Artículos (Física Atómica, Molecular y Nuclear)

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

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Measurement and Analysis of the 246Cm and 248Cm Neutron Capture Cross-sections at the EAR2 of the n_TOF Facility at CERN
(Springer, 2024) Alcayne, V.; Kimura, A.; Mendoza, E.; Cano-Ott, D.; Martínez, T.; Aberle, O.; Álvarez Velarde, F.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Cortés Giraldo, Miguel Antonio; Guerrero Sánchez, Carlos; Quesada Molina, José Manuel; Lerendegui Marco, Jorge; Reifarth, R.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE). H2020; Croatian Science Foundation
The 246Cm(n,γ) and 248Cm(n,γ) cross-sections have been measured at the Experimental Area 2 (EAR2) of the n_TOF facility at CERN with three C6D6 detectors. This measurement is part of a collective effort to improve the capture cross-section data for Minor Actinides (MAs), which are required to estimate the production and transmutation rates of these isotopes in light water reactors and innovative reactor systems. In particular, the neutron capture in 246Cm and 248Cm open the path for the formation of other Cm isotopes and heavier elements such as Bk and Cf and the knowledge of (n,γ) cross-sections of these Cm isotopes plays an important role in the transport, transmutation and storage of the spent nuclear fuel. The reactions 246Cm(n,γ) and 248Cm(n,γ) have been the two first capture measurements analyzed at n_TOF EAR2. Until this experiment and two recent measurements performed at J-PARC, there was only one set of data of the capture cross-sections of 246Cm and 248Cm, that was obtained in 1969 in an underground nuclear explosion experiment. In the measurement at n_TOF a total of 13 resonances of 246Cm between 4 and 400 eV and 5 of 248Cm between 7 and 100 eV have been identified and fitted. The radiative kernels obtained for 246Cm are compatible with JENDL-5, but some of them are not with JENDL-4, which has been adopted by JEFF-3.3 and ENDF/B-VIII.0. The radiative kernels obtained for the first three 248Cm resonances are compatible with JENDL-5, however, the other two are not compatible with any other evaluation and are 20 and 60% larger than JENDL-5.
First Measurement of the Mg II Forest Correlation Function in the Epoch of Reionization
(Oxford University Press, 2024) Tie, Suk Sien; Hennawi, Joseph F.; Wang, Feige; Onorato, Silvia; Yang, Jinyi; Bañados, Eduardo; Davies, Frederick B.; Oñorbe Bernis, José; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE). H2020; National Science Foundation (NSF). United States; Ministerio de Ciencia e Innovación (MICIN). España
Strong low-ionization transitions like the Mg IIλ2796, 2804 Å doublet are believed to produce a detectable ‘metal-line forest’, if metals pollute the neutral intergalatic medium (IGM). We measure the autocorrelation of the Mg II forest transmission using 10 ground-based z ≥ 6.80 quasar spectra probing the redshift range 5.96 < zMg II < 7.42 (zMg II,median = 6.47). The correlation function exhibits strong small-scale clustering and a pronounced peak at the doublet velocity (Δv = 768 km s−1) arising from discrete absorbers in the circumgalactic medium of galaxies. After these strong absorbers are identified and masked the signal is consistent with noise. Our measurements are compared to a suite of models generated by combining a large hydrodynamical simulation with a seminumerical reionization topology, assuming a simple uniform enrichment model. We obtain a 95 per cent credibility upper limit of [Mg/H] < −3.73 at zMg II,median = 6.47, assuming uninformative priors on [Mg/H] and the IGM neutral fraction xH I. Splitting the data into low-z (5.96 < zMg II < 6.47; zMg II,median = 6.235) and high-z (6.47 < zMg II < 7.42; zMg II,median = 6.72) subsamples again yields null detections and 95 per cent upper limits of [Mg/H] < −3.75 and < −3.45, respectively. These first measurements set the stage for making the Mg II forest an emerging tool to precisely constrain the Universe reionization and enrichment history.
