Artículos (Física Aplicada II)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10854

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Site-dependent shaping of field potential waveforms
(Oxford University Press, 2023) Herreras, Óscar; Torres, Daniel; Martín Vázquez, Gonzalo; Hernández Recio, Sara; López Madrona, Víctor José; Benito, Nuria; Makarov, Valeri A.; Makarova, Julia; Física Aplicada II
The activity of neuron populations gives rise to field potentials (FPs) that extend beyond the sources. Their mixing in the volume dilutes the original temporal motifs in a site-dependent manner, a fact that has received little attention. And yet, it potentially rids of physiological significance the time-frequency parameters of individual waves (amplitude, phase, duration). This is most likely to happen when a single source or a local origin is erroneously assumed. Recent studies using spatial treatment of these signals and anatomically realistic modeling of neuron aggregates provide convincing evidence for the multisource origin and site-dependent blend of FPs. Thus, FPs generated in primary structures like the neocortex and hippocampus reach far and cross-contaminate each other but also, they add and even impose their temporal traits on distant regions. Furthermore, both structures house neurons that act as spatially distinct (but overlapped) FP sources whose activation is state,region, and time dependent,making the composition of so-called local FPs highly volatile and strongly site dependent.Since the spatial reach cannot be predicted without source geometry,it is important to assess whetherwaveformsandtemporalmotifsarisefromasinglesource;otherwise,thosefromeachoftheco-active sources should be sought.
RULES: Free desktop application to perform activity calculations and radiometric dating
(Springer, 2026) Martínez Rojas, Manuel; Mantero Cabrera, Juan; García León, Manuel; Física Aplicada II; Física Atómica, Molecular y Nuclear
Calculation of activities and radiometric dating through radioactive series may lead to long or non-explicit mathematical expressions. Thus, dedicated software is required to help solve related questions. RULES (RaPCUBES, URADS and LEADS Encompassed Software) is a new computer application dedicated to calculating activities and populations for radionuclides that belong to the four radioactive series ( 238 U, 237 235 U, 232 Th and Np) and performing dating estimations using methods based on disequilibria between isotopes within the family. RULES contains three different tools. - RaPCUBES: Radioactivity and Population Calculator Using Bateman Equations’ Solutions.- URADS: Uranium Routines Application for Dating Samples through R or 234 U/ 238 238 U U and T or 230 Th/ 234 U methods.- LEADS: Lead Employed Approaches for Dating Sediments through 210 Pb simplest physical models, i.e., CA (Constant Activity), CS (Constant Sedimentation), CF (Constant Flux) and CFCS (Constant Flux Constant Sedimentation). RULES has been programmed in the environment of MATLAB’s AppDesigner (v. 2021b), with a database built in Microsoft Excel. It is available as completely free software via e-mail request and Manuel Martínez Rojas’ profile at idUS (Research Repository of the University of Seville). Only the 9.11 version of MATLAB’s Runtime is required. This does not need MATLAB’s license to operate and makes the installation process straightforward through a unique link. Also, as a desktop application, RULES is able to work offline. RULES’s main purpose is to provide simple-to-use software that encompasses three different tools of interest with intuitive user interfaces, so no programming knowledge is required to use the application. Also, novel revised propagation of uncertainties is implemented at all levels of the calculation processes. Furthermore, it has been demonstrated that RULES performs satisfactorily when used in actual high-quality research works. Discrepancies in results between RULES and some widespread similar software do not exceed 4 % and the implemented propagation of uncertainties seems more conservative than that of the other tools. Finally, thanks to its simplicity and results visualization possibilities, RULES stands out as a useful educational instrument to study radioactive series, secular and transient equilibrium and some radiometric dating strategies.
