Artículos (Física Atómica, Molecular y Nuclear)

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

Examinar

Mostrando 1 - 20 de 1410

Impact of Aquaporin-4 and CD11c + Microglia in the Development of Ependymal Cells in the Aqueduct: Inferences to Hydrocephalus
(Springer Nature, 2024) Domínguez Mayo, Francisco José; González Vinceiro, Lourdes; Hiraldo González, Laura; Rodríguez Gómez, Francisco D.; Calle Castillejo, Claudia; Mayo León, Manuel; Netti, Vanina; Ramírez Lorca, Reposo; Echevarría Irusta, Miriam; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Fisiología Médica y Biofísica; Universidad de Sevilla. Departamento de Lenguajes y Sistemas Informáticos; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía
AQP4 is expressed in the endfeet membranes of subpial and perivascular astrocytes and in the ependymal cells that line the ventricular system. The sporadic appearance of obstructive congenital hydrocephalus (OCHC) has been observed in the offspring of AQP4−/− mice (KO) due to stenosis of Silvio’s aqueduct. Here, we explore whether the lack of AQP4 expression leads to abnormal development of ependymal cells in the aqueduct of mice. We compared periaqueductal samples from wild-type and KO mice. The microarray-based transcriptome analysis reflected a large number of genes with differential expression (809). Gene sets (GS) associated with ependymal development, ciliary function and the immune system were specially modified qPCR confirmed reduced expression in the KO mice genes: (i) coding for transcription factors for ependymal differentiation (Rfx4 and FoxJ1), (ii) involved in the constitution of the central apparatus of the axoneme (Spag16 and Hydin), (iii) associated with ciliary assembly (Cfap43, Cfap69 and Ccdc170), and (iv) involved in intercellular junction complexes of the ependyma (Cdhr4). By contrast, genes such as Spp1, Gpnmb, Itgax, and Cd68, associated with a Cd11c-positive microglial population, were overexpressed in the KO mice. Electron microscopy and Immunofluorescence of vimentin and γ-tubulin revealed a disorganized ependyma in the KO mice, with changes in the intercellular complex union, unevenly orientated cilia, and variations in the planar cell polarity of the apical membrane. These structural alterations translate into reduced cilia beat frequency, which might alter cerebrospinal fluid movement. The presence of CD11c + microglia cells in the periaqueductal zone of mice during the first postnatal week is a novel finding. In AQP4−/− mice, these cells remain present around the aqueduct for an extended period, showing peak expression at P11. We propose that these cells play an important role in the normal development of the ependyma and that their overexpression in KO mice is crucial to reduce ependyma abnormalities that could otherwise contribute to the development of obstructive hydrocephalus.
Effect of applied magnetic fields on the morphology of nematic nanobridges in slit pores
(Taylor & Francis, 2024-11-19) Romero Llorente, Pablo; Romero Enrique, José Manuel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICINN). España
In this paper, we report a molecular dynamics study of the effect of the application of magnetic fields on the morphology of nematic nanobridges of 32,000 oblate Gay-Berne particles in slit pores favouring homeotropic anchoring. In absence of magnetic fields, previous studies show that there are different conformations of the nanobridge, depending on the slit pore width D and the wettability of the walls. Under the application of uniform magnetic field cycles, in which the intensity of the field is increased stepwise until a maximum value and then decreased at the same rate, switching between different nanobridge conformations can be observed if the magnetic field is applied in a perpendicular direction to the global nematic director of the nanobridge. However, there are situations in which the initial bridge conformation is recovered after the magnetic field application, indicating that the switching can only be observed if there are different locally stable nanobridge conformations under the same thermodynamic conditions. Moreover, magnetic fields can destabilise the nanobridge, leading to its breakdown into isolated nanodroplets attached to a single wall.
