Artículos (Centro Nacional de Aceleradores)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10939

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Radiation damage study of three-dimensional cylindrical silicon microdosimeters
(Elsevier, 2026-12) Torres Muñoz, Carmen; Jiménez Ramos, María del Carmen; García López, Francisco Javier; García Osuna, Adrián; Fleta, C.; Gómez, Faustino; Guardiola, Consuelo; Física Atómica, Molecular y Nuclear; Física Aplicada II; European Union (UE); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía; Fundación la Caixa
A novel silicon microdosimeter with a 3D cylindrical ‘‘dartboard’’ geometry has been developed at the National Center of Microelectronics (IMB-CNM) in Barcelona, Spain. The detector features concentric 3D electrodes etched into a 20 μm-thick sensitive silicon volume. Its performance has been characterized using the ion beam-induced charge (IBIC) technique, and its radiation hardness has been investigated in view of potential applications in proton therapy. The central region was irradiated with 1.17 MeV protons up to a cumulative fluence of 1.7×1012 cm−2, with a bias voltage of 5 V. Spatially resolved charge collection efficiency (CCE) maps and pulse height spectra were analyzed as a function of the accumulated fluence. No significant degradation was observed for fluences below 6×1010 cm−2. At higher fluences, however, progressive CCE reduction occurs, accompanied by peak broadening, spectral redistribution towards lower pulse height and contraction of the effective high-efficiency sensor region. This degradation is more pronounced at the periphery of the sensitive volume, which is consistent with the radial electric field distribution inherent to the 3D geometry.
Enhancing charge collection efficiency in radiation-damaged unmetallized 4H-SiC detectors via sub-bandgap LED illumination
(Elsevier, 2026-08-04) Rodríguez Ramos, Mauricio; Torres Muñoz, Carmen; Jiménez Ramos, María del Carmen; Baachouch, Chaimae; Pellegrini, Giulio; Rafí, Joan Marc; Rius, Gemma; García López, Javier; Física Atómica, Molecular y Nuclear; Física Aplicada II; Centro Nacional de Aceleradores (CNA); European Union (UE); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía; Universidad de Sevilla
A new generation of 4H-SiC radiation detectors has demonstrated stable spectroscopic performance at temperatures up to 450°C, making this material a strong candidate for suprathermal alpha particle diagnostics in fusion environments such as ITER and DEMO. However, ion irradiation introduces defect-related trapping centers, including deep levels and defect clusters, which degrade charge transport and reduce charge collection efficiency, ultimately limiting detector performance under extreme conditions. This work investigates recovery mechanisms in an unmetallized 4H-SiC p-n junction detector irradiated with 3.5 MeV He++ ions at fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2 and irradiation temperatures between room temperature and 400°C, allowing assessment of damage evolution under different thermal conditions. The detector response was characterized by using ion beam induced charge at room temperature under controlled blue LED illumination at different intensities, enabling systematic evaluation of light-induced effects on charge transport. Results show that optical excitation induces a light-assisted increase in CCE, partially restoring spectroscopic response in heavily damaged regions, with the strongest effect observed at higher trap densities and increasing monotonically with illumination intensity. Comparison with a charge collection model provides additional insight into carrier dynamics in the presence of deep trapping centers, consistent with defects characterized by large capture cross sections and long carrier detrapping times. Overall, light-assisted trapping mitigation emerges as an effective mechanism to enhance detector stability and operational lifetime in harsh fusion-relevant environments. In parallel, dynamic annealing contributes to damage mitigation by reducing defect formation during irradiation rather than repairing pre-existing defects.