Mechanical performance of sub-stoichiometric titanium carbide ceramics synthesized by a hybrid SHS and SPS methodology
(Elsevier, 2026) Moshtaghion, Bibi Malmal; Cano Crespo, Rafael; Cumbrera Hernández, Francisco Luis; Gómez García, Diego; García Fernández, María; Rodríguez Barbero, Miguel Angel; Moreno, Rodrigo; Física Aplicada II; Física de la Materia Condensada
Sub-stoichiometric titanium carbide ceramics were synthesized via a hybrid route combining self-propagating high-temperature synthesis (SHS) and spark plasma sintering (SPS). TiC₁₋ₓ powders were produced through a single, rapid SHS step by the direct reaction of titanium and graphite, followed by attrition milling to achieve an average particle size of 3–5 μ ◦ m. Particular attention was devoted to analyzing sub-stoichiometry variations associated with carbon vacancy formation during both SHS and SPS processes. SPS treatments at temperatures up to 1800 C promoted sub-stoichiometric deviations reaching compositions as low as TiC 0.74 , which remained nearly stable even under more extreme SPS conditions. Additionally, a minor and unexpected precipitation of a disordered graphite phase was detected. The resulting sub-stoichiometric titanium carbide ceramics exhibited high Vickers hardness values, reaching up to 27 GPa. Microstructural analysis revealed plastic deformation, attributed to dislocation interactions with graphite precipitates. The dislocation dynamics were found to be governed by cationic diffusion mechanisms.
How to avoid (apparent) signaling in Bell tests
(Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften, 2025) Smania, Massimiliano; Kleinmann, Matthias; Cabello Quintero, Adán; Bourennane, Mohamed; Física Aplicada II
Bell tests have become a powerful tool for quantifying security, randomness, entanglement, and many other properties, as well as for investigating fundamental physical limits. In all these cases, the specific experimental value of the Bell parameter is important as it leads to a quantitative conclusion. However, experimental implementations can also produce experimental data with (apparent) signaling. This signaling can be attributed to systematic errors occurring due to weaknesses in the experimental designs. Here we point out the importance, for quantitative applications, to identify and address this problem. We present a set of experiments with polarization-entangled photons in which we identify common sources of systematic errors and demonstrate approaches to avoid them. In addition, we establish the highest experimental value for the Bell-CHSH parameter obtained after applying strategies to minimize signaling that we are aware of: S=2.812±0.003 and negligible systematic errors. The experiments did not randomize the settings and did not close the locality loophole.
Energy-time and time-bin entanglement: past, present and future
(Springer Nature, 2025) Xavier, Guilherme B.; Larsson, Jan Ake; Villoresi, Paolo; Vallone, Giuseppe; Cabello Quintero, Adán; Física Aplicada II
Entanglement is a key resource in many quantum information tasks. From a fundamental perspective entanglement is at the forefront of major philosophical discussions advancing our understanding of nature. An experimental scheme was proposed in 1989 by Franson that exploited the unpredictability in the generation time of a photon pair in order to produce a then new form of quantum entanglement, known as energy-time entanglement. A later modification gave rise to the very popular time-bin entanglement, an important cornerstone in many real-world quantum communication applications. Both forms of entanglement have radically pushed forward our understanding of quantum mechanics throughout the 1990s and 2000s. A decade later modifications to the original proposals were proposed and demonstrated, which opens the path for the highly sought-after device-independence capability for entanglement certification, with a goal of ultra-secure quantum communication. In this review we cover the beginnings of energy-time and time-bin entanglement, many key experiments that expanded our understanding of what was achievable in quantum information experiments all the way down to modern demonstrations based on new technological advances. We will then point out to the future discussing the important place that energy-time and time-bin entanglement will have in upcoming quantum networks and novel protocols based on nonlocality.
Alternative Input Architecture for Balanced Diplexers Based on Over-Coupled H-Shaped Resonators With Independent Dual-Band Response
(Institute of Electrical and Electronics Engineers (IEEE) Xplore, 2025-10-22) Medrán del Río, José Luis; Fernández Prieto, Armando; Martel Villagrán, Jesús; Medina Mena, Francisco; Electrónica y Electromagnetismo; Física Aplicada II; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
A novel technique for designing balanced-to-balanced diplexers with enhanced common-mode rejection is presented. In this approach, the conventional T-junction typically used to feed the diplexer output channels is replaced by a pair of over-coupled H-shaped resonators. Each output channel is implemented using a second-order balanced filter, also based on H-shaped resonators. These filters are independently designed using standard coupled-resonator theory and are subsequently electromagnetically coupled to a common differential input port to achieve diplexing functionality. For performance comparison, two diplexers are designed: one employing the traditional T-junction and the other utilizing the proposed over-coupled H-shaped resonators. Both simulation and measurement results confirm the superiority of the proposed architecture in terms of common-mode rejection and overall performance.
