17th Varenna Conference on Nuclear Reaction Mechanisms

14 Jun 2026, 17:00 → 19 Jun 2026, 14:00 Europe/Zurich

Villa Monastero

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Monday 15 June

09:30 → 09:40 Opening

Speaker: Francesco Cerutti (CERN)

09:40 → 11:00 Nuclear Structure

Convener: Enrico Vigezzi

09:40 Spectral Properties of Pygmy and Giant Resonances

Recent studies of γ-decays of dipole excited states, including the regions of pygmy and giant dipole resonances relative to the ground and low-energy excited states in heavy nuclei, are presented, which were achieved using a theoretical approach based on energy-density functional theory and the quasiparticle-phonon model [1]. The theoretical method and its recent developments, including reaction theory [2, 3], have been successfully applied in spectroscopic studies of nuclear excitations in different nuclei, including two-phonon states, pygmy and giant resonances, demonstrating its effectiveness and reliability. In addition to the single-particle nature of the the PDR [2, 3], analysis of inelastic photon and proton scattering data and branching ratios reveals various properties of the low-energy dipole strength that can be used to investigate the role of the quasicontinuum coupling [3, 4]. Due to this effect, we observe a shift of the dipole strength around the neutron threshold region and the GDR to low excitation energies [5].
Furthermore, our particular interest lies in the γ-decay of GDR into the ground and excited 2+ states in tin isotopes. The γ-decay of GDR has not yet been systematically investigated. Recently, a new NRF experiment on the γ-decay of GDR from the deformed Sm-154 nucleus was conducted at HIγS to explore its properties [6]. The obtained branching ratios of the γ-decay of GDR into the first 2+ and the ground states can serve as a new observable for interpreting the structure of GDR. In this context, new theoretical results are discussed.
This research was supported in part by ELI-RO_RDI_2024_AMAP of the Romanian Government.
[1] N. Tsoneva, H. Lenske, The energy density functional theory plus the quasiparticle-phonon model as a powerful tool for nuclear
structure and astrophysics, Physics of Atomic Nuclei 79, 885–903 (2016) and references cited therein.
[2] M. Spieker, A. Heusler, B.A. Braun, T. Festermann, R. Hertenberger, G. Potel, M. Szek, N. Tsoneva, M. Weinert, H.-F. Wirth and A. Zilges, Accessing the single-particle structure of the pygmy dipole resonance in 208Pb, Phys. Rev. Lett. 125, 102503 (2020).
[3] M. Weinert, M. Spieker, G. Potel, N. Tsoneva, M. Müscher, J. Wilhelmi and A. Zilges, Microscopic structure of the low-energy electric dipole response of 120Sn, Phys. Rev. Lett. 127, 242501 (2021). [4] T. Shizuma, S. Endo, A. Kimura, R. Massarczyk, R. Schwengner, R. Beyer, T. Hensel, H. Hofmann, A. Junghans, K. Römer, S.
Turkat, A. Wagner and N. Tsoneva, Distribution of the strength of a low-lying dipole in 204Pb, Phys. Rev. C 106, 044326 (2022).
[5] P.-A. Söderström, M. Markova, N. Tsoneva et al., “Statistical properties and photon power functions of the isotopes 112,114Sn below the neutron splitting threshold”, Phys. Rev. C 112, 024327 (2025).
[6] J. Kleemann, N. Pietralla, U. Friman-Gayer et al., Gamma Decay of the 154Sm Isovector Giant Dipole Resonance: Smekal-
Raman scattering as a new probe for nuclear deformation in the ground state, Phys. Rev. Lett. 134, 022503 (2025).

Speaker: Dr Nadia Tsoneva (Extreme Light Infrastructure-Nuclear Physics (ELI-NP))

10:10 Structure of 14N via $\alpha$+$^{10}$B reactions at sub-barrier energies

We investigate the spectroscopy of $^{14}$N via the $^{10}$B($\alpha$, p)$^{13}$C and $^{10}$B($\alpha$, d)$^{12}$C compound nucleus reactions at energies lower than the Coulomb barrier. The experiment is performed at the AN2000 accelerator of INFN-LNL (Italy), exploiting an array of solid-state detectors designed to cover a wide angular range. Various reaction channels are unambiguously identified, and detailed angular distributions of the differential cross section in absolute units are obtained for the first time in the explored energy region. The new data highlight the presence of resonant phenomena, allowing us to gather detailed information on the structure of some $^{14}$N excited states, try to solve ambiguities affecting various $J^\pi$ assignments, and shed light on some still-standing literature uncertainties. Furthermore, a new calculation of the reaction rate of the $^{10}$B($\alpha$, p)$^{13}$C reaction, of great interest in the nuclear astrophysics field, is performed on the basis of the newly obtained experimental data.

Speaker: Daniele Dell'Aquila

10:40 Probing nuclear excited-state properties

The intrinsic properties of the nucleus can be probed by various nuclear sensors, such as the nuclear moments that provide direct information on underlying single-particle configurations, sensitive to the distribution of protons and neutrons, and the coupling between collective and single-particle degrees of freedom. Except allowing stringent tests of nuclear models, including shell-model and mean-field approaches, these observables can probe variations across several isotopes and reveal changes in deformation, shell closures, configuration mixing.

Excited states and their nuclear moments, may be accessed in different reaction mechanisms. Therefore, different angular momenta may be studied. Together, reactions and nuclear-moment measurements form a powerful framework for exploring the underlying structure and dynamics of atomic nuclei. Examples will be discussed in the contribution, along with future plans for such investigations.

Speaker: Radomira LOZEVA

11:00 → 11:30 COFFEE BREAK

11:30 → 12:00 Form Factors

Convener: Simone Pacetti (Università degli Studi di Perugia and INFN Perugia)

11:30 How to "read" hadron timelike form factors.

For spacelike form factors (SLFFs) there is a well known interpretation in terms of static space distribution of charge and magnetic dipole. We first recall the limits of this picture, that were present in the literature of some decades ago but seem to be forgotten today. Next we discuss the corresponding picture for timelike form factors (TLFFs). These represent a time distribution of charge in generalized sense. "Time distribution" means that no space properties can be directly extracted form the TLFFs (exactly as no time evolution property can be extracted from the SLFFs). "Charge in generalized sense" means amplitude for a virtual photon to convert into a quark-antiquark pair. After this general framing, we discuss properties related to the fine measurements of the TLFFs on nucleons and baryons in the recent years, in particular those features descending from interactions of the final/initial baryon-antibaryon state. These determine visible fluctuations of the TLFFs around the fast decrease associated with the known large-q quark counting rules.

Speaker: Andrea Bianconi (Università di Brescia)

12:00 → 12:40 QCD

Convener: Simone Pacetti (Università degli Studi di Perugia and INFN Perugia)

12:00 Hyperon Form Factors in the complex plane

Hyperon electromagnetic form factors (EMFFs) of the neutral $\Lambda$ and the $\Sigma^+$ are analyzed with a model-independent approach based on dispersion relations (DRs) techniques, relying only on unitarity and analyticity of the hadronic current. The procedure, alongside the experimental data for the polarized cross section for time-like momentum transfer $q^2$, allows to extract a data-driven behavior of the EMFFs ratio for every value of the momentum transfer on the complex plane. In particular, the relative phase between the EMFFs is unraveled, extracting the passage between Riemann planes of this multivalued function. Alongside this, the charge radius of the $\Lambda$ hyperon is extracted, alongside the difference between the electric and magnetic radius of the $\Sigma^+$.
Lastly, the procedure allows to locate the zeros of the electric FF in the $q^2$ complex plane. The presence of these critical points together with their possible interpretations will be discussed.

Speaker: Francesco Rosini

12:20 The $H$-dibaryon from lattice QCD

The existence of the $I=0$, $S=-2$ $H$ dibaryon remains one of the open questions in nuclear physics and, despite decades of experimental searches and extensive theoretical investigations, its existence has yet to be conclusively established. Lattice QCD provides a first-principles, systematically improvable framework to study hadron physics in a non-perturbative way and allows the extraction of infinite volume scattering quantities through L\"uscher's formalism. I present lattice QCD results for the $H$ dibaryon both in the $SU(3)$-symmetric limit and at quark masses closer to the physical point, where all three relevant coupled channels, $\Lambda\Lambda$, $N\Xi$, and $\Sigma\Sigma$, are investigated. This work is part of the ongoing efforts to determine the properties of di-hyperons and to establish whether the $H$ dibaryon exists down to physical quark masses.

Speaker: Davide Laudicina (Ruhr University Bochum)

15:00 → 17:00 Astrophysics

Convener: Hirokazu Sasaki

15:00 Astrophysical $S$ factors for $p+{}^{7}$Li-, $n+{}^{7}$Be-, and $d+{}^{6}$Li-induced reactions in a microscopic many-channel cluster model

We present a unified microscopic analysis of astrophysical $S$ factors for reactions proceeding through the $^{8}$Be compound system with entrance channels $p+{}^{7}$Li, $n+{}^{7}$Be, and $d+{}^{6}$Li. The study addresses the key lithium-related reactions $^{7}$Li($p,\alpha)^{4}$He, $^{7}$Be($n,\alpha)^{4}$He, $^{7}$Be($n,p)^{7}$Li, $^{6}$Li($d,\alpha)^{4}$He, $^{6}$Li($d,p)^{7}$Li, and $^{6}$Li($d,n)^{7}$Be in the energy range relevant for primordial and stellar nucleosynthesis.

The calculations are performed within the microscopic many-channel three-cluster framework benchmarked for the high-lying $^{8}$Be spectrum in Ref. [1]. The model treats on the same footing the three-cluster configurations $^{4}$He+$^{3}$H+$p$, $^{4}$He+$^{3}$He+$n$, $^{4}$He+$d$+$d$, and $^{4}$He+$2p$+$2n$, and embeds binary rearrangement channels including ground and excited states of $^{7}$Be, $^{7}$Li, $^{5}$Li, and $^{5}$He. This unified channel space enables a direct link between the microscopic $^{8}$Be spectrum and observable low-energy reaction dynamics, and it allows us to quantify the impact of cluster polarization of binary subsystems on the $S$ factors.

For the mirror pair $^{7}$Li($p,\alpha)^{4}$He / $^{7}$Be($n,\alpha)^{4}$He and for $^{7}$Be($n,p)^{7}$Li the calculated $S$ factors reproduce both the absolute scale and the low-energy trends of the experimental data within their quoted uncertainties, whereas the absolute $S$ factors for the deuteron-induced channels on $^{6}$Li are underestimated at low energy, consistent with the shifted $^{6}$Li+$d$ threshold and the absence of a broad subthreshold $2^{+}$ structure in the present implementation. A partial-wave analysis identifies the dominant $J^{\pi}$ contributions in each channel and relates them to specific $^{8}$Be resonances, while demonstrating that cluster polarization, previously shown to be crucial for the $^{8}$Be spectrum, is likewise essential for the normalization and energy dependence of several $S$ factors.