Radiobiology studies of gold nanoparticle-enhanced radiosensitization in proton therapy
(Wiley, 2026-08) Fuster Martínez, Nuria; Saucedo Cuberes, Demetrio Hermenegildo; Jiménez Ramos, María del Carmen; Esperante Pereira, Daniel; Espino Navas, José Manuel; González López, Lucía; Huertas Sánchez, Pablo; Jimeno González, Sonia; Suárez García, Daniel; García Murria, María Jesús; Física Aplicada II; Física Atómica, Molecular y Nuclear; Genética; Centro Nacional de Aceleradores (CNA); Centro Andaluz de Investigaciones en Biología Molecular y Medicina Regenerativa (CABIMER); Generalitat Valenciana; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Fundación Científica Asociación Española Contra el Cáncer; RNM138: Física Nuclear Aplicada; FQM160: Física Nuclear Básica; BIO026: Metabolismo del DNA
Background: Approximately 50% of newly diagnosed cancer patients worldwide receive radiotherapy, most commonly with X-rays. Proton therapy has emerged as a promising alternative, offering complementary advantages over conventional X-rays due to its highly localized energy deposition at the Bragg peak, thereby reducing radiation exposure to surrounding healthy tissues. In recent years, advances in both technology and biomedicine have driven significant progress in proton therapy, with ongoing research aiming to minimize toxicity and long-term side effects while improving patients’ quality of life. An emerging research direction investigates the combination of proton therapy with irradiated nanoparticles acting as radiosensitizers. This approach seeks synergistic effects that could further improve therapeutic outcomes. These effects arise from a complex interplay of physical,chemical,and biological mechanisms. Although previous in vitro and in vivo studies report promising radiosensitization effects of nanoparticles, the literature also includes contradictory results, and the underlying mechanisms remain under debate. This highlighting the need for systematic studies under well-controlled irradiation conditions of different nanoparticles and beam parameters, which are often difficult to perform due to the limited availability of particle accelerators and facilities suitably adapted for such experiments. Purpose: This work investigates the radiosensitizing effect of gold anoparticles under proton irradiation and optimizes the irradiation setup to enable more efficient and reproducible future experiments. Methods: HeLa cells were used as the biological model for the radiobiological experiments. Irradiation conditions were optimized by incorporating a Mylar film into the culture plates to maintain a minimal medium volume and ensure rapid post-irradiation coverage. Cells with and without AuNPs were irradiated with 12.6 MeV proton beams. Radiosensitivity was assessed using clonogenic survival assays, and the radiosensitizing effect, together with its associated uncertainty, was quantified. DNA damage analysis was also performed to corroborate the observed effects and explore underlying mechanisms. Results: The radiobiology experiments confirmed and quantified a significant radiosensitizing effect of gold nanoparticles (AuNPs) on HeLa cells at doses from 4 Gy, with Sensitization Enhancement Ratio (SER) values of 1.53 ± 0.07 in 2022 and 1.30 ± 0.20 in 2023 using 50 nm diameter AuNPs. Experiments in 2023 with 20 nm diameter AuNPs yielded a comparable SER of 1.38 ± 0.18, indicating no significant size-dependent differences. The radiosensitizing effect exhibited dose-dependent amplification, with higher doses producing greater cell killing.Linear-Quadratic (LQ) model fits showed an increased 𝛼 parameter in the presence of AuNPs, consistent with an increase in non-repairable damage. This trend was further supported by double-strand break assays. Furthermore, oxidative stress assays showed that AuNPs do not increase basal ROS levels, but enhance ROS production under oxidative stress conditions. Conclusion: The radiobiology experiments presented quantitatively confirm that both 20 and 50 nm diameter AuNPs enhance the radiosensitivity of HeLa cells under proton irradiation. The radiosensitizing effect increases with dose, indicating a dose-dependent response, while no significant differences were observed between nanoparticle sizes. Consistent trends of increased DNA double-strand breaks further support the observed radiosensitization. Evidence from oxidative stress assays suggests that AuNPs may enhance ROS production under oxidative conditions, potentially contributing to the observed radiosensitization and DNA damage.
