Colloque GANIL 2026

21 sept. 2026, 08:30 → 25 sept. 2026, 15:25 Europe/Paris

Laurent Gaudefroy (CEA-France), Marek Lewitowicz (GANIL)

The next GANIL Colloque will be held in France, in Vosges Moutain. It is co-organized by CEA Saclay and GANIL.

 

Sessions will start on Monday morning, September 21^st and end at lunch on Friday, September, 25^th.

 

The purpose of the conference is to review and discuss the research carried out at GANIL, and related activities at other facilities around the world. Traditionally the Colloque covers the following topics:

• Shell evolution
• Nuclei at the drip-line
• Collective modes
• Fission
• Heavy ion Collisions
• Equation of state of nuclear matter
• Heavy and Superheavy nuclei
• Present & Future GANIL Facilities (physics@S3; physics@NFS; physics@DESIR)
• Fundamental Interactions
• Interdisciplinary Research
• Application
• Astrophysics
• Facilities and associated instrumentation

1st circular_colloque.pdf

2nd_circular_colloque GANIL 2026.pdf

PhD Award 2026.docx

lun. 21 septembre

08:30 → 09:15 Introduction

09:15 → 10:45 FISSION

Président de session: Dr Antoine Lemasson (GANIL / CNRS)

09:15 Invited talk

Orateur: MANUEL CAAMAÑO FRESCO (Universidade de Santiago de Compostela)

09:40 Invited talk

Orateur: Dr Pierre Morfouace (CEA, DAM, DIF)

10:05 PISTA@VAMOS: Upgrade of the Fission Program in Inverse Kinematics at GANIL

PISTA@VAMOS: Upgrade of the Fission Program in Inverse
Kinematics at GANIL

D. Ramos 1 , A. Lemasson 1 , M.Rejmund 1 , P. Morfouace 2 , J. Taieb 2 , e849 collaboration, and e850 collaboration

1 GANIL,CEA/DRF-CNRS/IN2P3, Caen, France
2 CEA,DAM, DIF, Arpajon, France

The fission process has intrigued physicist for a long time from both, experimental and theoretical approaches. From a qualitative point of view, it is well known that nuclear structure dominates the production of fission fragments at low excitation energy [1, 2]. However, the large deformation reached by the system and the fission dynamics that drives the system from one single object to two separated fragments prevent, so far, from a quantitave microscopic description of the problem. A great effort has been made in the last decades in order to modeling the fission process [3, 4, 5], but the accuracy of these models could not be experimentally endorsed because of the limited number of avaliable systems as well as a reduced number of physical observables.

The GANIL facility and the VAMOS magnetic spectrometer offer a unique opportunity for fission studies. The high-intensity ${}^{238}$U and $^{232}$Th beams produced at GANIL at Coulomb energies make it possible to explore exotic actinides through multi-nucleon transfer and fusion reactions in inverse kinematics, with minimal angular and energy straggling. The combination of these beams with the VAMOS++ magnetic spectrometer provides a powerful tool to directly measure the full isotopic distribution of fission fragments and to reconstruct the reaction kinematics [6, 7, 8, 9, 10].

In addition, information about the entrance channel including isotopic identification of the fissioning system, reconstruction of the initial excitation energy, and measurements of the fission barrier is obtained by placing a high-granularity silicon telescope downstream of the target. This setup detects the target-like residues produced in the multinucleon transfer reaction [11]. Moreover, transfer and fusion reactions create fissioning systems with a wide range of initial excitation energies, from near the fission barrier threshold up to intermediate energies around ∼50 MeV. This variation enables the study the evolution of structural effects in the nascent fragments.

The fission-fragment identification capabilities of the VAMOS spectrometer have significantly improved in recent years, thanks to new technical and analytical developments [12, 13], as well as the development of a new silicon telescope PISTA —Particle Identification Silicon Telescope Array— [14] with enhanced performance for entrance-channel identification. This effort, led by the GANILCEA/DAM collaboration, enables a better characterization of the fissioning system. The newly combined setup provides unprecedented resolution.
A global overview of the experimental setup and a selection of relevant results recently achieved will be presented.

References
[1] B.D. Wilkins, E.P. Steinberg, and R.R. Chasman, Phys. Rev. C 14, 1832 (1976).
[2] U. Brosa, S. Grossman, and A. Muller, Phys. Reports 197, 167 (1990).
[3] K.-H. Schmidt et al, Nucl. Data Sheets 131, 107 (2016).
[4] G. Scamps and C. Simenel, Nature 564, 382 (2018).
[5] A. Bulgac et al., Phys. Rev. Lett. 116, 122504 (2019).
[6] M. Caamao et al., Phys. Rev. C 88, 024605 (2013).[7] M. Caamano et al., Phys. Rev. C 92, 034606 (2015).
[8] D. Ramos et al., Phys. Rev. C 97, 054612 (2018).
[9] D. Ramos et al., Phys. Rev. Lett. 123, 092503 (2019).
[10] D. Ramos et al., Phys. Rev. C 107, L021601 (2023).
[11] C. Rodrguez-Tajes et al., Phys. Rev. C 89, 024614 (2014).
[12] A. Lemasson and M. Rejmund, Nucl. Instrum. Methods Phys. Res. A 1054, 168407 (2023).
[13] M. Rejmund and A. Lemasson, Nucl. Instrum. Methods Phys. Res. A 1076, 170445 (2025).
[14] arXiv:2601.20907, https://arxiv.org/abs/2601.20907

Orateur: Dr Diego RAMOS DOVAL (GANIL)

10:25 Investigation of Shell Effect Damping in Nuclear Fission Using VAMOS and PISTA

Studying nuclear fission provides insight into the interplay between the dynamic evolution of the compound nucleus and microscopic effects such as shell structure and pairing correlations. Measuring fission fragment yields not only advances our understanding of nuclear structure but also has important applications in nuclear reactor physics.

This work focuses on the evolution of fission fragment yields as a function of the excitation energy (E$^{*}$) of the fissioning system. As E$^{*}$ increases, the symmetric component of the yield becomes more pronounced, indicating the gradual suppression of nuclear structure effects. Precise measurements of this effect are crucial to constrain state-of-the-art fission models and have direct implications for the development of Generation-IV fast neutron nuclear reactors.

To precisely investigate the evolution of fission yield with the excitation energy, a dedicated experimental campaign was conducted, integrating the Particle Identification Silicon Telescope Array (PISTA), alongside enhancements to the VAMOS++ spectrometer at GANIL. The experiment employed the inverse kinematics technique, where a beam of $^{238}$U impinged on a $^{12}$C target, inducing transfer reactions that populated various fissioning systems alongside their associated light recoils. This setup allows for the study of shell effect damping in nuclei near $^{238}$U within an excitation energy range of 6 to 20 MeV, achieving an excitation energy resolution of ∼700 keV (FWHM).

This work presents the experimental setup as implemented at GANIL with a focus on the first time use of the PISTA array. Particular focus will be given to the Pu fissioning systems $^{(240,241,242)}\text{Pu}$. Preliminary results on the evolution of mass and charge distributions as a function of the excitation energy will be presented. Results on the evolution of the neutron excess and global odd-even staggering will be presented as well.

Orateur: Theodore Efremov (CEA)

10:45 → 11:05 Coffee break

11:05 → 13:15 Shell evolution

Président de session: Dr Frédéric Nowacki (IPHC Strasbourg)

11:05 Study of stretched states at CCB

Stretched resonances represent a unique class of high-lying nuclear excitations, characterized by a relatively simple structure. Their wave functions are dominated by a single particle-hole configuration, in which both the particle and the hole occupy orbitals with the highest angular momentum in their respective shells and couple to the highest possible spin value.

In light nuclei, stretched excitations arise from $p_{3/2}→d_{5/2}$, $M4$ transitions and are often located above particle separation thresholds, in the energy continuum region. Information on the properties of these resonances, in particular on their decay branchings, may provide an excellent testing ground for advanced theoretical approaches, such as the Gamow Shell Model (GSM), which incorporate the description of unbound states in the continuum.

Recent experiments have demonstrated the feasibility of populating stretched states in the $^{12}$C, $^{13}$C, $^{14}$N, and $^{16}$O nuclei via inelastic proton scattering at 135 MeV at the Cyclotron Centre Bronowice (CCB) IFJ PAN. By employing γ–proton and particle–proton coincidence techniques, it has become possible to extract information on their decay channels.

The experimental setup consisted of (i) the KRATTA telescope array for detection of scattered protons, (ii) two clusters of the PARIS scintillator array and four LaBr$_3$ detectors for γ-ray measurements, and (iii) four thick DSSD detectors for detection of light charged particles.

The presentation will review the experimental findings on the decays of stretched excitations located around 20 MeV in the $^{12}$C, $^{13}$C, $^{14}$N, and $^{16}$O isotopes. Particular focus will be placed on the preliminary results from the latest measurement at CCB IFJ PAN, which aimed at investigating the decay channels of stretched states in the $^{12}$C nucleus.

Orateur: Natalia Cieplicka-Orynczak (Institute of Nuclear Physics Polish Academy of Sciences)

11:30 Invited talk

Orateur: Agota Koszorus (KU Leuven, SCK CEN)

11:55 Shell evolution investigated in 10Be, 12Be and 20O using solid and active targets

Current experimental and theoretical efforts focus on shell-structure evolution to explain the variation of magic numbers with isospin asymmetry and to constrain the underlying nucleon-nucleon interactions. Advanced shell-model interactions attribute this to the monopole part of the nuclear Hamiltonian, for which additional experimental information on the two-body matrix elements is essential to improve predictive power [1]. Moreover, nucleon-nucleon correlations limit the fraction of measurable spectroscopic strength to \qty{60(10)}{\percent} at low excitation energy [2]. Constraining this quenching of spectroscopic strength is essential for understanding shell-structure changes towards exotic nuclei.

To shed more light on these two topics, two experiments were performed. The first, conducted at LISE, measured one-nucleon transfer reactions $^{10,12}$Be(d,t) and $^{10,12}$Be(d,$^3$He) to study the quenching of spectroscopic factors in the final nuclei. Using MUST2 telescopes [3] to detect and identify the light ejectiles, low-lying states in $^{9,11}$Be and $^{9,11}$Li were populated. Their spectroscopic factors, compared with shell-model calculations, yielded a quenching factor consistent with the literature and showed no significant dependence on the asymmetry energy. In $^{11}$Li, an anomalously large quenching indicated geometrical-mismatch effects [4] that theoretical models fail to completely reproduce.

The second experiment, also at LISE, measured the one-neutron removal reaction $^{20}$O(d,t)$^{19}$O to investigate shell migration in $^{20}$O. Using ACTAR TPC [5-7] to perform 3D particle tracking coupled to silicon pad detectors to measure the light-particle residual energy, eleven excited states were populated in $^{19}$O, demonstrating the suitability of active targets for transfer-reaction experiments [8]. Effective single-particle energies for the $1s_{1/2}$, $0d_{5/2}$, $0p_{1/2}$ and $0p_{3/2}$ neutron orbitals were extracted with full strength except for the $\nu0p_{3/2}$ (only \qty{40}{\percent}). Comparison with the SFO-tls shell-model interaction [9] suggests that more attractive neutron-neutron monopole matrix elements of the $p-sd$ shells are needed to better reproduce experimental ESPEs. Further theoretical developments are required towards a universal interaction describing spectroscopy in this region of the nuclear chart.

References
[1] T. Otsuka et al., Rev. Mod. Phys. 92, 15002 (2020).
[2] T. Aumann et al., Prog. Part. Nucl. Phys. 118, 103847 (2021).
[3] E. Pollacco et al., in 4th conference on exotic nuclei and atomic masses (ENAM’04), Vol. 25 (2004).
[4] A. Matta et al., Phys. Rev. C 92, 41302 (2015).
[5] T. Roger et al., Nucl. Instrum. Methods Phys. Res., Sect. A 895, 126–134 (2018).
[6] B. Mauss et al., Nucl. Instrum. Methods Phys. Res., Sect. A 940, 498–
504 (2019).
[7] J. Giovinazzo et al., Nucl. Instrum. Methods Phys. Res., Sect. A 953, 163184 (2020).
[8] J. Lois-Fuentes et al., Accepted to Phys. Rev. Lett. (2026).
[9] T. Suzuki et al., Phys. Rev. C 78, 061301 (2008).

Orateur: Miguel Lozano-González (IGFAE-USC)

12:15 Interplay between quadrupole deformation and proton-neutron pairing through the prism of Anderson's limit

Proton-neutron pairing is an exotic type of pairing that appears in nuclei with $N\sim Z$, as pairing requires an important overlap of the wave functions at the Fermi surface. Unlike standard like-particle pairing (neutron-neutron, proton-proton) that exists only in the isovector ($T = 1$) channel, proton-neutron pairing can exist in both the isovector and isosacalar ($T = 0$) channels. The possibility to observe pairing condensation of two different fermionic fluids is a unique phenomenon, and its understanding is crucial to infer the structure of $N=Z$ nuclei.

Pairing can be probed using transfer reactions since the two-nucleon transfer cross section is enhanced by the collectivity of the nucleon pairs condensate. For proton-neutron pairing, the relative contribution of the isovector and isoscalar channels can be accessed by measuring transfer cross sections to the low-lying ($J=0^+$, $T=1$) and ($J=1^+$, $T=0$) states in odd-odd $N=Z$ nuclei. We chose to use the (p,$^3$He) reaction as its selection rules allow to populate both states at once.

As pairing is a collective effect, it is expected to be stronger in the middle of high $j$ orbitals. The $f_{7/2}$ shell is the highest $j$ shell currently accessible with sufficient beam intensity for two-nucleon transfer reactions in $N=Z$ nuclei. We are thus investigating $^{48}$Cr, which lies in the middle of this shell. Moreover, $^{48}$Cr is a good candidate to study the interplay between pairing and deformation since it is known to be a good rotor up to spin 10$^+$ [1].

The experiment to measure the two-nucleon transfer reaction $^{48}$Cr(p,$^3$He)$^{46}$V was performed at GANIL. A radioactive $^{48}$Cr beam was produced by fragmentation of a primary $^{50}$Cr beam and selected by the LISE spectrometer, before impinging on a CH$_2$ target. A forward array of DSSD-CsI telescopes (MUGAST) was used to detect and identify light charged particles, and was coupled to twelve EXOGAM Germanium clovers around the target, a zero-degree detection (ZDD) and MWPC detectors to reconstruct event by event the beam position on the target.

I will present cross sections and angular distributions for the low-lying states of $^{46}$V. They will be compared with second-order distorted wave Born approximation (DWBA) calculations for two-nucleon transfer performed with both shell model and single particle two-nucleon amplitudes (TNA). The results will be put into perspective with the systematics in the $f_{7/2}$ shell, and will also be discussed in light of Anderson's limit, which predicts a disappearance of superfluidity if the level spacing at the Fermi surface becomes greater than the BCS gap [2].

[1] Robinson, S. J. Q. and Hoang, T. and Zamick, L. and Escuderos, A. and Sharon, Y. Y., Phys. Rev. C, 89, (2014), 014316. https://link.aps.org/doi/10.1103/PhysRevC.89.014316.
[2] P.W. Anderson, Journal of Physics and Chemistry of Solids, 11, (1959), https://doi.org/10.1016/0022-3697(59)90036-8.

Orateur: Hugo JACOB (GANIL)

12:35 Investigating the Shell Evolution and Neutron Structure of $^{68}$Ni through (d,p) and (p,d) Transfer Reactions

The evolution of nuclear shell structure in exotic nuclei provides key insights into the
fundamental nature of nuclear forces. In nuclei far from stability, conventional magic
numbers can disappear, while new ones may emerge, a phenomenon known as shell evolution [1].
A well-known example is the evolution of the N=28 shell gap from $^{40}$Ca to $^{48}$Ca,
which has been successfully explained by three-nucleon (3N) forces [2]. Similarly, the
N=14 shell gap in oxygen isotopes shows a comparable trend [3]. These studies highlight
the crucial role of many-body interactions in shaping shell structure.

To extend our
understanding to heavier nuclei, we investigate the evolution of the N=50 shell gap
for which the isotopic chain of Ni would be the perfect candidate.
An experiment was
carried out at GANIL to study $^{68}$Ni via (p,d) and (d,p) reactions, as this nucleus
is the anchor point to determine the amplitude of the N=50 shell gap in $^{78}$Ni, from
relatively well known neutron-neutron effective interaction from experimental data. By
performing neutron-adding and neutron-removing reactions on $^{68}$Ni, we also get a
unique access to the spectroscopic strengths and thus, the occupancy of the orbitals
below and above N=40. This allows to characterize the magicity at N=40. Indeed, depending
on whether a sharp occupancy drop is observed or not, the nucleus can be concluded to
have either a magic or a superfluid nature [4]. Moreover, it is also planned to
deduce the information on the 2p$_{1/2}$ - 2p$_{3/2}$, 1g$_{7/2}$ - 1g$_{9/2}$ and
1f$_{5/2}$ - 1f$_{7/2}$ spin-orbit splittings.

In this contribution, I will present the status of the ongoing analysis
and the results obtained so far, with particular emphasis on
the (d,p) channel. Some preliminary results on the (p,d) channel will also be presented.

References
[1] O. Sorlin and M.G. Porquet, Prog. Part. Nucl. Phys. 98, 602-673 (2008).
[2] J. D. Holt et al., J. Phys. G: Nucl. Part. Phys. 39, 085111 (2012).
[3] T. Otsuka et al., Phys. Rev. Lett. 105, 032501 (2010).
[4] O.Sorlin, S.Leenhardt, C.Donzaud, J.Duprat, F. Azaiez, et al., Phys. Rev. Lett. 88, 092501 (2002).

Orateur: Prabhat Sharma (GANIL)

12:55 Quadrupole and octupole collectivity in 106Cd explored via "unsafe" Coulomb excitation

Stable cadmium isotopes were thought to have spherical ground states due to their phonon-like level structure, however, this was put into question in recent studies that suggested shape coexistence in $^{110,112}$Cd [1]. Further evidence supporting the presence of ground-state deformation in mid-shell Cd nuclei came from a Coulomb-excitation study of $^{106}$Cd [2] in line with Beyond-Mean-Field (BMF) calculations [3]. This intriguing structural puzzle was addressed in more detail using "unsafe" Coulomb-excitation data, obtained as a byproduct of lifetime measurements [4] performed at GANIL using the AGATA and VAMOS++ spectrometers.