Our results are systematically validated against a comprehensive set of experimental data across all considered entrance channels and exit partitions, enabling a consistent assessment of both the absolute scale and the energy dependence of $S(E)$ over the relevant low-energy range. Evaluating $S(E)$ at Gamow energies, we obtain a transparent hierarchy of competing neutron- and deuteron-induced channels that quantifies their
relative role in the production and destruction of $^{7}$Li and $^{7}$Be. The results demonstrate that a single microscopic, many-channel cluster approach can provide a coherent and predictive description of both the $^{8}$Be spectrum and low-energy reaction observables.

[1] V.I. Zhaba, Yu.A. Lashko, and V.S. Vasilevsky (2025). Many-channel microscopic cluster model of $^{8}$Be: Formation of high-energy resonance states. Phys. Rev. C, 112, 014328.

Speaker: Yuliya Lashko (Bogolyubov Institute for Theoretical Physics, Kyiv, Ukraine; Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Italy)

15:30 Four-body reaction analysis of the astrophysical factor $S_{18}$ of the $^8$B($p$,$\gamma$)$^9$C reaction via $^9$C breakup

We present a four-body reaction study of the astrophysical S factor $S_{18}$ for the $^8$B($p$,$\gamma$)$^9$C reaction, which is a key process in the hot $pp$ chain of nucleosynthesis. Direct measurements at the relevant low energies are extremely challenging; consequently, several indirect approaches have been employed to constrain $S_{18}$. However, the extracted $S_{18}$ values remain mutually inconsistent, motivating new measurements of $^9$C breakup reactions and, in parallel, a more quantitative theoretical understanding of the $^9$C breakup mechanism.

In this study, we analyze the $^{208}$Pb($^9$C,$p$$^8$B) reaction by modeling $^9$C as a $p$+$p$+$^7$Be three-body system. The breakup dynamics are described within the four-body continuum-discretized coupled-channels method (CDCC), which provides a highly accurate treatment of breakup processes for weakly bound nuclei with three-body structure. In four-body CDCC, the final states of the $p$+$p$+$^7$Be three-body system is expanded in eigenstates of the three-body Hamiltonian, which generally contain admixtures of both $p$+$p$+$^7$Be and $p$+$^8$B configurations. For a direct comparison with $^{208}$Pb($^9$C,$p$$^8$B) data, it is therefore essential to extract the $p$+$^8$B component from the final states of the four-body CDCC.

To this end, we couple four-body CDCC with the complex-scaled Lippmann–Schwinger formalism (CSLS). This combined approach enables an explicit specification of the final state in terms of the two-body breakup channel and allows us to compute the $^{208}$Pb($^9$C,$p$$^8$B) breakup cross section accordingly. We will report our four-body CDCC+CSLS results for $^{208}$Pb($^9$C,$p$$^8$B) and discuss the effect of a four-body description of $^9$C on the reaction analysis.

Speaker: Shoya Ogawa

16:00 Nuclear astrophysics at LUNA

At astrophysical energies, the cross section of nuclear processes is significantly reduced by the Coulomb barrier and the cosmogenic background usually prevents direct measurement. An underground location is perfect to mitigate the effects of cosmic-ray background and to allow for cross sections investigations at stellar energies. Since the nineties, this approach has been exploited by the LUNA Collaboration in the Gran Sasso underground laboratory. The activity is now continuing with both LUNA-400KV and the 3.5 MV IBF accelerators. Key reactions are currently being studied such as 12C+12C whose cross-section is crucial for determining the fate of a star. This contribution is aimed to present the recent results and to highlight the efforts in progress at both facilities.

Speaker: Dr Sandra Zavatarelli (INFN e Universita Genova (IT))

16:30 Twenty-five Years of Nuclear Astrophysics at the n_TOF Facility

Over the past twenty-five years, the neutron time-of-flight facility n_TOF at CERN has played a cornerstone role in advancing experimental nuclear astrophysics through high-precision measurements of neutron-induced reactions. Since the commencement of operations in 2001, n_TOF has provided a unique combination of a wide neutron energy range, high instantaneous flux, excellent energy resolution, and low background, enabling the investigation of key nuclear reactions that govern stellar nucleosynthesis.
A primary focus of the n_TOF astrophysics programme has been the determination of neutron capture cross-sections for isotopes involved in the slow neutron capture process (s-process). Particular emphasis has been placed on nuclei near magic neutron numbers—which act as bottlenecks in the nucleosynthesis path—and branching points that provide clues to stellar temperature and density. High-accuracy measurements of these isotopes, along with several neutron poisons, have significantly reduced nuclear uncertainties and improved the reliability of stellar models. These results have provided crucial constraints on the s-process in Asymptotic Giant Branch (AGB) stars and on the chemical evolution of the Galaxy.
The success of the astrophysics programme has been driven by continuous innovations in experimental techniques. This includes the development of state-of-the-art detector systems and the implementation of advanced digital data acquisition systems based on high-performance Flash-ADCs. The facility’s evolution from the initial experimental area (EAR1) to the addition of the vertical flight path (EAR2) and the more recent NEAR activation station has vastly expanded the range of accessible isotopes, allowing for the study of radioactive samples and extremely low cross-sections.
This contribution reviews a quarter-century of nuclear astrophysics at n_TOF, highlighting the most significant experimental achievements, their impact on astrophysical modelling, and the technical evolution of the facility. Finally, we discuss the perspectives for future measurements and the strategic role of n_TOF in addressing remaining open questions in nucleosynthesis and nuclear data for astrophysics.

Speaker: Giuseppe Tagliente (Universita e INFN, Bari (IT))

17:00 → 17:30 TEA BREAK

17:30 → 19:10 Astrophysics

Convener: Dr Sandra Zavatarelli (INFN e Universita Genova (IT))

17:30 Nuclear reactions in neutron stars and binary neutron star mergers

Speaker: Domenico Logoteta (INFN sezione Milano Bicocca)

18:00 Thermal deuteron-deuteron fusion in accelerator experiments at sub-keV energies

A direct observation of the deuteron-deuteron (DD) fusion reaction at thermal meV energies by emission of its nuclear products, although theoretically possible, was not succeeded up to now. The electron screening effect that reduces the repulsive Coulomb barrier between reacting nuclei in metallic environments by several hundreds of eV and is additionally increased by crystal lattice defects in the hosting material, leads to strongly enhanced cross sections which means that this effect might be studied in laboratories. Here, the results of the 2H(d,p)3H reaction measurements performed on different deuterated metallic targets at sub-keV energies, using an ultra-high vacuum accelerator system will be presented. The experimentally determined thick target yield, decreasing over many orders of magnitude for lowering beam energies, could be well described by the electron screening effect and the Jπ = 0+ threshold resonance in 4He. At the lowest energies of several keV, a constant plateau yield value could be observed for different metallic targets used. As indicated by significantly increased energies of emitted protons, this effect can be associated with the thermal DD fusion. A theoretical model explains the experimental observations by creation of ion tracks, induced in the target by projectiles, and a high phonon density which locally increases temperature above the melting point. The nuclear reaction rates taking into account the enhanced electron screening effect for different target materials and DD threshold resonance agrees very well with the experimental data.

Speaker: Prof. Konrad Czerski

18:30 Background-Limited Studies of Low-Energy Deuteron– Deuteron Fusion Using Silicon Detector Telescope

Deuteron–deuteron (DD) fusion plays a key role in both prospective fusion energy concepts and energy generation in dense astrophysical environments, including giant planets, brown dwarfs, and white dwarf supernova progenitors [1]. At low energies, charged-particle-induced nuclear reaction cross sections are strongly suppressed by the Coulomb barrier, leading to exponentially decreasing fusion probabilities. However, systematic laboratory experiments have demonstrated a pronounced enhancement of DD fusion cross sections in metallic environments, particularly at projectile energies below 10 keV. This enhancement is attributed to strong electron screening effects in metals, which effectively enhances the barrier penetration between reacting nuclei [2]. Recent studies further show that lattice defects and impurities, such as oxygen and carbon, can significantly modify the determined screening energy and the resulting fusion enhancement [3,4].
Recent studies have shown that, in addition to electron screening, a narrow 0⁺ threshold resonance in the ⁴He nucleus can significantly enhance the DD fusion rate at very low energies [5]. This single-particle resonance is predicted to decay via internal pair creation, emitting e⁻–e⁺ pairs with a total energy of 22.84 MeV. At the ultra-high-vacuum accelerator facility of the University of Szczecin, thin silicon detectors were used to search for these high-energy lepton signatures [6]. The measured partial energy deposition was compared with Geant4 detector response simulations, enabling extraction of the electron-to-proton branching ratio down to projectile energies of 6 keV [7,8]. The observed strong increase of this ratio toward lower energies confirms excitation of the threshold resonance and motivates measurements to further low energies.
These measurements necessitates accurate background charecterization for reliable branching ratio determination. Previous studies identified cosmic-ray showers and terrestrial gamma radiation as the dominant background sources in silicon detectors [9]. In the present work, these contributions were quantified using Geant4 Monte Carlo simulations. Cosmic-ray–induced events were modelled using the Cosmic RaY (CRY) library, while terrestrial gamma background was simulated based on spectra measured with a large-volume NaI(Tl) detector and and using it to model repsone function in silicon detectors. Further background suppression was achieved using a ΔE–E telescope configuration with coincidence analysis. The resulting two-dimensional background spectra enabled extraction of the electron–proton branching ratio down to the lowest deuteron energy of 3.5 keV. These results provide a foundation for future measurements at even lower energies, targeting to validate the predicted electron-proton branching ratio of up to ~15.
[1] R. Ouyed et al., Astrophys. Space Sci. 361 (2016) 89.
[2] J. Kasagi et al., J. Phys. Soc. Jpn. 71 (2002) 2881–2885.
[3] A. Kowalska et al., Materials 16 (2023) 6255
[4] A. Kowalska et al., Materials 18 (2025) 1331
[5] K. Czerski et al., Phys. Rev. C (Letters) L011601 (2022) 106.
[6] K. Czerski et al., Phys. Rev. C (Letters) L021601 (2024) 109.
[7] H.Gokul Das et al., Measurement 114392 (2024) 228
[8] R. Dubey et al., Phys. Rev. X 15 (2025) 041004
[9] J. W. Fowler et al., Phys. Rev. X Quantum 5 (2024) 040323.

Speaker: Mr Gokul Das Haridas (University of Szczecin)

18:50 Relativistic QRPA calculation of neutrino–nucleus cross sections on 92Zr.