Characterizing the ELG Luminosity Functions in the Nearby Universe
(EDP Sciences, 2024) Favole, G.; González Pérez, V.; Ascasibar, Y.; Corcho Caballero, P.; Montero Dorta, A. D.; Benson, A. J.; Comparat, J.; Cora, S. A.; Croton, D.; Guo, H.; Izquierdo Villalba, D.; Knebe, A.; Orsi, A.; Stoppacher, Doris; Vega Martínez, C. A.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Agencia Estatal de Investigación. España; Comunidad Autónoma de Madrid; Ministerio de Ciencia e Innovación (MICIN). España; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Argentina; Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación. Argentina; Universidad Nacional de La Plata. Argentina
Context. Nebular emission lines are powerful diagnostics for the physical processes at play in galaxy formation and evolution. Moreover, emission-line galaxies (ELGs) are one of the main targets of current and forthcoming spectroscopic cosmological surveys. Aims. We investigate the contributions to the line luminosity functions (LFs) of different galaxy populations in the local Universe, providing a benchmark for future surveys of earlier cosmic epochs. Methods. The large statistics of the observations from the SDSS DR7 main galaxy sample and the MPA-JHU spectral catalog enabled us to precisely measure the Hα, Hβ, [O ii], [O iii], and, for the first time, the [N ii], and [S ii] emission-line LFs over ∼2.4 Gyrs in the low-z Universe, 0.02 < z < 0.22. We present a generalized 1/Vmax LF estimator capable of simultaneously correcting for spectroscopic, r-band magnitude, and emission-line incompleteness. We studied the contribution to the LF of different types of ELGs classified using two methods: (i) the value of the specific star formation rate (sSFR), and (ii) the line ratios on the Baldwin–Phillips–Terlevich (BPT) and the WHAN (i.e., Hα equivalent width, EWHα, versus the [N ii]/Hα line ratio) diagrams. Results. The ELGs in our sample are mostly star forming, with 84 percent having sSFR > 10−11 yr−1. When classifying ELGs using the BPT+WHAN diagrams, we find that 63.3 percent are star forming, only 0.03 are passively evolving, and 1.3 have nuclear activity (Seyfert). The rest are low-ionization narrow emission-line regions (LINERs) and composite ELGs. We found that a Saunders function is the most appropriate to describe all of the emission-line LFs, both observed and dust-extinction-corrected (i.e., intrinsic). They are dominated by star-forming regions, except for the bright end of the [O iii] and [N ii] LFs (i.e., L[N ii] > 1042erg s−1, L[O iii] > 1043erg s−1), where the contribution of Seyfert galaxies is not negligible. In addition to the star-forming population, composite galaxies, and LINERs are the ones that contribute the most to the ELG numbers at L < 1041 erg s−1. We do not observe significant evolution with redshift of our ELGs at 0.02 < z < 0.22. All of our results, including data points and analytical fits, are publicly available. Conclusions. Local ELGs are dominated by star-forming galaxies, except for the brightest [N ii] and [O iii] emitters, which have a large contribution of Seyfert galaxies. The local line luminosity functions are best described by Saunders functions. We expect these two conclusions to hold up at higher redshifts for the ELG targeted by current cosmological surveys, such as DESI and Euclid.
Characterization of New Silicon Carbide Neutron Detectors with Thermal and Fast Neutrons
(Elsevier, 2024) Pérez, Martín; Zamorano, Felipe; Fleta, Celeste; Fernández Martínez, Begoña; Guerrero Sánchez, Carlos; Godignon, Philippe; Pellegrini, Giulio; Pérez Maroto, Pablo; Guardiola, Consuelo; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE). H2022; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
The aim of this work is to present a characterization of a new silicon carbide (SiC) neutron detector fabricated at the Institute of Microelectronics of Barcelona (IMB-CNM-CSIC). The device is based on a 50μm thick p-n diode built in a 4H-SiC wafer. Performance studies were carried out under different neutron energy spectra, including thermal and quasi-monoenergetic fast neutrons at the CNA HiSPANoS facility. We implemented a method for the fabrication of enriched LiF conversion layers to use for the detection of thermal neutrons. The detector was proven to be capable of being used for thermal neutron detection with conversion layers of 10B and LiF. A detection efficiency of 6 ± 1% was achieved with a 25μm thick LiF conversion layer. It was also confirmed that the device can be employed for the detection of recoil nuclei and protons produced by fast neutrons. The spectra obtained experimentally were compared with PHITS simulations. This work represents the first step towards the design and fabrication of new SiC neutron detectors in the IMB-CNM-CSIC clean room with potential applications in various scientific and technological fields.