8B Reaction Dynamics Researched at HIE-ISOLDE
(Editrice Compositori s.r.l., 2024) Spartà, R.; DiPietro, A.; Figuera, P.; Tengblad, O.; Moro Muñoz, Antonio Matías; Lei, J.; Martel, I.; Fernández García, Juan Pablo; Acosta, L.; Borge, M. J.G.; Onses, S. Viñal; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE). H2020
For the first time a measurement of 8B + 64Zn reaction has been performed at HIE-ISOLDE at CERN at energies around the Coulomb barrier, to understand how the debated halo structure of the light nucleus can affect reaction dynamics.
Beam modulation and bump-on-tail effects on Alfvén eigenmode stability in DIII-D
(Institute of Physics Publishing, 2021-05) Van Zeeland, Michael A.; Bardóczi, László; Gonzalez Martin, Javier; Heidbrink, William W.; García Muñoz, Manuel; Wang, Xin; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE)
Beam modulation effects on Alfvén eigenmode stability have been investigated in a recent DIII-D experiment and show that variations in neutral beam modulation period can have an impact on the beam driven Alfvén eigenmode spectrum and resultant fast ion transport despite similar time-averaged input power. The experiment was carried out during the current ramp phase of L-mode discharges heated with sub-Alfvénic 50-80 kV deuterium neutral beams that drive a variety of Alfvén eigenmodes unstable. The modulation period of two interleaved beams with different tangency radii was varied from shot to shot in order to modify the relative time dependent mix of the beam pitch angle distribution as well as the persistence of a bump-on-tail feature near the injection energy (a feature confirmed by imaging neutral particle analyzer measurements). As the beam modulation period is varied from 7 ms to 30 ms on/off (typical full energy slowing down time of τ slow ≈ 50 ms at mid-radius), toroidicity-induced Alfvén eigenmodes (TAEs) located in the outer periphery of the plasma become intermittent and coincident with the more tangential beam. Core mode activity changes from reversed shear Alfvén eigenmodes (RSAEs) to a mix of RSAE and beta-induced Alfvén eigenmodes. Discharges with 30 ms on/off period do not have a persistent bump-on-tail feature, have the lowest average mode amplitude and least fast ion transport. Detailed analysis of an individual TAE using TRANSP kick modeling (Monte Carlo evolution of the distribution function with probabilistic 'kicks' by the AEs) and the resistive MHD code with kinetic fast ions, MEGA, find no strong role of energy gradient drive due to bump-on-tail features. Instead, the observed TAE modulation with interleaved beams is likely a pitch angle dependent result combined with slowing down of the tangential beam between pulses. For the conditions investigated, bump-on-tail contributions to TAE drive were found to be 5% or less of the total drive at any given time.
Asymptotic Normalization Coefficient Investigation of the 17O(d, p) Transfer for Astrophysical Application to the 17O(n, α)14C Reaction at Low Energies
(American Astronomical Society, 2024-10-24) Giovanni Luca, Guardo; Lamia, Livio; Fernández García, Juan Pablo; Piskoř, Š.; Cognata, Marco La; D’Agata, Giuseppe; Tumino, Aurora; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Agencia Estatal de Investigación. España; Ministry of Education, Youth and Sports. Czech Republic
Indirect methods have proven to be a complementary approach for extending our knowledge of nuclear structure and low-energy cross sections. Among these, the neutron-induced reaction cross sections appear to be of particular interest since their role both for unstable and stable beams. In view of this, we report here the combined study of the 17O(n, α)14C reaction accomplished by the Trojan Horse Method (THM) and the asymptotic normalization coefficient (ANC) method. The low-lying 8038, 8125, 8213, and 8282 keV resonances in 18O are studied, and their Γn are derived. A comparison with recent direct data and recent THM experimental data is presented. The independent ANC investigation corroborates our previous THM results, confirms the consistence of the two indirect investigations, and shows new frontiers for neutron-induced reactions with radioactive ion beams. Moreover, we examined the impact of adopting the newly recommended 17O(n, α)14C reaction rate on asymptotic giant branch stars' nucleosynthesis. Our findings reveal significant variations (≳10%) in the production of the neutron-rich heavy isotopes sensitive to neutron density, underlining the neutron-poisoning effect of 17O on the s-process.