Neutrino-induced reactions on $^{92}\mathrm{Zr}$ play an important role in the production of $^{92}\mathrm{Nb}$ through the neutrino process in core-collapse supernovae. In this work, we investigate cross sections for the $^{92}\mathrm{Zr}(\nu_e,e^-)^{92}\mathrm{Nb}$ reaction within the standard weak lepton–hadron current formalism. Since astrophysical environments probe nuclear systems under extreme conditions, predictive and microscopic descriptions of nuclear structure are required. The nuclear transition matrix elements are therefore obtained in a self-consistent framework, where the ground state is described by relativistic energy density functional theory and excited states are treated within the relativistic quasiparticle random-phase approximation. As a validation of the nuclear response, the low-momentum limit of the calculation is benchmarked against available experimental Gamow–Teller strength distributions. Finally, the resulting cross sections are folded with representative supernova neutrino spectra to estimate reaction yields under astrophysical conditions.

Speaker: Rade Smolović

Tuesday 16 June

09:00 → 10:50 Nuclear Potential

Convener: Prof. Hugo Arellano

09:00 Toward Consistent Nuclear Level Densities from the Optical Potential

Nuclear level densities play a central role in reaction modeling, governing
compound-nucleus decay and emission probabilities. In widely used reaction
codes such as TALYS, level densities are commonly described by phenomenological
or semi-microscopic models that are not consistent with the optical potential
employed to describe scattering. This mismatch limits predictive power and
introduces uncontrolled model dependencies.

We investigate an alternative approach in which nuclear level densities are
derived directly from the optical potential. Using the formal connection
between the optical potential and the one-body self-energy, single-particle
level densities are extracted from the corresponding Green’s function,
naturally incorporating continuum effects, absorption, and energy dependence.
Partial-wave–resolved densities can then be combined to construct spin- and
parity-dependent level densities suitable for reaction calculations. This
framework opens the way toward more coherent and self-consistent reaction
modeling.

Speaker: Guillaume Blanchon (CEA,DAM,DIF)

09:30 Microscopic optical potentials: new results and perspectives

The optical potential is a well-established and widely used tool to describe
nucleon-nucleus scattering processes. Within this approach, it is possible to
compute the scattering observables for elastic processes across a wide region
of the nuclear landscape and extend its usage to inelastic scattering and other
types of reactions.

Since phenomenological approaches lack predictive power, we strongly believe that
a microscopic approach will be the preferred tool to make reliable predictions,
in particular for upcoming experiments concerning exotic nuclei.

The Watson multiple scattering theory provides a successful framework to derive
such an optical potential for intermediate energies.
In its simplest formulation, derived at the first order, the optical potential
is obtained as the folding integral
of the nucleon-nucleon scattering matrix and the target density, representing
the two fundamental ingredients
of the model. After many years of advances in theoretical nuclear physics,
it is now possible to calculate
these two quantities using the same nucleon-nucleon interaction that is the
only input of our calculations.
Results obtained within this framework will be presented for light- and medium-mass nuclei,
adopting different ab initio approaches to calculate the densities, such as the No-Core
Shell Model and Self-Consistent Green’s Function [1-7]. Novel extensions of the model,
such as the calculation of nucleus-nucleus collisions [8] or inelastic transitions [9] will also be presented.

References

[1] M. Vorabbi, P. Finelli, C. Giusti, Phys. Rev. C93, 034619 (2016)
[2] M. Vorabbi, P. Finelli, C. Giusti, Phys. Rev. C96, 044001 (2017)
[3] M. Vorabbi, P. Finelli, C. Giusti, Phys. Rev. C98, 064602 (2018)
[4] M. Vorabbi, M. Gennari, P. Finelli, C. Giusti, P. Navratil, Phys. Rev. Lett. 124, 162501 (2020)
[5] M. Vorabbi, M. Gennari, P. Finelli, C. Giusti, P. Navratil, Phys. Rev. C103 024604 (2021)
[6] M. Vorabbi, M. Gennari, P. Finelli, C. Giusti, P. Navratil, Phys. Rev. C105 014621 (2022)
[7] M. Vorabbi ,C. Barbieri ,V. Somà ,P. Finelli , and C. Giusti, Phys.Rev. C109 (2024) 3, 034613
[8] M. Vorabbi, M. Gennari, P. Finelli, C. Giusti, P. Navratil, Phys. Rev. Lett. 135,172501 (2025)
[9] M. Vorabbi, M. Gennari, P. Finelli, C. Giusti, P. Navratil, submitted to Phys.Rev. C (2026)

Speaker: Paolo Finelli

10:00 Collectivity and mass in nuclear scattering potentials

Analyses of low-energy elastic scattering cross-section data in the resonant regime require consideration of the dynamics of the scattering bodies; the behavior of the nuclei in different energy states - vibrational, rotational, single-particle, or clusterization - should be considered when describing the compound system's resonances.

Collectivity is often considered a behaviour of heavier nuclei, which would be assumed to be more fluid-drop-like than lighter nuclei. However, many light nuclei exhibit the signatures of collective spectra, and even assuming some collective nature of those that don't show the canonical energy-level patterns can lead to successful analysis of their scattering. Conversely, the scattering of heavy nuclei with emblematic collective behavior can prove highly challenging to model.

This topic is explored in this talk within the context of the multi-channel algebraic scattering (MCAS) approach [1]. MCAS uses scattering potentials derived from structure models that account for the collective models, but which are semi-microscopic in that they incorporate the Pauli principle between target and projectile nucleons.

[1] S. Karataglidis, K. Amos, P. R. Fraser, and L. Canton, A New Development at the Intersection of Nuclear Structure and Reaction Theory (Springer Cham, 2019), ISBN 978-3-030-21069-4.

Speaker: Paul Fraser

10:30 Beyond ADC(2): A Multichannel Dyson Equation Approach to Nuclear Optical Potentials

The one-body self-energy provides a unified microscopic description of bound states, spectroscopic properties, and nuclear reaction observables through the one-body Green’s function. Reliable many-body approximations to the self-energy are therefore a key ingredient in modern reaction theory. In this work, we formulate the Multichannel Dyson Equation (MCDE) within the Algebraic Diagrammatic Construction (ADC) formalism, establishing a direct connection with widely used self-energy expansions in nuclear many-body physics. The MCDE can be interpreted as an approximation that goes beyond the ADC(2) level. We benchmark the MCDE against ADC(2) by comparing their self-energies and spectral functions in extended model systems, showing that the MCDE captures correlation-induced structures absent at the ADC(2) level. Finally, we present a first application of the MCDE using a chiral nucleon–nucleon interaction and discuss its implications for microscopic descriptions of nuclear reactions.

Speaker: Mr Thibault Demartini (CEA,DAM,DIF)

10:50 → 11:20 COFFEE BREAK

11:20 → 13:00 Nuclear Potential

Convener: Guillaume Blanchon (CEA,DAM,DIF)

11:20 Self-consistent microscopic folding-model approach for positive and negative energies

Most current state-of-the-art microscopic folding optical model potentials for nucleon-
nucleus scattering make use, as an ad-hoc input, a description of the ground state of
the target. This common practice has allowed to stretch our knowledge of the under-
lying physics of the process but with some limited success due to the hybrid nature of
the approach. From a formal standpoint, the optical potential can be considered as a
one-body operator which is a function of an energy parameter in the complex plane.
Motivated by this natural assumption, in this contribution we present results from
calculations of folding potentials at negative energies, to extract the target ground
state density matrix, which are then applied to elastic scattering processes. In this
way, the only input in these calculations is the bare nucleon-nucleon potential, apart
from the specification of the isotopic composition of the target (N, Z). The in-medium
folding approach makes use of the genuine off-shell Brueckner-Hartree-Fock g matrix
convoluted with the exact density matrix. Bound states are obtained from the full
Green’s function Ĝ(z) = 1/(z − Ĥ). The resulting density matrix is then used for
scattering calculations. We report results based on the AV18, N3LO and N3LO+3N
interactions, focused on 12 C as nucleus of interest, with elastic scattering applications
at nucleon beam energies up to 300 MeV.

Speaker: Prof. Hugo Arellano

11:50 Towards optical potentials from ab initio theories

While the ab initio approach has made tremendous progress in nuclear structure applications, the first-principle description of reaction observables remains very demanding. In particular, recent calculations of microscopic optical potentials have shown both promising results and the need for improvement in key aspects. I will review some of these developments and discuss possible future strategies.

Speaker: Vittorio Soma

12:20 Low-Energy Nucleon–Nucleus Interactions in a Quadrupole Rotor Framework Using MCAS

We investigate low-energy nucleon– and alpha–nucleus interactions using the Multichannel Algebraic Scattering (MCAS) method combined with scattering potentials derived within the quadrupole rotor model framework. The approach explicitly incorporates coupled-channel effects arising from quadrupole collective excitations and enforces Pauli principle constraints on the projectile–target system.

Calculations are performed for light and medium-mass nuclei $^{16}$O and $^{20}$Ne as well as for heavy systems including $^{190}$Os and $^{248}$Cm. Results are compared with available elastic scattering data and bound-state spectra to assess the influence of nuclear deformation and coupling strength on resonance structures and scattering observables.

The study demonstrates that MCAS modeling reproduces key experimental features and provides reliable predictions in energy regions where data are scarce or unavailable. These results highlight the ability of MCAS to consistently link nuclear structure effects with reaction dynamics, and motivate further applications to heavy systems dominated by strong collective behavior.

Speaker: Ms Deeparna Bhattacharyya

12:40 Application of the iterative perturbative approach to nonlocal and deformed potentials in N–alpha scattering and (alpha, n) reactions

We assess the versatility and numerical efficiency of the iterative perturbative approach (IPA) [Phys. Rev. C${\bf 98}$, 024605 (2018)] for solving the nonlocal integro-differential Schrödinger equation in two complementary nuclear reaction settings. First, we compute nucleon–alpha (N–$\alpha$) scattering phase shifts and differential cross sections with the global nonlocal optical potential of Jaghoub and Aqel [Eur. Phys. J. A 61, 214 (2025)] over the laboratory energy range 0.84–20.97 MeV. Second, we extend the approach to ($\alpha$, n) reactions on deformed targets, constructing the $\alpha$–nucleus optical potential within a semimicroscopic folding framework based on effective nucleon–nucleon interactions and realistic nuclear density distributions. The performance of the IPA in the simultaneous presence of nonlocality and deformation is examined by comparison with the theoretical framework of Ref. [Phys. Rev. C${\bf 113}$, 014609 (2026)]. We further test the predictive capabilities of the IPA-based calculations against experimental ($\alpha$, n) cross sections relevant to $\gamma$-process nucleosynthesis. The robustness and numerical stability of the method are quantified by systematically evaluating infinity norms of the residuals obtained when the converged wave functions are reinserted into the original integro-differential equations.

