NUC-RIA Internal Days 2026

13 Jul 2026, 09:00 → 17 Jul 2026, 11:00 Europe/Lisbon

 

 

 

 

 

Welcome to the 2^nd edition of the NUC-RIA Internal Days! This is a series of 20 minutes talks to share your current research topic with the rest of the members of the group who are not so familiar with it. 

The meeting will take place in hybrid format. The in-person sessions will take place at room 1.4.14 at FCUL. The Zoom connection will be the following:

https://cern.zoom.us/j/65161287340?pwd=R2yvjxcMYKabduvkMSlSNjcuaPXy5E.1

Meeting ID: 651 6128 7340
Passcode: 511237

The call for abstracts is open now! No need to elaborate too much, since all abstracts are by default accepted! However, you can train the fact of submitting a real abstract to a workshop or conference, and eventually use it for a future occasion. 

(Update 10/7/26: call for abstracts is closed!)

Monday 13 July

09:30 → 13:30 NUC-RIA Internal Days

09:30 Manuel Xarepe's Presentation

Speaker: Manuel Xarepe (Faculty of Science of the University of Lisbon)

10:30 Carolina Felgueira's Talk

Speaker: Carolina Felgueiras

11:00 Paula de Dios' Talk

Speaker: Paula De Dios Caro

11:30 Developments towards laser spectroscopy of molecules in a supersonic gas jet at S3-LEB

Radioactive molecules have recently emerged as precision probes for anomalous electromagnetic moments, possibly offering unprecedented sensitivity to parity violation and time reversal symmetry violation [1]. In current experiments at radioactive ion beam facilities, the high temperature of the different molecular degrees of freedom is a crucial limiting factor for sensitive measurements. To reach the required temperatures of a few millikelvins, several cooling techniques are available; however, the gap to bridge from ambient temperature to a few millikelvin is too large.
This challenge can be directly addressed at the SPIRAL2-S3 facility in GANIL. At the Super Separator Spectrometer (S3) focal point, the S3 Low Energy Branch (S3-LEB) is a setup dedicated to the study of radionuclides using laser spectroscopy, decay spectroscopy and mass spectrometry [2]. The key aspect of S3-LEB is the application of the in-gas-jet laser ionization spectroscopy technique [3], which would allow to produce cold molecules within a long and collimated supersonic gas jet, at temperatures of T_trans ~ 13 K [4].
Recently, a R&D offline setup for S3-LEB, called FRIENDS3 (Fast Radioactive Ion Extraction and Neutralization Device for S3), has been conceived, assembled and is currently in its test phase at GANIL [5,6]. The FRIENDS3 setup provides an opportunity for offline development focused on controlled production of cold molecules. Our objectives in this current phase are the implementation of a gas purification system, an efficient ion neutralization mechanism, and stable, long-range laser scans for probing the produced molecules.
In this contribution, the efforts made towards laser spectroscopy of molecules at S3-LEB will be presented. I will contextualize these efforts in the framework of our long-term goals and show the current status of FRIENDS3, which include its recent developments and the required laser setup, as well as our future steps.

[1] G. Arrowsmith-Kron et al., Rep. Prog. Phys. 87 (2024)
[2] A. Ajayakumar et al. Nucl.Instrum.Meth.B 539 102 (2023)
[3] R. Ferrer. et.al., Nat. Commun. 8, 14520 (2017)
[4] W. Dong, PhD thesis, Université Paris-Saclay (2024)
[5] W. Dong et al., arXiv:2601.12009 [physics] (2026)
[6] E. Morin et al., NIM B, 166027 (2026)

Speaker: Afonso Vicente (IJCLab-IN2P3-CNRS)

12:00 Margarida Paulino's Talk

Speaker: Margarida Paulino

Tuesday 14 July

13:00 → 15:30 Manuel Xarepe's PhD Defense

Convener: Manuel Xarepe (Faculty of Science of the University of Lisbon)