Anthropogenic actinides in seawater and biota from the west coast of Sweden
(Elsevier, 2024-11-10) López Lora, Mercedes; Chamizo Calvo, Elena; Eriksson, Mats; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Swedish Radiation Safety Authority; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; European Union (UE)
The assessment of the origin of the anthropogenic contamination in marine regions impacted by other sources than global fallout is a challenge. This is the case of the west coast of Sweden, influenced by the liquid effluents released by the European Nuclear Reprocessing Plants through North Sea currents and by Baltic Sea local and regional sources, among others. This work focused on the study of anthropogenic actinides (236U, 237Np and 239,240Pu) in seawater and biota from a region close to Gothenburg where radioactive wastes with an unknown composition were dumped in 1964. To this aim, a radiochemical procedure for the sequential extraction of U, Np and Pu from biota samples and the subsequent analysis of 236U, 237Np, 239Pu and 240Pu by Accelerator Mass Spectrometry was developed. The method was validated through the study of two reference materials provided by the International Atomic Energy Agency (IAEA): IAEA-446 (Baltic Sea seaweed) and IAEA-437 (Mediterranean Sea mussels). The 233U/236U atom ratio was also studied in the seawater samples. The obtained results indicate that the North Sea currents and global fallout are the major sources for 236U, 237Np and 239,240Pu to the studied area, without clear evidence of other local sources. Complementary, information on the Concentrations Factors (CF) in biota was obtained, for which the available information is very scarce. For seaweed, CF values of (4.07 ± 0.90)·103, 61 ± 22 and 76 ± 16 have been obtained for Pu, Np and U, respectively. Lower CF values of (3.37 ± 0.78)·102, 34 ± 10 and 15.9 ± 3.4 for Pu, Np and U, respectively, have been obtained for mussels.
Reaching environmental levels of 244Pu by accelerator mass spectrometry at the Centro Nacional de Aceleradores
(Elsevier, 2024-09) Chamizo Calvo, Elena; López Lora, Mercedes; Levy, Isabelle; Lérida Toro, Victoria; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Agencia Estatal de Investigación. España; European Union (UE)
244Pu (T1/2 = 81 My) is the longest-lived, most minor, and the most understudied Pu isotope. The anthropogenic production of 244Pu is linked to nuclear detonations. Reported 244Pu/239Pu atom ratios in environmental samples range from below 10−6 to above 10−3. This work discusses the performance of the 1 MV Accelerator Mass Spectrometry system at the Centro Nacional de Aceleradores (CNA, Seville, Spain) to analyse 244Pu at environmental levels. The presence of 232Th traces in the Pu sample limits the sensitivity of the technique through the formation of the diatomic trication (232Th12C)3+, of mass 244 u, which must be suppressed by adjusting the stripper gas pressure. A244Pu background of 0.0075 fg (2 × 104 at) is demonstrated for samples that have undergone a chemical treatment. The reliability of the technique is proved through the analysis of three reference sediments provided by the International Atomic Energy Agency (IAEA-412, IAEA-465, IAEA-385). 244Pu results are complemented with 239Pu, 240Pu, 241Pu and 236U and their relative isotopic abundances are discussed.
MHD stability analysis against pressure and current-driven modes in the SMall Aspect Ratio Tokamak
(IOP Publishing, 2024-10-08) Domínguez Palacios Durán, Jesús José; García Muñoz, Manuel; Toscano Jiménez, Manuel; Liu, Y. Q.; Mancini, Alessio; Cruz Zabala, Diego José; Berkery, J. W.; Labbate, J. A.; Viezzer, Eleonora; Oyola Domínguez, Pablo; Futatani, S.; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); Junta de Andalucía
Linear magnetohydrodynamic (MHD) simulations for the SMall Aspect Ratio Tokamak (SMART) have been carried out for the first time, for both positive (PT) and negative triangularity (NT) shaped plasmas using the MARS-F code. The MHD stability of projected SMART plasmas against internal kinks, infernal modes and edge peeling-ballooning modes have been analyzed for a wide range of realistic equilibria. A stabilization of internal kinks and infernal modes is observed when increasing the safety factor profile and reducing plasma beta. PT shaped plasmas are more stable against both internal kinks and infernal modes than their counterpart NT shaped plasmas. Toroidal flows have little impact on the MHD stability of the internal kinks, but they have a strong stabilizing effect on infernal modes, which can be further mitigated in NT shaped plasmas. The MHD stability of peeling-ballooning modes is reduced in NT shaped plasmas, as observed in conventional tokamaks.