Speaker: Dr N. J. Upadhyay (Department of Physics, Amity School of Applied Sciences, Amity University Maharashtra, Panvel - 410206, INDIA)

15:00 → 17:00 Reaction Theory

Convener: Toshihiko Kawano (LANL)

15:00 From Nuclear Double Charge Exchange Reactions to Lepton Number Violating Electron Scattering

Abstract: Lepton number violation (LNV) as underlying neutrinoless nuclear double beta decay (DBD) and equal-charged lepton pair plus di-jet production in ultra-relativistic hadron collisions are expected to deliver the heavily searched on signatures for physics beyond the standard model (BSM). In order to study independently the totally unexplored rank-2 nuclear isotensor spectroscopy inherent to DBD, peripheral heavy ion double charge exchange (DCE) reactions as studied in the NUMEN project are the proper tool. They include sequential (DCSE) and direct (MDCE) processes formally corresponding to two-neutrino and neutrinoless DBD, respectively. DSCE reactions are the perfect tool for isotensor two particle - two hole spectroscopy. MDBD leads to pion potentials as surrogates of the neutrino potentials in neutrinoless DBD. Direct probes for LNV are lepton DCE (LDCE) reactions at accelerators, apparently and surprisingly never considered before. Theoretical concepts are discussed, merging into a second order approach. As a first application. total cross sections of L=+2 (e-,e+) reactions on nuclear targets are estimated. At beam energies beyond 10 GeV, cross sections of magnitudes are predicted which might be measurable at existing facilities.

Speaker: Prof. Horst Lenske (Justus-Liebig-Universitaet Giessen)

15:30 Application of a noniterative finite amplitude method to direct and pre-equilibrium processes in neutron-induced reactions

Model development for neutron-induced reactions is essential for
advancing nuclear astrophysics and for producing reliable nuclear data
for practical applications. We have combined a noniterative finite
amplitude method with the distorted-wave Born approximation
framework and applied this approach to direct and pre-equilibrium
processes in neutron-induced inelastic scattering for heavy nuclei.
Scattering processes to both discrete and continuum states are
consistently calculated within the same framework. The calculated
differential and double-differential cross sections show good agreement
with experimental data.

Speaker: Hirokazu Sasaki

16:00 Investigating the Validity of Hauser Feshbach Theory on Compound Nuclear Reactions

Nuclear reactions involving the formation of a compound nucleus are difficult to treat explicitly. As a result, the compound contribution to the reaction cross section is typically treated via statistical methods, i.e. Hauser Feshbach theory, which assumes the underlying compound Hamiltonian can be approximated as a member of the Gaussian Orthogonal Ensemble. This work investigates the validity of this assumption by using more realistic Hamiltonians taken from nuclear shell model. A Green’s function approach is used to generate an ensemble of scattering matrices, after which Monte Carlo sampling is employed to take an ensemble average and extract the compound cross section. We focus on neutron and proton scattering of light/medium mass nuclei reactions.

Speaker: Ibrahim Abdurrahman

16:20 Towards Predictive Modeling for Reactions on Rare Isotopes

Modeling nuclear reactions typically requires reducing the full many-body model space through effective few-body interactions between the reacting species: optical potentials. Through this reduction, these effective interactions contain rich information about the many-body compound system. They are ubiquitous in reaction theory, and a variety of approaches have been taken to construct them from microscopic structure calculations (see e.g. [Baker2024,Sargsayan2024]). In most cases, however, phenomenological global potentials are still required for making predictions away from stability, and are extrapolated into the regions of the chart of isotopes of interest for nuclear astrophysics and other applications, often without uncertainty quantification [Hebborn2023]. We are addressing this problem in two ways.

First, we demonstrate the development of the East Lansing Model, a new, global, uncertainty-quantified optical potential for protons and neutrons. We develop a new, Lane-consistent model form which allows for independent isoscalar and isovector geometries, and include (p,n) reactions to the isobaric analog state in the experimental constraints. Critically, we develop a new statistical model underlying the Bayesian calibration, and show that choices and approximations made in developing the statistical model can have significant impacts on the results - even larger in some cases than the impact of model form and experimental constraints. We put previous work [Pruitt2023a,Pruitt2023b] into context based on these findings, and recommend a path forward for future efforts to develop uncertainty quantified potentials.

Second, we adapt the formalism for determining nucleon-nucleus optical potentials from Green’s function theory [Rotureau2018,Burrows2024] to coupled reaction channels, and demonstrate it for coupled-channels calculations of (p,n) to the isobaric analog state for Mg isotopes. We use valence shell model calculations for the compound states, elucidating the microscopic origin of effective isovector forces in nuclear reactions. We compare this approach, which expands the single-particle propagator in the compound states, with other approaches, which expand the dynamic part of the optical potential. We demonstrate that our approach allows for a smooth connection to the physics of compound nuclei.

Finally, we share perspectives on the synergy between the phenomenological and microscopic approaches, using techniques like Bayesian Model Mixing [Sempowski2025] and model orthogonalization [Giuliani2024] to equip future phenomenological efforts with theory-driven model forms, improving inference of structure quantities from reactions.

[Hebborn2023] C Hebborn et al 2023 J. Phys. G: Nucl. Part. Phys. 50 060501
[Baker2024] R. B. Baker et al., Phys. Rev. C 110, 034605 (2024)
[Sargsayan2024] G. H. Sargsayan et al., Phys. Rev. C 112, 054606 (2024)
[Pruitt2023a] C. D. Pruitt et al., Phys. Rev. C 110, 064606 (2023)
[Pruitt2023b] C. D. Pruitt et al., Phys. Rev. C 107, 014602 (2023)
[Rotureau2018] J. Rotureau et al., Phys. Rev. C 98, 044625 (2018)
[Burrows2024] M Burrows et al., Phys. Rev. C 109, 014616 (2024)
[Sempowski2025] A. C. Sempowski et al., arXiv:2505.18921
[Giuliani2024] P. Giuliani et al., Phys. Rev. Research 6, 033266 (2024)

Speaker: Kyle Beyer

16:40 Pre-Equilibrium Emission Microscopic Modelisation

At incident energy above 5-10 MeV, nucleon-induced reactions on medium-heavy nuclei may occur through the pre-equilibrium mechanism. It describes the composite system (projectile & target) evolution via intermediate states of increasing complexity eventually reaching statistical equilibrium, i.e. forming the compound nucleus. Nucleons (or light nuclei) emission from these intermediate states are refered to as pre-equilibrium emission.

Quantum pre-equilibrium models split the intermediate states into two categories according to wether all nucleons are (temporarily) bounded or there is (at least) one in the continuum. An emission process proceedings exclusively through the latter type of intermediate states is called a Multi-Step Direct (MSD) process while if it forms an all-bound state once, it is a Mult-Step Compound (MSC) process. Unlike MSC, MSD has received some attention since 2000. In particular, a more appropriate description of the target/residual nucleus via (Q)RPA enables a coherent description of single-particle and collective excitations [1]. I am therefore focusing on the MSC process.

A stochastic pre-equilibrium model has been developed by the "Heidelberg group" in the 80s [2,3] and led to a numerical implementation of MSC used in EMPIRE [4]. This implementation nonetheless relies on some assumptions/approximations that I aim to investigate :
1) It assumes a weak coupling between different steps states even though authors have emphasized that a strong coupling is physically more relevant. Some strong coupling ingredients (effective partial level density taking into account residual interaction mixing) have been evaluated subsequently for closed shell nuclei [5] and it has not been used in any MSC calculation (though it was used to describe the target/residual nucleus level density in MSD [6]).
2) It neglects the MSD effects (similar to Engelbrecht Weidenmüller transformation), but a coherent implementation of MSC and MSC may help to relax the assumption and/or assess its validity.
3) It uses an objectionable systematic to feed MSC steps. This gradual absorption is formally derived from MSD optical potential: there should be some middle-ground to be found.

[1] M. Dupuis, Microscopic description of elastic and direct inelastic nucleon scattering off spherical nuclei, The European physical journal. A, Hadrons and Nuclei 53, 111 (2017).
[2] H. Nishioka, J. Verbaarschot, H. Weidenmüller, and S. Yoshida, Statistical theory of precompound reactions: The multistep compound process, Annals of Physics 172, 67 (1986).
[3] H. Nishioka, H. Weidenmüller, and S. Yoshida, "Statistical theory of precompound reactions: The multistep direct process", Annals of Physics 183, 166 (1988).
[4] M. Herman, G. Reffo, and H. Weidenmüller, Multistep-compound contribution to precompound reaction cross section, Nuclear Physics. A 536, 124 (1992).
[5] K. Sato, Y. Takahashi, and S. Yoshida, Exciton level densities with spin and parity based on random matrix model, Zeitschrift Für Physik. A Hadrons and Nuclei 339, 129 (1991).
[6] T. Kawano and S. Yoshida, Interference effect in the scattering amplitudes for nucleon-induced two-step direct process using the sudden approximation, Phys. Rev. C 64, 24603 (2001).

Speaker: Mr Benjamin Menant (CEA, DAM, DIF)

17:00 → 17:30 TEA BREAK

17:30 → 19:00 Medical Radioisotopes

Convener: Dr Nadia Tsoneva (Extreme Light Infrastructure-Nuclear Physics (ELI-NP))

17:30 Medical radionuclides production at GIP ARRONAX and impact of systematic cross section measurements

MEDICAL RADIONUCLIDES PRODUCTION AT GIP ARRONAX AND IMPACT OF SYSTEMATIC CROSS SECTION MEASUREMENTS
Arnaud Guertina* et al. on behalf of PRISMAa and GIP ARRONAXb teams

aSubatech, UMR6457, CNRS/IN2P3, Nantes Université, IMT Atlantique: 4 rue A. Kastler, Nantes, 44307, France;
bGIP ARRONAX: 1 rue Aronnax, Saint-Herblain, 44800, France; *Arnaud.Guertin@subatech.in2p3.fr

Applications of radiations for health is a long story that have started soon after the discovery of radioactivity. Nowadays, radiations are used in oncology (external radiation, targeted therapies, SPECT, PET), neurology and cardiology. Since 2013, a new wave of applications in nuclear medicine has started, focused on therapeutic agent and the so-called theranostics approach [1]. It combines imaging information and therapeutic use of radionuclides. This new paradigm shows great promises especially because it may allow personalizing the treatment to each patient. The diagnosis test done prior to the treatment allows to determine patient response and to determine the needed injected dose for the therapeutic agent. After treatment, the imaging agent can be used to follow the patient response to the injected radiopharmaceutical. Finally, this approach allows a better control of the targeting and increases the benefit/toxicity ratio as useless treatments on patients with no response to the diagnosis test are avoided. The use of alpha emitters in some patients also shows very promising results [2].