Wednesday 15 July

09:00 → 10:30 NUC-RIA Internal Days

09:00 Atomic Data for Elemental Kilonovae Identification

Observations of kilonovae, the electromagnetic counterparts to (binary) neutron star mergers, confirm their role as key sites for $r$-process nucleosynthesis, producing elements heavier than ion in the expanding ejecta following this event. The groundbreaking observation of the 2017’s kilonova (astronomical transient AT2017gfo) associated with the renowned gravitational wave event GW170817 provided robust evidence for the formation of lanthanides and, potentially, actinides. This conclusion was drawn from the temporal evolution of the kilonova’s luminosity curve across the ultraviolet, visible, and infrared regions of the electromagnetic spectrum. It marked the first observational confirmation that elements are there being synthesized through the rapid neutron-capture process ($r$-process), a mechanism proposed several decades ago. However, identifying specific features, which can be attributed to the absorption and emission lines of individual elements produced in the ejecta, in the luminosity curve remains a significant challenge, mainly due to the lack of atomic data for heavy atoms/ions.

The main difficulties in analyzing kilonova spectra are the severe lack of both atomic data for lanthanides and actinides, as well as collisional atomic data required to model the late stages ($>4$ days post-NSM) of the expanding ejecta. While it is reasonable to assume local thermodynamic equilibrium (LTE) and that atomic absorption processes dominate during the early epochs ($<1$ day after the merger), this assumption breaks down during the nebular phase (non-LTE). At these late stages, relevant physical processes include collisional processes such as electron-impact excitation and radiative recombination – all of which suffer from a scarcity of accurate atomic data.

To address this challenge, we have calculated key atomic parameters for lanthanides and actinides: for the former, atomic structure and recombination processes will be the main focus; for the latter, only atomic structure will be shown.

Speaker: Tomás Campante (Deparment of Physics, Faculty of Sciences of the University of Lisbon (FCUL). Laboratory of Instrumentation and Experimental Particle Physics (LIP).)

NUC-RIA_InternalDays2026_TCampante.pptx.pdf

09:30 Resonant Excitation Contributions to Electron-Impact Collision Strengths for r-Process Ions: Implications for Non-LTE Kilonova Modelling

Comprehensive datasets of electron-impact excitation (EIE) collision strengths for near-neutral lanthanides and other r-process elements remain notably incomplete, despite their central role in setting the level populations of neutron-star merger ejecta during the late phase (non local thermodynamic equilibrium, more commonly known as non-LTE, regime), of kilonova emission [1, 2]. A long-recognised difficulty in this context is the treatment of resonant excitation (RE), the indirect channel in which electron capture populates an intermediate autoionising state that subsequently stabilises radiatively onto a bound excited level. At the nebular electron temperatures characteristic in kilonovae (2000 to 5000 K), the density of low-lying autoionising resonances in complex open-shell ions is such that RE can exceed the direct distorted-wave (DW) contribution over a broad range of transitions and temperatures [3, 4]. The computational expense of accounting for these channels, together with the structural complexity of open-f-shell systems, has nevertheless driven their usual omission from astrophysical applications.

In this work we report systematic calculations of EIE collision strengths for a large set of singly and doubly ionised lanthanides and other astrophysically important r-process ions, performed within the fully relativistic distorted-wave method implemented in the Flexible Atomic Code (FAC) [5]. Resonant contributions are incorporated through the Independent Process, Isolated Resonance Distorted-Wave (IPIRDW) approximation [6], with atomic structures constructed from tailored central potentials [7] and calibrated level energies [8]. Where recent R-Matrix results are available, we find that including RE systematically reduces the discrepancy between the DW and close-coupling effective collision strengths across the full temperature range of astrophysical interest [9].

The resulting datasets quantify, across a broad range of r-process ions, the magnitude of the resonant contribution that has been absent from virtually all non-LTE kilonova modelling to date. These data are ready for direct use in radiative transfer simulations of both lanthanide-rich ejecta and second r-process peak emission features in late-time kilonova spectra.

