been designed, constructed, and is currently being operated by the Plasma Science Fusion Technology (PSFT) Laboratory at the University of Seville. SMART has a total of 21 coils, organized into seven independent circuits and driven by five modular power supplies (PS). The PS operation relies on switching converter technology based on IGBT and supercapacitors (SCs). The PS delivers predefined current waveforms to the copper coil system consisting of the central solenoid (CS), 12 toroidal field (TF) coils, three series pairs of poloidal field (PF) coils, and two independent PF coils. This study details the commissioning and validation of the PS toroidal and solenoid coils, as well as the assembly of coils in SMART. The maximum rated current and slope were measured, along with the series impedance of the coils, the output current ripple, and the noise levels. The internal parameters of the SCs were measured, and optimized current profiles were proposed to enhance overall performance. A comparison has been made between the theoretical values and the experimental results, providing insight into the performance of the PS and areas for improvement.
Single-event fast neutron time-of-flight spectrometry with a petawatt-laser-driven neutron source
(Nature Research, 2026-05-01) Millán Callado, María de los Ángeles; Scheuren, S.; Alejo, A.; Benlliure, J.; Beyer, R.; Cowan, T.E.; Fernández Martínez, Begoña; Rodríguez González, María Teresa; Guerrero Sánchez, Carlos; Guerrero Sánchez, Carlos; Física Atómica, Molecular y Nuclear; Ministerio de Economía y Competitividad (MINECO). España; Xunta de Galicia
Laser-driven neutron sources (LDNSs) offer unique advantages for fundamental physics and applications: ultrashort pulses providing superior energy resolution, high instantaneous flux, and a reduced footprint. While single-event neutron spectroscopy has been demonstrated with epithermal neutrons, its application for fast neutrons is more challenging and remains unproven. This demands stable multi-shot operation and detectors resilient to this particularly extreme environment. Here, a proof-of-concept experiment at the DRACO PW laser is presented. This setup stably produced ~ 108 fast neutrons per shot sustained over more than 200 shots at a shot-per-minute rate. Neutron time-of-flight measurements with a diamond detector at only 150 cm from the source resolved individual neutron-induced reactions at a rate consistent with simulations informed by real-time diagnostics of accompanying gammas, ions, and electrons. Combined with the recent advances in the field, this work establishes LDNSs as a promising, scalable platform for future fast neutron-induced reaction studies, particularly those involving short-lived isotopes.
Formation and Coherent Propagation of Femtosecond-Laser-Induced Periodic Surface Structures (LIPSS) in Fluorine-Doped Tin Oxide: Control, Potential Applications, and Challenges
(American Chemical Society (ACS), 2026-06-22) Gómez-Munoz, Gonzalo; Ariza, Rocío; Núñez Gálvez, Fernando; López Flores, Víctor; Cabello-Pardos, Fátima; Sotillo, Belén; Prieto, Carlos; García López, Francisco Javier; López Santos, Carmen; Solís, Javier; Física Aplicada I; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; Comunidad Autónoma de Madrid
We have analyzed the formation and coherent propagation of laserinduced periodic surfa cestructures (LIPSS) upon fs-laser irradiation of fluorine-doped tin oxide (FTO) films. The aim is the generation of large electrical anisotropies in macroscopic áreas for applications including laser-written transparent heaters, sensors, or substrates for electrically controlable wettability, among others. The films have been processed with high-repetition-rate (hundreds of kHz) fs-laser pulses at 1030nm using different laser (fluence and pulse duration) and scanning parameters (speedand line overlap). Optimal LIPSS formation and coherent propagation are conditioned by the dynamic evolution of the F content in the laser-processed regions that can be controlled via processing parameters. However, the homogeneity in the spatial distribution of F in the microscale in the pristine samples can generate important issues that are carefully considered and discussed in the present work. Still, the formation of optically and electrically highly anisotropic surfaces for laser scanning speeds well above 1.0m/s has been demonstrated, reaching electrical resistivity anisotropy factors of > 103. Consequently, the large-area applications using LIPSS-structured FTO films seems feasible, as we have demonstrated by fabricating an efficient laser-written electrothermal transparent device as a proof-of-concept.