Radionuclides are traditionally produced in (research) reactors, in cyclotrons accelerating protons or are, in some cases, obtained from radionuclide generators. The rapidly growing demand for theranostic applications has stimulated researchers to explore alternative approaches for effectively producing radionuclides. Among them, several have been established or are in development, such as photonuclear reactions, nuclear reactions induced by charged particles other than proton (At-211, Ru-97, Pb-203, Hg-197m …), extraction of progeny from very long-lived sources (Sr-82/Rb-82,Ti-44/Sc-44 …), spallation reactions employing high-energy accelerators possibly combined with mass separation techniques.
GIP ARRONAX is hosting a high energy high intensity multiparticle cyclotron (C70XP). It allows to produce non-conventional radionuclides for the scientific community and the industry. Since 2010, in collaboration with the PRISMA team of the Subatech laboratory, a campaign of systematic production cross section measurements is conducting. This presentation will show the broad spectra of research activities conducted in the facility its current status and recent upgrades. In 2025, an internal target system has been installed to allow access to variable energies for our alpha beam and in parallel, a biomedical cyclotron (KIUBE-180) equipped with a beam line and target station connected to the existing rabbit system, is being commissioned.

These developments allow the ARRONAX facility to better fulfil its missions that are to support research in nuclear medicine by providing non-conventional radionuclides and radiopharmaceuticals for clinical trials and also support research in related fields: radiotherapy and radiobiology, radiolysis, physics, ion beam analysis, mass separation through the SMILES project, detector testing…

References
[1] Srivastava, S. C. (2012). Paving the Way to Personalized Medicine: Production of Some Promising Theragnostic Radionuclides at Brookhaven National Laboratory. Seminar in Nuclear Medicine, volume 42 (issue 3), 151-163.
[2] Kratochwil, C. et al (2016). 225Ac-PSMA-617 for PSMA-Targeted α-Radiation Therapy of Metastatic Castration-Resistant Prostate Cancer. Journal of Nuclear Medicine 57(12):1941-1944

Speaker: Arnaud GUERTIN

18:00 Study of retention effects in radio-isotope production with the Szilard-Chalmers reaction

We will discuss the results of a new radio-chemistry experiment where we studied the production and the separation of the short-lived $^{128}$I radioisotope with the Szilard-Chalmers reaction induced by thermal neutrons on Ethyl iodide liquid samples. In particular, we investigated retention effects as a function of the concentration of Ethanol, that was used as a scavenger to avoid the re-trapping and the exchange of the radioactive atoms. The retention curve shown the presence of an optimum concentration of the scavenger, useful for practical purposes. At the same time, the peculiar trend of the whole retention curve point out the possible onset of complex inter-molecular interactions that can lower the yields of free radioactive atoms at very large Ethanol concentrations. A plan for future experiments to investigate the onset and the strength of such inter-molecular effect in radio-isotope separation will also be discussed.

Speaker: Ivano Lombardo (INFN Sezione di Catania & Univ. Catania)

18:30 Radioisotope Centre POLATOM at the National Centre for Nuclear Research (NCBJ): research and development programmes for novel radiopharmaceuticals

The Radioisotope Centre POLATOM at the National Centre for Nuclear Research, located in Otwock, Poland, is not only a manufacturer of radioisotopes and radiopharmaceuticals but also conducts research programs encompassing both fundamental and applied research on the use of ionising radiation across various disciplines. Maria research reactor is an important nuclear facility of the Centre.
The POLATOM’s Research Department deals with various aspects of producing radionuclides with high specific activity for medical use. These radionuclides are produced through neutron irradiation in the MARIA research reactor and are then processed using separation techniques. The department's research also involves developing radionuclide production technologies with cyclotrons, designing and developing novel radiolabels for diagnostic and therapeutic applications based on biologically active carriers such as small molecules, peptides and monoclonal antibodies, radiosynthesis methods for PET tracers, and establishing analytical and biological methods to assess the diagnostic and therapeutic effectiveness of newly developed radiopharmaceuticals. Our labs are also approved for GMP in clinical trials. At present, our group contributes to three different clinical trial collaborative projects funded by the Medical Research Agency in Poland, among them one will evaluate the potential of 161Tb therapy.
Through participation in the SECURE and PRISMAP* projects, we gained new experience in laboratory-scale production of radionuclides such as ¹⁶¹Tb and ⁴⁷Sc, as well as in the quality control of ²¹²Pb and ¹⁸⁸Re, strengthening collaboration with other European research institutions. It is fascinating to continue this work in PRISMAP+, where additional novel radioisotopes will be produced. A key project currently underway at the POLATOM is the Centre for the Design and Synthesis of Molecularly Targeted Radiopharmaceuticals (CERAD), with its multiparticle cyclotron Cyclone 30 XP (IBA) accelerates protons and alpha particles to 30 MeV and deuterons to 15 MeV enabling the production of cyclotron-based radionuclides for PET, SPECT and therapy, including ¹²³I, ¹⁸F, ⁶⁴Cu/⁶⁷Cu, ⁶⁸Ga, ⁴³Sc/⁴⁴Sc, and ²¹¹At.

SECURE project (Strengthening the European Chain of Supply for Next-Generation Medical Radionuclides), funded under HORIZON-EURATOM-2021-NRT-01-10; grant agreement No. 101061230.
*PRISMAP project (The European Medical Isotope Programme: Production of High-Purity Isotopes by Mass Separation), funded by the European Union under grant agreement No 101008571.

Speaker: Małgorzata Żółtowska

Wednesday 17 June

09:00 → 11:10 Reaction Theory

Convener: Prof. Horst Lenske (Justus-Liebig-Universitaet Giessen)

09:00 Pair strength, two-nucleon transfer reactions and and many-body processes

We present a quantitative microscopic calculations of the strength function associated with 0+ pairing modes, going beyond the RPA [1,2].
This is a prerequisite for a reliable computation of absolute two-nucleon transfer cross sections.
We can treat the full excitation spectrum of pairing modes, including the well-known low-lying and bound pairing vibrations on par with the predicted high-lying pairing vibrations, often called giant pairing vibrations. Our formalism includes the coupling to
low-energy collective modes of the core, in such a way that both single-particle self-energy effects and the pairing interaction induced by phonon exchange are accounted for. The coupling with the
continuum plays an important role and is also taken into account. The theory is applied to the case of the excitation spectrum of nuclei in various mass regions, including 14C [3] and 118Sn [4], recently populated by two-neutron transfer reactions.

[1] F. Barranco, G. Potel and E. Vigezzi, Phys, Rev. Lett. 134 (2025)
062501
[2] F. Barranco and E. Vigezzi, EPJ A61 (2025) 257
[3] F. Cappuzzello et al., Nat. Comm. 6 (2015) 6743
[4] M. Dozono et al., unpublished

Speaker: Enrico Vigezzi

09:30 Microscopic Framework for Multi-Nucleon Transfer Reactions

Multi-nucleon transfer reactions have been used for decades to produce elements not found on Earth: neutron-rich and proton-rich nuclei and super-heavy elements. Time-dependent DFT (TDDFT) theory in various incarnations is the only microscopic framework used so far in the literature to describe multi-nucleon transfer (MNT) reactions, while these reactions are primarily treated with a wide variety of phenomenological models. In any MNT reaction, the total many-body wave function of the system has azimuthal symmetry, as in any scattering experiment on unpolarized targets with unpolarized projectiles. So far, no microscopic framework has ever reproduced a many-body wave function with these correct symmetry properties, and furthermore all existing microscopic calculations also neglect many crucial nucleon-nucleon correlations. The most sophisticated microscopic approach to this problem considered to date involves a combination of (TD)HF and the (time-dependent) Generator Coordinate Method, [(TD)GCM]. However, GCM and its existing time-dependent extension have several known shortcomings, only some of which have been resolved to date, and one serious outstanding problem involves rather arbitrary restrictions on which many-body wave functions are included in the GCM many-body wave function at any given time. In this contribution we will present an enhanced version of GCM and apply it to the near-Coulomb-barrier collision of 48Ca+208Pb. The many-body wave functions describing MNT reactions have the expected axial symmetry, corresponding to collisions at all relevant impact parameters, describe the transfer of many nucleons, and also describe the conversion of the initial kinetic energy of the projectile in the lab system into the excitation energy of the emerging fragments. This is the first detailed microscopic framework applied to multi-nucleon transfer reactions, which includes nucleon-nucleon correlations, non-equilibrium dynamics, and very important contributions beyond the TDDFT and some included in previous versions of GCM.

Speaker: Aurel Bulgac (University of Washington, Seattle, WA, USA)

10:00 Are breakup reactions sensitive to spectroscopic factors? (Spoiler alert: they ain’t)

Exotic nuclear structures such as halos are mostly studied through reactions. In breakup reactions, the radioactive projectile is sent upon a target, which induces the dissociation of the loosely-bound halo from the core of the nucleus [1]. In most cases, a spectroscopic factor for the core-halo structure is inferred from experimental data. It has been shown that such reactions are purely peripheral in the sense that they probe only the tail of the projectile wave function, viz. its asymptotic normalisation constant [2–4].
Not being sensitive to the internal part of that wave function, these reactions cannot be used to infer spectroscopic factors. Nevertheless, since the calculations in Refs. [2–4] have been performed with single-particle wave function in only one core-neutron configuration, that conclusion was not firmly established. In the present contribution, we present a new calculation of the Coulomb breakup of $^{11}$Be performed with a multi-channel effective particle-rotor model of the projectile, which accounts for the excitation of the $^{10}$Be core. As expected from the previous work [2–4], the cross sections are insensitive to the spectroscopic factor.
In the near future, we plan to extend this model to nuclear-dominated breakup, knockout and transfer reactions.

References:
[1] N. Fukuda et al. Phys. Rev. C 70, 054606 (2004).
[2] P. Capel and F. M. Nunes, Phys. Rev. C 73, 014615 (2006)
[3] P. Capel and F. M. Nunes, Phys. Rev. C 75, 054609 (2007)
[4] P. Capel, D. R. Phillips, and H.-W. Hammer, Phys. Rev. C 98, 034610 (2018)

Speaker: Pierre Capel

10:30 Reactions in three-body nuclear and hypernuclear systems

A rigorous few-body scattering theory as proposed by Faddeev and extended by Yakubovsky and Alt, Grassberger and Sandhas (AGS) is implemented in the momentum-space framework. Past applications include the nucleon-deuteron scattering, three-cluster nuclear reactions, and four-nucleon scattering. Recent and ongoing extensions of this framework will be presented.
First, we made a two-fold extension of the standard dynamics by developing a new nonlocal form of optical potentials and simultaneously including the excitation of the nuclear core. Example results for nucleon transfer reactions (d,p) and (p,d) and deuteron inelastic scattering (d,d')
10Be and 24Mg nuclei demonstrate a good reproduction of the experimental data and an improved consistency between the two-body (elastic and inelastic nucleon-nucleus scattering) and three-body description [1,2].
Second, the nonelastic deuteron breakup (d,pX) is for the first time is formulated in terms of AGS transition operators and calculated numerically [3] for several targets ranging from 12C to 90Zr.
The core-excitation method is extended to hypernuclear three-body systems, fully including the coupling between the nucleon-Lambda and nucleon-Sigma(+,0,-) states, which a highly complicated problem with many thresholds. The impact of the resonant states on various elastic and inelastic cross sections is studied [4].