Excited states of $^{106}$Cd were populated via inelastic scattering on a $^{92}$Mo target at beam energies exceeding the "safe" Coulomb excitation energy [5] by 8-40%, depending on the scattering angle. The balance between the Coulomb and nuclear interactions in the population of individual excited states and the effects introduced by the Coulomb-nuclear interference on the experimental excitation cross sections were explored as a function of the scattering angle between the collision partners. Coupled-channel codes FRESCO [6] and GOSIA [7] were employed to demonstrate that unsafe Coulomb-excitation data can be used to extract spectroscopic information, such as quadrupole and octupole transition strengths.

Selected results will be presented, including the first measurement of B(E3) values involving several negative-parity states, and discussed in terms of a possible quadrupole-octupole coupling scenario. The extracted B(E2) values will be compared with new BMF calculations using the symmetry-conserving configuration mixing method, which includes intrinsically rotating states [8].

[1] P.E. Garrett et al., Phys. Rev. Lett. 123, 142502 (2020).

[2] T.J. Gray et al., Phys. Lett. B 834, 137446 (2021).

[3] M. Siciliano et al., Phys. Rev. C 104 (2021) 034320.

[4] M. Siciliano et al., Phys. Lett. B 806, 135474 (2020).

[5] D. Cline, Annu. Rev. Nucl. Part. Sci. 36, (1986) 683.

[6] I.J. Thompson, Comput. Phys. Rep. 7, 167 (1988).

[7] T. Czosnyka et al., Bull. Am. Phys. Soc. 28, (1983) 745.

[8] D. Kalaydjieva et al., submitted to EPJ A.

Orateur: Desislava Kalaydjieva (University of Guelph)

13:15 → 15:00 Lunch

15:00 → 16:30 Collective modes

Président de session: Kamila Sieja (Institut Pluridisciplinaire Hubert Curien)

15:00 Invited talk

Orateur: Marine Vandebrouck (CEA Saclay Irfu)

15:25 Invited talk

Orateur: Adam Maj (IFJ PAN)

15:50 From Global E1 Strength to the Pygmy Dipole: A Shell-Model Perspective on Light Nuclei

Understanding how atomic nuclei respond to electromagnetic perturbations provides key insights into their structure and dynamics.
In this talk, I will address nuclear response functions, focusing on the electric dipole (E1) mode, one of the most fundamental collective excitations in nuclei. Particular attention will be paid to the Pygmy Dipole Resonance (PDR), an exotic low-energy mode appearing in neutron-rich nuclei. I will present how these excitations can be theoretically described within the Configuration Interaction Shell Model (CI-SM) framework. First, systematically computed E1 strength distributions for all long-lived nuclei in the p- and sd-shell regions will be discussed, compared to predictions from other models and to available photoabsorption data [1,2,3]. The impact of those predictions on the propagation of ultra-high-energy cosmic rays will be presented. Then I will focus on the structure and evolution of the PDR along the Neon and Oxygen isotopic chains, its degree of collectivity, the classical interpretation as a neutron-skin oscillation mode and the isospin-mixed character [1,4].

[1] O. Le Noan and K. Sieja, “Electric dipole response of sd-shell nuclei within the Configuration-Interaction Shell Model approach,” Physical Review C 111, 064308 (2025).
[2] R. W. Fearick, O. Le Noan, H. Matsubara, P. von Neumann-Cosel, K. Sieja, and A. Tamii, “Electric dipole strength in sd-shell nuclei from small-angle proton scattering.” Submitted.
[3] O. Le Noan, S. Goriely, E. Khan, and K. Sieja, Modeling ultra-high-energy cosmic rays propagation using the input from configuration interaction shell model, arXiv:2512.16329 submitted.
[4] O. Le Noan and K. Sieja, ‘’Nature of the pygmy dipole resonance: the Configuration-Interaction Shell-Model point of view. ’’ In Preparation.

Orateur: Oscar Le Noan (IPHC - CNRS - University of Strasbourg)

16:10 Discrete Non-Orthogonal Shell Model: from mid-mass to heavy deformed nuclei

We present an extension of the Discrete Non-Orthogonal Shell Model [1, 2] within a Variation After Projection approach [3] recently developed at IPHC, Strasbourg. This method is an alternative to the exact shell-model diagonalization [4] using non-orthogonal many-body expansions combined with symmetry restoration techniques [5]. We discuss the prospective of the new method for applications from mid-mass nuclei in the Islands of Inversion at N = 40 and N = 50 to superheavy nuclei [6].

[1] D. D. Dao and F. Nowacki, Phys. Rev. C 105, 054314 (2022).
[2] A. Gade et al., Nat. Phys. 21, 37 (2025).
[3] D. D. Dao and F. Nowacki, arXiv:2507.09073 [nucl-th].
[4] E. Caurier, G. Martinez-Pinedo, F. Nowacki, A. Poves and A. P. Zuker, Rev. Mod. Phys. 77, 427 (2005).
[5] J. A. Sheikh, J. Dobaczewski, P. Ring, L. M. Robledo and C. Yannouleas, J. Phys. G: Nucl. Part. Phys. 48, 123001 (2021).
[6] D. D. Dao and F. Nowacki, arXiv:2409.08210 [nucl-th].

Orateur: M. Duy Duc Dao (IPHC Strasbourg)

16:30 → 17:00 Coffee break

17:00 → 19:10 Application & Instru.

17:00 Invited Talk

Orateur: Dr Arnaud Guertin (CNRS/IN2P3)

17:25 Lightweight pulse-shape analysis using a machine learning ensemble algorithm for segmented HPGe

Pulse-shape analysis (PSA) techniques are widely used to measure quantities such as energy, time as well as other valuable information including particle identification and position of interaction.
In the case of large segmented high-purity germanium (HPGe) detector arrays, such as AGATA, analysing the pulse-shapes of the primary hit segment and its first neighbours is performed to determine all the interaction positions of a single $\gamma$-ray event. These positions are an indispensable ingredient for $\gamma$-ray tracking, used for Compton-background reduction and Doppler correction. Typical PSA on such arrays generally requires substantial computing resources to handle advanced sample-by-sample minimisation algorithms of large number of samples ($\sim$100 per pulse) in order to determine the interaction position(s).

In this work we present an alternative lightweight PSA approach using a reduced number of global pulse features ($\lesssim$15), easily extracted from the hit segment and its first neighbours pulses. The collected features are thenceforth injected in an ensemble of machine learning models based on a \emph{gradient boosted regression trees} algorithm to determine the hit position.
Source data, measured with an AGATA crystal at the IPHC scanning table, provided the training and validation data sets. The first application of this algorithm demonstrated a position resolution comparable to those obtained with computationally expensive \emph{classic} PSA. This new approach requiring modest computational resources is typically, but not exclusively, useful for applications such as an ambulant Compton imaging device.

An overview of the construction and training of the machine learning models will be presented, as well as the achieved position measurement performances in the context of a novel HPGe Compton imaging device.

Orateur: Dr Mohamad Moukaddam (University of Strasbourg)

17:50 MEASUREMENT OF THE 19F(n,a)16N CROSS SECTION WITH THE SCALP DETECTOR

Accurate nuclear data are essential for the design and safety optimization of nuclear reactors, as uncertainties directly impact key reactor parameters. In particular, the 19F(n,a)16N reaction is of great interest for fluorine-based molten salt reactors. However, experimental data for the (n,a) channel remain scarce, with cross sections discrepant by up to a factor of three measured from the reaction threshold up to 20 MeV, leading to significant uncertainty propagation on the neutron multiplication factor $k_{eff}$, up to 140 pcm (1 pcm = $10^{-5}$).

We report on a new 19F(n,a)16N cross section measurement performed with the SCALP detector developed at LPC Caen. SCALP consists of a scintillating ionization chamber, operated as a gaseous active target, for the identification of (n,a) reaction channels. Four Photo-Multiplier Tubes surrounding the chamber detect scintillation light produced by particle interactions in the gas for precise neutron kinetic energy determination through time-of-flight measurements. The experiment was carried out at the Neutrons For Science (NFS) facility (GANIL-SPIRAL2, Caen, France), using a pulsed neutron beam with a continuous energy distribution between 1 and 40 MeV.

Preliminary results on the energy-differential 19F(n,a)16N cross section are presented. Data analysis is currently ongoing, and first results will be compared to existing experimental data as well as theoretical evaluations.

Orateur: nathan rousseaux (Laboratoire de Physique Corpusculaire de Caen)

18:10 Development of a New $^3$He Cryogenic Target within the ATRACT Project

Transfer reactions are powerful probes to provide single-particle and collective properties of nuclear states, such as excitation energies, spin-parity assignments, and spectroscopic factors, extending even to unbound states. The extensive use of CH$_2$/CD$_2$ plastic and H$_2$/D$_2$ cryogenic targets has boosted the study of the neutron wave functions and thus research fields such as neutron shell evolution, neutron capture rates for nuclear astrophysics, and neutron-neutron pairing. Conversely, the experimental challenges posed by their counterparts for proton transfer have proven to be a significant hindrance to the study of the proton shell evolution, the spectroscopy of unbound proton-rich nuclei, the study of neutron-proton pairing in self-conjugate ($N=Z$) nuclei, and proton-capture surrogate reactions for nuclear astrophysics.

Indeed, the unavailability of sufficiently thick $^3$He targets (about $10^{20}$at/cm$^2$, see ref.[1] and references therein) represents a significant obstacle to the study of the one-proton stripping ($^3He,d$) and deuteron-stripping ($^3He,p$) reactions. Few have been developed for reaction measurements, with a focus on high energy beams (particularly for RIKEN) [2]. The only compact $^3$He target specifically designed and employed for transfer reactions experiments with low-energy (around 10 MeV/u) and low-intensity (10$^4$-10$^6$ pps) beams is the HeCTOr target [1]. It was used during the MUGAST-AGATA VAMOS campaign at GANIL [3], to study the proton structure at $N=28$ via the reaction $^{46}$Ar($^3He,d$)$^{47}$K.

The ATRACT project aims to produce, in addition to an active $^3$He target, a $^3$He cryogenic target that overcomes the shortcomings of the HeCTOr target, such as ice growing on the windows at a rate of 11 $\mu$m/window/day (for a vacuum of 10$^{-6}$ mbar), non-negligible background reactions, large energy losses and additional straggling due to the gas cell size and window material (3.8$\mu$m thick Havar foils). These limitations also include a significant absorption of the low energy and long half-life $\gamma$ rays, as well as an important LHe consumption to cool down the $^3$He cell.

The new strategy incorporates the use of a cryogen-free technique (pulse-tube type cryocooler), combined with innovative solutions for window materials and de-icing protocols. This will be achieved through several phases of testing samples and the prototype target, at room and cryogenic temperatures. This procedure allows us to study the properties of the windows: resistance to pressure, surface deformation, He leak tightness, but also the time constant and efficiency of different de-icing techniques.
To guide the technical decisions that are made, mechanical and thermal calculations, as well as simulations of the relevant reactions (using the NPTool framework[4]), are performed. The latter are crucial to determine the energy thresholds, the energy straggling into the target and its windows, the excitation energy resolution for the particle measurements and the absorption of $\gamma$-rays for each physics case. The final cryogenic $^3$He target is planned for use during the future GRIT-AGATA-VAMOS at GANIL(2029-2030).

In this presentation, I will show the results of tests conducted on porosity to helium, resistance to pressure, and the measurement of the deformation of the selected windows, in addition to the current status of the target development. Detailed simulations of typical physics cases will also be shown.

$[1]$ F. Galtarossa et al., NIM A 1018, 165830 (2022).
$[2]$ H. Ryuto et al., Nucl. Instr. and Meth. in Phys. Res. A 555, 1 (2005).
$[3]$ D. Brugnara et al., submitted to PRL, https://arxiv.org/pdf/2506.23228 .
$[4]$ A. Matta et al., J. Phys. G: Nucl. Part. Phys. 43, 045113 (2016).

Orateur: Dr Antoine Barrière (IJCLab)

18:30 High-precision TDRIV g-factor measurements at GANIL:\\ the $2^+_1$ state in $^{22}$Ne and its implications

The magnetic dipole moment of a nuclear state provides unique insight on the single-particle structure of the nucleus. Its experimental observable, the $g$ factor, can yield valuable information e.g. on the effective single-particle energies of proton and neutron orbitals, and shell evolution away from the valley of stability. One of the available methods for measuring $g$ factors of excited nuclear states with picosecond lifetimes, is the Time-Differential Recoil In Vacuum (TDRIV) method. This method is based on observing the Larmor frequency, proportional to the $g$ factor, at which the nuclear and atomic spins precess around the total spin of the projectile as it recoils between the target and a secondary foil within a plunger device.

А modification of the TDRIV method was proposed [1] to overcome one of its limitations, namely applying it on radioactive ion beams. After a successful proof-of-principle experiment using a stable $^{24}$Mg beam [2], the first application of the modified TDRIV method on a radioactive $^{28}$Mg beam was performed at the HIE-ISOLDE facility to probe the nature of the transition towards the $N=20$ Island of Inversion around $^{32}$Mg along the Mg isotopic chain, where modern theoretical models give varying predictions [3,4]. An additional TDRIV measurement was performed using a stable $^{22}$Ne beam in order to constrain some experimental parameters, making use of the precise literature value for the $g$ factor of the $2^+_1$ state in this nucleus [5]. However, the results obtained from the $^{22}$Ne measurement put into question the accuracy and precision of the adopted $g$-factor value, and in turn hindered the achievable precision for the $2^+_1$ $g$ factor in $^{28}$Mg.

These discrepancies led to an initiative to develop better tools in order to reach new levels of precision for $g$-factor measurements in both stable and radioactive ion beam measurements, such as the Orsay Particle Scintillator Array (OPSA), designed specifically for TDRIV measurements. For its first use in an experiment, the OPSA array was coupled to the EXOGAM $\gamma$-ray spectrometer and the OUPS plunger device in a dedicated TDRIV measurement on $^{22}$Ne performed at GANIL in 2024. The main goals of the experiment were to resolve the observed discrepancy in $^{22}$Ne, to minimize systematic uncertainties for the $^{28}$Mg results from HIE-ISOLDE, and to establish the application of the TDRIV method at GANIL for future studies on stable and radioactive ion beams.

Details on the above-mentioned experiments will be reported with a main focus on the successful experiment at GANIL and the current status of the data analysis. The implications of the obtained preliminary results on the transition towards the $N=20$ Island of Inversion in Mg isotopes will be highlighted. The directions for further advances with the TDRIV method as well as plans for future measurements on radioactive ion beams will be mentioned.

[1] A. E. Stuchbery, P. F. Mantica and A. N. Wilson, Phys. Rev. C 71 047302 (2005).

[2] A. Kusoglu, A. E. Stuchbery, G. Georgiev et al. Phys. Rev. Lett. 114 062501 (2015).

[3] N. Tsunoda et al., Phys. Rev. C 95 021304 (2017).

[4] T. Miyagi et al., Phys. Rev. C 102, 034320 (2020).

[5] R. E. Horstman et al., Nucl. Phys. A, 275(1) 1977.

Orateur: Konstantin Stoychev (University of Guelph)

18:50 Laser Radiofrequency Double Resonance Spectroscopy in a Collimated Supersonic Gas-jet Expansion

Laser spectroscopic techniques have become essential tools for probing the properties of nuclei produced at radioactive ion beam (RIB) facilities. By exploiting the interaction between nuclear and electronic structures, key nuclear observables such as electromagnetic moments, nuclear spins, and mean-squared charge radii can be extracted from measurements of hyperfine structures and isotope shifts [1]. These quantities provide critical benchmarks for advancing modern nuclear theory and improving our understanding of nuclear structure.
Nonetheless, a persistent limitation remains in the trade-off between achievable resolution and sensitivity. This is evident in the lack of measurements of nuclear electromagnetic moments beyond the electric quadrupole moment in radioactive nuclei. Probing the next order, namely the magnetic octupole moment, would provide a new observable to investigate core polarization and effective-current contributions [2]. Moreover, measurements along chains of radioactive isotopes will enable the systematic exploration of how octupole moments evolve with changes in nuclear composition. Such studies will help isolate and quantify contributions from core polarization, pairing effects, and shell evolution, thereby improving the predictive power of both shell-model and mean-field approaches [3].
At the IGLIS facility at KU Leuven [4], in collaboration with LPC Caen, we have recently developed a novel spectroscopic technique based on established in-gas-jet resonance ionization spectroscopy [5] and Laser Radiofrequency Double Resonance (LRDR) techniques [6]. This approach combines the high sensitivity of the former with the resolution achievable with the LRDR method. It enables the measurement of hyperfine structure splittings at the kHz level, representing a three-order-of-magnitude improvement over state-of-the-art high-resolution laser spectroscopy methods applied to radioactive atoms, while maintaining efficiencies comparable to the standard in-gas-jet resonance ionization method. Moreover, the homogeneous and collision-free gas-jet environment has been shown to provide long coherence times, enabling the manipulation of the quantum state of the atomic ensemble via Rabi oscillations and Ramsey excitations.
Overall, these developments provide a significant enhancement of experimental capabilities for the study of radioactive nuclei, particularly in connection with the development of new radioactive ion beam facilities such as S$^3$-LEB [7] at GANIL. This work opens a new window for investigating nuclei across the nuclide chart.

---

References
[1] Yang, X., et al. Progress in Particle and Nuclear Physics 129 (2020): 104005.
[2] Sen’Kov, R. A., and V. F. Dmitriev. Nuclear Physics A 706.3-4 (2002): 351-364.
[3] de Groote, R. P., et al. Physics Letters B 827 (2022): 136930.
[4] Kudryavtsev, Y., et al. Nuclear Instruments Methods B 376 (2016): 345–352.
[5] Ferrer, R., et al. Nature Communication 8.1 (2017): 14520.
[6] Childs, W. J. Physics reports 211.3 (1992): 113-165.
[7] Ajayakumar, A., et al. Nuclear Instruments and Methods B 539 (2023): 102-107.