Digital–Analog Quantum Simulation and Computing: A Perspective on Past and Future Developments
(Wikey, 2026-07-01) Lamata Manuel, Lucas; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
Traditionally, quantum simulation and computing have been based on two main paradigms, namely, digital and analog. In thedigital paradigm, usually single- and two-qubit gates (where qubit is an acronym for quantum bit) are employed as building blocksfor scalable, universal quantum computing, although errors add up fast and error correction will be ultimately needed for scalingup. In the analog paradigm, large analog blocks are normally employed for a unitary dynamics that carries out the computation,enabling quantum operations on many qubits with reduced errors, but with the drawback of a limited choice of evolutions andlack of universality. In the past decade, a new paradigm has emerged, showing interesting possibilities for quantum simulation andcomputing in the near and mid-term. This is the paradigm of digital–analog quantum technologies, which proposes to combinethe best of both paradigms: large analog blocks, provided by native interactions of the employed quantum platform, enablingscalability, combined with digital gates, allowing for more versatility and, ultimately, universality. In this perspective, I give anoverview of the evolution of the field along the past decade, and an outlook for its future possibilities
Systematic optical potentials for reactions with cluster-structured nuclei
(American Physical Society, 2024-05-08) Garrido Gómez, Lucas; Vegas Díaz, Alejandro; Fernández García, Juan Pablo; González Álvarez, Marcos Aurelio; Física Atómica, Molecular y Nuclear
Breakup effects in the 6He+27 Al reaction dynamics
(American Physical Society, 2026-02-12) Arruda, H. F. G.; Pires, K. C. C.; Santos, O. C. B.; Lichtenthäler, R.; Lépine-Szily, A.; Serra, A. S.; Umbelino, U.; Rodríguez Gallardo, Manuela; Moro Muñoz, Antonio Matías; De Faria, P. N.; Física Atómica, Molecular y Nuclear; Conselho Nacional de Desenvolvimento Científico e Tecnológico. Brasil; São Paulo Research Foundation; Instituto Nacional de Ciência e Tecnologia: Física Nuclear Aplicada. Brasil; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
New experimental data for the 6He+27Al collision at Elab = 17.9 MeV bombarding energy is presented. An abundant production of α-particles has been observed, with energies close to those of the scattered 6He beam. The 6He+27Al elastic scattering and the α-particle angular and energy distributions were obtained. Theoretical analyzes were performed using continuum-discretized coupled-channels (CDCC) calculations in both three-and four-bodyf rameworks, nonelastic break up calculations via the Ichimura-Austern-Vincent (IAV) model, and fusion-evaporation simulations. The results demonstrate that α-particle production is predominantly driven by nonelastic break up processes, with negligible contributions from elastic break up and alpha particle evaporation.
Nuclear reaction dynamics in 12C+120Sn collisions
(American Physical Society, 2025-12-02) Garrido Gómez, Lucas; Fernández García, Juan Pablo; González Álvarez, Marcos Aurelio; Martinis, L. M.; Chaves, J. K. L.; Hatano, W. A. Y.; Scarduelli, V.; Gasques, L. R.; Chamon, L. C.; Arazi, A.; Física Atómica, Molecular y Nuclear; Fondo para la Investigación Científica y Tecnológica. Argentina; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. Brasil; Conselho Nacional de Desenvolvimento CientíficoeTecnológico. Brasil; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España
Validity test of 20Ne as a Trojan Horse nucleus toward the measurement of the 16O+16O fusion cross section
(Springer, 2026-01-20) Hayakawa, S.; Typel, S.; La Cognata, M.; Chieffi, A.; Pietro, A. di; Fernández García, Juan Pablo; Figuera, P.; Limongi, M.; Lamia, L.; Urkinbayev, A.; Física Atómica, Molecular y Nuclear
The 16O+16O fusión reaction is important for understanding explosive oxygen burning during late evolutionary stages of massive stars as well as for understanding low-energy heavy-ion fusion-reaction mechanism. This paper represents the first step to determine the excitation function for the major exit channels, α+28Si and p+31P, toward stellar energies indirectly by the Trojan Horse Method via the 16O(20Ne,α28Si)4He and 16O(20Ne,p31P)4He three- body reactions. Indeed, here we report on a validity test of the approach showing, for the first time, the possibility to use 20Ne as Trojan Horse nucleus. Results on the reaction cannel identification and reaction mechanism determination, with particular emphasis on the momentum distribution of the α−16O intercluster motion in the projectile 20Ne nucleus are thoroughly discussed. Fair agreements of the present results with theoretical predictions indicate apossibility to identify the quasi-free process, which is the first step for the application of the Trojan Horse method to independently measurethe 16O+16O fusión crosss ection in the next future.
Self-diffusion in confined systems
(American Physical Society, 2025-11-12) Mayo León, Manuel; García de Soria Lucena, María Isabel; Maynar Blanco, Pablo; Brey Abalo, José Javier; Física Atómica, Molecular y Nuclear; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
The self-diffusion process of a hard sphere fluid confined by two parallel plates separated by a distance on the order of the particle diameter is studied. The starting point is a closed kinetic equation for the distribution function that takes into account the effects of the confinement and that is valid in the low-density limit. From it, the Boltzmann-Lorentz equation that describes the dynamics of some tagged particles when the whole system is in equilibrium is derived. An equation that describes the diffusion in the directions parallel to the walls is deduced by applying the Zwanzig-Mori projection technique to the Boltzmann-Lorentz equation, obtaining an explicit expression for the self-diffusion coefficient that depends on the height of the system. A very good agreement between its theoretical prediction and Molecular Dynamics simulation results is obtained for the whole range of heights.
Self-induced electrostatic field and hydrodynamic flow in an electrolyte solution in contact with an ion-pairs releasing active patch on a planar wall
(Elsevier, 2026-03) Nicola Popescu, Mihail; Domínguez Álvarez, Álvaro; Uspal, William E.; Gáspár, Szilveszter; Física Atómica, Molecular y Nuclear; Executive Agency for Higher Education, Research, Development and Innovation Funding of Romania; Ministry of Research, Innovation and Digitalization. Romanian; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
Patches of catalyst imprinted on supporting walls induce motion of the fluid around them once they are supplied with the chemical species (“fuel”) that are converted by the catalytic chemical reaction. In many cases (e.g., enzymes catalyzing the breakup of molecular substrates), pairs of oppositely charged ionic species are released in the surrounding solution as a result of the reaction at the patch. By using a simple model of activity for an ion-pairs releasing patch imprinted on a planar wall in contact with an electrolyte solution, we determine analytically the self-induced chemical composition inhomogeneities and electric field in the solution, as well as the resulting Stokes flow, in a half space geometry. The results provide the necessary tools for interpreting the motion of point-like tracer particles, which is the observable typically studied in experimental investigations.

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