Advancing ³⁶Cl measurement capabilities: Performance limits of the 1 MV AMS system at Centro Nacional de Aceleradores (CNA, Seville, Spain)
(Elsevier, 2026-09) Sánchez Jiménez, D.; Chamizo, Elena; López Gutiérrez, José María; Centro Nacional de Aceleradores (CNA); Física Aplicada I; European Union (UE). H2020; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC); RNM138: Física Nuclear Aplicada
The detection limit for ³⁶Cl (T1/2 = 0.301 My) using mass spectrometry techniques is primarily constrained by the system’s ability to discriminate between ³⁶Cl and its stable isobar ³⁶S. Conventional accelerator mass spectrometry (AMS) systems typically operating at terminal voltages of 3 MV and above, achieve background levels for the isotopic ratio of ³⁶Cl/³⁵Cl on the order of 10⁻¹⁵ using techniques based on the stopping power difference. However, compact AMS systems are limited in their ability to discriminate heavy isobars due to their lower operating terminal voltages (i.e., 1 MV and below). Driven by the need to study ³⁶Cl in low- and intermediate-level nuclear waste (LILW), for which ³⁶Cl/³⁵Cl atom ratios on the order of 10⁻⁹ represent the detection limit of radiometric techniques, the performance of the 1 MV AMS system for the analysis of ³⁶Cl at the Centro Nacional de Aceleradores (CNA, Seville, Spain) was investigated in this work. Two strategies were adopted: (i) optimisation of radiochemistry and control of the ³⁶S signal using ³³S as a proxy, and (ii) exploitation of the partial overlap between the ³⁶Cl and ³⁶S signals in a ΔE–Eres gas detector. These approaches yielded background levels of approximately 10⁻⁹ and 10⁻¹⁰, respectively. To enable these experiments, the stripping process of chlorine in helium gas at terminal voltages below 1 MV was investigated. Results from standard samples and blanks are presented in this paper.
Status of low-energy AMS detection of Iodine-129 at the Centro Nacional de Aceleradores: performance and background correction
(Elsevier, 2026-08) Lérida Toro, Victoria; López Gutiérrez, José María; Centro Nacional de Aceleradores (CNA); Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE); RNM138: Física Nuclear Aplicada
¹²⁹I is a long–lived radionuclide of environmental and nuclear relevance. At the CNA, its detection via Accelerator Mass Spectrometry (AMS) is routinely performed using the 1 MV SARA system. Recent upgrades—such as the introduction of helium as stripper gas and the selection of the 2+ charge state—have increased the transmission efficiency to more than 40% at 0.7 MV. This work presents a comprehensive analysis of background sources affecting ¹²⁹I²+ detection, including molecular interferences, high-energy tails of ¹²⁷I, and ion source cross-contamination. We introduce a two-step correction protocol: (1) subtraction of a fixed ¹²⁹I count rate to account for persistent contamination, and (2) subtraction of the average corrected blank ratio. This method effectively removes current-dependent effects, particularly in low-level samples. We analysed the influence of mixing AgI with Nb and observed only a minor impact on background levels. The optimal AgI:Nb mixing ratio was found to be between 1:1 and 1:2. Validation with real samples confirms improved accuracy and reliability in ultra–trace ¹²⁹I analysis. These findings strengthen the capabilities of the SARA facility for applications in oceanography, radioecology, and nuclear forensics.
Modeling the heliospheric modulation of cosmic rays in light of new data from AMS-02 in space
(Sissa Medialab, 2025-12-30) Pelosi, David; Barão, Fernando; Bertucci, Bruna; Faldi, Francesco; Fiandrini, Emanuele; Orcinha, Miguel; Reina Conde, Alejandro; Tomassetti, Nicola; Venterea, Ricco C.; Física Atómica, Molecular y Nuclear; Italian Ministry of University and Research; Fundação para a Ciência e a Tecnologia (FCT). Portugal
Understanding the heliospheric modulation of galactic cosmic rays is essential for studying the acceleration and propagation processes of these particles, as well as for establishing models of radiation exposure and associated risks in space missions. In this work, we build upon a previously developed long-term GCR forecasting tool and present our efforts to improve it by incorporating additional datasets and refined modeling details. The model is based on a numerical description of the transport mechanisms of charged particles in heliospheric turbulence and their relation to solar activity. In particular, we extend the cosmic-ray dataset to include monthly carbon fluxes from the ACE mission, time-resolved PAMELA proton flux and the latest high-precision AMS- 02 nuclei measurements, relating them to solar activity proxies. Utilizing multi-channel fitting provides new opportunities to investigate correlations between cosmic-ray fluxes and solar proxies across different solar cycle phases, and point toward possible advances in long-term forecasting capabilities.