The cohesive behavior of granular solids at high temperature in solar energy storage
(Elsevier, 2021-07-15) Durán Olivencia, Francisco José; Pérez Ebri, José Manuel; Espín Milla, Manuel Jesús; Valverde Millán, José Manuel; Física Aplicada II; Ministerio de Economía y Competitividad (MINECO). España
Solar technology has shown a keen interest in thermochemical storage to extend its operational timespan beyond a daily basis. Thermochemical solutions are operated by fine powders. Unlike regular granular media, fine powders become cohesive. However, despite the paramount importance of controlling powder flowability to integrate these solutions in solar technology, little research has focused on how powder cohesiveness shapes the flow regime through the storage circuit. This paper investigates two critical factors governing the granular flow through the storage route: temperature and consolidation. The experimental setup emulates the transition powders undergo from silos to reactors. Powders were consolidated before being fluidized at a given temperature, ranging from ambient to 500 °C. Tensile yield strength was then measured for different powders. The results exhibit the expected rising trend in the tensile yield strength of powders as temperature increases. But, interestingly, tensile yield strength skyrocketed when powders were subjected to higher consolidations. Backed by theoretical estimations based on mechanical models, the analysis unveils a cross effect between temperature and consolidation. A combined action that reinforces cohesion by promoting a plastic deformation; worsening, thus, powder flowability. In conclusion, consolidation introduces a multiplying effect on the powder cohesiveness as temperature increases, which represents a serious caveat to solar energy storage technology. To mitigate potential flowability issues, this work explores the use of nanoparticles of silica to layer limestone (calcium carbonate, CaCO3) particles. The nanosilica coatings turned out to be a very promising solution to preclude the enhancement of cohesion induced at high temperatures. Coated samples showed powder cohesiveness at high temperatures similar to the values obtained at room temperature. A solution that offers a simple and reliable alternative to smooth the flow regime in solid-based energy storage technologies at production environments.
Cross effect between temperature and consolidation on the flow behavior of granular materials in thermal energy storage systems
(Elsevier, 2020-03-01) Durán Olivencia, Francisco José; Espín Milla, Manuel Jesús; Valverde Millán, José Manuel; Física Aplicada II
Calcium looping (CaL) process offers a promising option to boost the energy efficiency and dispatchability in concentrated solar power (CSP) plants. Backed by ample experience on lime and cement industry, the CaL integration in CSP plants could be not only a feasible and reliable technology for energy storage but also a low-cost choice based on the abundance and cheap price of limestone (CaCO3). However, to date, there is no deep fundamental understanding about how different conditions through the pipes and in storage silos affect the flowability of the granular medium. This is a critical issue, therefore, concerning the ease with which the granular medium is transported, fluidized or stored. Our present work challenges the status quo on the granular-based energy storage systems in which many central questions about powder dynamics through the circuit have been dodged. To deeply explore and figure out optimal settings, we have investigated the potential side effects that changes in temperature and consolidations can induce in the powder flowability. In so doing, we analyze the variation of the tensile strength of the powder while it is being fluidized in a wide range of temperatures and consolidations. The powder, CaCO3 with a particle size around 50 μm, was chosen to mimic the actual conditions in CaL-CSP pilot plants (currently under development). The results show a severe impact on cohesion when the CaCO3 granular medium is exposed at different temperatures ranging from ambient to 500 °C, and consolidation stresses up to 2 kPa. With cohesion increasing up until an order of magnitude in this range of relatively low consolidations, it is a foregone conclusion that those changes uncover a scenario that has not been brought up so far.
Contact distribution–based prediction of yield stress in magnetorheological fluids
(Springer, 2025) Espín Milla, Manuel Jesús; Física Aplicada II; FQM253: Electrohidrodinámica y Medios Granulares Cohesivos
Magnetorheological (MR) fluids exhibit field-dependent rheological behavior arising from the reversible formation of particle chains under applied magnetic fields. Predicting the static yield stress of these systems remains a central challenge in their modeling and design. This work presents a closed-form analytical expression for the yield stress of MR fluids, derived from a particle-scale formulation that incorporates multipolar magnetic interactions and microstructural descriptors. The model explicitly accounts for the average number of interparticle contacts and the inclination angle of the chains relative to the internal magnetic field within the suspension, based on a simple microstructural hypothesis involving chain-like aggregates. A mechanical stability criterion is also formulated by identifying a critical inclination angle, , below which chains remain stable under the combined influence of magnetic attraction and hydrodynamic shear. This condition is obtained from force and torque balance at the chain–particle level and is applicable over a wide range of experimental conditions. Model validation is performed through complementary comparisons: the yield stress predicted by the model is directly contrasted with experimental data, while the corresponding chain inclination angles reconstructed from these measurements are compared with theoretical predictions of . The results show that the formulation captures observed trends and outperforms classical dipolar approaches across diverse particle sizes, magnetic properties, and field strengths, with confirmed applicability up to . Additionally, an analysis of competing interparticle forces reinforces the assumptions underlying the model and its domain of applicability.