Pushing the high count rate limits of scintillation detectors for challenging neutron-capture experiments
(Elsevier, 2024-04-25) Balibrea-Correa, J.; Lerendegui Marco, Jorge; Babiano Suarez, V.; Domingo Pardo, C.; Ladarescu, I.; Tarifeño Saldivia, A; Cortés Giraldo, Miguel Antonio; Guerrero Sánchez, Carlos; Pérez Maroto, Pablo; Quesada Molina, José Manuel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE). H2020; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Agencia Estatal de Investigación. España; Ministerio de Ciencia e Innovación (MICIN). España
One of the critical aspects for the accurate determination of neutron capture cross sections when combining time-of-flight and total energy detector techniques is the characterization and control of systematic uncertainties associated to the measuring devices. In this work we explore the most conspicuous effects associated to harsh count rate conditions: dead-time and pile-up effects. Both effects, when not properly treated, can lead to large systematic uncertainties and bias in the determination of neutron cross sections. In the majority of neutron capture measurements carried out at the CERN n_TOF facility, the detectors of choice are the C6D6 liquid-based either in form of large-volume cells or recently commissioned sTED detector array, consisting of much smaller-volume modules. To account for the aforementioned effects, we introduce a Monte Carlo model for these detectors mimicking harsh count rate conditions similar to those happening at the CERN n_TOF 20 m flight path vertical measuring station. The model parameters are extracted by comparison with the experimental data taken at the same facility during 2022 experimental campaign. We propose a novel methodology to consider both, dead-time and pile-up effects simultaneously for these fast detectors and check the applicability to experimental data from 197Au(𝑛, 𝛾), including the saturated 4.9 eV resonance which is an important component of normalization for neutron cross section measurements.
Thermo-mechanical assessment of the JT-60SA fast-ion loss detector
(Elsevier, 2021-06) Cobacho Rodríguez, Carlos; Segado Fernández, Jorge; Hidalgo Salaverri, Javier; Mancini, Alessio; Núñez Portillo, Juan Manuel; García Vallejo, Daniel; García Muñoz, Manuel; Davis, S.; Tomarchio, V.; Hajnal, N.; Piccinni, Carla; Ayllón Guerola, Juan Manuel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; Ministerio de Economía y Competitividad (MINECO). España; Ministerio de Economía y Competitividad (MINECO). España; Ministerio de Economía y Competitividad (MINECO). España; European Commission (EC); Universidad de Sevilla. TEP111: Ingeniería Mecánica; Universidad de Sevilla. FQM402: Ciencias y Tecnologías del Plasma y el Espacio; Universidad de Sevilla. TEP-945: Ingeniería Aeroespacial
A fast-ion loss detector (FILD) is being designed for the JT-60SA tokamak. In this work, the preliminary mechanical design of this diagnostic is described. The expected motion needed to move the probe head between the parking and the measuring positions has been estimated by numerical simulations. A finite element thermal assessment of the detector is presented, to characterize its thermal response during the operation of the machine. Finally, the results of a preliminary electromagnetic analysis are reported to evaluate the impact of major disruptions on the structural components the system. © 2021 The Author
Extended Lipkin model: Proposal for implementation in a quantum platform and machine learning analysis of its phase diagram
(American Physical Society, 2024-10-16) Baid, S.; Sáiz Castillo, Álvaro; Lamata Manuel, Lucas; Pérez Fernández, Pedro; Romero, A. M.; Rios, A.; Arias Carrasco, José Miguel; García Ramos, J. E.; 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