Results of a Geant4 benchmarking study for bio-medical applications, performed with the G4-Med system
(American Association of Physicists in Medicine, 2025-02-21) Arce, Pedro; Archer, Jay W.; Arsini, Lorenzo; Bagulya, Alexander; Bolst, David; Brown, Jeremy M. C.; Caccia, Barbara; Chacon, Andrew; Cortés Giraldo, Miguel Antonio; Guatelli, Susanna; Quesada Molina, José Manuel; Wright, Dennis H.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Australian Research Council; National Health and Medical Research Council; Ministerio de Ciencia e Innovación (MICIN). España; China Scholarship Council; National Plan for NRRP Complementary Investments
Background: Geant4, a Monte Carlo Simulation Toolkit extensively used in bio-medical physics, is in continuous evolution to include newest research findings to improve its accuracy and to respond to the evolving needs of a very diverse user community. In 2014, the G4-Med benchmarking system was born from the effort of the Geant4 Medical Simulation Benchmarking Group, to benchmark and monitor the evolution of Geant4 for medical physics applications. The G4-Med system was first described in our Medical Physics Special Report published in 2021. Results of the tests were reported for Geant4 10.5. Purpose: In this work, we describe the evolution of the G4-Med benchmarking system. Methods: The G4-Med benchmarking suite currently includes 23 tests, which benchmark Geant4 from the calculation of basic physical quantities to the simulation of more clinically relevant set-ups. New tests concern the benchmarking of Geant4-DNA physics and chemistry components for regression testing purposes, dosimetry for brachytherapy with a (Formula presented.) source, dosimetry for external x-ray and electron FLASH radiotherapy, experimental microdosimetry for proton therapy, and in vivo PET for carbon and oxygen beams. Regression testing has been performed between Geant4 10.5 and 11.1. Finally, a simple Geant4 simulation has been developed and used to compare Geant4 EM physics constructors and physics lists in terms of execution times. Results: In summary, our EM tests show that the parameters of the multiple scattering in the Geant4 EM constructor G4EmStandardPhysics_option3 in Geant4 11.1, while improving the modeling of the electron backscattering in high atomic number targets, are not adequate for dosimetry for clinical x-ray and electron beams. Therefore, these parameters have been reverted back to those of Geant4 10.5 in Geant4 11.2.1. The x-ray radiotherapy test shows significant differences in the modeling of the bremsstrahlung process, especially between G4EmPenelopePhysics and the other constructors under study (G4EmLivermorePhysics, G4EmStandardPhysics_option3, and G4EmStandardPhysics_option4). These differences will be studied in an in-depth investigation within our Group. Improvement in Geant4 11.1 has been observed for the modeling of the proton and carbon ion Bragg peak with energies of clinical interest, thanks to the adoption of ICRU90 to calculate the low energy proton stopping powers in water and of the Linhard–Sorensen ion model, available in Geant4 since version 11.0. Nuclear fragmentation tests of interest for carbon ion therapy show differences between Geant4 10.5 and 11.1 in terms of fragment yields. In particular, a higher production of boron fragments is observed with Geant4 11.1, leading to a better agreement with reference data for this fragment. Conclusions: Based on the overall results of our tests, we recommend to use G4EmStandardPhysics_option4 as EM constructor and QGSP_BIC_HP with G4EmStandardPhysics_option4, for hadrontherapy applications. The Geant4-DNA physics lists report differences in modeling electron interactions in water, however, the tests have a pure regression testing purpose so no recommendation can be formulated.
Design of a correlation reflectometer radiometer diagnostic and measurements of the electron density–temperature cross-phase angle in the H-mode pedestal with small edge localized modes at ASDEX Upgrade
(AIP Publishing, 2025-03-01) Yoo, C.; Conway, G. D.; Burke, W.; Molina Cabrera, P. A.; Vanovac, B.; Bielajew, R.; Cruz Zabala, Diego José; Silva, A.; White, A. E.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Department of Energy. United States; EUROfusion Consortium
This work presents the hardware design and first results from a newly commissioned correlation reflectometer radiometer diagnostic that measures the cross-phase angle between electron density and temperature fluctuations in ASDEX Upgrade plasmas. This diagnostic employs cross correlations between signals measured by a tunable, continuous wave, perpendicular incidence, fluctuation reflectometer, and a 24-channel radiometer sharing the same line of sight. Novel measurements in the pedestal of a helium H-mode plasma with small edge localized modes show changes in the cross-phase angle between the electron density and temperature fluctuations from ∼90○ to 120○, suggesting changes in the properties of the turbulence driving transport in the plasma edge.