Orateur: Dr Andrea Raggio (KU Leuven, Institute for Nuclear and Radiation Physics)

19:10 → 20:00 Welcome Cocktail

20:00 → 21:00 Dinner

mar. 22 septembre

09:00 → 10:50 Shell evolution

Président de session: BEATRIZ FERNANDEZ DOMINGUEZ (USC)

09:00 Invited talk

Orateur: Olivier Sorlin (GANIL)

09:25 Invited talk

Orateur: Pepijn Demol

09:50 First in-beam gamma-ray spectroscopy of (n, xn) reactions with EXOGAM at NFS

Fast-neutron-induced nxn reactions occupy a region of reaction phase space that has never been explored from the perspective of nuclear structure studies. Compared to fusion-evaporation they transfer modest angular momentum and populate states off the yrast line; compared to transfer reactions they impose no single-particle selectivity and reach residual nuclei through statistical population governed by level density. Until recently the $\gamma$-ray spectroscopy of $(n,xn)$ reactions has been limited by the lack of high-flux fast-neutron beams coupled to large HPGe arrays. The Neutrons for Science (NFS) facility at GANIL-SPIRAL2 changes this: with a white neutron beam extending to 44 MeV and a flux several orders of magnitude above competing facilities, it enables high-resolution multi-coincidence $\gamma$-ray spectroscopy of fast-neutron reactions for the first time.

I present results from the first experiment coupling the EXOGAM HPGe array to NFS, using $^{\mathrm{nat}}$Ni and $^{\mathrm{nat}}$Pb targets over fourteen days of effective beam time. The $(n,2n)$ channel on $^{58}$Ni provides the first nuclear-structure study of $^{57}$Ni via neutron removal and reveals a previously unobserved levels. One of the states observed is a strong candidate for a low-spin member of the $\nu(pf)^{-1}g_{9/2}$ intruder multiplet across the $N=28$ gap, invisible to fusion-evaporation and to pick-up reactions before. Cross-section measurements show discrepancies with TENDL evaluations in the $^{57}$Ni that provide independent evidence for the new state and an entry point for updating evaluated nuclear data. A short test measurement at the end of the campaign on $^{\mathrm{nat}}$Pb allowed extending cross-section measurements of nxn reactions to higher neutron energies beyond ~20 MeV.

Beyond the physics, the experiment also addressed an open question of feasibility: whether HPGe detectors can sustain prolonged operation in intense fast-neutron environments. We find resolution degradation consistent with cumulative dose, fully recovered through standard thermal annealing, with no permanent damage. The combination of NFS neutron flux, EXOGAM resolution, and tractable detector damage establishes a new spectroscopic platform for nuclear structure studies at NFS.

Orateur: Hemantika SENGAR (GANIL)

10:10 Cluster structure of the ground state of light exotic nuclei beyond alpha clustering

Understanding how cluster structures emerge within neutron-rich nuclei has become of great relevance in nuclear structure physics and it has been subject of different approaches of study. The present work aims to investigate this phenomenon in the ground state of light neutron-rich nuclei beyond alpha-clustering in the beryllium isotope chain via $^{10}$Be(p,$\alpha$)@38MeV/u and $^{10}$Be(d,$^{6}$Li)@ 17MeV/u pick-up reactions. This study is motivated by theoretical predictions of infinite nuclear matter \cite{Typel2013}, suggesting that light cluster formation, such as deuterons, tritons, and helium, tend to form at low nuclear densities \cite{Zhang2017}. Moreover, preliminary experimental results from knock-out reactions obtained in RIBF facilities suggest triton formation on the surface of the $^{14}$Be halo nucleus. Thus, this experiment offers an opportunity to complement the information through the Be isotope chain while comparing both methods.

The experiment was conducted at GANIL using fragmentation beams produced by the LISE spectrometer and the detection system of the MUGAST@LISE 2024 campaign \cite{GirardAlcindor2024}. It consists of the MUGAST array \cite{Pollacco2005} coupled with the EXOGAM gamma-ray spectrometer \cite{Simpson2000} and a zero degree detection system (ZDD). An event-by-event reconstruction of the fragmented beams was performed using a set of two CATS beam trackers \cite{Ottini1999} located upstream of the 5 mg/cm$^2$ CH$_2$ and CD$_2$ reaction targets.

In this contribution preliminary results of the data analysis for the three mentioned reactions will be presented. The detection and identification of heavy and light fragments ($^{6,7}$Li and $^{4,6}$He) in coincidence using the MUGAST array allowed a full kinematic reconstruction for each reaction. Using this information, the invariant mass method is applied to extract the excitation energies corresponding to the ground states of the beryllium isotopes, enabling the identification of the reaction channels of interest and the determination of the measured differential cross sections. These cross-sections will be compared to theoretical DWBA calculations by use of microscopic cluster wave functions as structure inputs. This comparison allows to probe the description of cluster structure of the $^{10}$Be ground states within these microscopic models.

Orateur: Valerian Girard-Alcindor (IJCLab)

10:30 Is there an Isobaric Analog State of the Tetra-Neutron in hydrogen-4 ?

The existence of tetra-neutron ($^{4}$n) has been a long-standing question in nuclear physics and few-body neutron systems are of great interest for understanding nuclear forces and the structure of neutron-rich matter. Since the beginning of the century, the discovery of possible candidate for the $^{4}$n state, has been reported several times. However, it triggered a lot of debate about the theoretical interpretation of the results. Assuming that the $^{4}$n state observed is a (T=2, T$_z$=2) and due to the isospin symmetry, it should exist an isobaric analog state (IAS) (T=2, T$_z$=1) in $^{4}$H nuclei. We proposed to study indirectly the $^{4}$n system via the IAS in $^{4}$H nuclei through $^{6}$He(p,$^{3}$He)$^{4}$H reaction. If such a state is observed, it will allow to add more input to current theoretical description of neutral nuclei.

The experiment was performed at GANIL facility using the LISE spectrometer in 2025 beam time. A secondary beam of $^{6}$He at 50 MeV/u was produced by fragmentation of a primary beam of $^{13}$C at 60 MeV/u on a Be target. The beam was transmitted to the experimental setup consisting of a reaction target (CH2 at 10 mg/cm$^2$) placed in the center of the four MUST2 telescopes (Silicon strip detectors coupled to CsI scintillators) and a simplified Zero Degree Detection with only plastic scintillators supplemented by a plastic scintillator placed upstream the target for normalization.

Both results from $^{6}$He(p,t)$^{4}$He useful for calibration purpose and from $^{6}$He(p,$^{3}$He)$^{4}$H will be presented. For the latter, the decay products of $^{4}$H are identified in MUST2 so that the excitation energy spectrum for each decay channel have been extracted. They will be compared with phase space calculations. Preliminary results concerning the IAS of the $^{4}$n will be presented.

Orateur: Quentin Délignac (IJCLab)

10:50 → 11:10 Coffee break

11:10 → 13:15 FISSION

Président de session: MANUEL CAAMAÑO FRESCO (Universidade de Santiago de Compostela)

11:10 Invited talk

Orateur: Guillaume Scamps (L2I Toulouse, CNRS/IN2P3, Université de Toulouse)

11:35 Fission studies at the ISOLDE Solenoidal Spectrometer

Nuclear fission remains a major challenge for both experimental and theoretical
studies due to its complexity, involving the collective motion of all nucleons
within a heavy nucleus. In this presentation, a novel experimental approach for
determining a key property of a nucleus, the fission barrier, is discussed.
The heavy radioactive ion beams of interest are provided by the ISOLDE
facility at CERN and impinge on a deuterated plastic target, in inverse kinematics.
Such reactions can result in nuclear fission if the incoming nucleus is
sufficiently fissile and the excitation energy after the reaction is higher than the
fission barrier. Extracting the height of the fission barrier is the key objective
of this project. This is possible by determining the fission probability of a nucleus
as a function of its excitation energy. By measuring such a reaction inside
a solenoidal spectrometer, the excitation energy resolution can be optimized,
limiting key challenges for inverse kinematics reactions, such as kinematic compression
and kinematic shift.
In this approach, protons from (d,p) reactions, fission fragments, and gamma
radiation are detected in coincidence by detectors mounted inside the 2T field
of a former MRI magnet. This project is motivated by the role of nuclear fission
in nucleosynthesis, namely the astrophysical r-process, which is responsible for
the creation of the heaviest elements we find in Nature. To understand this
role, it is necessary to extend fission studies towards neutron-rich nuclei. The
presented approach is a first step in this direction.

                          1

Orateur: Maria Vittoria Managlia (Chalmers University of Technology)

11:55 Isotopic fission fragments yields in the Thorium region produced in inverse-kinematics with a 232Th beam

Despite the development of different theoretical models [1] and simulation codes based on experimental data, such as GEF [2], the fission process is not reproduced with enough accuracy along the nuclear chart. Given that the fission mechanism is sensitive to the interplay between both microscopical quantities, such as nuclear structure of the fission fragments, and macroscopic effects; a fully microscopical description of the interaction has not been obtained so far. In order to further constrain the models, a large set of experimental needs to be provided.

Following the advantages of inverse-kinematics, the VAMOS group and collaborators decided to perform fission studies more than 10 years ago [3,4]. The VAMOS++ spectrometer, composed of a pair of magnetic quadrupoles and a dipole, is coupled to a set of Multi-Wire Proportional Counters (MWPCs) before and after the optical modules and an Ionization Chamber (IC) positioned at the end of the focal plane [5]. This configuration enables the isotopic identification of complete fission fragment distributions. The magnetic spectrometer is combined with a highly stripped silicon detector named PISTA [6], which allows the identification of the fissioning system and the reconstruction of its excitation energy with high resolution. The combination of both devices permit to systematically study the fission process.

Taking advantage of the VAMOS++ setup, A new experiment was conducted using the newly accelerated 232Th beam at Coulomb energies. Transfer reactions performed with a 12C target permitted to populate fissioning systems from 230Th up to 244Cm. The produced nuclei lay on a region closer to the known transition between asymmetric to symmetric fission in the actinides [7]. This allows the systematic study of the shell-closure effects occurring for different deformation parameters, like octupolar deformation, recently proposed to be responsible for the asymmetric fission in the actinides region [8]. Moreover, experimental results show that the isotopic distributions around Th isotopes deviate from the general actinide behaviour [9].

In this work, the isotopic and mass fission fragment yields of several nuclei such as 232Th or 234U will be presented. These distributions have been obtained as a function of the excitation energy, which allows to study the shell effect evolution. The comparison between Thorium yields and heavier actinides gives new experimental insight into understanding the so-called "Thorium anomaly" [10].

References
[1] Schunck, N and Robledo, LM , Reports on Progress in Physics 79 (2016) 116301.
[2] Karl-Heinz Schmidt and Beatriz Jurado , Reports on Progress in Physics 81 (2018) 106301.
[3] M. Caamaño, O. Delaune, F. Farget, X. Derkx, K.-H. Schmidt, L. Audouin, C.-O. Bacri, G.Barreau, J. Benlliure, E. Casarejos, et al., "Isotopic yield distributions of transfer- and fusion- induced fission from 238U+ 12C reactions in inverse kinematics", arXiv preprint arXiv:1304.2647, 2013.
[4] Ramos, D., et al. Isotopic fission-fragment distributions of 238U , 239Np, 240Pu, 244Cm, and 250Cf produced through inelastic scattering, transfer, and fusion reactions in inverse kinematics. Physical review C, 97(5), 054612.
[5] M.Rejmund et al., Nuclear Instruments and Methods in Physics Research A 646 (2011) 184-191.
[6] Bégué-Guillou, L., Lemasson, A., Morfouace, P., Ramos, D., Taieb, J., Frankland, J. D., ... & Tonchev, A. P. (2026). Performance of the Particle-Identification Silicon-Telescope Array Coupled with the VAMOS++ Magnetic Spectrometer. arXiv preprint arXiv:2601.20907.
[7] Möller, P., & Randrup, J. (2015). Calculated fission-fragment yield systematics in the region 74 ≤ Z≤ 94 and 90≤N≤ 150. Physical Review C, 91(4), 044316
[8] Scamps, G., & Simenel, C. (2019). Effect of shell structure on the fission of sub-lead nuclei. PhysicalReview C, 100(4), 041602.
[9] Schmidt, K. H., et al. (2024). Identifying and overcoming deficiencies of nuclear data on the fission of light actinides by use of the GEF code. Annals of Nuclear Energy, 208, 110784.
[10] Schmidt, K. H., et al. (2024). Identifying and overcoming deficiencies of nuclear data on the fission of light actinides by use of the GEF code. Annals of Nuclear Energy, 208, 110784.

Orateur: Alex Cobo Zarzuelo (GANIL)

12:15 Isotopic yield distributions of transfer-induced fission from 238U on light targets

The interplay between macroscopic liquid-drop properties and microscopic effects represents a fundamental challenge in nuclear fission [1]. This competition can be probed through excitation-energy distributions, as experimental evidence shows a systematic attenuation of structure-dependent effects, thereby progressively revealing the underlying macroscopic component of the potential-energy surface. In this context, fission-fragment isotopic yields provide a sensitive observable for quantifying this evolution [2,3]. In the actinide region, fission at low energy is characteristically dominated by asymmetric mass splits driven by shell effects; however, increasing excitation energy reduces these structure-induced asymmetries and enhances the relative contribution of symmetric fission modes [4].

This specific approach is part of a systematic research campaign at GANIL designed to exploit transfer- and fusion-induced fission reactions in inverse kinematics [5-7]. A $^{238}$U beam at 5.88 AMeV impinged on four different targets ($^{27}$Al, $^{24}$Mg, $^{nat}$B and $^{9}$Be), populating a variety of actinides at low-to-moderate excitation energies. The use of inverse kinematics allows for the full isotopic identification (A, Z) and kinematic reconstruction of one of the fission fragments using the VAMOS++ spectrometer [8] in combination with the AGATA gamma-ray array [9]. Additionally, the use of SPIDER silicon telescope to detect the target-like recoil produced in the transfer reaction, enables an event-by-event characterisation of the fissioning system [6].

In this framework, the present study focuses on the evolution of fission-fragment isotopic yield distributions for selected actinides as a function of excitation energy. Furthermore, the impact of the incoming channel in the fission dynamics is investigated by comparing the fission-fragment production from different reactions leading to the same fissioning system.

References
[1] V. Strutinsky, Nuclear Physics A 95, 420–442 (1967).
[2] K.-H. Schmidt et al., Reports on Progress in Physics 81, 106301 (2018).
[3] A. N. Andreyev et al., Reports on Progress in Physics 81, 016301 (2017).
[4] K. Nishio et al., Phys. Rev. C 111, 044609 (2025).
[5] M. Caamaño et al., Phys. Rev. C 88, 024605 (2013).
[6] C. Rodríguez-Tajes et al., Phys. Rev. C 89, 024614 (2014).
[7] D. Ramos et al., Phys. Rev. C 97, 054612 (2018).
[8] M. Rejmund et al., Nuclear Instruments and Methods in Physics Research Section A 646, 184–191 (2011).
[9] E. Clément et al., Nuclear Instruments and Methods in Physics Research Section A 855, 1–12 (2017).

Orateur: Beatriz Errandonea (IGFAE and Dpt. de Física de Partículas, Univ. of Santiago de Compostela, E-15758, Santiago de Compostela, Spain)

12:35 Evolution of the fission fragment angular momentum

This study [1] explores the role of nucleon exchange for the generation of the fission fragment angular momenta. For a number of typical fission cases, samples of 10,000 shape evolutions are generated by Langevin simulation [2] and, subsequently, for each such evolution, the nucleon exchange transport theory previously developed for damped nuclear reactions [3] is used to obtain the development of the fragment spin-spin distribution within the Fokker-Planck transport framework. The characteristic evolution of both parallel and perpendicular spin components is discussed. A common feature is that the rotational modes fall out of equilibrium before scission when the temperature rises rapidly while the concurrent shrinking of the neck suppresses further exchange. A number of fission observables are extracted from the event ensembles: the distribution of the magnitude of the fragment spin and its orientation relative to the fission axis, as well as the correlation between the two spins and the distribution of their opening angle. The dependence of these observables on the mass asymmetry is also examined.

[1] J. Randrup, P. Nadtochy, C. Schmitt, K. Mazurek, Correlated fission fragment spin dynamics, Phys. Rev. C, 113 (2026) 044605
[2] G.D. Adeev, A.V. Karpov, P.N. Nadtochii, and D.V.Vanin, Multidimensional Stochastic Approach to the Fission Dynamics of Excited Nuclei, Phys. Part. Nucl. 36, 378 (2005)
[3] J. Randrup, Theory of transfer-induced transport in nuclear collisions, Nucl. Phys. A 327, 490 (1979).

Orateur: Katarzyna Mazurek (Institute of Nuclear Physics PAN)

12:55 Probing fission fragments spin distribution from $^{238}U + ^{9}Be \rightarrow ^{247}Cm$ using AGATA & VAMOS++

Nuclear fission remains a complex quantum many-body process in which several fundamental properties are not yet fully understood. In particular, the origin of the angular momentum of fission fragments is still under debate. Recent experimental results tentatively probed the angular momentum at scission from the measurement of the spin distributions of fission fragments [1]. Their interpretation as a signature of spin being generated predominantly after scission is highly debated [2], [3].

In this context, we investigate the angular momentum generated in fusion–fission reactions using the system 238U + 9Be $\rightarrow$ 247Cm at an excitation energy of 47 MeV [4]. The experiment was performed using the AGATA $\gamma$-ray tracking array coupled to the VAMOS++ spectrometer [5], providing high-resolution spin distributions from the $\gamma$-ray spectra of isotopically identified fission fragments.
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The present results will be compared with previous measurements at lower excitation energies [6], especially through the observable of the average angular momenta of the reaction partners.

Preliminary results from the analysis will be presented and discussed in this talk.