Accuracy of Machine Learning algorithms for HPGe detector efficiency determination
(Elsevier, 2026) González González, Beatriz; Abascal Ruiz, Unai; Villa Alfageme, María; Hurtado Bermúdez, Santiago José; Física Aplicada II
The accurate determination of full-energy peak efficiency (FEPE) in High-Purity Germanium (HPGe) detectors is critical for gamma-ray spectrometry, especially when source-detector geometries vary. In this study, we investigate the application of six supervised machine learning (ML) algorithms—Polynomial Regression, Random Forest, XGBoost, LightGBM, Sparse Gaussian Process, and Multi-Layer Perceptron—for predicting FEPE of a Low Energy HPGe (LEGe) detector across a broad energy range (40–1600 keV) and diverse source types (point and volumetric). Datasets used for training, validation and testing the ML models were generated using Monte Carlo simulations (GESPECOR). Model performance was evaluated using cross-validation and standard error metrics (R2, RMSE, MRE). Among the tested models, Polynomial Regression and LightGBM demonstrated superior predictive accuracy and interpretability, achieving R2 values above 0.9999. SHAP values were used for explainability, demonstrating that the models successfully capture the key physical mechanisms influencing FEPE. These results position ML models as reliable and generalizable alternative to conventional FEPE calibration methods.
Evaluation of different parameters affecting the liquid scintillation spectrometry measurement of gross alpha and beta index in water samples
(Elsevier, 2011) Palomo, Marta; Villa Alfageme, María; Casacuberta, Nuria; Peñalver Hernando, Alejandra; Borrull Ballarín, Francesc; Aguilar Anguera, Carme; Física Aplicada II
Liquid scintillation spectrometry is a fast competitive technique for the simultaneous evaluation of gross alpha and beta indexes. However, the implementation of this technique should not be considered as straightforward, and the pre-concentration methods to decrease the detection limit together with quenching and alpha, and beta crossover corrections should be carefully chosen according to the needs of the laboratory. Both aspects are being approached in this work as to find an easy and robust method for alpha/beta measurement in water samples, taking into account the quenching and alpha/beta crossover interferences effects. Results showed that most of the pre-concentration methods increased the quenching in the measurement, although HNO3 0.05 M points to be the best solution for preconcentration and redissolution of the sample as converges into low quenching and maximum recovery. Subsequently, in the measurement of water samples with different conductivities, the analysis of the raw counts to obtain gross alpha and beta indexes was carried out using different approaches to implement quenching and interference corrections. If quenching and salt content in the sample are relatively low, interference and quenching-efficiency corrections do not improve the accuracy of the results within the usual precision assumed for a result of gross alpha and beta index (25%). Special attention must be paid when corrections are applied to high quenched or saline samples and when alpha and beta activities values are different in several orders of magnitude.
Reducing Global Warming Potential in Cement Production: A Comparative Study of Slate and Marble Waste as Sustainable
(IOP Publishing, 2025) Silva Calderón-Morales, Bianca Rafaela; Costal, Glauber Zerbini; García Martínez, Antonio; Pineda Palomo, Paloma; García-Tenorio García-Balmaseda, Rafael; Estructuras de Edificación e Ingeniería del Terreno; Física Aplicada II; Construcciones Arquitectónicas I
This study evaluates the reduction of Global Warming Potential (GWP) in Portland cement production through the incorporation of industrial waste from marble and slate as supplementary cementitious materials. Partial clinker substitutions between 5% and 20% were analyzed, assessing mechanical performance through compressive strength tests and environmental impact using the Life Cycle Assessment (LCA) methodology. The results demonstrated that replacing 20% of clinker with waste led to significant reductions in CO2 emissions: 16.44% for marble and 15.72% for slate. Formulations with 10% and 15% substitution showed the best balance between mechanical performance and environmental impact, meeting regulatory resistance requirements. Transportation logistics proved crucial, with longer distances negatively impacting GWP. The study concludes that reusing these residues represents a viable strategy to mitigate the environmental impacts of the cement industry, aligning with the principles of the circular economy and promoting more sustainable construction practices.