Measurement of the 33S(n,α)30Si Thermal Cross-Section with Slow Neutrons at ILL
(MDPI, 2025-09-22) Praena, Javier; Fernández Martínez, Begoña; Macías, Miguel; Porras, Ignacio; Pedrosa Rivera, María; Koivunoro, Hanna; Sabaté Gilarte, Marta; Arias de Saavedra, Fernando; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; Asociación Española Contra el Cáncer (AECC); Junta de Andalucía
This work is focused on an accurate experimental determination of the thermal 33S(n,α)30Si cross-section. This cross-section is a critical parameter for the potential use of 33S as a cooperative target in boron neutron capture therapy or to understand its role in the stellar nucleosynthesis of 36S. At present, there are large discrepancies in this experimental value; therefore, in this work we measured it relative to the 10B(n,α)7Li standard cross-section at the high flux reactor of the Institut Laue-Langevin. The experimental setup was based on a double-sided silicon strip detector. Two 33S samples were used. One 10B sample was used as reference. Particular attention was taken to the characterization of the mass thickness of the samples before and after the experiment because of the high volatility of 33S. Such work was already published in a dedicated paper. A cross-check of the 10B sample was carried out with the neutron flux monitor at the n_TOF-CERN facility. The obtained cross-section of (280 ± 33) mb is significantly higher than the existing data.
New data for the definition of neutron beams for Boron Neutron capture therapy
(Elsevier, 2021-08) Macías Martínez, Miguel; Fernández Martínez, Begoña; Praena, J.; Física Atómica, Molecular y Nuclear; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía; Asociación Española contra el Cárcer (AECC)
Boron Neutron Capture Therapy (BNCT) is neutron radiotherapy used to treat tumours cells previously doped with Boron-10. This therapy requires an epithermal neutron beam for the treatment of deep tumours and a thermal beam for shallow ones. Thanks to recent high-current commercial accelerators, Accelerator-Based Neutron Sources (ABNS) are a competitive option for providing therapeutic neutron beams in hospitals. In this work, the neutron field generated by the 7Li (p,n)7Be reaction at 1950 keV is studied as a neutron source in ABNS, being measured by the Time-Of-Flight (TOF) technique at HiSPANoS facility (Spain). Moreover, two Beam Shaping Assemblies (BSA) for deep and shallow tumour treatment, which are specially designed for the 1950 keV neutron field, are evaluated for BNCT via Monte Carlo simulations (MCNP). Results in agreement with the International Atomic Energy Agency (IAEA) figures of merit endorse the use of this neutron field for BNCT.
The first neutron time-of-flight line in Spain: Commissioning and new data for the definition of a neutron standard field
(Elsevier, 2020-03) Macías Martínez, Miguel; Fernández Martínez, Begoña; Praena, Javier; Física Atómica, Molecular y Nuclear; Ministerio de Economía y Competitividad (MINECO). España; Asociación Española contra el Cáncer (AECC); Junta de Andalucía
The National Accelerator Laboratory (CNA) has developed the first accelerator line in Spain devoted to the measurement of cross sections involving neutrons by means of the time-of-flight technique. For neutron generation, pulsed proton beams with 1 nsec pulse width and with variable repetition rates are delivered. The data acquisition has been built using a CAEN Digitizer. The aim of this work is to demonstrate the good performance of the time-of-flight system. The commissioning of the line has consisted of the measurement of the neutron field generated by protons at 1912 keV impinging on a thick lithium target. Such a field has been extensively used in nuclear astrophysics since 1988. Recently, there have been experimental works with the goal to support it as a standard neutron field. The results show the good performance of the time-of-flight system and also support its possible definition as a standard.
Soft error rate comparison of 6T and 8T SRAM ICs using mono-energetic proton and neutron irradiation sources
(Elsevier, 2017-11) Malagón, D.; Bota, S. A.; Torrens, G.; Praena, J.; Fernández Martínez, Begoña; Macías Martínez, Miguel; Quesada Molina, José Manuel; Guerrero Sánchez, Carlos; Jiménez Ramos, María del Carmen; García López, Francisco Javier; Merino, J. L.; Segura, J.; Física Atómica, Molecular y Nuclear; Física Aplicada II; Ministerio de Economía y Competitividad (MINECO). España
We present experimental results of soft errors produced by proton and neutron irradiation of minimum-size six-transistors (6T) and eight-transistors (8T) bit-cells SRAM memories produced with 65 nm CMOS technology using an 18 MeV proton beam and a neutron beam of 4.3–8.5 MeV. All experiments have been carried out at the National Center of Accelerators (CNA) in Seville, Spain. Similar soft error rate levels have been observed for both cell designs despite the larger area occupied by the 8T cells, although the trend for multiple events has been higher in 6T.