[1] : J.N. Wilson et al. “Angular momentum generation in nuclear fission.”. Nature (2021).
[2] : J. Randrup and R. Vogt. “Generation of Fragment Angular Momentum in Fission”. Phys. Rev. Lett (2021).
[3] : G. Scamps and G. Bertsch. “Generation, dynamics, and correlations of the fission fragments’ angular momenta”. Phys. Rev. C (2023).
[4] Y.H. Kim et al. “Prompt-delayed γ -ray spectroscopy with AGATA, EXOGAM
and VAMOS++”. Eur. Phys. J. A (2017).
[5] Lemasson, A. et al. “Advancements of gamma-ray spectroscopy of isotopically identified fission fragments with AGATA and VAMOS++”. Eur. Phys. J. A (2023).
[6] A. Francheteau et al. “Excitation energy, angular momentum, and deformation of the 118Pd/134Te neutronless fragmentation in 252Cf(sf)”. Phys. Rev. C (2026).

Orateur: J. Bequet (GANIL)

13:15 → 15:00 Lunch

15:00 → 16:50 Heavy and Superheavy nuclei

Président de session: Dieter Ackermann (GANIL)

15:00 Invited talk

Orateur: Araceli LOPEZ-MARTENS (IJCLab)

15:25 Invited talk

Orateur: Yannen Jaganathen (National Centre for Nuclear Research, Pasteur 7, Warsaw, Poland)

15:50 First results of the SEASON detector commissioning and insights on the octupole collectivity in 221Ac

Nuclear deformation has been a topic of interest for many decades. While most nuclei can be described using only quadrupole deformation, recent experimental results [1, 2], in agreement with theoretical predictions [3, 4], indicate that a more exotic type of deformation, namely octupole deformation, is needed to best describe nuclei in certain regions of the nuclear chart. In particular, the region of most enhanced octupole collectivity can be observed in the actinides around Z = 88 and N = 134.

In this framework and more generally for the study of heavy nuclei, a new decay station named SEASON (Spectroscopy Electron Alpha in Silicon bOx couNter) has been developed at CEA-Irfu. The online commissioning of the instrument was performed at the IGISOL facility of the Accelerator Laboratory of the University of Jyväskylä, Finland, in February 2026. SEASON is designed to meet the constraints of a high-energy-resolution decay station and an efficient counter for laser spectroscopy of heavy and superheavy nuclei. The detection system is made of 7 DSSD (Double-sided Silicon Stripped Detector) for the detection of alpha particles and conversion electrons, and is coupled with 2 HPGe (High Purity Germanium) detectors for the gamma-rays.

At IGISOL [5], a proton beam of energy 65 MeV induced fusion-evaporation reactions on a $^{232}$Th target, producing, among other neutron-deficient actinide isotopes, $^{225}$Pa, which decays to $^{221}$Ac by alpha emission. This reaction, previously studied at IGISOL with a different setup [6], allowed for the evaluation of SEASON performances and the better quantification of conversion electron factors, which are crucial to perform spin-parity assignments of the states. The resulting level scheme will provide insights into the nature of the deformation of $^{221}$Ac.

First, the detection characteristics of SEASON, including energy resolution and efficiency, will be presented. Then, preliminary online commissioning results will be shown. These results will provide precision on the limits of the static octupole deformation in the neutron-deficient actinide region, illustrating the potential of what could be achieved in the future with SEASON at IGISOL and later at the S3-LEB facility, in GANIL, of which SEASON will be an integral part.

References
(1) Gaffney, L. P. et al. Nature 2013, 497, 199–204.
(2) Verstraelen, E.; Teigelhöfer, A.; Ryssens, W.; Ames, F.; Barzakh, A.; Bender, M.; Ferrer, R.; Goriely, S.; Heenen, P. - H.; Huyse, M.; Kunz, P.; Lassen, J.; Manea, V.; Raeder, S.; Van Duppen,P. Physical Review C 2019, 100, 044321.
(3) Butler, P. A. Journal of Physics G: Nuclear and Particle Physics 2016, 43, 073002.
(4) Cao, Y.; Agbemava, S. E.; Afanasjev, A. V.; Nazarewicz, W.; Olsen, E. Physical Review C 2020, 102, 024311.
(5) Moore, I. D.; Dendooven, P.; Ärje, J. Hyperfine Interactions 2014, 223, 17–62.
(6) Rey-herme, E. et al. Physical Review C 2023, 108, 014304.

Orateur: Mathilde Ragot (CEA)

16:10 Impact of Nuclear Structure on Fusion–Fission Dynamics in Superheavy Element Synthesis

Yoshihiro Aritomo$^{1}$, Kosuke Kawa$^{1}$i, Kohta Nakajima$^{1}$, Shinya Takagi$^{2}$, Akira Yumikura$^{1}$

$^{1}$ Graduate School of Science and Engineering, Kindai University, Osaka, 577-8502, Japan
$^{2}$ RIKEN Center for Computational Science, Kobe, 650-0047, Japan

Currently, investigations into the synthesis of superheavy elements are pursued with two principal objectives. The first is the extension of the periodic table toward higher atomic numbers, and the second is the experimental approach to the predicted “island of stability,” corresponding to the next doubly magic nucleus. The periodic table has been extended up to element 118, oganesson (Og) [1], and ongoing experimental efforts are directed toward the synthesis of element 119 as the next undiscovered element. Recently, a successful synthesis experiment, $^{54}\mathrm{Cr} + ^{238}\mathrm{U} \rightarrow ^{292-x}\mathrm{Lv} $ has been reported employing a chromium beam [2].

In this work, we discuss methods employing secondary beams of neutron-rich nuclei. In such approaches, a key concern is whether measurable evaporation-residue cross sections can be achieved, given the inherently low beam intensities.

However, theoretical analyses indicate that relatively large evaporation-residue cross sections may be achieved, owing to both the fusion mechanism associated with neutron-rich beams and the decay properties of the resulting nuclei. These advantages are expected to sufficiently compensate for the limitation imposed by the low beam intensity. In this study, we elucidate and examine these mechanisms and discuss the feasibility of synthesizing new elements using secondary beams.

Dynamical and statistical models are employed to describe the formation of compound nuclei in the neutron-rich region, their subsequent decay processes, and to evaluate the corresponding evaporation-residue cross sections. The production of neutron-rich compound nuclei, together with future experimental prospects, including the advantages associated with enhanced survival probabilities, is discussed [3]. Furthermore, the potential for the synthesis of new elements through the exploitation of the “dynamical effects of shell structure” is examined.

References
[1] Yu. Ts. Oganessian, et al.,“Results from the first 249Cf+48Ca experiment”. JINR Communication (JINR, Dubna) (2002)
[2] Yu. Ys. Oganessian, et al., Phys. Rev. C 112, 014603 (2025).
[3] Y. Aritomo, Phys. Rev. C 75, 024602 (2007).

Orateur: Yoshihiro Aritomo (Kindai University)

16:30 Studying spontaneous fission in neutron-deficient Md isotopes

In the transfermium region (Z $\geq 100$), spontaneous fission (SF) is a prominent decay mode, often competing with alpha and beta decay. However, experimental measurements remain challenging for most super-heavy nuclei (SHN) due to their low production cross-section. Stability against SF is governed by the fission barrier, which is strongly influenced by shell effects [2]. Hence, studies of mendelevium isotopes, located one proton beyond the closed Z=100 shell, could provide important information on the effect of single particle orbitals on SF.

An experiment was performed at Argonne National Laboratory (ANL) to study the alpha-decay properties of the neutron-deficient $^{244,245}$Md, aiming to resolve discrepancies between two previous studies. These earlier experiments, carried out at the TASCA separator of GSI [3] and at the BGS separator of LBNL [4], measured the isotopes using fusion-evaporation reactions. However, they reported two different assignments for the alpha-decaying states of $^{244}$Md and $^{245}$Md.

In the ANL experiment, neutron-deficient Md isotopes were produced via the fusion-evaporation channels of the reaction $^{40}$Ar+$^{209}$Bi, and separated using the Fragment Mass Analyser (FMA) of the ATLAS facility [1]. The M/Q separation performed at the FMA, combined with the focal plane detection system, enables decay spectroscopy studies of exotic nuclei even at low production rates.

The results of alpha decay analysis have been reported elsewhere [5]. However, in addition to these, multiple SF events were observed tens of microseconds after recoil implantation. SF events were also observed in [3] during measurements of $^{244}$Md, but a definitive isotopic assignment was not made for these events. The present work will focus on the analysis of the fission events observed at ANL and on the investigation of their possible origin.

[1] C. N. Davis and J. D. Larson, NIM-B 40/41, 1224-1228 (1989)

[2] J. Khuyagbaatar, Eur. Phys. J. A 55, 134 (2019)

[3] J. Khuyagbaatar et al., Phys. Rev. Let. 125, 142504 (2020)

[4] J. L. Pore et al., Phys. Rev. Let. 124, 252502 (2020)

[5] S. Kumar et al., Acta Phys. Pol. B Proc. Suppl. 19, 1-A24 (2026)

Orateur: Margarida Paulino (GANIL)

16:50 → 17:20 Coffee break

17:20 → 19:10 Astrophysics

Président de session: Olivier Sorlin (GANIL)

17:20 Invited talk

Orateur: Fairouz HAMMACHE (IJCLab Orsay)

17:45 Invited talk

Orateur: Stephane Goriely (Université Libre de Bruxelles)

18:10 Core deformation in weakly-bound exotic nuclei and the transfer to the continuum of 17C

The study of reactions involving weakly bound exotic nuclei is an active field due to advances in radioactive beam facilities. Many of these nuclei can be approximately described by a model consisting of an inert core and one or more valence nucleons. However, to properly describe some of these nuclei within few-body models, additional effects must be considered, such as deformations and possible excitations of the core. This is the case of $^{17}$C and $^{19}$C, which can be approximately described as a deformed core and a weakly-bound neutron.

In this contribution, we will describe these nuclei using the NAMD model [Phys. Rev. C 111 (2025) 064614]. This model follows the outline of the Nilsson model scheme, but including microscopic information of the core from Antisymmetrized Molecular Dynamics (AMD) calculations. Different methods are considered in order to explore the effect of blocking occupied Nilsson states and including pairing correlations.

The model has been recently extended to explore transfer reactions populating the continuum of the weakly bound nucleus [arXiv:2604.14423] to analyze the 16C(d,p)17C reaction measured at GANIL [Phys. Lett. B 811 (2020) 135939; Phys. Lett. B 867 (2025) 139600], taking into appropriate consideration the treatment of the continuum and the deformation of these carbon isotopes. This model is also flexible enough to allow us to perform different calculations to illustrate how the results are affected by the energy of the $1d_{3/2}$ orbital, related with the emergence of the $N=16$ magic number.

We will show how a shell-gap greater than 5 MeV is required to be consistent with the experimental data. These findings further support the existence of an $N=16$ shell-gap as stated in [Phys. Lett. B 867 (2025) 139600].

Orateur: JOSE ANTONIO LAY VALERA (Universidad de Sevilla)

18:30 12Be structure study via resonant elastic scattering with ACTAR TPC

The ¹²Be nucleus lies far from the valley of stability in the neutron-rich region of the beryllium isotopes. As a light exotic nucleus exhibiting a breakdown of the classical magic number N = 8, ¹²Be provides a valuable testing ground for exploring the interplay between shell evolution, clustering, and deformation.

The structure of ¹²Be was investigated through the resonant elastic scattering reaction ⁴He(⁸He,⁸He)⁴He, measured with the ACTAR TPC active target at GANIL in March 2024. The detector, filled with helium gas, enabled a continuous scan of the excitation-energy region between 11.5 and 13 MeV. The achieved energy resolution of 83 keV (FWHM), a significant improvement over previous measurements (~800 keV), allows precise reconstruction of excitation functions and angular distributions, leading to reliable spin–parity assignments.

Two resonant states were identified:

• A previously observed resonance is reassigned a spin–parity of 4⁺. In agreement with GCM calculations, this new spin assignment impacts the previous interpretation of the rotational band of ¹²Be. This state exhibits a strong ⁴He + ⁸He cluster structure, with some mixing of a ⁶He + ⁶He configuration.

• A new 3⁻ state is observed just above the ⁵He + ⁷He threshold. Unlike the 4⁺ state, it does not show strong ⁶He + ⁶He or ⁴He + ⁸He clustering. Instead, it is a candidate for a possible ⁵He + ⁷He molecular configuration.

These results highlight the structural complexity of ¹²Be, where multiple cluster configurations coexist and mix.

Orateur: Lou Dienis (GANIL - Université de Caen Normandie)

18:50 Universal Few-Body Correlations in Four-Particle Halo Structures: Application to Carbon-22

Halo nuclei, where weakly bound nucleons extend far beyond a compact
core, offer a unique window into universal few-body physics near the
limits of nuclear stability. Their properties are controlled by
low-energy parameters, such as separation energies, scattering lengths
and correlations among the valence particles, making them ideal
benchmarks for testing universality in nuclear systems.

We present a four-particle halo model for systems composed of a compact
core and weakly bound particles. The wave function is constructed
from two universal three-body states, each characterized by an
independent binding momentum scale, allowing the effective five-body
system to be built from well-understood few-body building blocks. The
unitary limit serves as the natural reference point, while the formulation
is flexible enough to explore finite-scattering-length effects. This
two-scale structure makes it possible to investigate how three-body
correlations are reorganized within the extended four-particle halo
structure.

The model is first benchmarked against identical bosons, where universal
scaling relations can be tested cleanly. We then apply it to Carbon-22,
treated as a Carbon-18 core plus four valence neutrons organized by two
distinct halo energy scales, with proper antisymmetrization of the halo
neutrons. One-body densities, root-mean-square distances and the matter
radius are computed and expressed in dimensionless form using the relevant
halo momentum scales. The results test the emergence and robustness of
universal scaling behavior across a wide range of scale ratios.

Orateur: Dr Rafael Francisco (Laboratoire De Physique Des 2 Infinite Irène Joliot-Curie)

19:10 → 21:00 Poster session

19:10 Ab Initio Nuclear Inputs from NCSMC for Precision Atomic Measurements

Recent advances in high-precision experimental techniques, such as the QUARTET collaboration with muonic atom spectroscopy, are pushing the boundaries of our ability to measure the absolute charge radii and structural properties of light nuclei. However, extracting fundamental physics from these high-precision measurements requires equally precise, first-principles theoretical inputs. Here, I will discuss our work utilizing the ab initio No-Core Shell Model with Continuum (NCSMC), which provides an unified approach to describe both nuclear structure and reactions, to meet this need and more specifically to calculate nuclear charge and magnetic densities. These inputs can also be used for the pipeline that we are developing from nuclear to atomic ab initio QED calculation, namely Multi-Configuration Dirac-Fock method, to solve for muonic hyperfine splitting.

Orateur: Hoang Dang Khoa Nguyen (IJCLab)

19:10 Calibration of Phoswich detectors for the MORA Experiment

The observed matter–antimatter asymmetry in the Universe remains one of the major open questions in modern physics. The Matter’s Origin from RadioActivity experiment (MORA) aims to answer this question by searching for CP violation by measuring the so-called D correlation parameter from nuclear beta decay. This parameter is sensitive to time-reversal symmetry violation and therefore to CP violation via the CPT theorem.The D correlation is the triple correlation between the nuclear spin and the decay product momenta (the positron/electron and the neutrino/antineutrino) and is accessed experimentally through measuring an angular asymmetry between recoil ions (instead of the neutrino/antineutrino) and the charged leptons in the plane perpendicular to the nuclear spin.
For the detection of these products, MORA has 4 phoswich detectors to detect the beta particles and 4 MCP based recoil ion detectors. This poster will present the energy calibration of the phoswich detectors, which is essential for setting a unique energy threshold for all detectors so that we do not create a fake D correlation, and also to test the theoretical values of the final state interactions, which depend on the energy of the emitted beta. MORA will be sensitive to such effects in the future when it moves to DESIR, where a sensitivity of 10⁻⁵ will be reached.
The phoswich detector is made of a fast thin scintillator and a slow thick one, enabling the discrimination between emitted betas and gammas. This adds complexity to the calibration process since the signals are correlated and each layer has a different gain.

Orateur: Mme Marah Jbayli (GANIL)

19:10 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 phase are the implementation of a control gas mixing system, an efficient ion neutralization mechanism, and stable, long-range laser scans for probing the produced molecules.
In this contribution, the efforts made towards the fulfilment of these objectives will be presented. I will show the developments of a pulsed, broadband Ti:sa grating cavity, as well finite-element simulations for gas mixing and ion neutralization, which are the first steps for laser spectroscopy of molecules at S3-LEB.

[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)

Orateur: Afonso SIMOES DOS SANTOS VICENTE (IJCLab)

19:10 Exotic decay channels at S3-LEB: new detection setup for proton radioactivity and more

Most of the known unstable nuclei undergo one of the main decay channels by emitting α/β particles, or γ rays. In some cases, however, more rare and exotic phenomena, like proton radioactivity, cluster radioactivity or β-delayed fission, emerge and characterise different regions of the nuclear chart.

Neutron-deficient nuclei approaching the proton drip-line start having negative proton separation energy and can open up to the possibility of proton radioactivity. While this decay channel has been studied in several nuclei with 50 < Z < 83 [1], there are still some gaps in different isotopic chains of this region that prevent mapping a precise outline of the proton drip-line. Additionally, a systematic characterisation of the phase transition between β decay and proton emission was not conducted so far.

While proton radioactivity involves the loss of a single nucleon, cluster radioactivity is characterised by the emission of a product heavier than an α particle but lighter than usual fission fragments. This process has been mostly observed in heavy nuclei in the actinides region with emitted clusters between $^{12}$C and $^{34}$Si [2, 3], but theoretical calculations predict the possibility of observing such decay mode in nuclei above the doubly-magic $^{100}$Sn, pointing to a new island of cluster radioactivity for lighter nuclei [4].