1. Nonlocal optical potential with core excitation in 10Be(d, p)11Be and 11 Be(p, d)10Be reactions
   A. Deltuva, D. Jurčiukonis, Phys. Lett. B 840, 137867 (2023)
   https://doi.org/10.1016/j.physletb.2023.137867

2. Nonlocal optical potential in inelastic deuteron scattering off 24 Mg
   A. Deltuva, D. Jurčiukonis, Phys. Rev. C 107, 064602 (2023)
   http://dx.doi.org/10.1103/PhysRevC.107.064602

3. Faddeev-type calculation of nonelastic breakup in deuteron-nucleus scattering
   A. Deltuva, Phys. Lett. B 868, 139825 (2025)
   https://doi.org/10.1016/j.physletb.2025.139825

4. Resonant states in three- and four-body hypernuclear systems
   R. Lazauskas et al., to be published in Phys. Lett. B

Speaker: Arnoldas Deltuva (Vilnius University)

10:50 Quantum computing: a novel framework for reaction theory

Quantum computing holds the promise to revolutionize our understanding of quantum many-body systems. In particular, it offers new pathways to address the formidable challenges of quantum dynamics, where classical computations are hindered by the exponential growth of the Hilbert space. For example, simulations of nuclear reactions involving medium-mass and heavy nuclei require representing state vectors with more components than the number of particles in the Universe. While such calculations are inconceivable on classical architectures, quantum computers could, in principle, encode this information using fewer than 5,000 qubits.
Despite this potential, current quantum devices remain more prone to errors than their classical counterparts, as qubits are highly sensitive to environmental noise and decoherence. Nonetheless, rapid technological advances, ranging from improved qubit stability and error-correction protocols to refined quantum control, are steadily closing the gap toward practical applications.
In this talk, I will present our ongoing efforts at Los Alamos National Laboratory to prepare for the quantum era by developing quantum algorithms tailored to nuclear reaction theory. Specifically, I will discuss a novel hybrid quantum-classical algorithm designed to extract total cross sections as functions of incident neutron energy and elastic angular distributions. Finally, I will outline how this framework can be extended to compute additional observables, including semi-inclusive cross sections, paving the way for a broader application of quantum computing in nuclear physics.

Acknowledgments This work was carried out under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory under Contract No. 89233218CNA000001. The author gratefully acknowledges support by the Advanced Simulation and Computing program. LA-UR-25-31717

Speaker: Evan Rule

11:10 → 11:40 COFFEE BREAK

11:40 → 13:10 Fission

Convener: Stefano Marin

11:40 Prompt neutron and gamma emission in U238 fast-neutron-induced fission

Fission modeling is still the subject of much work. The objective is to understand the structure and dynamic effects involved in this reaction. From the point of view of fission applications, the objective is to provide precise data on the fission fragments yields and kinetic energies, but also on the emission of neutrons and γ-rays. The work being carried out in numerous laboratories ultimately aims to enable the provision of such data based on theories or phenomenological models. In this presentation I will describe the new results obtained with the large SCONE detector (Solid COunter for NEutrons), based on plastic scintillator bars. The detector design includes a significant amount of Gd, in order to carry out neutron counting with an efficiency of about 80 percent for fission neutrons. In addition, by design, SCONE is also a good γ-ray calorimeter, and in particular its granularity allows to determine the γ-ray multiplicities. I will present the experimental results of the fast neutron induced fission of uranium 238, obtained during a first experiment performed at the GANIL/NFS facility, for neutron energies ranging from 1 MeV to 30 MeV. The complete distributions of fission neutron multiplicities, the average total radiated γ-ray energies, and the average γ-ray multiplicities against the incoming neutron energy will be presented. Measuring the different observables continuously as a function of neutron energy makes it possible to study the effects of multi-chances which confer structures into those observables. For the first time the second and third chance fission probabilities on uranium 238 were measured experimentally. Concerning the prompt γ-ray emission, the multiplicities measurement against the neutron incoming energy allows to study the angular momentum generated at scission, and also to quantify the orbital angular momentum transfered to fission fragments. 
[1] B. Fraisse et al., Phys. Rev. C 108, 014610 (2023)

Speaker: Gilbert Bélier (CEA/DAM/DIF)

12:10 Prompt and delayed γ-ray emission as an experimental probe of fission

rompt and delayed gamma ray spectroscopy of nuclear reactions inducing fission can reveal a wealth of important information. Gamma ray spectroscopy of the de-exciting fragments after fission occurs not only allows study of the nuclear structure of neutron-rich nuclei, but also provides essential information on the fission process itself [1][2]. Conversely, study of delayed gamma emission can be used to extract isomeric yield ratios [3] and probe rare phenomena such as the population and back-decay of the fission shape isomers – metastable states with very large deformations which sit on the pathway to fission [4].
This presentation will give an overview of recent results on the gamma ray spectroscopy of fission with the nu-Ball2 spectrometer [5] at the ALTO facility of IJC Lab. Several open questions are currently being addressed, such as the evolution of fragment yield distributions in the sub-actinide region [6], the emission of high energy gamma rays in nuclear fission with potential population of collective excitations (PDR, GDR, etc.) in the emerging fragments [7]. The experiments have also explored other outstanding questions, such as the angular momentum carried away by neutron emission [8] and angular correlations between the spins of fission fragment partners and measurements of angular distributions of gamma rays with respect to the fission axis [9][10][11]. An overview of these new studies from the ν-Ball2 experimental campaign will be given and selected results will be presented along with future perspectives.

References

[1] S. Leoni, B. Fornal, N. Mărginean and J.N. Wilson, Eur. Phys. J. Spec. Top. 233, 1061–1074 (2024)
[2] J.N. Wilson et al., Nature 590, p566–570 (2021)
[3] D. Gjestvang, J.N. Wilson et al. Phys. Rev. C 108, 064602 (2023)
[4] C. Hiver, J.N. Wilson et al., Acta Physica Polonica, Vol. 18 (2025)
[5] G. Pasqualato and J.N. Wilson, Nuclear Physics News, 34 16-20, (2024)
[6] K. Miernik et al. Phys. Rev. C 108, 054608 (2023)
[7] H. Makii et al. Phys. Rev. C 100, (2019) 044610
[8] I. Stetcu et al., Phys. Rev. Lett. 127, 222502 (2021)
[9] J. Randrup, Phys. Rev. C 106, L051601 (2022)
[10] A. Bulgac et al., Phys. Rev. Lett. 128, 022501 (2022)
[11] G. Scamps et al., Phys. Rev. C 108, L061602 (2023)

Speaker: Jonathan WILSON

12:40 Nuclear Fission: Connecting Fundamental Physics and Real-World Applications

Nuclear fission continues to test our understanding of the atomic nucleus while enabling technologies from national security and energy to astrophysics. In this talk, I will highlight research areas where fundamental fission physics and application-driven needs truly meet, using examples such as cross sections, fragment observables, and prompt and beta-delayed emissions to trace how microscopic mechanisms flow through the nuclear data pipeline into evaluated libraries used in real systems. I will also “open the hood” on how these evaluations are built and updated in an era of AI-assisted workflows and large-scale optimization, and revisit what we mean by uncertainty and information content so that both basic research and applications can better benefit from each other.

Speaker: Dr Patrick Talou (Stardust Science Labs)

20:30 → 21:00 RECEPTION

21:00 → 23:00 Honorary session

Convener: Barbara Sulignano

Thursday 18 June

09:00 → 11:00 Fission

Convener: Patrick Talou (Stardust Science Labs)

09:00 The multiple facets of mass division in nuclear fission: an inexhaustible source of inspiration

The study of fission-fragment mass distribution never ceased to surprise us.
In the present study, an improved scission point model [1] is used to
calculate
the multiple aspects of the mass division in nuclear fission.
Nuclear shapes are described by generalized Cassini ovals [2].
Potential energy surfaces [3] are calculated "just before scission"
($\alpha$=0.98) as a function of five most relevant deformation parameters:
$\alpha_1$, $\alpha_2$, $\alpha_3$, $\alpha_4$, $\alpha_5$ (or $\alpha_6$).

A remarkable result has been the quantitative explanation of the sharp transition
observed in Fm and No isotopes and predicted to occur
also in Rf and Sg isotopes. Super-symmetric fission, with FWHM of the mass
distribution less than 7 amu, was found in $^{264}$Fm and $^{268}$Rf.

An incursion in the region of SHE has revealed the crucial role of
the octupole deformation at scission in determining the main feature of the
mass distribution: symmetric or asymmetric. With $\alpha_3$, the division is
asymmetric and the position of the light fragment peak is constant at $A_L$=136.

Finally, new results on super-asymmetric fission (SAF) are presented.
The fission fragment mass distributions for several U, Pu, Fm, No,
Hs and Fl isotopes are calculated
for a wide domain of fragment masses (from 40 to 210) in order to include SAF.
Indeed, in the potential energy of deformation as a function of fragment mass ratio
one can see a relativ minimum at large asymmetry besides the absolute
minimum at moderate asymmetry.

1) In all cases the most probable heavy fragment mass for the
super-asymmetric fragmentation is shifted from the "expected" $A_H$=208 to
$A_H$=190 probably due to proximity effects (the two pre-scission fragments are
connected).

2) The reason of the potential minima is the occurrence of very peculiar
shapes: one fragment pear-shaped at the absolute minimum (A$_H$=136) and
dumbbell shapes at the relative super-asymmetric minimum (A$_H$=190).
The existence of special nuclear shapes at the minima of the potential along the
scission line
is an original observation with implications on the post-scission properties of
the nascent fragments.

3) The super-asymmetric yield for No isotopes is $\approx 10^{-5}$. It increases
considerably for Fl isotopes: $\approx 10^{-2}$.

[1] N. Carjan, F. A. Ivanyuk, Yu. Oganessian, G. Ter-Akopian, Nucl. Phys.A 942 (2015) 97.
[2] V. V. Pashkevich, Nucl. Phys. A 169 (1971) 275.
[3] V. M. Strutinsky, Nucl. Phys. A 95 (1967) 420.