Ultra-Thin Plastic Scintillator-Based Proton Detector for Timing Applications
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-02-06) Rodríguez Ramos, Mauricio; García López, Francisco Javier; Seimetz, Michael; Juan Morales, Jessica; Torres Muñoz, Carmen; Jiménez Ramos, María del Carmen; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada II; Junta de Andalucía; Generalitat Valenciana; Consejo Superior de Investigaciones Científicas (CSIC)
The development of advanced detection systems for charged particles in laser-based accelerators and the need for precise time of flight measurements have led to the creation of detectors using ultra-thin plastic scintillators, indicating their use as transmission detectors with low energy loss and minimal dispersion for protons around a few MeV. This study introduces a new detection system designed by the Institute for Instrumentation in Molecular Imaging for time of flight and timing applications at the National Accelerator Center in Seville. The system includes an ultra-thin EJ-214 plastic scintillator coupled with a photomultiplier tube and shielded by aluminized mylar sheets. The prototype installation as an external trigger system at the ion beam nuclear microprobe of the aforementioned facility, along with its temporal performance and ion transmission, was thoroughly characterized. Additionally, the scintillator thickness and uniformity were analyzed using Rutherford backscattering spectrometry. Results showed that the experimental thickness of the EJ-214 sheet differs by approximately 46% from the supplier specifications. The detector response to MeV protons demonstrates a strong dependence on the impact position but remains mostly linear with the applied working bias. Finally, single ion detection was successfully achieved, demonstrating the applicability of this new system as a diagnostic tool.
Analytic and Monte Carlo calculations of dose-mean lineal energy for 1 MeV–1 GeV protons with application to radiation protection quality factor
(Springer Nature, 2025-02-10) Papadopoulos, Alexis; Kyriakou, Ioanna; Matsuya, Yusuke; Cortés Giraldo, Miguel Antonio; Galocha Oliva, Miguel; Plante, Ianik; Stewart, Robert D.; Tran, Ngoc Hoang; Li, Weibo; Daglis, Ioannis A.; Santin, Giovanni; Nieminen, Petteri; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Space Agency (ESA)
Radiation quality for determining biological effects is commonly linked to the microdosimetric quantity lineal energy (y) and to the dose-mean lineal energy (yD). Calculations of yD are typically performed by specialised Monte Carlo track-structure (MCTS) codes, which can be time-intensive. Thus, microdosimetry-based analytic models are potentially useful for practical calculations. Analytic model calculations of proton yD and radiation protection quality factor (Q) values in sub-micron liquid water spheres (diameter 10–1000 nm) over a broad energy range (1 MeV–1 GeV) are compared against MCTS simulations by PHITS, RITRACKS, and Geant4-DNA. Additionally, an improved analytic microdosimetry model is proposed. The original analytic model of Xapsos is refined and model parameters are updated based on Geant4-DNA physics model. Direct proton energy deposition is described by an alternative energy-loss straggling distribution and the contribution of secondary electrons is calculated using the dielectric formulation of the relativistic Born approximation. MCTS simulations of proton yD values using the latest versions of the PHITS, RITRACKS, and Geant4-DNA are reported along with the Monte Carlo Damage Simulation (MCDS) algorithm. The yD datasets are then used within the Theory of Dual Radiation Action (TDRA) to illustrate variations in Q with proton energy. By a careful selection of parameters, overall differences at the ~ 10% level between the proposed analytic model and the MCTS codes can be attained, significantly improving upon existing models. MCDS estimates of yD are generally much lower than estimates from MCTS simulations. The differences of Q among the examined methods are somewhat smaller than those of yD. Still, estimates of proton Q values by the present model are in better agreement with MCTS-based estimates than the existing analytic models. An improved microdosimetry-based analytic model is presented for calculating proton yD values over a broad range of proton energies (1 MeV–1 GeV) and target sizes (10–1000 nm) in very good agreement with state-of-the-art MCTS simulations. It is envisioned that the proposed model might be used as an alternative to CPU-intensive MCTS simulations and advance practical microdosimetry and quality factor calculations in medical, accelerator, and space radiation applications.