Beta-delayed fission (βDF), on the other hand, is a two-step process and has been so far studied in neutron-deficient and neutron-rich nuclei above thallium, with most of the experimental results in the neutron-deficient lead and trans-uranium regions of the nuclear chart [5, 6]. A recently developed theoretical framework can satisfactorily reproduce the experimental βDF probabilities with a global RMS deviation of two orders of magnitude, and was used to predict new cases to be studied experimentally both in the neutron-deficient and neutron-rich regions of the nuclear chart [6].

The nuclei undergoing the decays described above could be studied using the pure beams that will be achieved at S$^3$-LEB. Because of the rarity of these phenomena, it is important to build an experimental setup that would enable the detection of the decay products in the different exotic processes. The decay channels of interest are in competition with the other main decay modes, thus, the setup needs to have a good sensitivity and the capability of neglecting (if needed) all signals coming from the competing processes. Moreover, the system needs to be coupled to the S$^3$-LEB beamline where radioactive ion beams are delivered to the experimental setup with an energy of 3 keV. For this purpose, the possibility of using systems like a Time Projection Chamber (TPC), Si-Si or gas-Si telescope detectors is under investigation. This contribution will discuss the results from the first studies and tests, and future developments foreseen for the setup.

Acknowledgements
S3LEB has received funding from the French Research Ministry through the National Research Agency under contract number ANR-13-BS05-0013, from the Research Foundation - Flanders (FWO) under the International Research Infrastructure program number I002219N, from the Research Coordination Office – KU Leuven (C14/22/104), from the European Research Council under contract number ERC-2011-AdG-291561-HELIOS, from the FWO and F.R.S.-FNRS under the Excellence of Science (EOS) programme (40007501),from the European Union’s Horizon 2020 research and innovation program under grant agreement number 654002–ENSAR2–H2020-INFRAIA-2014-2015 and under grant agreement number 861198–LISA–H2020-MSCA-ITN-2019 and from IN2P3-DSM/CEA and GSI under the French-German collaboration agreement number PN1064.

References
[1] P. J. Woods, C. N. Davids, Annu. Rev. Nucl. Part. Sci. 47:541-90 (1997)
[2] D. N. Poenaru et al., J. Phys. G: Nucl. Phys. 10 L183 (1984)
[3] R. Bonetti, A. Guglielmetti, Rep. Phys. 59 (2), 301–310 (2007)
[4] C. Qi et al., Phys. Rev. C 80, 044326 (2009)
[5] S. Bara et al., Phys. Rev. C 111, 065803 (2025)
[6] A. N. Andreyev et al., Rev. Mod. Phys. 85, 1541 (2013)
[7] S. Bara, Experimental and theoretical studies of $\beta$-delayed fission. PhD thesis, KU Leuven (2025)

Orateur: Silvia Bara (IKS, KU Leuven, Belgium)

19:10 Probing Beyond the Standard Model with Beta Decay and Electron Capture

Nuclear beta decay and electron capture allow us to probe the Standard Model (SM) and search for new physics in competitive and complementary ways to the LHC. In particular, beta decay can be extremely sensitive to exotic scalar and tensor currents at the TeV scale through precision measurements. This sensitivity shows up most clearly in the Fierz interference term, $b_F$, which is linearly dependent on these exotic currents.
Electron capture and $\beta^+$ decay show an opposite dependence to $b_F$ but probe the same nuclear matrix element, such that their ratio becomes a very sensitive probe to new physics with reduced nuclear structure contributions. The remaining nucleus-sensitive corrections depend on the shape factor, $C$, for both. The latter can be expressed as a combination of form factors, which will contain the nuclear structure information and the convolution of the lepton wave functions. We will report on the calculation of these residual nuclear structure corrections using the Behrens-Bühring formalism and shell model calculations.

Orateur: M. Victor Dumenil (LPC Caen)

19:10 Revisiting 48Cr: New Shell Model Insights into Nuclear Structure

The 48Cr nucleus stands as a paradigmatic example of a nuclear rotor within the pf-shell.
Available shell-model and mean-field calculations for this nucleus consistently
reveal features of well-deformed systems: a rotational-type energy spectrum,
a bell-shaped trend in B(E2; 2+->0+) transitions across the Cr isotopic chain (peaking at 48Cr),
and significant ground-state deformation parameters.
Despite this robust theoretical framework, the experimentally measured B(E2; 4+->2+)/B(E2; 2+->0+)
ratio—close to 1 is not consistent with the expectations for a deformed rotor (value near 1.8).
This discrepancy has motivated a new experimental proposal for Coulomb excitation of 48Cr at GANIL (E890_23).
In this work, we present a comprehensive, updated shell-model analysis of 48Cr and of neighbouring nuclei.
We provide a complete set of predictions for the energy spectra, B(E2) transition strengths,
deformation parameters, and, for the first time, of the shape invariants, and discuss their implications
in the context of existing experimental data and other theoretical approaches.

Orateur: M. Oscar Le Noan (IPHC Strasbourg)

19:15 Development of Control and Data Acquisition Systems for the S3-Low Energy Branch

The S$^3$-Low Energy Branch (S$^{3}$-LEB) was designed as a low-energy radioactive beam experiment that incorporates in-gas-jet laser resonance ionization spectroscopy (IGLIS)[1], mass spectrometry (PILGRIM)[2], and decay spectroscopy (SEASON)[3,4]. This combination of experimental techniques provides a unique capability to produce, purify, and characterize low-energy radioactive ion beams with high efficiency and low background. After a successful offline commissioning at LPC Caen with stable Er isotopes [5], the experiment was moved to the focal plane of the Super Separator Spectrometer (S$^3$) [6] at GANIL.

The design and implementation of control system and data acquisition software is critical to experimental nuclear physics, where automation and increasingly complex algorithms provide enhanced functionality and time-saving procedures for existing hardware. These tools are particularly vital to the commissioning of new experiments, where many parameters need to be tested to diagnose issues before receiving the online beam. Free and open-source tools that exist today can be used to create versatile software tailored to suit the needs of a specific experimental setup.

In this contribution the development of control system and data acquisition software, created with the aforementioned tools, will be reported upon. This Python-based software controls the S$^{3}$-LEB beamline using EPICS and PyEpics in order to perform automated processes and diagnostic tests, as well as controlling the MCS8A time-to-digital converter. Additionally, plans for future developments will be discussed.

S$^3$-LEB has received funding from the French Research Ministry through the National Research Agency under contract number ANR-13-BS05-0013, from the Research Foundation - Flanders (FWO) under the International Research Infrastructure program number I002219N, from the Research Coordination Office – KU Leuven (C14/22/104), from the European Research Council under contract number ERC-2011-AdG-291561-HELIOS, from the FWO and F.R.S.-FNRS under the Excellence of Science (EOS) programme (40007501),from the European Union’s Horizon 2020 research and innovation program under grant agreement number 654002–ENSAR2–H2020-INFRAIA-2014-2015 and under grant agreement number 861198–LISA–H2020-MSCA-ITN-2019 and from IN2P3-DSM/CEA and GSI under the French-German collaboration agreement number PN1064.

[1] R. Ferrer et al. “In gas laser ionization and spectroscopy experiments at the Superconducting Separator Spectrometer (S3): Conceptual studies and preliminary design”. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 317 (2013). XVIth International Conference on ElectroMagnetic Isotope Separators and Techniques Related to their Applications, December 2–7, 2012 at Matsue, Japan, 570–581.
[2] P. Chauveau et al. “PILGRIM, a Multi-Reflection Time-of-Flight Mass Spectrometer for Spiral2-S3 at GANIL”. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 376 (2016). Proceedings of the XVIIth International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS2015), Grand Rapids, MI, U.S.A., 11-15 May 2015, 211–215.
[3] M. Vandebrouck. “Spectroscopy Electron Alpha in Silicon bOx couNter” (2020).
[4] E. Rey-Herme. “Octupole deformation in 221Ac and development of the SEASON detector”. PhD thesis. Université Paris-Saclay, 2023.
[5] A. Ajayakumar et al. “In-gas-jet laser spectroscopy with S3-LEB”. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 539 (2023), 102–107.
[6] F. Déchery et al. “Toward the drip lines and the superheavy island of stability with the Super Separator Spectrometer S3”. The European Physical Journal A 51 (2015).

Orateur: Skyy Pineda (Laboratoire de Physique Corpusculaire de Caen)

19:15 Effect of Constraining the shell gap of $^{40}\text{Ca}$ using Modified RMF approach

Excitations across the Z=20 shell gap ($1d_{3/2} - 1f_{7/2}$) have been studied within the framework of the cranked relativistic mean field (RMF) model (Physics  Reports 322, 1 (1999)). A systematic increase in the discrepancy between theoretical predictions and experimental shell gap energy differences was observed with increasing isospin asymmetry. To address this limitation, the RMF Lagrangian was modified by incorporating additional constraints on shell gap energies during the parameter optimization procedure. The strength of the constraint was determined following the prescription of (Phys. Rev. C 6, 532 (1972)). A similar approach has also been adopted within the non relativistic framework (Phys. Rev. C 71, 024305 (2005)).
The revised parameter set exhibits a significant reduction in the discrepancy between theoretical and experimental shell gap energy differences compared with the widely used NL1 and NL3* parameterizations. In particular, a notable improvement in the description of single particle energies around $^{40}\text{Ca}$ is achieved without affecting the bulk nuclear properties. These results demonstrate the importance of incorporating shell gap constraints for improving the predictive power of RMF models in nuclear structure studies.

Orateur: Nitin Mahavar (School of Physical Sciences, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Vidyanagari Campus, Santacruz East, Mumbai - 400098, INDIA)

19:15 Probing the Nature of the Charge Radii Kink at N=126: In-source Laser Spectroscopy in the Lead Region

Nuclei near doubly magic shell closures are key benchmarks for different theoretical models, as their properties in these regions often exhibit sharp discontinuities. In the lead region ($Z=82$), isotopic chains exhibit a pronounced increase in mean-square charge radii when crossing the neutron shell closure at $N=126$. Although this “kink” feature is systematically observed, its physical origin remains under debate. Different theoretical approaches successfully reproduce the experimental trend but attribute it to distinct mechanisms [1, 2]. Additional experimental data on the mercury ($Z=80$), thallium ($Z=81$) and bismuth ($Z=83$) isotopes in this region, particularly from both ground and isomeric states, is therefore essential to constrain these physical mechanisms.

In this contribution, we present a laser spectroscopy campaign by the RILIS-IDS-ISOLTRAP collaboration targeting mercury, thallium and bismuth isotopes across the $N=126$ shell closure. The powerful in-source laser spectroscopy technique, combined with the decay-tagging method, offers a high-sensitivity approach to deduce changes in mean-square charge radii for both ground and isomeric states. The published data for neutron-rich $^{207-209}$Tl, as well as preliminary results for high-spin isomeric states in $^{212,213}$Bi and ground states in $^{209,210}$Hg, will be presented to probe the influence that the $\nu2g_{9/2}$ and $\nu1i_{11/2}$ single-particle states have on these nuclides. The experimental thallium results are compared with state-of-the-art calculations using TFFS-Fayans functionals to investigate the existence of the kink [3]. In addition, shell effects are observed in the measured nuclear magnetic dipole moments [4]. These trends offer further insight into the evolution of nuclear structure near the N=126 shell closure.

[1] P. M. Goddard et al., Phys. Rev. Lett., vol. 110, p. 032 503, 3 Jan. 2013.
[2] T. Day Goodacre et al., Phys. Rev. Lett., vol. 126, p. 032 502, 3 Jan. 2021.
[3] Z.Yue et al, Phys. Rev. C vol. 110, p. 034 315, 13 Sep. 2024
[4] Z. Yue et al., Physics Letters B 849, 138452 (2024).

Orateur: Zixuan Yue (University of York)

19:20 A new intruder state in ⁵⁷Ni revealed by fast-neutron (n,2n) spectroscopy at NFS

The $^{57}$Ni nucleus, with $Z=28$ and $N=29$, sits one neutron above the doubly-magic $^{56}$Ni core and provides a clean testing ground for cross-shell excitations across the $N=28$ gap. Its level scheme has been mapped extensively through fusion-evaporation at high spin and through single-neutron pickup at low excitation, yet a substantial region of $(J, E_x)$ phase space, low-spin states off the yrast line above 3 MeV, has been never seen before with any probe applied to date. We report the first nuclear structure study of $^{58}$Ni$(n,2n)^{57}$Ni, performed with the EXOGAM HPGe array at the NFS facility of GANIL-SPIRAL2 using a white neutron beam spanning 10-40 MeV. Coincidence $\gamma$-ray spectroscopy reveals a previously unobserved levels. The transitions are absent from background, activation, and $^{\mathrm{nat}}$Pb control measurements, and its E1 character, established from combined angular and polarization asymmetry analysis, constrains the new level to a positive parity state. The state seems to be a strong candidate for a low-spin member of the $\nu(pf)^{-1}g_{9/2}$ intruder multiplet whose $9/2^+$ bandhead lies 400 keV higher. Cross-section measurements show discrepancies of opposite sign relative to TENDL evaluations, providing independent evidence that the new level carries significant population strength absent from current nuclear data libraries.

Orateur: Hemantika SENGAR (GANIL)

19:20 Developments of the S3-LEB ion transport and trapping : simulations and measurements

The SPIRAL2 facility in GANIL will extend the capabilities of studying exotic nuclei by producing beams of radioactive isotopes with very high intensities [1]. The Super Separator Spectrometer (S$^{3}$) will select the short-lived nuclei produced by fusion-evaporation reactions, and the S$^{3}$-Low Energy Branch (S$^{3}$-LEB), installed at the focal plane of S$^{3}$, will be dedicated to the study of ground- and isomeric-state properties using resonance laser ionization, yielding high efficiency and selectivity [2,3].

The key feature of S$^{3}$-LEB is the application of in-gas laser ionization and spectroscopy (IGLIS) in the hypersonic gas-jet [4], which reduces the Doppler and pressure broadening by at least an order of magnitude compared to the gas cell-based spectroscopy [5]. Laser spectroscopy with S$^{3}$-LEB will offer improved spectral resolution ($\approx 200$ MHz) while maintaining high efficiency. Measurements of isotope shifts and hyperfine constants at this resolution will provide access to key properties of exotic nuclei, such as nuclear spins, electromagnetic moments and changes in mean-squared charge radii even in the N=Z region of the nuclear chart [6].

Once the atoms of interest are ionized, they are guided through multiple radiofrequency quadrupole for their cooling and bunching, before being sent to the multi-reflection time-of-flight mass spectrometer, PILGRIM. In the first commissioning tests, the ions were continuously accumulated in the buncher up to the moment of their extraction, leading to a mixture of ions with different cooling times in the extracted bunch. To improve bunching, ions can be accumulated before their arrival in the buncher in order to homogenise their cooling. In this contribution, details about this new technique will be presented, and compared with detailed SIMION simulations of the S$^{3}$-LEB setup.

References

[1] F. Déchery et al., Eur. Phys. J. A 51, 66 (2015)

[2] A. Ajayakumar, et al., Nucl. Instrum. Meth. B 539, 102 (2023)

[3] J. Romans, et.al., NIM B, 536, 72 (2023)

[4] R. Ferrer. et.al., NIMS B, 317570 (2013)

[5] R. Ferrer et al., Nature Communications, 8:14520, (2017)

[6] X.F. Yang, et al., Prog. Part. Nucl. Phys. 129 (2023)

Orateur: M. Y. Merrer (Université de Caen Normandie)

19:20 Probing nuclear structure and astrophysical processes with direct reactions: overview of the INDRA-FAZIA 2025-2026 campaign

Since 2025, the INDRA-FAZIA collaboration launched a new scientific program at GANIL to explore the structure of light nuclei and astrophysical processes using direct reactions. A first experiment focused on measuring the matter radius of the carbon-12 Hoyle state via 12C+12C elastic and inelastic scattering at 105 MeV. Preliminary analysis confirms the excellent performance of FAZIA in missing-mass and invariant-mass studies, while INDRA’s scintillators demonstrated unexpected potential for gamma-ray detection.

Building on these results, a 2026 test experiment targeted the gamma decay width of the 3⁻ state in carbon-12 using (p,p’) reactions, with direct implications for the triple-alpha reaction rate in hot astrophysical environments. The setup’s unique capability to simultaneously probe multiple reaction channels, from exotic transfers (single nucleons, nucleon pairs, helium-3) to (p,alpha) and fusion reactions, enables comprehensive studies of direct reactions and light nuclei structure. A newly accepted alpha-transfer experiment will further investigate alpha-particle pre-formation probabilities in the skin of oxygen isotopes.

In this contribution, I will give an overview of the recent direct reaction campaign in D5 and discuss future plans, including the use of SPIRAL1’s radioactive ion beams and possible upgrades of FAZIA’s angular resolution to enhance invariant-mass performances.

Orateur: Dr Diego Gruyer (LPC Caen)

19:25 Grain Size Effects on Radiation-Induced Structural Disorder and Local Bonding Evolution in Ce0.75Gd0.25O2 Correlated with First-Principles Insights

Understanding how fluorite oxides accommodate irradiation-induced defects is important for the development of radiation-tolerant materials for advanced nuclear systems. In this work, 25 mol% Gd₂O₃-doped CeO₂ nanopowders were synthesized and sintered at 800°C and 1300°C to obtain fluorite microstructures with different grain sizes and investigate their grain-size-dependent response under swift heavy ion (SHI) irradiation. The pellets were irradiated with 100 MeV iodine ions at room temperature to simulate electronic excitation damage caused by fission fragments in nuclear reactor environments. Structural and local electronic modifications were systematically studied using synchrotron GIXRD, Raman spectroscopy, and XANES/EXAFS analyses. Both samples retained the fluorite cubic structure up to the highest fluence of 1×10¹⁴ ions/cm², although the fine-grained sample exhibited comparatively stronger irradiation-induced disorder than the coarse-grained sample. Synchrotron GIXRD revealed lattice distortion, peak broadening, and microstrain accumulation after irradiation. Raman spectroscopy showed broadening and redshift of the Raman-active modes, indicating enhanced oxygen sublattice disorder and defect-complex formation. XANES analysis suggested partial irradiation-induced Ce⁴⁺ to Ce³⁺ reduction, while EXAFS revealed local coordination changes, including Ce–O bond elongation and perturbation of the Gd–O environment associated with oxygen-vacancy-mediated structural relaxation. First-principles GGA–PBE calculations further supported oxygen vacancy stabilization in Gd-doped ceria. These findings provide important insight into defect evolution and local structural relaxation in irradiated fluorite oxides for advanced nuclear applications.

