Artículos (Física Atómica, Molecular y Nuclear)

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

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Production and measurement of a stellar neutron spectrum at 30 keV
(Springer, 2024-10-06) Praena, Javier; Verdera, Antònia; García López, Javier; Martín Hernández, Guido; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC)
A few years ago, we theoretically studied the production of a stellar neutron spectrum at kT = 30 keV using a shaped proton beam impinging on a thick lithium target. Here, we first measure the proton distribution to better control the produced neutron spectrum. Then, we measure the forward-emitted angle-integrated neutron spectrum of the 7Li(p,n)7Be reaction via time-of-flight neutron spectrometry with such proton distribution. The result resembles a stellar neutron spectrum at kT = 30 keV. This method avoids in activation experiments the need for spectrum correction. In the case of spherical samples, no knowledge of the cross-section of the isotope being measured by activation would be necessary. Therefore, the present method is of interest for isotopes with unknown or poorly known cross-sections, such as branching points in astrophysics. The key point of our method is the experimental control of the proton distribution that impinges on the lithium target.
Performance prediction applying different reduced turbulence models to the SMART tokamak
(2024-11-07) Cruz Zabala, Diego José; Podestà, M.; Francesca M.; Kaye, Stanley M.; García Muñoz, Manuel; Viezzer, Eleonora; Berkery, John W.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; EUROfusion Consortium; Universidad de Sevilla
The SMall Aspect Ratio Tokamak (SMART) is currently being commissioned at the University of Seville and will be able to compare the performance of positive and negative triangularity plasmas at low aspect ratio. Predictive simulations have been performed for different machine scenarios and heating schemes using the TRANSP code. The objectives of these simulations are to predict the parameters expected in positive triangularity plasmas, to guide diagnostic development, and to validate transport models. Several reduced turbulence models have been used to predict electron and ion temperatures for the operational phase 2. All models provide similar results from approximately mid-radius to the separatrix but important discrepancies are found in the core region. These positive triangularity results are compared with experiments from a similar size machine like GLOBUS-M2. The multi-mode model (MMM) shows the best agreement. Simulations with different boundary conditions have been performed and no strong differences have been observed between them. The impact of neutral beam injection (NBI) on the predicted profiles has also been addressed. Rotation reduces turbulence levels so higher temperatures are achieved when included in the simulations. Studying the different contributions to the thermal diffusivities, it is observed that electron temperature gradient (ETG) turbulence dominates at the plasma core while micro-tearing modes (MTM) dominate at the edge in the electron channel. In the ion channel, the neoclassical contribution is dominant at the core and at the very edge while the Weiland component, which includes ion temperature gradient mode (ITG), trapped electron mode (TEM), kinetic ballooning mode (KBM), peeling mode (PM) and collisionless and collision dominated magnetohydrodynamic (MHD) modes governs the mid-radius region. For phase 3, two plasmas with different electron densities have been studied. The case with lower density matches well a specific discharge of GLOBUS-M2. The higher density plasma shows high performance with βN ≈ 3.8.
Nuclear double charge exchange reactions by induced isotensor interactions
(Società Italiana di Fisica, 2024-09-20) Lenske, H.; Bellone, J. I.; Colonna, M.; Gambacurta, D.; Lay Valera, José Antonio; NUMEN Collaboration; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear
The theory of heavy ion double charge exchange (DCE) reactions is recapitulated with focus on Double Single Charge Exchange (DSCE) and Majorana DCE (MDCE) reactions. DSCE reactions are of second–order distorted wave (DW) character, mediated by isovector nucleon-nucleon (NN) interactions and matrix elements similar to 2ν2β decay. The MDCE process proceeds by an induced rank-2 isotensor interaction, given by off–shell pion–nucleon scattering, leading to pion potentials similar to the neutrino potentials in 0ν2β decay.
Multichannel approach for the analysis of 1g O
(Società Italiana di Fisica, 2024-09-20) Carbone, D.; Agodi, C.; Bellone, J. I.; Burrello, S.; Cappuzzello, F.; Cavallaro, M.; Lay Valera, José Antonio; Zagatto, V. A. B.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; European Research Council (ERC)
A multichannel approach for the analysis of many different reactions channels induced by the 18O + 40Ca collisions at 275 MeV incident energy is introduced. The reactions are simultaneously measured and analysed consistently within the same reaction and structure frameworks within the NUMEN project. In particular, the elastic and inelastic scattering, one- and two-proton transfer, one-neutron transfer, and single charge exchange reactions are explored. The full quantummechanical calculations, performed by including microscopic nuclear structure inputs, describe well all the experimental data.
Measurements of the thermal and ionization state of the intergalactic medium during the cosmic afternoon
(Oxford University Press, 2024-11-04) Hu, Teng; Khaire, Vikram; Hennawi, Joseph F.; Tripp, Todd M.; Oñorbe Bernis, José; Walther, Michael; Lukic, Zarija; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia y Tecnología (MCYT). España