Compositional and microstructural study of joining methods in archaeological gold objects
(John Wiley and Sons Ltd, 2017-03) Scrivano, Simona; Gómez-Tubio, Blanca María; Ortega-Feliú, Inés; Ager Vázquez, Francisco José; Paúl Escolano, Antonio; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). España
This work arises in response to the need to understand the production techniques of pre-roman gold jewels, starting from the systematic characterization of the different methods of metal joining used in antiquity to produce these objects. To meet this requirement, different procedures used in antiquity were reproduced by means of experimental archaeology. These models correspond to three metal-joining methods reported by ancient recipes: solid-state diffusion with copper salt, brazing and autogenous welding. These techniques were studied by different analytical methods in order to characterize them at both compositional and microstructural level (SEM-EDS, metallography, μ-XRF and μ-PIXE). The results obtained show that the solid-state diffusion bonding with copper salt presents a crystal hexagonal structure without phase changes in the joining point, where only a variation in the grain size is observed. At the compositional level, this soldering method is characterized by a local increase in copper concentration and a small decrease in gold content. In contrast, brazing shows a dendritic-porous structure due to the superposition of the soldering alloy and the crystal structure of the original foils. Besides, the compositional analysis revealed an increment of silver and copper concentrations and a simultaneous reduction of gold concentration. Finally, in the autogenous welding, no changes at the microstructural and compositional levels were observed. The results obtained have also demonstrated the usefulness of a portable μ-XRF system for the in-situ characterization of ancient jewels.
Combining XRF and GRT for the analysis of ancient silver coins
(Elsevier, 2016-05) Ager Vázquez, Francisco José; Gómez-Tubio, Blanca María; Paúl Escolano, Antonio; Gómez-Morón, A.; Scrivano, Simona; Ortega-Feliú, Inés; Respaldiza Galisteo, Miguel Ángel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). España
Archaeological silver-copper alloys are usually affected by silver enrichment of the near surface layers, either intentional or fortuitous. In previous studies we have shown that surface composition of archaeological bronzes and leaded copper coins obtained by XRF can be corrected by means of gamma-ray transmission (GRT) to obtain the bulk composition. In the present work, we have studied the applicability of this method to silver-copper alloys and established the most suitable conditions for the GRT correction calculation. The analysis of the microstructure of the core and the corrosion layers of a set of silver roman coins shows that copper could be leached from the surface during corrosion and cleaning treatments, resulting in an apparent silver surface enrichment. After the correction calculations by GRT method, the concentrations of the major elements, Ag and Cu, were found to be in good agreement with the bulk composition obtained by direct analysis of the cut cross-sections of the coins. The GRT method shows to be a useful tool to study metal artefacts having a surface composition modified by corrosion or cleaning treatments.
Visible core spectroscopy at Wendelstein 7-X
(American Institute of Physics, 2024-08-13) Ford, O. P.; Langenberg, A.; Romba, T.; Pölöskei, P.; Zanini, M.; Bannmann, S.; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE)
Review of Scientific Instruments ARTICLE pubs.aip.org/aip/rsi Visible core spectroscopy at Wendelstein 7-X Cite as: Rev. Sci. Instrum. 95, 083526 (2024); doi: 10.1063/5.0219469 Submitted: 17 May 2024 • Accepted: 13 July 2024 • Published Online: 13 August 2024 O. P. Ford,1,a) A. Langenberg,1 T. Romba,1 P. Pölöskei,1 M. Zanini,1 S. Bannmann,1 T. Gonda,2 K. Ida,3 R. Lopez Cansino,4 N. Pablant,5 J. de la Riva Villen,6 C. Swee,7 M. Yoshinuma,3 A. Alonso,6 B. Geiger,7 V. Perseo,1 E. Viezzer,4 and W7-X Teamb) AFFILIATIONS 1 Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany 2 Auburn University, Auburn, Alabama 36849, USA 3 National Institute for Fusion Science, Toki 509-5292, Japan 4Department of Atomic, Molecular, and Nuclear Physics, University Seville, Seville, Spain 5 Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA 6 Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense 40, 28040 Madrid, Spain 7 Department of Engineering Physics, University Wisconsin-Madison, Madison, Wisconsin 53706, USA Note: This paper is part of the Special Topic on Proceedings of the 25th Topical Conference on High-Temperature Plasma Diagnostics. a)Author to whom correspondence should be addressed: htpd24@oliford.co.uk b)For the complete member list, please refer to T. Sunn Pedersen, Nucl. Fusion 62, 042022 (2022). ABSTRACT This paper presents an overview of recent hardware extensions and data analysis developments to the Wendelstein 7-X visible core spec- troscopy systems. These include upgrades to prepare the in-vessel components for long-pulse operation, nine additional spectrometers, a new line of sight array for passive spectroscopy, and a coherence imaging charge exchange spectroscopy diagnostic. Progress in data analysis includes ion temperatures and densities from multiple impurity species, a statistical comparison with x-ray crystal spectrometer measure- ments, neutral density measurements from thermal passive Balmer-alpha emission, and a Bayesian analysis of active hydrogen emission, which is able to infer electron density and main ion temperature profiles.