Trace americium contamination sources in the environment can be detected using 243Am/241Am
(Springer Nature, 2026) Chamizo, Elena; López Lora, Mercedes; López Fuentes, Antonio Jesús; Física Atómica, Molecular y Nuclear; Física Aplicada II; Centro Nacional de Aceleradores (CNA); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España
Despite the widespread presence of americium in the environment since the 1950s from nuclear activities, the use of americium isotopic composition to trace contamination sources has not been investigated. Here we report the detection of 243 Am in environmental samples and demonstrate that the ratio of 243 Am to 241 Am can serve as a distinctive fingerprint of radioactive emissions, with characteristic values of 0.05 for thermonuclear explosions, 0.023 for global fallout, below 0.0015 for low-yield nuclear tests, and 0.0013 for releases from a nuclear reprocessing facility. In nuclear detonations, 243 Am is produced as the decay product of 243 Pu. The ratio of 243 Am to 239 Pu in global fallout is about 3.2 × 10⁻⁴, supporting the predicted formation of neutron-rich heavy plutonium isotopes during nuclear detonations.
Calibration and Performance Tests of Detectors for Laser-Accelerated Protons
(Institute of Electrical and Electronics Engineers (IEEE), 2015-11-09) Seimetz, M.; Bellido, P.; Soriano, A.; García López, Francisco Javier; Jiménez Ramos, María del Carmen; Fernández Martínez, Begoña; Conde, P.; Crespo, E.; González, A. J.; Benlloch, J. M.; Física Atómica, Molecular y Nuclear; Física Aplicada II; Ministerio de Economía y Competitividad (MINECO). España; Agencia Estatal de Investigación. España; Generalitat Valenciana
We present the calibration and performance tests carried out with two detectors for intense proton pulses accelerated by lasers. Most of the procedures were realized with proton beams of 0.46-5.60 MeV from a tandem accelerator. One approach made use of radiochromic films, for which we calibrated the relation between optical density and energy deposition over more than three orders of magnitude. The validity of these results and of our analysis algorithms has been confirmed by controlled irradiation of film stacks and reconstruction of the total beam charge for strongly non-uniform beam profiles. For the spectral analysis of protons from repeated laser shots, we have designed an online monitor based on a plastic scintillator. The resulting signal from a photomultiplier directly measured on a fast oscilloscope is especially useful for time-of-flight applications. Variable optical filters allow for suppression of saturation and an extension of the dynamic range. With pulsed proton beams we have tested the detector response to a wide range of beam intensities from single particles to 3 ×105 protons per 100 ns time interval.
Structure and Nonlinear Optical Properties of TeO2–WO3–PbO Thin Film Glasses
(Elsevier, 2025) Gorni, G.; Muñoz Martín, D.; Ruiz de la Cruz, A.; Martin Diaconescu, V.; Simonelli, L.; García López, Francisco Javier; Fernández Navarro, J. M.; Solís, J.; Gonzalo, J.; Física Atómica, Molecular y Nuclear; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Consejo Superior de Investigaciones Científicas (CSIC); Ministerio de Ciencia e Innovación (MICIN). España
Lead tungsten tellurite thin film glasses have been produced by pulsed laser deposition in a broad TeO2 compositional range (50–85 mol%). Films present high transparency with an optical band gap Eg =3.3–3.4 eV, large refractive index (n >2) and reduced absorption (k <10 4) in the visible and near infrared ranges, whereas their nonlinear optical response (∣χ(3)∣) is found to be ≥10 12 esu at 1.3 μm. The dependence of n, Eg and ∣χ(3)∣ with film composition is analyzed and compared with the values determined for the parent bulk glasses. ∣χ(3)∣ increases as the TeO2 content in the film glasses decreases, while it remains constant for bulk glasses. This behaviour is analyzed in the frame of Line’s model and correlated to the structural differences between bulk and film glasses. In the case of bulk glasses, X-ray absorption spectroscopy results at the W L3 and L1-edges clearly indicate the presence of W6+ions in a distorted octahedral coordination, with the coordination environment and W–O bond distance remaining unchanged regardless of the WO3 content. Raman analysis suggests that films have a structure close to that of bulk glasses, with a moderate WO3 and PbO enrichment, and a relative increase of the non-bridging oxygen fraction that are proposed to be responsible for the observed increase of ∣χ(3)∣ in the films.