Orateur: VIVEK KUMAR (Jawaharlal Nehru University)

19:25 Status of the RFQ Cooler-Buncher for the MORA Experiment at DESIR

The MORA project [1] aims to perform a high-precision measurement of the
D correlation in nuclear beta decay in order to search for CP violation,
using a transparent Paul trap combined with laser orientation
techniques. The experiment is currently installed at JYFL (Finland),
where it operates with a Mg beam provided by the IGISOL facility. In
the near future, MORA will be moved to the DESIR experimental hall
(GANIL, France), where measurements with both 23Mg and 39Ca beams will
be performed. This relocation is motivated by the higher beam
intensities and improved purity available at DESIR, which are required
to reach the targeted sensitivity.

To connect MORA to DESIR, a dedicated RFQ cooler-buncher (RFQ-CB) has
been built; the mechanical construction is now nearing completion, and
the commissioning will start by the end of this year. Installed a few
meters upstream of the MORA Paul trap, it is designed to deliver up to
10e7 ions per bunch into the trapping system, with a target capture of
up to 10e6 ions in the Paul trap.

This poster presents the current status of the RFQ-CB system. The RFQ-CB
design and the pulse drift tubes used for bunch energy matching are
briefly described, together with ion optics simulations performed using
SIMION. The status of the installation and the incoming commissioning of
the system will be discussed.

[1] P. Delahaye, E. Liénard, I. Moore et al., The MORA project,
Hyperfine Interactions 240, 1–13 (2019).

Orateur: vincent bosquet (LPC Caen)

20:00 Dinner

21:00 → 22:00 Dinner

mer. 23 septembre

09:00 → 10:30 Interdisciplinary Research / Applications

Président de session: emmanuel TOURON (CEA/DRF/IRFU/GANIL - Directeur Adjoint GANIL)

09:00 Invited talk

Orateur: Héloise GOUTTE (GANIL)

09:25 Invited talk

Orateur: Francois Chevalier (CEA)

09:50 Advancing Nuclear Data for Next-Generation Reactors: (n, xn γ) Cross Section Measurements at NFS

The "Nuclear Data for Reactors" (DNR) group at the Institut Pluridisciplinaire Hubert Curien (IPHC, CNRS/University of Strasbourg) leads experimental research to characterize inelastic neutron scattering and (n, xn) reaction cross sections. These data are essential for the design and safety of advanced nuclear reactors, as they influence neutron energy distribution, material activation, and reactor performance. However, current evaluated nuclear data libraries still contain significant uncertainties, especially for actinides relevant to innovative fuel cycles.
At the Neutrons For Science (NFS) facility, the DNR group recently completed measurements of the 238U(n, 2n γ) and 238U(n, 3n γ) reaction cross sections. Conducted in late 2024, this campaign utilized the MAELS (Multidetector Array for inELastic Scattering) setup, combining up to 12 High-Purity Germanium (HPGe) detectors from international partners (IPHC, JRC-Geel, IFIN-HH). The experiment integrated both prompt γ-ray spectroscopy and activation techniques, leveraging the half-life of 237U. Preliminary results show a good ability to measure the incoming neutron flux, encouraging quality of (n, xn γ) first analysis outcomes, and demonstrates the potential to measure new, precise data that will be used to effectively constrain theoretical models and subsequently the evaluated data used to simulate reactors.
Building on this success, the DNR group envisions a comprehensive measurement program covering many actinides, that started with 238U, and for which the next step will be the study of 232Th(n, 2n γ) and 232Th(n, 3n γ) reactions, to be submitted to the next PAC. Thorium-232 is a key isotope in the 232Th/233U fuel cycle, and precise cross-section data are vital for optimizing neutron economics and addressing radioprotection challenges in thorium-based reactors. The proposed experiment will feature an upgraded MAELS setup, with enhanced shielding and dual fission chambers (235U and 238U) for improved neutron flux monitoring, and activation measurements, using the 25-hour half-life of 231Th to provide independent integral cross-section data.
The DNR group’s activities at NFS highlight its commitment to improving nuclear data precision, supporting next-generation reactor development, and fostering international collaboration. Future plans include extending these methodologies to other actinides, such as 233U, 235U, and 239Pu, while addressing radioprotection constraints and optimizing experimental setups for high-activity samples.

Orateur: Dr Greg Henning (IPHC)

10:10 Neutron-Induced Light-Ion Emission Studies at GANIL-NFS with the Medley Setup

The emission of light-ion (p, d, t, He3, α) in a neutron-induced reaction can be described by different mechanisms, whose relative contribution evolves with the energy available in the system. While the compound nucleus formation dominates at lower energies, following the thermalization of excited states, a continuous, smooth process progressively emerges when moving towards intermediate energy regimes (around 20 MeV and above). This component, connecting the gap between the low-energy evaporation peak and the high-energy peaks produced by the direct reactions (such as pick-up and knock-out) can be described by the so-called pre-equilibrium process. The models used to predict the emission in this regime are strongly relying on high-quality experimental data, in order to adjust its free parameters.

In order to further investigate the pre-equilibrium emission, we carried out a study of neutron-induced light-ions emission at the Neutrons for Science (NFS) facility in GANIL, covering the (2 to 40) MeV energy range. This work comprises the commissioning of the MEDLEY setup for operation with the white neutron beam produced in the facility. Conceived and built by Uppsala University, this experimental setup is specifically designed to provide large angular coverage and optimal particle-identification capability, allowing for a clean distinction between H and He isotopes throughout the wide energy range of the experiment.

In this contribution we focus on Fe-nat measurements, as it is a structural material for which new data are of importance for different areas. We present light-ion double-differential cross section results, measured from 20° to 160°, as well as the respective angular differential cross sections, derived from the former. Total production cross sections for different neutron energies were also obtained. Our results are compared with TALYS code calculations using different parameter sets, as well as with other available datasets, which remain scarce in the literature. Specific channels were also measured, highlighting the possibility of future exclusive reactions studies at NFS.

Orateur: Lucas De Arruda Serra Filho (GANIL / Uppsala University)

10:30 → 11:00 Coffee break

11:00 → 13:05 Shell evolution

11:00 Regularities and inheritance near N = 126 probed by beams far from the valley of stability

The study of the evolution of properties of the nucleus as a function of excitation energy, angular momentum and isospin is a path for searching for simple patterns to understand its structure. Among challenging problems in physics is the understanding of emergent collective excitation modes in interacting quantum many-body systems in terms of the microscopic degrees of freedom. Such investigations along a chain of isotopes are an ideal playground in this direction.

High-spin excited states of odd-even or odd-odd nuclei typically arise from the interplay between the odd nucleons in high-$j$ orbitals and the collective behaviour of the underlying core. In this context, Au (Z = 79) isotopes provide an excellent opportunity to explore how collective nuclear modes evolve along with high-$j$ single-particle excitations over a long isotopic chain allowing us to thus probe such an interplay. However, high-spin states in neutron-rich Au isotopes approaching N = 126 remain largely unexplored due to limited methods for their production.

In this talk we will present the investigations of such states using Multi-Nucleon Transfer reactions of $^{136}$Xe (7 MeV/u) + $^{198}$Pt performed at GANIL. The spectrometers VAMOS++ and CATLIFE were combined with AGATA and EXOGAM to measure prompt and delayed - $\gamma$-rays as a function of the excitation energy of the isotopically identified fragments. After highlighting the specificities of the measurement, we will discuss the observed regularity of the measured excitation energies as a function of neutron number and their inheritance with the corresponding states in the corresponding Hg (Z = 80) isotope along with other interesting results.

Orateur: Dr Navin ALAHARI (GANIL)

11:25 Spectroscopy of neutron-rich Li isotopes for the s2384 experiment with ACTAR TPC

Neutron-rich lithium nuclei are ideal systems for studying the interplay between many-body correlations and the properties of the particle continuum. For example, $^{11}$Li and $^{12}$Li have a large neutron-to-proton imbalance and a very low neutron-separation energy, and their structure is expected to be influenced by coupling to the continuum. To date, only a few models, like the Gamow Shell Model (GSM) [1], currently treat bound, resonance, and scattering states on equal footing, making experimental data essential for constraining continuum effects.

The structure study of $^{12}$Li was measured through a one-neutron transfer reaction using a $^{11}$Li beam produced at TRIUMF with an intensity of 2000 pps at 7.5 AMeV. We used the ACTAR TPC detector[2,3], which served both as the target and the detection medium, resulting in an overall enhancement in detection efficiency. The goal of the experiment is to measure the location of the first p- and d-wave resonances and to deduce the nature of the low-energy states in $^{12}$Li. The measured states will provide crucial information on the relative positions of the 0p$_{1/2}$, 0d$_{5/2}$, and 1s$_{1/2}$ orbitals at N=9. This was the first experiment to measure the particles stopped inside the active volume of the ACTAR-TPC detector.

This talk will present preliminary results of the $^{11}$Li(d,p)$^{12}$Li experiment.

[1] N. Michel et al., Physical Review Letters 89, 42502 (2002).
[2] B. Mauss et al., Nucl. Instrum. Methods Phys. Res. A 940, 498–504 (2019).
[3] T. Roger et al., Nucl. Instrum. Methods Phys. Res. A 895, 126–134 (2018).

Orateur: Iván Blanco Calviño (IGFAE-USC)

11:45 Exotic phenomena at the dripline : the most neutron-rich boron isotopes

The study of nuclei around the neutron dripline allows to investigate surprising or unexpected phenomena that occur at the edges of the nuclear landscape. Neutron-rich nuclei provide access to regimes where the description of states becomes sensitive to nucleon-nucleon interactions, and the structure models to be challenged. In this context, the boron isotopic chain is an ideal case of study as it exhibits a wide variety of structures. Here, we focus on the most neutron-rich boron isotopes $^{18-21}$B. Although they consist of 18 to 21 nucleons, their core+neutron(s) structures allow a description using models with only two or three bodies.

First, $^{18}$B is unbound by one-neutron emission and its ground state was characterized as a virtual state [1]. In the low-energy scattering formalism within the effective range approximation, the $^{17}$B+n virtual state is described with two parameters : the scattering length $a_s$ and the effective range $r_e$ of the interaction [2]. At present, we only have an upper limit on the scattering length with $a_{s} < -50$ fm, and the effective range has not been investigated [1, 3]. For comparison, the largest scattering length at the nuclear scale is the neutron-neutron one with $a_{s} = -18,5$ fm and is of the order of several fm for most nuclear systems. If the $^{17}$B+n scattering length were large enough, of hundreds (or even thousands) of fm, $^{19}$B could exhibit universal behavior, including the possible emergence of a phenomenon never observed in nuclear physics : Efimov states [4, 5]. Finally, it is on this already very exotic system that $^{21}$B is built, the last known isotope in the chain. $^{21}$B was found to decay through direct two-neutron emission [6] but correlations between emitted neutrons were not investigated.

The structure of these boron isotopes is studied through two experiments conducted at RIKEN Nishina Center (Japan) as part of the SAMURAI collaboration using radioactive beams at $\sim230$ MeV/nucleon sent on a carbon target. $^{18}$B was populated by knockout reactions from $^{19}$C(-p) and $^{19}$B(-n) while $^{21}$B was populated from $^{22}$C(-p). The complete kinematics of the reactions were measured and the reaction products of interest, $^{17,19}$B and neutrons, were respectively detected using the SAMURAI spectrometer and the NEBULA and NeuLAND multi-neutron detectors. The relative energy spectra of the $^{17,19}B+xn$ systems were reconstructed by invariant mass method.

The ($^{19}$C, $^{17}$B+n) reaction populates only the virtual state, and the large acceptance and high resolution of the SAMURAI setup enabled its full characterization. The first measurement of the effective range of the interaction and the surprisingly large scattering length observed open the way for Efimov physics in $^{19}$B. The ($^{19}$B, $^{17}$B+n) reaction populates the virtual state but also two additional resonances. While the latter represents the first spectroscopy of $^{18}$B, the former is found to be very sensitive to the neutron separation energy of $^{19}$B. The population of a $^{21}$B resonant state via the ($^{22}$C, $^{19}$B+n+n) reaction and its decay through direct two-neutron emission was confirmed. The investigation of the correlations between emitted neutrons revealed strong neutron-neutron final-state interactions and a suppression of phase space during the two-neutron decay, a behavior that had never been reported in the literature.

[1] A. Spyrou et al. Phys. Lett. B 686 (2010) , 129-133
[2] F. Miguel Marqués and Emeline Oliveira, EPJ Web of Conf, 311,00006 (2024)
[3] S. Leblond, PhD Thesis, Université de Caen Normandie (2015)
[4] E. Hiyama et al. Phys. Rev. C 100,011603 (2019)
[5] S. Endo et al. Eur. Phys. J. A (2025)
[6] S. Leblond et al. Phys. Rev. Lett. 121,262502 (2018)

Orateur: Emeline Oliveira (CEA IRFU-DPHN)

12:05 Probing spin-orbit splitting and shell evolution in $^{34}$Si via the $^{34}$Si$(p,d)$$^{33}$Si transfer reaction

Exotic nuclei offer a unique window into the fundamental properties of nuclear forces, particularly through the evolution of their shell structure. Far from the valley of stability, canonical magic numbers are no longer preserved: shell gaps can weaken or vanish entirely, driven by the proton-neutron interaction at the microscopic level. The monopole component of this interaction is understood to be a key driver, reshaping effective single-particle energies across the nuclear chart. However, isolating and quantifying the contributions of individual interaction terms remains an open challenge in nuclear structure.

The $N = 20$ isotonic chain, from $^{40}$Ca to $^{34}$Si, offers a favourable framework to isolate the spin-orbit interaction. In this region, proton occupation of the $2s_{1/2}$ orbital suppresses tensor-force contributions, making the neutron $d$-shell spin-orbit splitting a sensitive probe of the spin-orbit term and its dependence on nuclear density and isospin. Existing data for $^{39}$Ca and $^{35}$S already hint at deviations from semi-empirical trends, yet the chain remains incomplete toward $Z = 14$.

The nucleus $^{34}$Si stands out as a particularly interesting case. Several observables point to a doubly-magic character: the first excited state is a $0^+$, and the $2^+$ state lies above 3 MeV, indicative of a robust shell closure. At the same time, $^{34}$Si sits at the edge of the $N = 20$ island of inversion, where the weakening of the $N = 20$ shell gap favours intruder configurations involving particle-hole excitations across the $sd$-$pf$ shell gap, in contrast to the behaviour expected of a magic nucleus.

To address these open questions, we performed a one-neutron transfer experiment at GANIL using the reaction $^{34}$Si$(p,d)$$^{33}$Si in inverse kinematics at 50 MeV/u. A radioactive $^{34}$Si beam (produced by fragmentation and selected by the LISE spectrometer) impinged on a CH$_2$ target. The MUST2+EXOGAM+Zero-Degree Detection setup enabled the measurement of deuterons, $\gamma$ rays, and heavy recoils in coincidence. Via the missing-mass technique, this gave access to differential cross sections and spectroscopic factors for the ground state, isomeric, and
neutron-unbound states.

This experiment pursues two complementary physics goals: (i) measuring the neutron $1d_{3/2}$-$1d_{5/2}$ spin-orbit splitting in $^{33}$Si, thereby extending the isotonic chain to $Z = 14$; and (ii) probing the doubly-magic character of $^{34}$Si through the stiffness of its Fermi surface, complementing existing $^{34}$Si$(d,p)$$^{35}$Si data. Preliminary results and perspectives for comparison with theoretical calculations will be presented.

Orateur: Raquel Nicolás Del Álamo (INFN Padova and Università degli studi di Padova)

12:25 Probing the low-spin structure of $^{46}$K via $^{46}$Ar~$\beta$ decay

Beta-decay studies provide a powerful and selective tool for investigating low-spin states in atomic nuclei, offering information that is complementary to, and often extends, that obtained from direct reaction studies.
In this work, we present a study of low-spin excited states in $^{46}$K, populated via the $\beta$ decay from the $0^{+}$ ground state of $^{46}$Ar. The nucleus $^{46}$K ($Z=19$, $N=27$) lies in the vicinity of the $Z=20$ and $N=28$ shell closures, a region that has attracted considerable attention due to the evolution of the proton shell gap between the $1d_{3/2}$ and $2s_{1/2}$ orbitals [1-3]. Recent transfer-reaction studies of the neighboring $^{46}$Ar [4] have shown that its ground state is largely characterized by a $\pi(2s_{1/2}^{0}1d_{3/2}^{4})$ configuration, making it a candidate for a bubble nucleus and for a possible new proton magic number at $Z=18$. In parallel, direct-reaction studies on potassium isotopes have explored the degree of mixing between proton configurations, driven by the near-degeneracy of of the $\pi(2s_{1/2})$ and $\pi(1d_{3/2})$ orbitals in this mass region, as well as cross-shell excitations through reactions such as $^{48}$Ca(d,$\alpha$),$^{48}$Ca(p,$^{3}$He) and $^{47}$K(d,t)$^{46}$K [5-7]. The latter reaction has been shown to preferentially populate states in $^{46}$K with a dominant $\pi(2s_{1/2}^{-1}1d_{3/2}^{3})$ character, reflecting the structure of the $^{47}$K ground state.
Within this framework, $\beta$-decay spectroscopy of $^{46}$K provides complementary and overlapping insights into its low-spin structure, populating states that are weakly or not observed in direct reactions while also probing configurations accessed by both mechanisms. Owing to the higher intensity of the radioactive ion beam and the use of the state-of-the-art AGATA spectrometer [8], an extended level scheme has been established compared to previous $\beta$-decay studies [9,10], together with new estimates of $\beta$-decay branching ratios. These results will provide additional constraints on spin and parity assignments and contribute to a more detailed characterization of the underlying nuclear wave functions. Combined with the additional data sets obtained at the GANIL facility--namely transfer reactions on $^{46}$Ar and $^{47}$K beams--this work allows us to establish a coherent picture of the proton shell evolution in the vicinity of the $Z=20$ and $N=28$ shell closures.