Background: In recent years, the implementation of nuclear physics models in quantum computers has emerged as a promising and novel area of research. Simultaneously, the study of quantum shape phase transitions in nuclear models has gained significant attention. Specifically, the phase diagram of the interacting boson approximation (IBA) has been extensively explored, particularly in connection with large-particle-number-limit considerations. Interestingly, the extended Lipkin model (ELM) serves as a valuable alternative for mimicking the IBA phase diagram and holds the advantage of being more straightforward to implement within a quantum computing platform. Purpose: We explore the ELM and provide: (i) calculations of the ground-state energy using a variational quantum eigensolver; (ii) a comprehensive formulation for implementing the dynamics of the ELM within a quantum computing platform, enabling the experimental exploration of the IBA phase diagram for systems with a small number of particles; and (iii) a determination of the phase diagram of the model using different machine learning (ML) methods. We note that in the ELM, unlike the usual Lipkin model, both first- and second-order quantum shape phase transitions take place depending on the model parameters. Methods: Initially, we employ the adaptive derivative-assembled pseudo-Trotter ansatz variational quantum eigensolver (ADAPT-VQE) to calculate the ground-state energy of the ELM. Next, we introduce the essential formulation and procedures required to implement this model effectively in a quantum computing environment. Finally, we use ML techniques to identify the different phases and critical points of the ELM. Results: We successfully reproduce the ground-state energy of the ELM across the complete phase space of the model using the ADAPT-VQE algorithm. We provide the necessary framework for implementing the ELM in a quantum computing platform, ensuring that the model can be executed with controlled errors. Finally, we obtain meaningful ML predictions that allow us to determine the phase diagram of the model. Conclusions: Our findings offer compelling evidence that the implementation of a nuclear model like the ELM in a quantum computing environment is not only feasible but can also be achieved with manageable error rates. This realization opens the door to detailed experimental investigations of the phase diagram of the ELM (and indirectly of the IBA) in a quantum computer, further advancing our understanding of quantum shape phase transitions and nuclear structure.
Production of carbon-11 for PET preclinical imaging using a high-repetition rate laser-driven proton source
(Nature Research, 2024-05-20) Peñas, Juan; Alejo, Aarón; Bembibre, Adrián; Apiñaniz, Jon Imanol; García García, Enrique; Guerrero Sánchez, Carlos; Millán Callado, María Ángeles; Benlliure, José; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Xunta de Galicia; Generalitat Valenciana; Ministerio de Ciencia e Innovación (MICIN). España
Most advanced medical imaging techniques, such as positron-emission tomography (PET), require tracers that are produced in conventional particle accelerators. This paper focuses on the evaluation of a potential alternative technology based on laser-driven ion acceleration for the production of radioisotopes for PET imaging. We report for the frst time the use of a high-repetition rate, ultraintense laser system for the production of carbon-11 in multi-shot operation. Proton bunches with energies up to 10–14 MeV were systematically accelerated in long series at pulse rates between 0.1 and 1 Hz using a PW-class laser. These protons were used to activate a boron target via the 11B(p,n)11C nuclear reaction. A peak activity of 234 kBq was obtained in multi-shot operation with laser pulses with an energy of 25 J. Signifcant carbon-11 production was also achieved for lower pulse energies. The experimental carbon-11 activities measured in this work are comparable to the levels required for preclinical PET, which would be feasible by operating at the repetition rate of current state-of-theart technology (10 Hz). The scalability of next-generation laser-driven accelerators in terms of this parameter for sustained operation over time could increase these overall levels into the clinical PET range.