Microstructure and composition evolution of He Charged solid-gas Nanocomposite Films of Different Matrix Elements During Thermal Annealing in Vacuum
(Nature Publishing Group, 2025) Fernández, Asunción; Jiménez de Haro, María del Carmen; Hufschmidt, Dirk; Montes, Olga; Sauvage, Thierry; Ferrer Fernández, Francisco Javier; Caillard, Amaël; Brault, Pascal; Thomann, Anne Lise; Física Atómica, Molecular y Nuclear
Sputtering of cobalt, silicon and zirconium in a helium magnetron discharge (MS) is reported as a bottom-up procedure to obtain He-charged films (i.e. 4He and 3He filled nanopores encapsulated in the matrix material). Composition and microstructural analyses are presented from ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). Helium desorption was investigated by IBA in a dedicated chamber for “in situ” thermal evolution in vacuum. The simultaneous recording of the helium and matrix-element signals shows different behaviors of the different matrix elements (i.e. Co, Si and Zr) and deposition conditions (i.e., DC or RF discharge modes and dynamic or quasistatic vacuum). Effusion, blistering, delamination and flaking have been observed for the different samples leading to the formation of nano-porous/nanostructured thin films. The methodology is being envisaged as a process for nanostructured thin-films fabrication with potential applications.
The Lyon Mint in the Roman Tomares Hoard (Seville): Some Considerations on Its Metallic Composition Determined by XRF
(Willey, 2025-06-15) Pliego Vázquez, Ruth; Gómez-Tubio, Blanca María; Alcaide Ramírez, María; Scrivano, Simona; Respaldiza Galisteo, Miguel Ángel; Física Atómica, Molecular y Nuclear; Prehistoria y Arqueología; Física Aplicada III; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla
COSMONAUT: A COmpact Spectrometer for Measurements of Neutrons at the ASDEX Upgrade Tokamak
(American Institute of Physics, 2024) Nocente, M.; Molin, A. D.; D Rigamonti, D.; Rosa, M. D.; Fernández Martínez, Begoña; Fugazza, S.; Guerrero Sánchez, Carlos; Gorini, G.; Kazakov, Y. O.; Tardini, G.; Tardocchi, M.; ASDEX Upgrade Team; Eurofus Tokamak Exploitat Team; Física Atómica, Molecular y Nuclear; European Union (UE); European Union (UE). H2020
A COmpact Spectrometer for Measurements Of Neutrons at the ASDEX Upgrade Tokamak (COSMONAUT) has been developed for spectroscopy measurements of the 2.45 MeV neutron emission from deuterium plasmas at the ASDEX Upgrade. The instrument is based on a CLYC-7 inorganic scintillator, whereby the detection of fusion neutrons occurs via their interaction with 35Cl nuclei in the detector crystal, leading to a peak in the detector response function and providing excellent neutron/gamma-ray discrimination capabilities. The diagnostics is installed along a radial line of sight and makes use of a digital system to record time resolved data for the whole duration of the discharge. Measurements in ASDEX Upgrade plasmas with neutral beam injection have been carried out and are successfully interpreted using state-of-the-art modeling codes. Next step applications of the diagnostics are in experiments aimed at generating energetic particles by ion cyclotron resonance heating schemes. In these scenarios, COSMONAUT will provide unique information on the acceleration of deuterons beyond the beam injection energy and on their confinement, for comparison with modeling.