[1] C. J. Paxman et al., Phys. Rev. Lett. 134.16, 162504 (2025).
[2] Y. L. Sun et al., Phys. Lett. B 802 135215 (2020).
[3] J. Papuga et al., Phys. Rev. C 90.3, 034321 (2014).
[4] D. Brugnara, et al., arXiv preprint arXiv:2506.23228 (2025).
[5] W. W. Daehnick, J. H. Orloff, and T. S. Bhatia, Phys. Rev. C 10.1, 136 (1974).
[6] W. W. Daehnick, and R. Sherr, Phys. Rev. C 7.1, 150 (1973).
[7] C. J. Paxman et al., arXiv: 2601.06242. (2026).
[8] S. Akkoyun et al., Nucl. Instrum. Methods A 668, 26-58 (2012).
[9] A. Huck et al., Phys. Rev. C 21.2, 712 (1980).
[10] R. F. Petry et al., Phys. Rev. C 17.6, 2197 (1978).

Orateur: Sara Pigliapoco (GANIL)

12:45 Shell evolution in oxygen probed through unbound states via 19O(d,p$\gamma$)

The neutron dripline in oxygen isotopes presents a clear challenge and unique opportunity for studies of shell evolution and nuclear structure. The heaviest observed bound isotope of fluorine (Z=9) has 22 neutrons, whereas oxygen -- with only one fewer proton, Z=8 -- can only bind 16 neutrons. This striking anomaly is a result of an increase in the spacing between the $\nu$(d$_{3/2}$) orbital and the $\nu$(s$_{1/2}$ d$_{5/2}$) orbitals, which could only be explained by the inclusion of three-body forces. As such, measurements relating to the $\nu$(d$_{3/2}$) orbital in oxygen isotopes are of significant interest, in order to test our current models. Unfortunately, comprehensive spectroscopy close to the dripline is limited by the intensity and quality of radioactive isotope beams. In this work, we instead search for $\nu$(d$_{3/2}$) orbital occupation in the the high-energy states of a less-exotic isotope.

The single-neutron transfer reaction $^{19}$O(d,p)$^{20}$O has been performed at GANIL using a high-quality radioactive beam of the near-stable isotope 19O. This beam was impinged on a solid CD2 target (both with and without gold foil backing) and states up to and above the neutron separation energy were populated. The resulting $^{20}$O heavy recoil, ejected proton, and prompt gamma-ray emissions were detected using the state-of-the-art MUGAST+AGATA+VAMOS triple-coincidence experimental set-up. Bound states populated by s-wave and d-wave transfer have been identified, and angular distributions of at least three unbound states between 7.6 MeV and 9.0 MeV have been observed. These unbound states have been accessed for the first time through the 19O(d,p) channel, providing insight into the distribution of single-particle strength in this high-energy region.

Orateur: Charlie James PAXMAN (GANIL)

13:05 → 14:30 Lunch

14:30 → 19:00 Excursion & Free time

19:30 → 20:30 Dinner

20:30 → 22:00 GUEC Session

jeu. 24 septembre

09:00 → 10:40 Present & Future GANIL Facilities

Président de session: Jean-Charles THOMAS (Grand Accélérateur National d'Ions Lourds)

09:00 Invited talk

Orateur: Dr Emmanuel CLEMENT (GANIL)

09:25 Invited talk

Orateur: Julien PIOT (GANIL)

09:50 Invited talk

Orateur: Sarina Geldhof (GANIL)

10:15 Invited talk

Orateur: Dr Oleg Tarasov (FRIB / MSU)

10:40 → 11:00 Coffee break

11:00 → 13:10 Heavy and Superheavy nuclei

Président de session: Araceli LOPEZ-MARTENS (IJCLab)

11:00 Invited talk

Orateur: Dr Frédéric Nowacki (IPHC Strasbourg)

11:25 Reaction dynamics in the synthesis of superheavy nuclei

The synthesis of superheavy nuclei (SHN) in heavy-ion fusion-evaporation reactions is governed by a delicate interplay between two competing effects. On one hand, the capture and fusion cross section rises with the bombarding energy as the projectile overcomes the Coulomb barrier and the dinuclear system evolves toward a compound nucleus. On the other hand, the survival probability of the excited compound nucleus against fission decreases rapidly with increasing excitation energy, since each neutron evaporation step competes with the dominant fission channel. The convolution of these two opposing trends produces sharply peaked excitation functions and pushes the production cross sections for the heaviest elements down to the picobarn level, and approaching the femtobarn regime for the most exotic systems.

This contribution discusses what can be learned about the reaction mechanism from the available experimental data — including excitation functions, evaporation residue cross sections, and quasifission signatures — and how this understanding can be used to constrain theoretical models and guide predictions for as-yet unobserved reactions. Particular emphasis is placed on the synthesis of elements 119 and 120, where the unavailability of suitable actinide targets paired with 48Ca beams forces the use of heavier projectiles. In such asymmetric systems the entrance-channel dynamics and the choice of the optimal excitation energy window become decisive factors for the success of the experimental campaigns currently being prepared at major SHE factories worldwide.

Orateur: Tomasz Cap (National Centre for Nuclear Research)

11:50 A compact continuous-wave laser cavity for laser spectroscopy at GISELE/FRIENDS$^{3}$

The GANIL accelerator complex in Caen (France) recently commissioned a new superconducting linear accelerator as part of the SPIRAL2 facility. This facility enables the production of heavy and super-heavy radionuclides via fusion-evaporation reactions at the entrance of the Super Separator Spectrometer (S$^{3}$) experimental area. There, the secondary beam undergoes mass separation and focusing to be finally delivered to the focal plane for experiments [1]. Located at the S$^{3}$ focal point, the S$^{3}$ Low Energy Branch (S$^{3}$-LEB) is a low-energy experiment dedicated to the study of nuclides using the In-Gas Laser Ionization Spectroscopy (IGLIS) technique, as well as decay spectroscopy and mass spectrometry [2]. These techniques allow to probe the structure of exotic nuclei, providing access to properties such as the mean-square charge radius, the spin and the magnetic and quadrupole moments.

Due to its limited extraction time, the current S$^{3}$-LEB gas cell allows only the study of nuclides with a half-life of approximately 600 ms. In order to enhance the experimental possibilities of S$^{3}$-LEB, an R&D platform called FRIENDS$^{3}$ (Fast Radioactive Ion Extraction and Neutralization Device for S$^{3}$) has been conceived, constructed and is currently in test phase at GANIL [3],[4],[5]. This platform is used to characterize a new gas cell design, and to study new neutralization techniques. Specifically, we aim to minimize the extraction time, while maximizing the extraction and neutralization efficiency at the same time.

The lasers required to perform In-Gas Jet Laser Ionization Spectroscopy at the FRIENDS$^{3}$ setup are delivered from the GISELE laboratory [6]. High resolution spectroscopy is achieved using a pulsed single-mode Injection-Locked Ti:sa cavity (ILC) seeded by an External Cavity Diode Laser (ECDL). However, in response to our needs for a seed with a wider tunable wavelength range, a home-made continuous wave (CW) Ti:sa laser [7] is under development.

During the first part of this contribution I will introduce the GISELE and FRIENDS$^{3}$ setups and their current status. Thereafter, recent progress regarding the CW Ti:sa and preliminary results of the laser spectroscopy of stable dysprosium obtained with the CW Ti:sa as seed, will be presented. The first result of the characterization studies of the FRIENDS$^{3}$ new gas cell will be finally reported.

Acknowledgements

S$^{3}$ has been funded by the French Research Ministry, National Research Agency (ANR), through the EQUIPEX(EQUIPment of EXcellence) reference ANR-10EQPX- 46, the FEDER (Fonds Européen de Développement Economique et Régional), the CPER (Contrat Plan Etat Région) E2S2 and E2S3, and supported by the U.S.Department of Energy, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357 and by the E.C.FP7-INFRASTRUCTURES 2007, SPIRAL2 Preparatory Phase, Grant agreement No.: 212692.

S$^{3}$LEB has received funding from the French Research Ministry through the National Research Agency under contract number ANR-13-BS05-0013 and ANR-21-CE31-0001, from the Research Foundation - Flanders (FWO) under the International Research Infrastructure program number I002219N, from the Research CoordinationOffice – KU Leuven (C14/22/104), from the European Research Council under contract number ERC-2011-AdG-291561-HELIOS, from the FWO and F.R.S.-FNRS under the Excellence of Science (EOS) programme(40007501), from the European Union’s Horizon 2020 research and innovation program under grant agreement number 654002–ENSAR2–H2020-INFRAIA-2014-2015 and under grant agreement number 861198–LISA–H2020-MSCA-ITN-2019 and from IN2P3-DSM/CEA and GSI under the French-German collaboration agreement number PN1064.

References

[1] A. Drouart et al. en. In: J. Phys.: Conf. Ser. 1643.1 (Dec. 2020), p. 012032.
[2] A. Ajayakumar et al. In: Nucl.Instrum.Meth.B. Vol. 539. Daejeon, South Korea, Oct. 2022, pp. 102–107.
[3] W. Dong. en. PhD thesis. Université Paris-Saclay, Nov. 2024.
[4]E. Morin et al. In: Nucl.Instrum.Meth.B 573 (Apr. 2026), p. 166027.
[5] W. Dong et al. In: (Jan. 2026). arXiv:2601.12009 [physics].
[6] A. M. Sj ̈odin et al. en. In: Hyperfine Interact 216.1-3 (Apr. 2013), pp. 121–126.
[7] V. Sonnenschein et al. In: Hyperfine Interact 241.1 (Feb. 2020), p. 32.

Orateur: Valentin MARCHAND (IJCLab : Nucléaire - SDF)

12:10 MR-ToF measurements of the exotic 94Ag

In the last decade Multi-Reflection Time-of-Flight Mass-Spectrometers (MR-ToF-MS) [1] have been established as integral parts of radioactive ion beam facilities. These devices are used to separate and to measure the atomic masses of particularly exotic, short-lived radioactive nuclei to high precision, shedding light on the nuclear forces [2], the composition of neutron stars [3], and the yields of radioactive ion production [4]. An MR-ToF-MS has been integrated to the University of Jyväskylä Ion-Guide Isotope-Separator On-Line (IGISOL) facility [5] and utilized for mass separation and measurements of exotic radioactive nuclei. This talk will feature technical developments of the IGISOL MR-ToF-MS and the miniaturized radiofrequency quadrupole cooler-buncher [6] as well on-line measurements that present the solution to the long-standing two-proton decay conundrum of 94Ag(21+).

References

[1] W. R. Plaß, et al., “Multiple-reflection time-of-flight mass spectrometry”, International Journal of Mass Spectrometry, vol. 349-350, pp. 134–144, 2013. doi: 10.1016/j.ijms.2013.06.005.

[2] F. Wienholtz et al. “Masses of exotic calcium isotopes pin down nuclear forces.” Nature vol. 498, pp. 346–349 (2013). doi: 10.1038/nature12226

[3] R. N. Wolf et al. “Plumbing Neutron Stars to New Depths with the Binding Energy of the Exotic Nuclide 82Zn”, Physical Review Letters, vol. 110, iss. 4, 2013. doi: 10.1103/PhysRevLett.110.041101

[4] S. Canarozzo et al. “Isomeric yield ratios and mass spectrometry of Y and Nb isotopes in the neutron-rich N=60 region: the unusual case of 98Y” arXiv 2025 url: https://arxiv.org/abs/2504.11274

[5] I. Moore et al., “Towards commissioning the new IGISOL-4 facility”, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, vol. 317, pp. 208–213, 2013. doi: 10.1016/j.nimb.2013.06.036.

[6] V. A. Virtanen, et al., “Miniaturised cooler-buncher for reduction of longitudinal emittance at IGISOL”, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment vol. 1072, 170186, 2025. doi: 10.1016/j.nima.2024.170186.

Orateur: Ville Virtanen (University of Jyväskylä)

12:30 Laser resonance chromatography at S3: a novel method for superheavy element spectroscopy

Optical spectral lines serve as unique fingerprints for the elements and provide the most precise means to study their electronic structure, as well as reveal properties of atomic nuclei. Atomic spectroscopy has been advancing towards ever heavier atomic species, with superheavy elements (SHE) being of particular interest due to their role in understanding nuclear stability at the top of the nuclear chart.

Currently, it has reached as far as nobelium (Z = 102), which has been studied via resonance ionization spectroscopy [1, 2]. The spectra of even heavier elements have remained elusive, primarily due to the short half-lives of the radionuclides combined with low production rates in nuclear fusion-evaporation reactions, requiring faster measurements and higher experimental sensitivities.

A potential solution to overcome these obstacles is the newly conceived technique of laser resonance chromatography (LRC) [3], which combines laser probing with ion mobility spectrometry. LRC reveals the resonant laser excitation from if an ion from the ground to an excited state by the change in its drift time towards a particle detector for different electronic states. This method circumvents the need for resonance ionization and fluorescence detection, allowing for a fast and sensitive laser spectroscopy of next heavy elements such as lawrencium (Z=103) and rutherfordium (Z=104) [4, 5], as well as some SHEs of extremely reduced production rates.

In this contribution I will present the LRC technique and discuss the SIMION simulation efforts dedicated to the development of the steering and detection section of the LRC experiment, as well as present the experimental design to be implemented at the S3 installation of GANIL/SPIRAL2 for the LRC study of neutron-deficient actinium (Z = 89) and lawrencium isotopes.

References:
[1] M. Laatiaoui et al., Nature 538 (2016) 495.
[2] J. Lantis et al., Phys. Rev. Res. 6 (2024) 023318
[3] M. Laatiaoui et al., PRL 125 (2020) 023002.
[4] H. Ramanantoanina et al., Phys. Rev. A (2021) 022813
[5] G.Visentin et al., Phys. Rev. A (2024) 012805

S3 has been funded by the French Research Ministry, National Research Agency (ANR), through the EQUIPEX (EQUIPment of EXcellence) reference ANR-10EQPX- 46, the FEDER (Fonds Européen de Développement Economique et Régional), the CPER (Contrat Plan Etat Région) E2S2 and E2S3, and supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357 and by the E.C.FP7-INFRASTRUCTURES 2007, SPIRAL2 Preparatory Phase, Grant agreement No.: 212692.

Orateur: Tudor Stefan (GANIL)

12:50 Commissioning results of the S3 Low Energy Branch at GANIL-SPIRAL2

Laser spectroscopy for studying the ground- and isomeric-state properties of exotic nuclei has established itself as a versatile and powerful tool, capable of providing access to nuclear-model-independent data such as mean-square charge radii, magnetic dipole and electric quadrupole moments, and nuclear spins [1]. For resonance ionization spectroscopy, a critical set of conditions is having tunable laser sources with narrow bandwidth (100-200 MHz), high repetition rate (10 kHz) and high power (∼ hundreds of μJ average energy per pulse), which assure high efficiency and allow measuring the hyperfine structure and isotope shift along isotopic chains.

The Low-Energy-Branch (LEB) coupled to the Super Separator Spectrometer (S3) facility at GANIL-SPIRAL2 will enable high-resolution in-gas-jet laser ionization spectroscopy of fusion-evaporation products, overcoming the present experimental constraints of low production while maintaining an excellent spectral resolution ([2, 3, 4]). Following resonance laser ionization, the highly pure radioactive ion beams can be sent to a number of different experimental setups, such as the SEASON decay station [5], a MR-TOF-MS setup referred to PILGRIM [6]; or be transported to the DESIR facility [7] in the coming years enabling further high precision studies.

The setup has been installed at the focal plane of S3 and new tests have been performed to ensure its performance in preparation for the first experiments with S3 beams. The first foreseen fusion-evaporation reaction during the on-line commissioning will give the opportunity to obtain nuclear and atomic information of neutron-deficient isotopes around erbium and towards the N = 82 shell closure.

In this contribution I will present results of recent off-line experiments performed with S3-LEB in its current location, including the trapping and mass selection of ions with PILGRIM. Furthermore, the different laser systems currently under preparation in the new laser laboratory ALTISA will be shown, as well as laser spectroscopy results of stable dysprosium and gadolinium isotopes in an atomic beam unit, in preparation of the on-line commissioning.

References
[1] X.F. Yang, et al., Prog. Part. Nucl. Phys. 129 (2023).
[2] R. Ferrer et al., Nucl. Instrum. Meth. B 317 (2013) 570–581.
[3] A. Ajayakumar, et al., Nucl. Instrum. Meth. B 539, 102 (2023).
[4] J. Romans, et al., Nucl. Instrum. Meth. B 536, 72 (2023).
[5] E. Rey-herme, PhD thesis. Universit´e Paris-Saclay (2023).
[6] P. Chauveau, et al., Nucl. Instrum. Meth. B 376 (2016) 211–215.
[7] Thomas, B. Blank, French-Japanese sym. on nuclear structure, (2011).

Orateur: Andres Felipe LOPEZ (PhD GANIL CNRS)

13:10 → 15:00 Lunch

15:00 → 16:05 Heavy ion Collisions

15:00 Invited talk

Orateur: Caterina Ciampi (GANIL)

15:25 Constraining the nuclear equation of state with heavy-ion collisions at GANIL

The equation of state (EoS) of neutron-rich matter is a cornerstone for understanding the structure and dynamics of neutron stars, from their radii and tidal deformability to cooling mechanisms. However, the density dependence of the nuclear symmetry energy term remains a major source of uncertainty, particularly at densities near, and above, nuclear saturation density. While astrophysical observations (e.g., gravitational waves, pulsar measurements) provide integrated constraints, laboratory experiments at GANIL energies are uniquely suited to probe the EoS between 0.5 and 1.5 saturation density, bridging the gap between nuclear structure and astrophysics.