Digital-analog quantum genetic algorithm using Rydberg-atom arrays
(American Physical Society, 2024-10-03) Llenas, Aleix; Lamata Manuel, Lucas; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear
Digital-analog quantum computing (DAQC) combines digital gates with analog operations, offering an alternative paradigm for universal quantum computation. This approach leverages the higher fidelities of analog operations and the flexibility of local single-qubit gates. In this paper, we propose a quantum genetic algorithm within the DAQC framework using a Rydberg-atom emulator. The algorithm employs single-qubit operations in the digital domain and a global driving interaction based on the Rydberg Hamiltonian in the analog domain. We evaluate the algorithm performance by estimating the ground-state energy of Hamiltonians, with a focus on molecules such as H2, LiH, and BeH2. Our results show energy estimations with less than 1% error and state overlaps nearing 1, with computation times ranging from a few minutes for H2 (two-qubit circuits) to one to two days for LiH and BeH2 (six-qubit circuits). The gate fidelities of global analog operations further underscore DAQC as a promising quantum computing strategy in the noisy intermediate-scale quantum era.
Prediction of two-neutron halos in the N = 28 isotones 40Mg and 39Na
(Elsevier, 2024-05-07) Singh, Jagjit; Casal Berbel, Jesús; Horiuchi, W.; Walet, N. R.; Satuła, W.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Science and Technology Funding Council, United Kingdom; National Science Centre (NCN), Poland; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Society for the Promotion of Science (JSPS) KAKENHI . Japan
The ground states of the nuclei 40Mg and 39Na are investigated using the hyperspherical formalism. Since they are located at the edge of the “big island of inversion”, we concentrate on whether we are likely to find twoneutron Borromean halos in these nuclei. A three-body model with effective 𝑛-𝑛 and 38Mg+𝑛 interactions is built for 40Mg based on the available data. We also give predictions for the low-lying spectrum of 38Na = 37Na +𝑛 and two-neutron separation energy of the 39Na nucleus. Depending on parameter choice, we report an increase in the matter radii in the range 0.1 - 0.5 fm relative to those of the core nuclei. The results suggest a two-neutron halo structure in 40Mg for a subset of parameters, reinforcing the prediction of a Borromean halo nucleus. The calculations indicate that a two-neutron halo is even more likely for 39Na. As expected, the halo is linked to the disappearance of the shell gap in these nuclei due to the inversion of the 2𝑝3∕2 and 1𝑓7∕2 orbitals. We study the total cross section for scattering of these nuclei from a carbon target using a Glauber model and show that these provide a clear signal to assess the halo structure.
Radiated power and soft x-ray diagnostics in the SMART tokamak
(American Institute of Physics, 2024-09-01) Salas Suárez-Bárcena, Jesús; Delgado Aparicio, L. F.; Segado Fernández, Jorge; Rodríguez González, A.; McKay, Kiera Anne; Cruz Zabala, Diego José; Hidalgo Salaverri, Javier; García Domínguez, J.; García Muñoz, Manuel; Viezzer, Eleonora; Galdón Quiroga, Joaquín; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Research Council (ERC)
A multi-energy soft x-ray diagnostic is planned to operate in the small aspect ratio tokamak (SMART), consisting of five cameras: one for core measurements, two for edge, and two for divertors. Each camera is equipped with four absolute extreme ultra-violet diodes, with three of them filtered by Ti and Al foils for C and O line emissions, respectively, and Be foils for temperature measurements. In addition, two spectrometers will be installed with a vertical line of sight for impurity control. This study introduces a synthetic model designed to characterize radiated power and soft x-ray emissions. The developed code extracts the radiated power and Zeff values by leveraging distributions of electron density, temperatures, and impurity concentrations. The investigation is centered on the predicted scenarios of SMART’s first phase of operation (Ip = 100 kA; Bt = 0.1 T), employing a double-null configuration with positive and negative triangularity. The anticipated impurities encompass C (1%) and Fe (0.01%) from the vessel, as well as O and N (0.1%) from air and water. For simplicity, the distribution is assumed to be homogeneous within the plasma, considering different mixtures with Zeff values ranging between 1 and 2. Finally, the model estimates signal strength for the diagnostic design, proving its feasibility.