Hybrid compton-PET imaging for ion-range verification: a preclinical study for proton, helium, and carbon therapy at HIT
(Springer Nature, 2025-08-26) Balibrea-Correa, Javier; Lerendegui-Marco, Jorge; Lerendegui Marco, Jorge; Morell, Sergio; Guerrero Sánchez, Carlos; Rodríguez González, María Teresa; Jiménez Ramos, María del Carmen; Quesada Molina, José Manuel; Bauer, Julia; Brons, Stephan; Domingo-Pardo, César; Física Aplicada II; Física Atómica, Molecular y Nuclear; European Union (UE); Ministerio de Ciencia e Innovación (MICIN). España; Generalitat Valenciana; Generalitat Valenciana; Universidad de Sevilla
Enhanced-accuracy ion-range verification in real time shall enable a significant step forward in the use of therapeutic ion beams. Positron-emission tomography (PET) and prompt-gamma imaging (PGI) are two of the most promising and researched methodologies, both of them with their own advantages and challenges. Thus far, both of them have been explored for ion-range verification in an independent way. However, the simultaneous combination of PET and PGI within the same imaging framework may open-up the possibility to exploit more efficiently all radiative emissions excited in the tissue by the ion beam. Here, we report on the first preclinical implementation of an hybrid PET-PGI imaging system, hereby exploring its performance over several ion beam species (H, He and C), energies (55–275 MeV) and intensities (- ions/spot), which are representative of clinical conditions. The measurements were carried out using the pencil-beam scanning technique at the synchrotron accelerator of the heavy ion therapy center in Heidelberg utilizing an array of four Compton cameras in a twofold front-to-front configuration. The results demonstrate that the hybrid PET-PGI technique can be well suited for relatively low energies (55–155 MeV) and beams of protons. On the other hand, for heavier beams of helium and carbon ions at higher energies (155–275 MeV), range monitoring becomes more challenging owing to large backgrounds from additional nuclear processes. The experimental results are well understood on the basis of realistic Monte Carlo calculations, which show a satisfactory agreement with the measured data. This work can guide further upgrades of the hybrid PET-PGI system toward a clinical implementation of this innovative technique.
Analysis of corrosion by speckle polarimetry
(MDPI, 2025-08-10) Gascón Latasa, Francisco; Rodríguez Ordóñez, Jorge; Bayón Rojo, Ana Isabel; Nieves Pavón, Francisco José; Salazar Bloise, Félix José; Física Aplicada II; Universidad Politécnica de Madrid (UPM); TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
One of the most common problems in material engineering is the appearance of corrosion. For this reason, numerous efforts are underway to design materials that are resistant to this damage. In the same context, the diagnosis of corrosion is also of great interest since its detection reveals the real state of a structure. This article is focused on the latter. The purpose of the presented study is to provide a simple optical methodology to analyze the corrosion process and its evolution by means of a non-destructive method based on changes in the polarization state of the speckle patterns. To carry this out, two experimental arrangements with different wavelengths are proposed: one in the far field and another in the near field. The samples are first subjected to accelerated acid corrosion in the laboratory, and then, the degree of corrosion is quantitatively analyzed using the proposed technique. Moreover, in order to ensure that the acid attack on the samples is uniform (generalized corrosion), a detailed study is performed on the specimen surfaces via Raman spectroscopy. The results obtained show the ranges of applicability of both setups and their limits for studying corrosion.
The Effects of High-Energy Carbon Co-Doping on IMB-CNM LGAD Fabrication and Performance
(MDPI, 2025-09-06) Villegas, Jairo; Dougados, Florent; Torres Muñoz, Carmen; Fernandez-Martinez, Pablo; Jiménez Ramos, María del Carmen; Hidalgo, Salvador; Física Aplicada II; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union; Universidad de Sevilla; Junta de Andalucía
Over the past few years, Low-Gain Avalanche Detectors (LGADs) have demonstrated excellent timing performance, showing great potential for use in 4D tracking of high-energy charged particles. Carbon co-doping is a key factor for enhancing LGAD performance, which are detectors with intrinsic amplification, in harsh radiation environments. This work presents a broad pre-irradiation characterization of the latest carbon-co-implanted (or carbonated) LGADs fabricated at IMB-CNM. The results indicate that the addition of carbon reduces the nominal gain of the devices compared with non-carbonated detectors. Furthermore, a comprehensive study is presented on how carbon co-implantation can either enhance or suppress the diffusion of the multiplication layer during LGAD fabrication, depending on the device structure and fabrication parameters.