Experimental study of 6He Coulomb breakup as an indirect measurement of 4He(2n,γ)6He reaction rate for the astrophysical r-process
(EDP Sciences, 2024-10-08) Godos, D.; Acosta, L.; Fernández García, Juan Pablo; O'Malley, P.; Sánchez Benítez, A. M.; Casal Berbel, Jesús; Gómez Camacho, Joaquín José; Arias Carrasco, José Miguel; Rodríguez Gallardo, Manuela; von Seeger, W.; Física Atómica, Molecular y Nuclear; National Science Foundation (NSF). United States; Universidad Autónoma de México (UNAM); Consejo Nacional de Ciencia y Tecnología (CONACYT). México
In this work, we report the measurement of elastic and Coulomb break-up channels in 6He+208Pb collisions at Elab = 19.3 MeV, close to the Coulomb barrier of this system ∼ 19 MeV. In the context of the astrophysical r-process, the reaction 4He(2n,γ)6He has been proposed to be a key reaction in the path of synthesizing seed nuclei for the r-process, as 12C, in an environment composed mainly of alpha particles and neutrons. Based on a theoretical approach for treating three body reactions by means of which its reaction rate can be inferred, our experimental approach aims to obtain an indirect measurement of the reaction rate of 4He(2n,γ)6He by measuring the Coulomb breakup of 6He under the intense electric field produced by a 208Pb target nucleus. The experiment was carried out at the TriSol facility operated in the Nuclear Science Laboratory of the University of Notre Dame, USA, which delivered a 6He beam together with other contaminants. Particular care must be taken for the alpha particles produced in the production reaction.
Tuning the Er3+ Sensitization by Si Nanoparticles in Nanostructured as-grown Al2 O3 Films
(American Institute of Physics, 2009) Núez Sánchez, S.; Serna, R.; García López, Francisco Javier; Petford Long, A. K.; Tanase, M.; Kabius, B.; Física Atómica, Molecular y Nuclear; Comisión Interministerial de Ciencia y Tecnología (CICYT). España; European Union (UE); Electron Microscopy Center. Chicago
Nanostructured films consisting of single Si nanoparticles (NPs) and Er3+ ions layers separated by nanometer-scale Al2 O 3 layers of controlled thickness have been prepared in order to tune the energy transfer between Si NPs and Er3+ ions. The amorphous Si NPs with an effective diameter of ∼4.5 nm are formed during growth and are able to sensitize the Er3+ ions efficiently with no postannealing treatments. The characteristic distance for energy transfer from Si NPs to Er3+ ions in Al2 O3 is found to be in the 1 nm range. It is shown that in the nanostructured films, it is possible to achieve an optimized configuration in which almost all the Er3+ ions have the potential to be excited by the Si NPs. This result stresses the importance of controlling the dopant distribution at the nanoscale to achieve improved device performance.
Modular Apparatus for Nuclear Reactions Spectroscopy (MARS): Characterization and First Application to Determine 12C(6Li,4He)14Ng.s Nuclear Reaction Cross Sections
(Springer, 2025) Garrido Gómez, Laura; Vegas Díaz, Alejandro; González Álvarez, Marcos Aurelio; Fernández García, Juan Pablo; Fernández Martínez, Begoña; Ferrer Fernández, Francisco Javier; Lopez Aires, D.; Física Atómica, Molecular y Nuclear; Gobierno de España; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; National Science Foundation (NSF). United States
This work presents MARS (Modular apparatus for nuclear reactions spectroscopy) and its characterization prior to its first application to measure 6Li+12C nuclear reactions. Measurements were performed at the 3 MV tandem accelerator of the CNA (National Accelerator Center), in Seville, Spain. The 6Li projectiles were accelerated at energies around the 6Li+12C Coulomb barrier (Vcm B ∼ 3.0 MeV - center of mass and V lab B ∼ 4.5 MeV - laboratory frame). Using a 6Li2+ beam, we measured at 13 laboratory energies from 4.00 to 7.75 MeV. Thus, we present the excitation function of 12C(6Li,4He)14Ng.s. reaction, at 2 backward angles (110.0◦ and 140.0◦). The projectile dissociation, leading to this reaction, increases with the bombarding energies around the Coulomb barrier. This dissociation is favored at an optimum energy Eop b ≥ VB + |Qbu|, where VB is the Coulomb barrier of the system, and |Qbu| is the module of Q-value for the 6Li dissociation into 4He+2H. This result corroborates a systematic analysis of weakly bound projectiles reacting on several targets
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; 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.

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