Speaker: Nicolae Carjan

09:30 Long relaxation times in fission dynamics in the mass-asymmetry degree of freedom

Present understanding of dynamic properties of nuclei relies heavily on
the study of heavy-ion collisions [1]. The slowing down of the relative velocity has been studied to determine the strength of dissipation. With increasing contact time, one observes the transition from local interactions and exchange of a few nucleons at the surface regions to a large-scale shape evolution of the dinuclear system, eventually ending up in the formation of a compound nucleus. The study of these reactions has provided rich information on, among others, the dynamical properties that rule large-scale collective nuclear motion. Fission, which is an important
decay channel of a heavy compound nucleus, is roughly the inverse process, leading in most cases to the formation of two separate fragments.
The large variety of the observables can mostly be well described by
stochastic models like the Langevin approach. This means that the process is strongly ruled by statistical mechanics. Often, data are even well described by restricted models:
(i) The influence of the inertial force is neglected by using the
Smolochowski equation.
(ii) Adiabatic approaches neglect dissipation completely.
(iii) Statistical scission models do not consider any dynamics at all.
This shows that these observables contain little information on the
dynamics in comparison to the above-mentioned inverse process.
In detail, one can identify several critical steps:
(i) Low-energy fission is ruled by the phase space at stages with minimum entropy. Here, the level density above the multi-dimensional potential-energy surface is very important.
(i) States at the first barrier are populated according to the phase space
that favours triaxial shapes.
(iii) States at the second barrier are populated according to the phase space that favours asymmetries according to shell effects at certain numbers of protons in the nascent fragments.
(iv) The descent towards scission follows so-called fission valleys that essentially preserve the mass asymmetry, but may change the fluctuations. Here, we have a certain influence of dynamics.
As a consequence, the transport properties, e.g. the friction tensor and
the inertial tensor, that rule nuclear fission are highly uncertain [2].
For microscopic dynamical fission models, this does not mean that they are not important, but the empirical information for testing these models in terms of fission dynamics seems to be weak. A better knowledge would be very interesting, because the conditions may differ substantially from those in heavy-ion collisions due to the lower relative velocities and the lower excitation energies involved. In particular, the presence of pairing correlations and the important role of shell effects are specific for low-energy fission.

In this contribution, we present and interpret existing experimental results that did not attract attention before. These data clearly show the suppression of fission events with high total kinetic energies (TKE) that exploit almost the complete Q value compared to a widely valid systematics. The suppression appears below a threshold energy that depends on the fissioning nucleus. The threshold is especially high for nuclei that previously showed indications for a third minimum in the fission barrier. The resemblance of these observations with the Hill-Wheeler formula for the transmission of a potential barrier at sub-barrier energies suggests that the suppression effect is caused by reduction of flux due to tunneling near the third fission barrier. We explain the disappearance of the suppression effect above the threshold energy by a long relaxation time of the mass-asymmetry degree of freedom, which is longer than the dynamical time for the evolution from second to third barrier.

[1] "Transport phenomena in dissipative heavy-ion collisions:
the one-body dissipation approach", H. Feldmeier,
Rep. Prog. Phys. 50 (1987) 915

[2] "Future of nuclear fission theory", M. Bender et al.,
J. Phys. G: Nucl. Part. Phys. 47 (2020) 113002

Speaker: Karl-Heinz Schmidt

10:00 Characteristics of Primary Fission Fragments from a Microscopic Perspective

Nuclear fission is a key ingredient for a wide variety of applications, ranging from basic science to abundant, carbon-free energy production, nuclear forensics, nonproliferation, and national security. However, on the experimental side, studying observables occurring before prompt emissions is extremely challenging, and so far, the few available data carry significant uncertainties. Hence, predictive, accurate theoretical modeling is needed to understand the complete fission process, but such an endeavor remains challenging. In this presentation, we present our latest results on predicting fission-fragment excitation and total kinetic energies using our novel, highly computationally efficient time-dependent HFB solver.

Speaker: Dr Marc Verriere (CEA,DAM,DIF)

10:20 Angular Momentum in Fission through 241Am(2nth,f) Isomeric Ratio measurements with the Lohengrin spectrometer

Despite decades of study, accurate modeling of nuclear fission remains difficult, as a wide variety of theoretical approaches — microscopic, macroscopic, or phenomenological models — are based on different underlying assumptions. To date, despite this diversity of approaches, none of the currently existing models can predict the angular-momentum generation mechanism with satisfactory accuracy. As a result, several questions remain open, among them whether the angular momentum is governed only by structural effects, or whether it is also influenced already at the moment of scission due to fragment deformation and other dynamical effects.

To investigate the angular momentum and gain insight into its underlying mechanism, an indirect method based on measuring isomeric ratios (IRs) is used. The IR is defined as the fission-induced production rate of the isomeric state divided by the sum of the production rates of both the ground and isomeric states. These ratios are particularly useful observables because they preserve information about the fragment’s initial angular momentum immediately after prompt-particle emission and may allow the study of nuclear structure.

A recent experimental campaign was conducted at the LOHENGRIN recoil spectrometer of the Institut Laue–Langevin (ILL) in Grenoble to measure the kinetic-energy dependence of the IR for several fission products produced by thermal-neutron-induced fission of $^{241}\mathrm{Am}$. The IRs were extracted using $\gamma$-ray spectrometry with two segmented High Purity Germanium (HPGe) Clover detectors placed in coincidence with an ionisation chamber at the end of the spectrometer. These measurements provide a sensitive probe of the total angular momentum generated in the fission fragments.

The choice of the $^{241}\mathrm{Am}(\mathrm{n}_{\mathrm{th}},\mathrm{f})$ reaction represents a unique case study, as the first neutron capture populates $^{242}\mathrm{Am}$ in both a long-lived metastable state with $t_{1/2,m} = 141$~y and $J^\pi = 5^-$, and a ground state with a half-life of $t_{1/2,g} = 16$~h and $J^\pi = 1^-$. These two competing states, which differ strongly in both half-life and angular momentum, undergo fission independently after capturing a second neutron and forming the compound nucleus $^{243\ast}\mathrm{Am}$.

As the reactor power varied over the time of the measurements, it is possible to determine the relative contributions of fission originating from the metastable and ground states of $^{242}\mathrm{Am}$ as a function of time. The time evolution of the IR, as well as its dependence on kinetic energy, has been extracted for several isotopes. Promising preliminary results show, for the first time, a clear kinetic-energy dependence of the IR for $^{100}\mathrm{Nb}$ and other isotopes in the mass region $A = 95-114$.

To interpret the experimental data, the FIFRELIN Monte Carlo code is used to simulate the de-excitation of the fission fragments. We aim to determine the angular-momentum distribution of the fission fragments as a function of their kinetic energy by combining the measured IRs with FIFRELIN calculations. The absolute efficiency of the detection system, including corrections for summing effects, was quantified using detailed Monte Carlo simulations implemented in MCNP6. This analysis will ultimately enable the exploration of angular-momentum generation mechanisms in fission.

Speaker: Anna Skouloudaki (CEA Cadarache)

10:40 A Theoretical Model for the Angular Correlations of Gamma Rays Emitted by Fission Fragments

The generation of the angular momenta (AM) of fission fragments has received renewed interest in recent years, driven by a convergence of differential experimental data and improved microscopic and phenomenological theories. Of particular interest are the correlations between the fission fragment AM vectors, which may probe the mechanism of AM generation. We study the spontaneous fission of even-even nuclei, whose fission process is expected to produce geometrically anti-correlated, and possibly entangled, fragment angular momenta along the fission axis. We present theoretical work on the angular correlations of gamma-rays emitted by the two fragments, and their dependence on the original alignment of the two fragment AM as well as any intervening, unobserved, radiation. We also develop statistical and machine-learning based methods trained on simulated noisy data, to reconstruct the original quantum state of fragment AM alignment given the angular correlations in the observed emission patterns. The connection between the angular correlations in the emission pattern, the orbital AM of the fragments, and ultimately the mechanisms of scission, is briefly explored. These theoretical studies will be integrated in radiation transport codes, such as FLUKA, to help quantitatively interpret experimental data and determine the fragment spin alignment at the moment of scission.

Speaker: Stefano Marin (CERN)

11:00 → 11:30 COFFEE BREAK

11:30 → 12:40 Measurements

Convener: Giuseppe Tagliente (Universita e INFN, Bari (IT))

11:30 Quadrupole moments of the first 2+ state in the even-even Sn isotopes approaching Sn-100

In this presentation we will give results from the first measurements of the quadrupole moment of the first excited 2+-state in the even-even isotopes Sn-110,Sn-108 and Sn-106 at the HIE-ISOLDE facility at CERN. The evolution of the reduced transition probabilities, the B(E2), between the first 2+-state and the ground state in the light even-even Sn isotopes have been a long-standing puzzle,showing clear deviations between theory and experiment. However, recent Monte Carlo Shell Model calculations have suggested that a non-negligible proton core-excitation component of the wave function may manifest itself in an observable oblate shape of the first 2+ state in Sn-110, with a shape change occurring in the same state in the lighter isotopes. That model is at the same time also more successful in reproducing the observed B(E2) values. In this work we will summarize our recently published result for Sn-110 (Phys. Rev. Lett. 135, 222502) and also present preliminary results for Sn-108 and Sn-106.

Speaker: Joakim Cederkall (Lund University (SE))

12:00 Nucleon transfer in 12C+12C reaction at 105 MeV beam energy

We investigate transfer reactions in 12C+12C collisions at 105 MeV impinging energy with the coupling of the INDRA and FAZIA multi-detectors at GANIL. This contribution focuses on a preliminary analysis of the 11C+13C and 11B+13N exit channels leading to various excited states of the residual nuclei. They are particularly powerful tools to explore the single-particle structure of the produced nuclei. The obtained angular distributions of the differential cross section are analyzed in terms of some optical model calculations with the purpose of evaluating one-nucleon spectroscopic factors of the involved levels. The peculiarity of this study is that INDRA-FAZIA is a state-of-the art 4π multi-detector designed to study heavy-ion collisions and multi-fragmentation processes; for this reason, the present work demonstrates, for the first time, the capabilities of this multi-detector in the investigation of nucleon transfer reactions.