Validation of a synthetic fast ion loss detector model for Wendelstein 7-X
(IOP Publishing, 2024-08) LeViness, A; Lazerson, S.A.; van Vuuren, A.J.; Rueda Rueda, José; Beurskens, M.; Bozhenkov, Sergey A.; García Muñoz, Manuel; Romba, T.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Department of Energy. United States; EUROfusion Consortium. European Union
We present the first validated synthetic diagnostic for fast ion loss detectors (FILDs) in the Wendelstein 7-X (W7-X) stellarator. This model has been developed on, and validated against experimental data from, a FILD provided by the National Institute for Fusion Science (NIFS-FILD), with potential future applicability to the existing Faraday Cup FILD (FC-FILD) on W7-X as well as the scintillating FILD (S-FILD) currently under development. A workflow combining Monte Carlo codes BEAMS3D and ASCOT5 is used to track fast ions produced by neutral beam injection from the moment of ionization until they are thermalized or lost from the last closed flux surface, and from there to a virtual plane which serves as a projection of the entrance aperture to the FILD. Simulations in ASCOT5 are analyzed via a geometric method to determine the probability of transmission through the FILD aperture and onto the detector as a function of normalized momentum, pitch angle, gyrophase, and position at the virtual plane. This probability is then applied to the simulated ions arriving from the plasma, producing a simulated signal from a computationally tractable number of simulated fast ions. Simulated signals are presented for two W7-X experiments with neutral beam injection and quantitatively compared with experimental measurements from the NIFS-FILD diagnostic. An estimate of the frequency of charge-exchange with neutral particles in the edge is performed, and it is found that this process may have a significant impact on the measured signals.
Shedding Light on the Origin of ^{204}Pb, the Heaviest s-Process-Only Isotope in the Solar System
(American Physical Society, 2024-07-31) Casanovas-Hoste, A.; Domingo-Pardo, C.; Lerendegui Marco, Jorge; Guerrero Sánchez, Carlos; Tarifeño-Saldivia, A.; Krtička, M.; Pignatari, M.; Cortés Giraldo, Miguel Antonio; Quesada Molina, José Manuel; Rajeev, K.; Ministerio de Economía y Competitividad (MINECO). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía; European Union (UE). H2020
Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the 𝑟-process contribution by their stable isobars are defined as 𝑠-only nuclei. For a long time the abundance of 204Pb, the heaviest 𝑠-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow, 204Tl (𝑡1/2=3.78 yr), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on 204Tl, conducted at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of 204Tl produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the 𝑠-process temperatures of 𝑘⁢𝑇 ≈8 keV and 𝑘⁢𝑇 ≈30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new 204Tl MACS, the uncertainty arising from the 204Tl⁢(n,𝛾) cross section on the 𝑠-process abundance of 204Pb has been reduced from ∼30% down to +8%/−6%, and the 𝑠-process calculations are in agreement with the latest solar system abundance of 204Pb reported by K. Lodders in 2021.