Microbial Remineralization Is a Depth-Varying Contributor to Particle Flux Attenuation in the Southern Ocean
(American Geophysical Union, 2025) Petiteau, Louis; Boyd, P. W.; Le Moigne, Frederic; Villa Alfageme, María; Vioque Romero, Ignacio; Laurenceau-Cornec, Emmanuel; Baker, Katherine B.; Lacour, L.; Rohr, Tyler; Strzepek, Robert F.; Bressac, Matthieu; Física Aplicada II; Gobierno de Australia; Australian Research Council; CSIRO Marine National Facility (MNF)
The biological carbon pump contributes to set the magnitude of carbon sequestration in the oceans' interior. Estimating the relative contribution of microbial versus zooplankton-mediated processes to particulate organic carbon (POC) flux attenuation provides insights into how this pump functions. Our study took place during the high productivity summer period in the Subantarctic and Polar Front Zone. In the upper mesopelagic (i.e., 180–300 m depth), we concurrently measured the downward POC flux, particle size and morphology, microbial remineralization rates and estimated size-specific sinking velocities. These concomitant measurements revealed two different export systems, dominated by fecal material in the Subantarctic, and phyto-aggregates in polar waters. These two systems were characterized by similar low particle sinking velocities (∼10 m d−1), while microbial remineralization rates differed by an order of magnitude. Higher microbial remineralization rates in the Subantarctic (0.11 d−1), compared to polar waters (0.04 d−1), were likely driven by the confounding effect of temperature and particle characteristics. Despite this difference in microbial remineralization rates, these two export systems were characterized by relatively similar transfer efficiencies, suggesting that microbes had differing influences. A comparison of microbially mediated (i.e., scaled using observed remineralization rates) with total POC flux attenuation (i.e., driven by the dual impact of microbes and flux-feeders) revealed a higher microbial contribution to the flux attenuation in the upper mesopelagic of the subantarctic compared to the polar region. This deconstruction of the flux attenuation revealed an increasing influence of microbes on POC degradation with depth to become the predominant actor in the lower mesopelagic.
Echo analysis in Iberian bullfighting arenas through objective parameters and acoustic simulation
(MDPI, 2025-07-12) Girón Borrero, Sara; Martín Castizo, Manuel; Galindo del Pozo, Miguel; Física Aplicada II; TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
The existence of echoes in an acoustic event can ruin the capture of a spoken message and the perception of a piece of music. Likewise, in the performers’ area, clear hearing is essential for the coordination and execution of the ensemble. Bullrings are buildings with a circular plan in which echo-encouraging focalisations can occur. Since bullrings lack a roof, the density of reflections is lower than that in a closed area, and therefore strong isolated reflections perceived by the audience as an echo can be created. In this work, calculations of the echo parameter (Echo Criterion EK) and inspection of impulse responses and energy decay curves are obtained in an on-site measurement campaign in the audience zones and in arena areas where the EK parameter exceeds the thresholds. To this end, four bullrings very emblematic of the Iberian Peninsula together with a very prominent Roman amphitheatre in a relatively good state of conservation in the Roman province of Hispania comprise the study cases. Experimental results of the EK parameter and from acoustic simulation in two of the bullrings present good concordance and show that there is no echo for music in any of the venues in the spectator zones and that the most critical area is when source and receiver are both in the arena, where even double and triple echoes appear.