References

[1] Pognan et al. MNRAS 510, 3806 (2022)
[2] Gillanders et al. MNRAS 529, 2918 (2024)
[3] McCann et al. MNRAS 538, 537 (2025)
[4] Mulholland et al. JQSRT 345, 109545 (2025)
[5] Gu, Can. J. Phys. 86, 675 (2008)
[6] Li et al. Chin. Phys. B 24, 113401 (2015)
[7] Ferreira da Silva et al. Phys. Rev. A 112, 012802 (2025)

Speaker: Ricardo Ferreira da Silva (LIP)

10:00 Unveiling the Mysteries of p-Nuclei: A Comprehensive Study of Nuclear Physics Uncertainties in Supernovae

The astrophysical origin of the heavy neutron-deficient isotopes, commonly referred to as p-nuclei, remains one of the major open problems in Nuclear Astrophysics. Among the proposed production sites, Core-Collapse Supernovae (CCSNe) are considered one of the most promising environments for their nucleosynthesis. In this presentation, I will discuss the current results of my PhD research, based on the analysis of a CCSN explosion model of a 20 M⊙ star with solar metallicity. I will highlight the ejecta trajectories that play the most significant role in p-nuclei production and examine the influence of radioactive isotopes and their decay chains on the resulting abundance patterns.

Speaker: João Jantarada (Nuc-Ria)

10:30 → 11:00 Coffee Break

11:00 → 12:00 NUC-RIA Internal Days

11:00 Francisca Afonso's Talk

Speaker: Francisca Afonso (LIP)

NUCRIAdays.pptx

11:30 Pixel-based Target Recoil Tracker (TRT) for R$^{\text{3}}$B at FAIR

The upgraded setup for the R3B experiments at FAIR introduces a pixel-based Target Recoil Tracker (TRT) detector, designed to enhance the detection capabilities of light-charged particles, such as protons, emitted in nuclear reactions. The TRT surrounds the reaction
target and is further enclosed within a highly segmented calorimeter, named CALIFA, focusing on precise angle measurements of these particles . This innovative detector utilizes the fully developed ALPIDE Monolithic Active Pixel Sensor (ALPIDE MAPS) technology, originally designed for ALICE/CERN experiments. With the TRT the full kinematics of the recoil and scattered particles can be measured and the missing-mass and missing momentum spectra can be reconstructed on an event-by-event basis, enabling a modelindependent extraction of the complete spectral function. Such measurement will provide unprecedented insight into short-range correlations, single-particle strength quenching, and the underlying nuclear dynamics that drive both electron and hadron induced knockoutreactions.
The TRT consists of a barrel-shaped detector array with large angular coverage and an optimized material budget. A future stage of this detector envisions integrating nextgeneration sensors using large, ultra-thin silicon wafers bent and arranged in perfectly cylindrical layers.
In this contribution, we report on the latest performance studies of the final barrel design.
Using R3BRoot (Geant4) simulations, we evaluate its detection efficiency and spatial resolution, and we describe the assembly and characterization procedures for the individual modules. Finally, we will present the results from the last year experimental campaigns at GSI using ALPIDEs in beam, demonstrating the excellent performance of the TRT.

Speaker: Beatriz Amorim (University of York)

12:00 → 14:00 Lunch Break

14:00 → 16:00 NUC-RIA Internal Days

14:00 Filipa and Duarte's Talk

Speakers: Duarte Casquilho, Filipa Quadrilheiro

14:30 Heavy baryon spectroscopy with a quark-diquark approach

Simplifying the three-body equations that describe baryons in low-energy non-perturbative QCD into two-body equations, introducing the diquark, quark-quark bound states, as baryon constituents. From these, baryon mass calculations, partial wave decompositions and diquark contributions to the baryon states can be done.

Speaker: André Torcato (LIP)

15:00 José Graça's Talk

Speaker: José Graça