Recent progress of JT-60SA project toward plasma operation
(2024-09-12) Shirai, H.; Takahashi, K.; Di Pietro, E.; Abate, D.; Abdel Maksoud, W.; Abe, H.; Ayllón Guerola, Juan Manuel; Garcia Dominguez, Javier; García López, Francisco Javier; García Muñoz, Manuel; Gonzalez Martin, Javier; Higashijima, S.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación
Superconducting (SC) tokamak JT-60SA plays an essential role in fusion research and development by supporting and complementing the ITER project, providing directions to the DEMO design activity and fostering next generation scientists and engineers. Since the short circuit incident at the terminal joints of equilibrium field coil #1 during the integrated commissioning (IC) in March 2021, both EU and JA implementing agencies (IAs) have examined how to ensure safe operation of JT-60SA by mitigating the risk of possible discharge occurrence inside the cryostat. Based on the experience of the global Paschen tests, the IAs have established a strategy of risk mitigation measures, which is a combination of (i) reinforcement of insulation, (ii) avoiding unnecessary voltage application to the coil systems and (iii) immediate de-energization of the coils when deteriorated vacuum conditions are detected. Thanks to the considerable efforts of the Integrated Project Team members, the IC restarted in May 2023. After confirmation of the SC state of the coil systems (TF, EF and CS), the coil energization test and the plasma operation phase 1 (OP-1) started. The first plasma was successfully achieved on 23 October 2023 with a limited value of voltage and current applied to the coils. The plasma configuration control was also confirmed with low plasma current and low auxiliary heating power conditions. Based on the IO–F4E–QST collaboration, activities of JT-60SA have been shared with the IO and provided an important lesson for ITER assembly and commissioning, and will provide an outstanding contribution to fusion research at large. After OP-1, maintenance & enhancement phase 1 (M/E-1) starts from January 2024, in which in-vessel components are installed, and heating and diagnostic systems are extensively upgraded to allow a high power heating experiment planned in OP-2. In order to make the best use of JT-60SA, a newly organized JT-60SA experiment team will refine the research plan for the future high heating power operation phase.
Multi-section fission ionization chamber for measurement of 239Pu(n,γ) reaction in fission tagging method
(Elsevier, 2024-07) Perkowski, J.; Alcayne, V.; Andrzejewski, J.; Cano-Ott, D.; Gawlik-Ramięga, A.; Mendoza, E.; Cortés Giraldo, Miguel Antonio; Fernández Martínez, Begoña; Guerrero Sánchez, Carlos; Lerendegui Marco, Jorge; Pérez Maroto, Pablo; Pellegriti, M. G.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Narodowe Centrum Nauki (NCN), Poland; European Union (UE). H2020; Ministry of Science and Higher Education of Poland; European Atomic Energy Community (Euratom); University of Lodz; Agencia Estatal de Investigación. España; Ministerio de Ciencia e Innovación (MICIN). España
The 239𝑃 𝑢(𝑛, 𝛾) reaction cross section is very important for operation of both thermal and fast reactors, when loaded with MOX fuels. According to the NEA/OECD High Priority Request List the precision of cross section data for this reaction should be improved. The cross section of (𝑛, 𝑓 ) reaction is much higher compared to (𝑛, 𝛾) for this isotope. In such conditions the fission tagging technique could be applied to identify the fission background. In the past, this technique was successfully used for capture measurements at the n_TOF facility at CERN. The multi-section fission ionization chamber was constructed and used in the combination with Total Absorption Calorimeter (TAC) for detecting gamma rays for the precise measurement of 239𝑃 𝑢(𝑛, 𝛾) reaction cross section at the n_TOF facility.
Digital-Analog Quantum Machine Learning
(Wiley, 2025-02-13) Lamata Manuel, Lucas; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
Machine learning algorithms are extensively used in an increasing number of systems, applications, technologies, and products, both in industry and in society as a whole. They enable computing devices to learn from previous experience and therefore improve their performance in a certain context or environment. In this way, many useful possibilities have been made accessible. However, dealing with an increasing amount of data poses difficulties for classical devices. Quantum systems may offer a way forward, possibly enabling to scale up machine learning calculations in certain contexts. On the contrary, quantum systems themselves are also hard to scale up, due to decoherence and the fragility of quantum superpositions. In the short and mid term, it has been evidenced that a quantum paradigm that combines evolution under large analog blocks with discrete quantum gates, may be fruitful to achieve new knowledge of classical and quantum systems with no need of having a fault-tolerant quantum computer. In this perspective, we review some recent works that employ this digital-analog quantum paradigm to carry out efficient machine learning calculations with current quantum devices.