First Tests of an Opto-Electro-Mechanical System for 2D Dose Analysis in Low Energy Proton Irradiated Films
(IEEE, 2025) Mena, S.; Karkour, N.; Alaphilippe, V.; Crepin, D.; Jiménez Ramos, María del Carmen; García López, Francisco Javier; Espino Navas, José Manuel; Pascual-Álvarez, D.; Riera-Llobet, C.; Muñoz-Berbel, X.; Guirado, G.; Gibelin, L.; Linget, D.; Guardiola, C.; Física Aplicada II; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla; Generalitat de Catalunya; European Union (UE)
This work presents a 2D dosimetry analysis with a new micro-opto-electro-mechanical system of radiochromic films irradiated with a low energy proton beam. The new system is based on a 5× 10 matrix of photodetectors controlled by both an in-house electronic circuit and a graphical user interface, which allows direct optical density measurements. We have investigated the performance of this 2D readout system using Gafchromic EBT3 films. The results were compared with those obtained using a standard analysis method based on a flat-bed scanner, and the results showed the feasibility of this system for 2D dose map evaluation. To the best of the authors’ knowledge, this is the first time that a two-dimensional micro-opto-electro-mechanical system has been used to analyze radiochromic films irradiated with low-energy protons. We intend to develop a portable 2D dosimetry tool that provides dose maps to speed up the reading of radiochromic films in radiotherapy.
Performance of SiC Diodes at Very High Doses of Low-Energy Proton Beams Under FLASH Conditions
(IEEE, 2025) Jiménez Ramos, María del Carmen; Torres-Muñoz, Carmen; García López, Francisco Javier; Barroso-Molina, Diego; Guardiola, Consuelo; Fleta, Celeste; Física Aplicada II; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); Universidad de Sevilla; Fundación LaCaixa
FLASH therapy has emerged as a promising radiotherapy technique, minimizing damage to healthy tissues while maintaining effective tumor control. Achieving FLASH conditions requires dose rates exceeding 40 Gy/s, but conventional dosimetry systems fail under these conditions. Recently, IMB-CNM (CSIC) developed SiC p-n diodes with 30 μm diameter and 3 μm thickness, specifically designed for FLASH radiotherapy. This study investigates their response to low-energy UHDR proton beams after high and ultra-high accumulated doses for the first time. Experiments were performed in the 3 MV tandem accelerator at CNA using 1 MeV and 2 MeV protons with a pulsed beam system, achieving mean dose rates of 10 kGy/s, dose-per-pulse of 5.6 Gy, and dose rate within the pulse of 4.6 MGy/s. Ion pulses were characterized using a Faraday Cup and Rutherford Backscattering Spectrometry (RBS). Two SiC diodes were studied: one pre-irradiated with 3.6 MGy for extreme applications and another for early irradiation stages. The pre-irradiated diode showed a sensitivity decrease of -1.34 %/kGy up to 750 kGy, stabilizing within 7 % response variation up to 4.5 MGy. The response remained linear within 10 % at mean dose rate up to 5 kGy/s for 2 MeV protons, demonstrating the feasibility of this technology for FLASH applications.
Particle Export Fluxes in the Southern Ocean: Importance of Nonheterotrophic Processes in POC Flux Attenuation
(AGU, 2025-06-29) Le Moigne, Frédéric; Pabortsava, Katsiaryna; Villa Alfageme, María; Briggs, Nathan; Baker, Chelsy A.; Bourman, Heather A.; English, Chance J.; Blackbird, Sabena; Henson, Stephanie A.; Venables, Hugh; Carlson, Craig A.; Moore, C. Mark; Williams, Jack; Martin, Adrian P.; Física Aplicada II
The ocean contributes to regulating atmospheric CO2 levels via the biological carbon pump (BCP). One critical aspect of the BCP is the depth at which sinking particulate organic carbon (POC) remineralizes in the mesopelagic zone (200–1,000 m). In the Southern Ocean, the circulation is such that the products generated from POC remineralization may have drastically different fates depending on (a) the latitude at which sinking particulate material is produced and (b) the depth at which its remineralization occurs. Here, we assess latitudinal and depth variations of POC export marine aggregate abundance and composition in the Southeast Pacific sector of the Southern Ocean. We show changes in flux attenuation depth horizons in the upper mesopelagic in the subantarctic zone. These correspond to rapid particle accumulation below the depth of the euphotic zone followed by abrupt export. We believe that such rapid changes may be linked to diatom life cycles, including resting cell and spore formation and resulting changes in particle sinking velocities rather than attenuation due to heterotrophic degradation or solubilization in the upper mesopelagic zone. We further discuss the occurrence of such features in the Southern Ocean and at the global scale. Our results highlight the importance of alternative flux attenuation processes, such as sudden changes in particles sinking velocities, in explaining variability in organic carbon sequestration by the ocean's BCP.

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