Design and development of the magnetic diagnostic systems for the first operational phase of the SMART tokamak
(American Institute of Physics, 2024-08-01) Puentes del Pozo, Fernando; Vicente Torres, Pablo; Cruz Zabala, Diego José; Munaretto, S.; García Muñoz, Manuel; Viezzer, Eleonora; Mancini, Alessio; Rodríguez González, A.; Sánchez Gamino, Juan; Segado Fernández, Jorge; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Research Council (ERC); Department of Energy. United States
A set of magnetic diagnostics has been designed, manufactured, and calibrated for the first operational phase of the small aspect ratio tokamak. The sensor suite comprises of Rogowski coils; 2D magnetic probes; and poloidal, saddle, and diamagnetic flux loops. A set of continuous Rogowski coils has been manufactured for the measurement of plasma current and induced eddy currents in conductive elements. A set of flux loops and magnetic probes will be used as input for the reconstruction of the magnetohydrodynamic equilibrium. The quantity and position of these sensors have been verified to be sufficient with synthetic equilibrium reconstructions using the equilibrium fitting code and baseline scenarios computed with the Fiesta code. These sensors will also be used as input for the real-time control system, and magnetic probes will be used for the detection of plasma instabilities. The calibration procedure for the magnetic probes is described, and the results are shown. The signal conditioning and data acquisition systems are described.
Electromagnetic VDE and Disruption Analysis in the SMART Tokamak
(Institute of Electrical and Electronics Engineers, 2022-11-02) Mancini, Alessio; Doyle, Scott James; Segado Fernández, Jorge; Ayllón Guerola, Juan Manuel; Cruz Zabala, Diego José; García Domínguez, Javier; García Muñoz, Manuel; Viezzer, Eleonora; Buxton, P. F.; Chung, K. J.; Gryaznevich, M. P.; Hwang, Y. S.; García López, Francisco Javier; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; European Commission (EC)
The SMall aspect ratio tokamak (SMART) is a new spherical device, that is, currently being constructed at the University of Seville. The operation of SMART will cover three phases reaching a maximum plasma current ( $I_{P}$ ) of 400 kA, a toroidal magnetic field ( $B_{T}$ ) of 1 T, and a pulse length of 500 ms. Such operating conditions present notable challenges to the design and verification of SMARTs structural integrity during normal and off-normal operations. In particular, vertical displacement events (VDEs) and disruptions (Boozer, 2012) are most important as they can cause severe damage to the components directly exposed to the plasma due to the significant electromagnetic (EM) and thermal loads delivered over ms timescales. As a consequence, a detailed evaluation of the EM loads during plasma disruptions is mandatory for the correct dimensioning of the machine, in particular the vacuum vessel. The EM loads are mainly produced by: the poloidal flux variation during the thermal and current quench, halo currents (Boozer, 2013) that flow into the vacuum vessel and interacts with the toroidal magnetic field; and toroidal flux variation during the thermal and current quench. We present, here, the EM and structural analysis performed for the design of SMART. The modeling has been carried out by combining equilibrium scenarios obtained through the FIESTA code (Cunningham, 2013), estimating VDE and disruption time-scales by comparing other machines (Chen et al. 2015), (Hender et al. 2007), and (Bachmann et al. 2011) and computing EM forces through a finite element model (FEM) taking into account the effects of both eddy and halo currents (Roccella et al. 2008), (Titus et al. 2011), and (Ortwein et al. 2020). Finally, the structural assessment of the vacuum vessel is performed in order to verify its integrity during normal and off-normal events in phase 3.