Measurement of the 12C(e,e′) Cross Sections at Q2=0.8GeV2/c2
(Springer, 2024-08-01) Mihovilovič, M; Doria, L.; Achenbach, P.; Ankowski, A. M.; Bacca, S; Bosnar, D.; Megías Vázquez, Guillermo Daniel; Thiel, M.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Deutsche Forschungsgemeinschaft (DFG); Slovenian Research Agency (ARRS); European Union (UE). H2020; Croatian Science Foundation; University of Tokyo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía
We present the findings of a study based on a new inelastic electron-scattering experiment on the 12 C nucleus focusing on the kinematic region of Q2 = 0.8 GeV 2/c2 . The measured cross section is sensitive to the transverse response function and provides a stringent test of theoretical models, as well as of the theoretical assumptions made in Monte-Carlo event-generator codes developed for the interpretation of neutrino-nucleus experiments, such as DUNE and HyperK. We find that modern generators such as GENIE and GiBUU reproduce our new experimental data within 10%.
First observation of RMP ELM mitigation on MAST Upgrade
(2024-07-21) Ryan, DA; Ham, C. J.; Kirk, A.; Markovic, T; Munaretto, S.; Piron, L; Viezzer, Eleonora; Willensdorfer, M.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Department of Energy. United States; EUROfusion Consortium. European Union(UE); Engineering and Physical Sciences Research Council (EPSRC)
The first experimental attempts at controlling edge localised modes (ELMs) via the application of resonant magnetic perturbations on the MAST Upgrade tokamak are reported. Using the linear MHD model MARS-F, the phase shift between the upper and lower coil rows ∆Φ was optimised for toroidal mode number n = 1 and n = 2 fields, to provide forward guidance to experiments. In low βN discharges, the application of n = 1 3D fields caused the ELM frequency fELM to increase by over a factor 20 relative to the reference, and also induced a locked mode, which did not cause a plasma termination nor an H-L back transition. However when βN was raised, this induced locked mode caused plasma termination which precluded mitigation access. Initially, applying a numerically optimised n = 2 field had no effect. However applying a rigid toroidal shift to this field caused a locked mode disruption, demonstrating the presence of a substantial n = 2 error field. Coil current ramps were conducted with ∆Φ set at 6 different values, resulting in either locked mode disruptions or no effect, but mitigation with n = 2 fields was not established
Cherenkov probes and runaway electrons diagnostics
(Springer Nature, 2021-10-26) Kwiatkowski, R.; Rabinski, M.; Sadowski, M. J.; Zebrowski, J.; Karpinski, P.; TCV; Ayllón Guerola, Juan Manuel; García Muñoz, Manuel; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Union (UE)
The beams of fast runaway electrons (RE), which are often produced during tokamak discharges, are particularly dangerous and can induce serious damages of the vacuum vessel and internal components of the machine. The proper and fast diagnostics of RE beams is essential for controlling the discharge, e.g., by early mitigation of disruptions and potentially dangerous RE beams. The diagnostics of RE beams is usually based on measurements of the radiation emitted either by these electrons, or as a result of their interactions with plasma and/or vessel walls. Such a radiation is usually recorded by the means of probes placed outside the vacuum vessel. The method developed by our team is based on the probe located inside the vacuum vessel. The probe can be used to detect highly localized RE bunches and to determine their spatial and temporal characteristics. During last few years, the NCBJ team have developed and used the RE diagnostics based on the Cherenkov effect observed in diamond radiators coupled with fast photomultipliers. During the investigated discharges, the probe was inserted into the vacuum vessel, and its head was placed at the plasma edge, where fast RE are expected. A correlation between signals recorded using our probes and other diagnostics, e.g., hard x-ray signals, was also studied. In this paper, we present recent results of the RE measurements by means of Cherenkov probes, which were performed in the COMPASS and TCV tokamaks.
Evolution of the two-neutron configuration from 11Li to 13Li
(Elsevier, 2024-08-22) André, P.; Corsi, A.; Revel, A.; Kubota, Y.; Casal Berbel, Jesús; Fossez, K.; Gómez Camacho, Joaquín José; Zenihiro, J.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Consejo Europeo de Investigación (ERC); Ministerio de Ciencia, Innovación y Universidades (MICINN). España; European Union (UE). H2020; Institute for Basic Science. Korean; Fundación Alemana de Investigación Científica (DFG); Departamento de Energía (DOE). USA
In this work we investigate the two-neutron decay of 13Li and of the excited states of 11Li populated via oneproton removal from 14Be and 12Be, respectively. A phenomenological model is used to describe the decay of 11Li and 13Li. While the first one displays important sequential components, the second one appears dominated by the direct two-neutron decay. A microscopic three-body model is used to extract information on the spatial configuration of the emitted neutrons before the decay and shows that the average distance between the neutrons increases going from 11Li to 13Li.

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