We perform the first measurement of the thermal and ionization state of the intergalactic medium (IGM) across 0 . 9 < z < 1 . 5 using 301 Ly αabsorption lines fitted from 12 archi v al Hubble Space Telescope Space Telescope Imaging Spectrograph quasar spectra. We employ the machine-learning-based inference method that uses joint Doppler parameter–column density ( b −N H I ) distributions obtained from Ly αforest decomposition. Our results show that the H I photoionization rates, H I , agree with recent ultraviolet background synthesis models, with log ( H I / s −1 ) = −11 . 79 + 0 . 18 −0 . 15 , −11 . 98 + 0 . 09 −0 . 09 , and −12 . 32 + 0 . 10 −0 . 12 at z = 1 . 4, 1.2, and 1, respectively. We obtain the IGM temperature at the mean density, T 0 , and the adiabatic index, γ, as [ log ( T 0 / K ) , γ] = [ 4 . 13 + 0 . 12 −0 . 10 , 1 . 34 + 0 . 10 −0 . 15 ], [ 3 . 79 + 0 . 11 −0 . 11 , 1 . 70 + 0 . 09 −0 . 09 ], and [ 4 . 12 + 0 . 15 −0 . 25 , 1 . 34 + 0 . 21 −0 . 26 ] at z = 1 . 4, 1.2, and 1. Our measurements of T 0 at z = 1 . 4 and 1.2 are consistent with the trend predicted from previous z < 3 temperature measurements and theoretical expectations, where the IGM cools down after He II reionization in the absence of any non-standard heating. Ho we ver, our T 0 measurement at z = 1 shows unexpectedly high IGM temperature. Given the relatively large uncertainty in these measurements, where σT 0 ∼5000 K, mostly emanating from the limited size of our data set, we cannot conclude whether the IGM cools down as expected. Lastly, we generate mock data sets to test the constraining power of future measurement with larger data sets. The results demonstrate that, with redshift path-length z ∼2 for each redshift bin, three times the current data set, we can constrain the T 0 of IGM within 1500 K, which would be sufficient to constrain the IGM thermal history at z < 1 . 5 conclusively.
The Ghent Hybrid model in NuWro: a new neutrino single-pion production model in the GeV regime
(Springer, 2024-12-17) Yan, Quiyu; Niewczas, Kajetan; González Jiménez, Raúl; Jachowicz, Natalie; Lu, Xianguo; Sobczyk, Jan; Zheng, Yangheng; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Neutrino-induced single-pion production constitutes an essential interaction channel in modern neutrino oscillation experiments, with its products building up a significant fraction of the observable hadronic final states. Frameworks of oscillation analyses strongly rely on Monte Carlo neutrino event generators, which provide theoretical predictions of neutrino interactions on nuclear targets. Thus, it is crucial to integrate state-of-the-art single-pion production models with Monte Carlo simulations to prepare for the upcoming systematics-dominated landscape of neutrino measurements. In this work, we present the implementation of the Ghent Hybrid model for neutrino-induced single-pion production in the NuWro Monte Carlo event generator. The interaction dynamics includes coherently-added contributions from nucleon resonances and a non-resonant background, merged into the pythia branching predictions in the deep-inelastic regime, as instrumented by NuWro. This neutrino-nucleon interaction model is fully incorporated into the nuclear framework of the generator, allowing it to account for the influence of both initial- and final-state nuclear medium effects. We compare the predictions of this integrated implementation with recent pion production data from accelerator-based neutrino experiments. The results of the novel model show improved agreement of the generator predictions with the data and point to the significance of the refined treatment of the description of pion-production processes beyond the ∆ region.
Thermal helium beam diagnostic for 2D profile measurements in the divertor of ASDEX Upgrade
(American Institute of Physics, 2024-11-13) Hörmann, S.; Cavedon, M.; Griener, M.; Wendler, D.; Dux, R.; Schmid, K.; Kappatou, A.; Wischmeier, M.; Cruz Zabala, Diego José; Viezzer, Eleonora; Stroth, U.; ASDEX Upgrade Team; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; EUROfusion Consortium
A new thermal helium beam diagnostic has been implemented in the outer lower divertor of the ASDEX Upgrade tokamak. The purpose of this diagnostic is to measure two-dimensional profiles of electron density (ne) and temperature (Te) with high temporal and spatial resolution. The geometry of the lines of sight is chosen to avoid the influence of prompt recycling and to optimize the resolution without significantly impacting the divertor structure. Moreover, the effect of long-term helium recycling has been analyzed, and its amplitude compared to the active signal is negligible. Finally, the reconstruction of ne and Te is done via a collisional radiative model, while a static and a dynamic model were implemented and compared with SOLPS simulations as well as divertor Thomson scattering data. Furthermore, a new 2D parameterization of the outer divertor volume, which is required for the dynamic model, was developed. Due to its fast and local ne and Te profile measurements, the diagnostic is suitable for investigating fast processes such as divertor transitions and f ilaments.
Tuning light emission in Bi and V codoped MgAl2O4 nanostructured films
(Elsevier, 2025-02-24) Gorni, G.; Serna, R.; García López, Francisco Javier; Gonzalo, J.; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Agencia Estatal de Investigación. España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Consejo Superior de Investigaciones Científicas (CSIC); Ministerio de Ciencia e Innovación (MICIN). España; NextGeneration. U. E.
This study investigates the synthesis of novel Bi and V-codoped MgAl2O4 nanostructured thin films for near-white-light emission upon UV excitation. Sequential pulsed laser deposition (PLD) from Bi, V, and MgAl2O4 targets was employed to prepare nanostructured films with different compositions. The films have been thoroughly analyzed using Rutherford backscattering spectrometry (RBS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and photoluminescence spectroscopy (PL). Upon heat treatments at 500 °C and 800 °C, the films exhibit a broad blue emission in Bi-doped films and a broad yellow emission in V-doped films, respectively. We demonstrate that a strategic combination of Bi and V codoping in MgAl2O4 nanostructures results in near-white light emission. This study highlights the ability to finely control the nanostructure and emission properties of thin films using PLD, and the use of abundant and non-toxic elements to produce white light emission, with significant implications for advanced and sustainable photonic applications.
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.

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