In this contribution, I will present the EoS constraint recently published by the INDRA-FAZIA collaboration [1]. By combining the excellent isotopic resolution of FAZIA with a model-independent centrality reconstruction, we were able to extract the evolution of the isospin transport ratio (ITR) measured in 58,64Ni+58,64Ni collisions at 32 MeV/nucleon as a function of the impact parameter [2]. We then compared the experimental ITR data to predictions from the BUU@VECC-McGill transport model [3], employing state-of-the-art nuclear functionals, including ab initio chiral-EFT interactions and phenomenological models (SGII, NL3, SAMI) to extract a constraint on the symmetry energy (S(ρ)). A consistent study of the time evolution of baryonic density and isospin current density identifies the density region most sensitive to the ITR, peaking near saturation density.

Our analysis yields a precise constraint on the symmetry energy (S = 29.1±1.1 MeV) and slope parameter (L = 38.3±7.0 MeV) at saturation density. These results exclude stiff symmetry energy behaviors and align with softer ab initio predictions. This work strengthens the synergy between nuclear experiments at GANIL and neutron star physics, offering a critical input for Bayesian inferences of the EoS in astrophysical environments.

[1] Ciampi et al., Phys. Lett. B 868 (2025) 139815
[2] Ciampi et al., Phys. Rev. C 111 (2025) 044601
[3] Mallik et al., J. Phys. G: Nucl. Part. Phys. 49 (2022) 015102.

Orateur: Dr Diego Gruyer (LPC Caen)

15:45 Μeasurement of the Ηoyle state radius using single and mutual excitation inelastic scattering

The second $0_{2}^+$ state of $^{12}$C at an excitation energy of 7.654 MeV, known as the Hoyle state [1], is crucial to understanding how $^{12}$C is formed in stellar nucleosynthesis. Despite recent studies, there is no consensus on the properties of the Hoyle state, with different theoretical models predicting a range of radii and spatial arrangements[2,3].

Experimentally, only a few attempts have been made to measure the radius of the Hoyle state, mostly through inelastic scattering angular cross sections. The most frequently cited study reported a 0.5 fm larger Hoyle state radius than the ground state radius [4] from $^{12}$C + $^{12}$C diffusion at 121.5 MeV. However, the extraction of the Hoyle state radius was based on a simple diffusion model relying on strong assumptions. Moreover, the cross section was measured at large angles, leading to the first minimum, expected at smaller angles, being missed.

To overcome these limitations, a new experiment was conducted at GANIL in 2025 to measure the Hoyle state radius by comparing single and mutual excitation in $^{12}$C + $^{12}$C inelastic scattering using the multi-detector FAZIA [5]. This comparative analysis eliminates many of the assumptions that were previously required, allowing for more accurate comparisons with modern scattering theory that incorporates realistic nuclear potentials.

In this talk, I will present this new experiment as well as the its results.

Bibliography

[1] F. Hoyle, On Nuclear Reactions Occuring in Very Hot STARS.I. the Synthesis of Elements from Carbon to Nickel, Astrophys. J. Suppl. Ser. 1, 121, (1954).

[2] Shen, S., Elhatisari, S., Lähde, T.A. et al., Emergent geometry and duality in the carbon nucleus, Nat Commun, 14, (2023)

[3] Otsuka, T., Abe, T., Yoshida, T. et al., \textit{$\alpha$-Clustering in atomic nuclei from first principles with statistical learning and the Hoyle state character, Nat Commun,13 , (2022)

[4] V. A. Maslov et al., Study of the Diffraction Scattering (^{12}C + ^{12}C)
with the Excitation of the (^{12}C) Exotic State + (0_{2}^{+})
(the Hoyle State), Physics of Particles and Nuclei Letters, 8, (2011)

[5] S Barlini et al., FAZIA: a new performing detector for charged particles, J. Phys.: Conf. Ser, 1561, (2020).

Orateur: Ilham DEKHISSI

16:05 → 16:35 Coffee break

16:35 → 19:20 Fundamental Interactions

16:35 Invited talk

Orateur: Jean-Charles THOMAS (Grand Accélérateur National d'Ions Lourds)

17:00 On the correlation between the isospin-symmetry breaking correction and $E0$-transition strengths in superallowed $0^+\rightarrow0^+$ nuclear $\beta$ decay

We investigate the correlation between the isospin-symmetry breaking correction to superallowed $0^+\rightarrow0^+$ nuclear $\beta$ decay of isotriplets and the $E0$-transition strength between the isobaric analog and the first excited $0^+$ states in the $T_z=1$ nuclei. Specifically, the correction, as obtained within the shell-model approach, is suppressed where the experimental $E0$ strength is pronounced and enhanced elsewhere. To clarify the physical origin of this behavior, we perform shell-model calculations of $E0$ strengths in $T_z=1$ and nearby nuclei with available data, using identical valence spaces and effective interactions. With appropriately chosen effective charges, the results obtained in the ZBM2 and lower-edge ZBM spaces agree fairly well with experiment for most cases. Nevertheless, ZBM-space calculations do not reasonably reproduce the $E0$ strengths in $^{20}$Ne and $^{24}$Mg, where experimental values are sizable, and an $sd$-shell description yields vanishing results. Accordingly, both the ZBM and $sd$ calculations are likely insufficient for describing the superallowed $0^+\rightarrow0^+$ nuclear $\beta$ decay of $^{22}$Mg and $^{22m}$Na, although the $E0$ strength in $^{22}$Ne is not experimentally known. Similarly, a $p$-shell description for the $A=10$ mass multiplet cannot reproduce the observed $E0$ strength in $^{10}$Be. We also derive a consistent analytical relation between the isospin-symmetry breaking correction and the $E0$ strength, under the assumption that isospin mixing occurs only between the lowest and first excited $0^+$ states in the initial and final nuclei. This result further reveals the influence of the charge radii and neutron-skin thicknesses, although this effect is generally less obvious than that associated with the $E0$ strength.

Orateur: Latsamy Xayavong (Yonsei University)

17:20 Matter's origin from the radioactivity of trapped ions

Everything we observe in the universe is thanks to interactions of particles and antiparticles, from subatomic processes to the formation of galaxies since the Big Bang. But regardless of where we look, we do not see macroscopic quantities of antimatter in nature, only in quantum interactions or produced by us in laboratories. With our current understanding of physics, when matter originated right after the Big Bang the same amount of antimatter should have been created. The universe as we know would be greatly different.

Sakharov [1] proposed 3 conditions that would create an asymmetry during baryogenesis for matter and antimatter. Processes outside of thermal equilibrium, violation of baryonic number and charge-parity (CP) violation. The MORA experiment aims to measure a CP violation to help explain the matter-antimatter asymmetry. CPV has been observed in the standard model (SM) [2-3] but this contribution is not enough to explain the amount of matter in the universe. Instead of looking in the SM we aim to find CPV in new physics with the D correlation of beta decay [4].

D is a triple correlation between the spin orientation of the parent nucleus, the beta and neutrino momentum. It is non-zero for T reversal violation, and can be calculated by measuring the angle of coincidence between the recoil ions from the decay and beta emission with a polarised (aligned) parent nucleus. In order to precisely measure D (expected to be non-zero at the 10^{-4}/10^{-5} level) we use 23Mg ions in a state of the art ion trap setup , with an octagonal array of detectors to measure the coincidences between recoil ions (MCPs) and betas (double scintillators), a laser to laser-polarise the ion cloud inside of the Paul Trap and annular Si detectors in the axis of the polarisation to measure the polarisation degree (how many trapped ions are polarised).

In 2022 the online commissioning started, then in 2024 we were able to measure a non-zero polarisation degree for the first time, and in 2025 we improved the signal to background ratio and efficiencies to get more statistics. Now, in May of 2026, our week-long measurement will attempt to measure the polarisation degree and the D correlation for the first time, inject clean 23Mg bunches into the trap, and achieve 10^4 trapped Mg ions inside the trap. In this talk I will explain the consequences of a non-zero D correlation, the experimental setup of MORA and IGISOL, and the latest experimental results.

[1] A. D. Sakharov Violation of CP invariance, C asymmetry, and baryon
asymmetry of the universe, Sov. Phys. Usp. (1991)

[2] NA48Collaboration A new measurement of direct CP violastion in two
pion decays of the neutral kaon, Physics Letters B, Volume 465 Issues 1–4
335-348 (1999)
[3] BABAR Collaboration Measurement of CP-Violating Asymmetries in B0
Decays to CP Eigenstates, Phys. Rev. Lett. 86 2515 (2001)

[4] J.D. Jackson and S.B. Treiman and H.W. Wyld Coulomb corrections in
allowed beta transitions, Nucl. Phys. 4 206-212 (1957)

Orateur: Luis Miguel Motilla Martinez (University of Jyväskylä / GANIL)

17:40 Fermi beta decay of $^{10}C$ measured with AGATA: constraints on $V_{ud}$

The Cabibbo-Kobayashi-Maskawa (CKM) matrix describes the weak charged-current interactions of quarks within the framework of the Standard Model of particle physics. It governs, in particular, $\beta$ decays through coupling with the $W^{\pm}$ bosons. To test its validity, the terms of the CKM matrix must be determined with high precision, and their uncertainties must be well understood. One of the tests of its structure relies on the unitarity relation $( \lvert V_{ud} \rvert ^2 + \lvert V_{us} \rvert ^2 + \lvert V_{ub} \rvert ^2 = 1) $. Any deviation from this unitarity could indicate the emergence of new physics beyond the Standard Model.

The dominant element of the CKM matrix, $V_{ud}$, can be experimentally determined, particularly through superallowed β transitions (lifetime and branching ratio). For $0^+ \rightarrow 0^+$ transitions, the corrected value $\cal F$t (including radiative corrections and isospin symmetry-breaking corrections) allows the extraction of the $V_{ud}$ term. Among the nuclei studied, the decay of 10C stands out due to one of the largest uncertainties in the branching ratio.
Furthermore, these transitions provide a unique probe to test the Standard Model, which predicts a purely V-A (vector and axial) weak interaction. However, in the context of physics beyond the Standard Model, extensions such as leptoquarks or charged Higgs bosons could introduce exotic contributions, such as a scalar component in the weak interaction. Thus, the parameter $C_S$ can be constrained. This contribution introduces a Fierz interference term, $b_F$, for Fermi transitions, which modifies the shape of the $\beta$ spectrum and the branching ratio.

The experiment was performed at LNL using the AGATA $\gamma$-ray tracking array. The $^{10}C$ nucleus was produced via the (p,n) reaction induced by a proton beam at 10 MeV impinging on a $^{10}B$ target. In addition, the superallowed $\beta$ branch populates the excited 0+ state of $^{10}B$ at 1740 keV, which de-excites by emitting a 1021.7 keV $\gamma$ ray. This energy coincides with the pileup of two annihilation photons (2 × 511 keV) produced in the $\beta ^+$ decay, thus introducing a contamination of the peak. A highly segmented tracking detector allows this effect to be better identified and corrected.

The experimental setup and the preliminary results will be presented and discussed.

Orateur: F. Didierjean

18:00 Nuclear moments and mean-squared charge radii of neutron deficient rhodium isotopes measured using collinear laser spectroscopy

The region between the strongly deformed nuclei around the $Z \sim 40$, $N \sim 60$ mass region and the spherical Sn chain represents a rich testing ground for nuclear structure models, probing shell evolution and the interplay between single-particle and collective degrees of freedom, as well as phenomena such as shape coexistence. In this context nuclear magnetic dipole moments are sensitive probes of the single-particle nature of nuclear configurations, while electric quadrupole moments reflect the degree of nuclear deformation. The changes in mean square charge radii further provide information on the evolution of nuclear size across an isotopic chain. Laser spectroscopy experiments enable the extraction of all these observables, along with nuclear spins, for ground and isomeric states in a nuclear model-independent manner from the measurement of isotope shifts and hyperfine structures of the atomic spectra [1].

In this contribution, the results of first collinear laser spectroscopy studies performed on a series of neutron-deficient Rh isotopes will be presented. These isotopes are expected to exhibit a structural evolution from emerging collectivity in the mid-shell region towards sphericity approaching $^{95}$Rh at $N=50$, as evidenced by observations in the neighboring Ru and Pd isotopic chains [2,3].
The isotopes of interest were produced at the IGISOL facility, University of Jyväskylä, utilizing the ion guide method [4], essential for the successful production of refractory elements such as Rh. The isotope shifts and hyperfine structure parameters of ground and isomeric states between $^{95}$Rh and $^{104}$Rh were subsequently measured via collinear fluorescence laser spectroscopy[5]. These measurements provide the first determination of mean-square charge radii and nuclear moments of ground and isomeric states across this isotopic chain. Additionally, these results will contribute to resolve ambiguities in the spin assignments of $^{95m}$Rh, $^{98m,g}$Rh, $^{100m}$Rh, and $^{102}$Rh. The extracted nuclear observables will be compared with theoretical models describing single-particle configurations and shape transitions in the region.

[1] Yang, X., et al., Progress in Particle and Nuclear Physics 129 (2020) 104005.
[2] Geldhof, S., et al., Physical review letters 128.15 (2022): 152501.
[3] Maas, B., et al., Physical review letters 135.20 (2025): 202501.
[4] Moore, I. D., et al., Hyperfine interactions 223.1 (2014): 17-62.
[5] Koszorús, Á., et al., The European Physical Journal A 60.1 (2024): 20.

Orateur: Saikumar Chinthakayala (University of Caen / GANIL)

18:20 Testing the Standard Model with the WISArD experiment

The WISArD experiment is a high precision measurement of nuclear beta decay observables to test the existence of Physics Beyond the Standard Model in the weak sector. The angular correlation parameter $a_{\beta\nu}$ and the Fierz interference term $b$ in particular, are very sensitive probes to the existence of exotic scalar or tensor currents, which are not included in the standard V-A theory of the weak interaction. The goal of the WISArD experiment is to measure these parameters in the decay of $^{32}\mathrm{Ar}$ at the challenging level of precision of about 0.1%, at which they will provide constraints on new physics competitive with direct searches conducted at high energies at LHC. The experimental setup is installed in the ISOLDE experimental hall at CERN and received several $^{32}\mathrm{Ar}$ beamtimes over the past 8 years to reach this goal. The first one, in 2018, validated the principle of the measurement and the expected gain in sensitivity of the technique with respect to state of the art results. The world's third-best result on the angular correlation coefficient $a_{\beta\nu}$ was obtained in a single measurement of a pure Fermi decay. Following a full upgrade of the experimental setup and a second test beamtime in 2021, two experimental campaigns in 2024 and 2025 were successfully conducted, allowing to accumulate enough statistics to reach the required level of precision. A careful analysis of all sources of systematic errors has been carried out and no show-stopper has been identified yet. In this talk, we will present the final result of the WISArD measurement of the correlation parameter $a_{\beta\nu}$ from the 2024 and 2025 data takings and show how it compares with global constraints on exotic scalar currents.

Orateur: Samuel Lecanuet

20:00 → 21:30 Dinner

ven. 25 septembre

09:00 → 10:40 Present & Future GANIL Facilities

Président de session: Adam Maj (IFJ PAN)

09:00 Invited talk

Orateur: BEATRIZ FERNANDEZ DOMINGUEZ (USC)

09:25 Invited talk

Orateur: Pauline Ascher (LP2iB)

09:50 Invited talk

Orateur: muriel fallot (Université de Nantes)

10:15 The ALTO research platform of IJCLab

A set of platforms is present in the Laboratory of the Physics of the two Infinities Irène Joliot-Curie (IJCLab) at Orsay, offering a large range of techniques with a high level of expertise. They support the scientific axes around the physics of the two infinities and they have a national and international impact in many scientific communities. Radioactive Ion Beams (RIBs) are currently produced in the ALTO (Accélérateur Linéaire et Tandem à Orsay) research platform (alto.ijclab.in2p3.fr). A linear accelerator provides electrons up to 50 MeV 10µA that bombard an uranium carbide target as a driver to produce neutron-rich radioactive beams via the photo-fission process [1]. A 15 MV Tandem accelerator is also in operation at ALTO, it produces a wide range of heavy ion beams, from proton up to gold. ALTO is able to provide high-flux naturally directional neutron beams with the LICORNE neutron converter in inverse kinematics [2]. With the delivery of a broad range stable and radioactive beams, its 10 beam lines and experimental halls equipped with diverse instrumentation, spectrometers and detectors, a wide-ranging research is available at ALTO from the study of the fundamental properties of nuclei, key processes for nuclear astrophysics, interaction of ions with matter to the developments in dosimetry and radiobiology. Several projects carried out at ALTO, such as the laser spectroscopy, ion trapping will be pursued at GANIL in the future low energy experimental hall DESIR. ALTO started a project of reliability and sustainability and physics program of the research platform within the framework of a national strategy. This project has an impact on the fundamental physics program, the equipment upgrades for beam production [3,4], the opening to industry and society. ALTO’s reliability enhancement efforts offer the opportunity to produce low-energy neutron rich nuclei far from the stability region for the low-energy community in France and abroad. Recently, a common strategy for ISOL beam R&D between ALTO and GANIL has begun. The general characteristics of the current developments SPACE ALTO, to increase the added value of ALTO for industrials, and BioALTO, the new experimental platform dedicated to preclinical research in hadron therapy and radiobiology, will be described. A brief description of the ALTO facility, a status of the current development on the RIBs production as well as a selection of the latest experimental results [5,6] and on-going research program will be presented.

[1] S. Essabaa et al., Nucl. Instrum. Methods Phys. Res., Sect. B 317 (2013) 218
[2] M. Lebois et al. Nucl. Instr. Meth. A 735, 145 (2014)
[3] A. Segovia-Miranda et al., Nucl. Instr. Meth. A 1080 (2025) 170785
[4] J. Guillot, B. Roussière et al., Nucl. Instr. Meth. B 559 (2025) 165600
[5] G. Tocabens et al., Phys. Rev. C 111 (2025) 034306
[6] C. Hiver, et al., Acta Phys. Pol. 18 (2025) 2A-25

Orateur: Dr Enrique Minaya Ramirez (IJCLab)

10:40 → 11:10 Coffee break

11:10 → 12:05 Conclusion

11:10 Poster award

11:25 Thesis award

11:45 Conclusion

Orateur: Hervé SAVAJOLS (GANIL)

12:05 → 13:25 Lunch

14:30 → 15:25 Shuttle to Belfort