Design of a Thomson scattering diagnostic for the SMall Aspect Ratio Tokamak (SMART)
(American Institute of Physics, 2024-09-04) Kaur, M.; Diallo, A.; LeBlanc, B.; Segado Fernández, Jorge; Viezzer, Eleonora; Huxford, R. B.; Mancini, Alessio; Cruz Zabala, Diego José; Podesta, M.; Berkery, J. W.; García Muñoz, Manuel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Department of Energy. United States; EUROfusion Consortium
We describe the design of a Thomson scattering (TS) diagnostic to be used on the SMall Aspect Ratio Tokamak (SMART). SMART is a spherical tokamak being commissioned in Spain that aims to explore positive triangularity and negative triangularity plasma scenarios at a low aspect ratio. The SMART TS diagnostic is designed to operate at high spatial resolution, 6 mm scattering length in the low-field side and 9 mm in the high-field side regions, and a wide dynamic range, electron temperature from 1 eV to 1 keV and density from 5 × 1 0 18 m − 3 to 1 × 1 0 20 m − 3 , to resolve large gradients formed at the plasma edge and in the scrape-off layer (SOL) under different triangularities and low aspect ratios. A 2 J @ 1064 nm laser will be used that is capable of operating in the burst mode at 1, 2, and 4 kHz to investigate fast phenomena and at 30 Hz to study 1 s (or more) long discharges. The scattered light will be collected over an angular range of 60 ° - 120 ° from 28 spatial points in the midplane covering the entire plasma width and the outer midplane SOL. Each scattering signal will be spectrally resolved on five wavelength channels of a polychromator to obtain the electron temperature measurement. We will also present a method to monitor in situ laser alignment in the core during calibrations and plasma operations.
Design, characterization, and modeling of the Charge eXchange Recombination Spectroscopy (CXRS) suite at the SMall Aspect Ratio Tokamak (SMART)
(American Institute of Physics, 2024-07-01) Cruz Zabala, Diego José; Viezzer, Eleonora; Rodríguez González, A.; Segado Fernández, Jorge; Alvarado Reyes, A.; Pérez González, J.; García Muñoz, Manuel; Dux, R.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; EUROfusion Consortium
Ion temperature, rotation, and density are key parameters to evaluate the performance of present and future fusion reactors. These parameters are critical for understanding ion heat, momentum, and particle transport, making it mandatory to properly diagnose them. A common technique to measure these properties is charge exchange recombination spectroscopy (CXRS). For characterizing positive and negative triangularity plasmas at the small aspect ratio tokamak, a poloidal array of gas puff based CXRS diagnostics will be measuring the ion properties in different poloidal positions. In this work, the modeling of the expected signal and spatial coverage using the FIDASIM code is presented. Furthermore, the design and characterization of the low field side midplane CXRS diagnostic are described. Each diagnostic is composed of a gas injection system, an optical system that collects the light emitted by the plasma, and a spectrometer. These systems will provide ion temperature, rotation, and density with a radial resolution of 3.75 mm and a temporal resolution of 2.2 ms.
Parametrized uncertainties in the spectral function model of neutrino charged-current quasielastic interactions for oscillation analyses
(American Physical Society, 2024-04-15) Chakrani, J.; Dolan, S.; Avanzini, M. Buizza; Ershova, A.; Koch, L.; McFarland, K.; Megías Vázquez, Guillermo Daniel; Wret, C.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Agence Nationale de la Recherche. France; Ministry of Science and Higher Education. Poland; National Science Centre, Poland; Centre national de la recherche scientifique (CNRS). France; international inter universityresearch ICRR, Tokyo, Japan; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía, España
A substantial fraction of systematic uncertainties in neutrino oscillation experiments stem from the lack of precision in modeling the nuclear target in neutrino-nucleus interactions. Whilst this has driven significant progress in the development of improved nuclear models for neutrino scattering, it is crucial that the models used in neutrino data analyses be accompanied by parameters and associated uncertainties that allow the coverage of plausible nuclear physics. Based on constraints from electron scattering data, we propose such a set of parameters, which can be applied to nuclear shell models, and test their application to the Benhar et al. [Nucl. Phys. A579, 493 (1994)] spectral function model. The parametrization is validated through a series of maximum likelihood fits to cross section measurements made by the T2K and MINERvA experiments, which also permit an exploration of the power of near-detector data to provide constraints on the parameters in neutrino oscillation analyses.

Examinar

Envíos recientes