Speaker: Andrea De Rosa

12:20 Measurements of (n,cp) reactions for tritium breeding in fusion reactors at n_TOF

In the last decade, research in nuclear fusion has made several significant advancements. However, despite solving many problems, nuclear fusion still requires scientific and technological advancements before it can be used to produce energy. One of the key problems is Tritium breeding.
Most fusion reactor concepts employ deuterium-tritium fuel. The latter, being rare and radioactive, needs to be produced inside reactors, in tritium breeding modules. Several designs exist for this crucial component of reactors, and accurate modeling of the tritium cycle critically depends on precise nuclear data, as small deviations in tritium production rates can significantly impact reactor feasibility, blanket performance, and overall project costs.
Lithium is the only element capable of tritium breeding, via the $^6Li(n,t)\alpha$ and $^7Li(n,n't)\alpha$ reactions, with the latter playing a central role in advanced blanket concepts. Uncertainties in the $^7Li(n,n′t)\alpha$ cross section are large, with discrepancies among evaluated libraries and limited high-quality experimental data that directly affect Tritium Breeding Ratio (TBR) predictions. Similar problems affect other key reactions involved in Tritium Breeding, in particular $^9Be(n,2n)2\alpha$, used for neutron multiplication and ^19F(n,n’), which contributes to neutron moderation.
Recently, a measurement campaign has been undertaken at CERN’s n_TOF facility (EAR1), with the aim of improving the accuracy of key cross section data involved in tritium breeding. For measurements of (n,cp) reaction, a neutron-transmutation-doped (nTD) silicon detector array has been developed and tested at n_TOF. Innovative features of the detector, such as the combination of Pulse Shape Discrimination with digital Pulse Shape Analysis enable precise charged-particle identification, a fundamental pre-requisite for achieving uncertainties as low as 5%. The campaign will also provide energy and angular distribution of reaction products, delivering benchmarks for multi-body nuclear reaction theories.
In this talk, after describing the motivations for the proposed measurement campaign, we will present the new experimental setup specifically developed for this purpose, and its main features, obtained both from tests under the n_TOF neutron beam and from Monte Carlo simulations. Finally, we will present preliminary results on the $^7Li(n,n’t)\alpha$ reaction, whose measurement is expected to take place in the first half of the 2026 run at n_TOF.

Speaker: Giulio Perfetto (Universita e INFN, Bari (IT))

15:00 → 16:20 Measurements

Convener: Gilbert Bélier (CEA/DAM/DIF)

15:00 ALICE Highlights

ALICE is a dedicated experiment with a detector built to probe and explore the high-density, deconfined QCD matter produced in relativistic heavy-ion collisions at the Large Hadron Collider (LHC), CERN. The complexity of these collisions, driven by numerous competing physics processes leading to the formation of the detected final state particles, requires a vast amount of data and different measurements to study and disentangle the properties of strongly interacting matter at the highest temperatures and densities ever achieved in the laboratory. For this reason, ALICE measures a wide variety of particles, different observables, and has collected data since 2009 from various collision systems, including AA (Pb–Pb, Xe–Xe, Ne-Ne, OO), pA (p–Pb, pO), and pp.
This presentation will showcase recent highlights from ALICE and outline its ambitious short- and long-term upgrade plans.

Speaker: Siegfried Foertsch (iThemba LABS, National Research Foundation (ZA))

15:30 Observed oscillations in neutron capture cross sections

Recent 149Sm results from the DICER (Device for Indirect Capture Experiments on Radionuclides) and DANCE (Detector for Advanced Neutron Capture Experiments) instruments, indicated an oscillatory behavior in the neutron capture cross section. Analysis of neutron-capture cross sections in the resolved resonance range of other nuclides reveals that a large fraction of them (13 of 21, or 62%) exhibit highly significant (> 99.9% confidence level) oscillations about their average value. Oscillations exceed a significance level of 5σ in nine cases (43%). Oscillations comprise 10.86 ± 0.64% of the average cross section with periods ranging from 68.2 to 2380 eV. This contradicts random matrix theory (RMT), which predicts that fluctuations about the average cross section should be entirely random and demonstrates that deviations from RMT are common and widespread in neutron-capture data. These facts suggest there is a widespread physical mechanism that is missing from current nuclear physics models describing neutron-capture cross sections. Descriptions of the DICER and DANCE instruments along with the findings will be discussed.

Speaker: Thanos Stamatopoulos

16:00 New measurements of capture gamma ray production cross sections at UMass Lowell Research Reactor

New data measurements from neutron capture reactions are the main thrusts of the research by the Nuclear Applications and Nuclear Data (NAaND) group at University of Massachusetts Lowell (UML). New facility for measurements of capture gamma rays was designed and built at the UML’s 1 MW Research Reactor in recent years [1]. The measurements are using the collimated thermal neutron beam and the array of high-resolution actively suppressed high-purity germanium detectors. The measurements are carried out using a modern high-density and high-speed digital data acquisition system that enables state-of-the-art coincidence spectroscopy of gamma-rays from excited compound nuclei after neutron capture. Custom electronics was designed to handle the transistor-reset preamplifier signals from HPGe detectors and enable data collection at high rates without loss of energy resolution. Comprehensive thermal cross sections and gamma-decay data will be created through the nuclear data evaluation process by partnership with a National Nuclear Data Center (NNDC) staff scientist at Brookhaven National Laboratory (BNL). In this talk we will present an overview of the current and future program at this facility and new data for thermal neutron capture on Mn, Cu, Ni, Gd, Fe, Cl and Cr. We will also present the Geant4 model of the experimental setup and compare the theoretical calculations of capture gamma-ray cascades for selected elements with experimental results.

This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Data under Award No. DE-SC0022907, the U.S. Department of Energy under the Funding for Accelerated, Inclusive Research (FAIR) under Award No. DE-SC0024373, the National Science Foundation under Grant No. 2144226 and the DOE National Nuclear Security Administration under Award Number DE-NA0004150.

[1] M. Jandel et al, Neutron capture measurements at UMass Lowell research reactor, Nuclear Physics A, Volume 1060, 2025, https://doi.org/10.1016/j.nuclphysa.2025.123116.

Speaker: Daniel Fernandez (University of Massachusetts Lowell)

16:20 → 17:00 Evaluations

Convener: Gilbert Bélier (CEA/DAM/DIF)

16:20 Zr-90 in the Nuclear Data Evaluation Pipeline of Uppsala (NEPU): Uncertainty Quantification with Model Defect Treatment

Zirconium alloys are widely used as structural and cladding materials in reactors, with Zr-90 being the most abundant isotope ($\sim51\%$) in natural zirconium. Reliable neutron-induced cross-section data with uncertainty estimates for Zr-90 are therefore essential for reactor physics calculations, safety assessments, and material damage predictions. In the fast neutron energy range, however, evaluations remain challenging due to inconsistent experimental data and limitations in nuclear reaction models to fully reproduce observed values.

In this work, we present NEPU, an automated Nuclear data Evaluation Pipeline at Uppsala University, and demonstrate its application to the evaluation of Zr-90. The pipeline systematically integrates TALYS [1] nuclear reaction modeling with differential experimental data extracted from the EXFOR database through Levenberg-Marquardt optimization [2], implemented within a containerized and reproducible computational framework. A key methodological aspect of the pipeline is the explicit treatment of model defects using heteroscedastic Gaussian process [3]. These processes are used to describe energy-dependent deviations between theoretical predictions and experimental data, including unresolved resonance-like structures that cannot be reproduced by smooth statistical reaction model parameters. By treating such discrepancies separately, the approach avoids forcing model parameters to compensate for missing structure, which would otherwise result in biased parameter estimates and unrealistic uncertainties.

The contribution outlines the architecture of NEPU, including automated data retrieval, uncertainty treatment, parameter sensitivity analysis, Gaussian process implementation, and covariance matrix generation. The methodology has been validated through evaluations of Fe-56 and Cr-52 [3] and is here applied to Zr-90 in the fast-neutron energy region. The results illustrate how explicit treatment of model defects leads to more realistic cross-section uncertainties and covariance data suitable for uncertainty propagation in reactor physics applications. Implications for uncertainty quantification of structural materials in Generation IV reactor concepts are discussed.

References
[1] A. J. Koning and D. Rochman, Nucl. Data Sheets 113, 2841 (2012).
[2] G. Schnabel et al., Nuc. Data Sheets 173, 239 (2021).
[3] A. Göök et al., EPJ Web Conf. 294, 04005 (2024).

Speaker: Dr Jinti Barman (Uppsala University)

16:40 Photonuclear evaluation using ML-enabled framework

Photonuclear data libraries remain significantly less constrained than their neutron-induced counterparts, primarily due to the scarcity of experimental data and inconsistencies among available datasets and theoretical models. Machine Learning (ML) supported methods enable computationally intensive evaluation methodologies to be performed at a fraction of their traditional cost, while reducing reliance on simplifying assumptions and mitigating biases inherent in existing methodologies. This talk will discuss ongoing efforts at Los Alamos National Laboratory to leverage ML-enabled frameworks for consistent evaluation of photonuclear reactions across multiple nuclei, reaction channels, and observables. By integrating ML techniques with Markov Chain Monte Carlo (MCMC) methods, we aim to improve the robustness, precision and internal consistency of the evaluated photonuclear data, while systematically identifying gaps and tensions within existing datasets.

Speaker: Dr Ajeeta Khatiwada (Los Alamos National Laboratory)

17:00 → 17:30 TEA BREAK

19:30 → 21:30 Ettore Gadioli Wine Party

Convener: Lembit Sihver (The University of Rio Grande Texas)

Friday 19 June

09:00 → 10:50 Heavy Ions

Convener: Egle Tomasi (CEA Saclay)

09:00 Quarkonia spectroscopy in the quark-gluon plasma

In relativistic heavy-ion collisions at RHIC and LHC energies, the spectroscopy of heavy-quarkonia states such as $J/\psi$ and $\Upsilon(nS)$ that are mostly produced in the initial stages of the collision is modified through the presence of the hot plasma of gluons and light quarks. Here, we investigate the in-medium effects on the $\Upsilon$ and $\chi_b$ states in our theoretical Heidelberg model.

It considers, in particular, screening of the real quark-antiquark potential, collisional damping through the imaginary part of this potential, gluon-induced dissociation of the six states involved below threshold, and reduction of the feed-down contribution to the $\Upsilon(1S)$ spin-triplet ground state because of the screening of the higher-lying states [1]. Centrality- and transverse-momentum dependent results are compared with CMS and STAR data for the $\Upsilon(nS)$ states, including recent CMS results [2] for $\Upsilon(3S)$. The model has also been applied to $\Upsilon$ physics in p-Pb collisions, where the hot-medium influence can not be neglected, although cold-matter effects are dominant -- as is shown in a detailed comparison with LHCb and ALICE data.

[1] G. Wolschin, Int. J. Mod. Phys. A 35, 2030016 (2020).

[2] A. Tumasyan et al. (CMS Collaboration), Phys. Rev. Lett. 133, 022302 (2024).

Speaker: Georg Wolschin

09:30 Surrogate reactions in inverse kinematics at heavy-ion storage rings

Neutron-induced reaction cross sections of short-lived nuclei are essential for applications in nuclear technology. However, these cross sections are very difficult or impossible to measure due to the difficulty to produce and handle the necessary radioactive targets. We are developing a project that uses for the first time surrogate reactions in inverse kinematics at a heavy-ion storage ring. This allows one to measure all the de-excitation probabilities as a function of the excitation energy of the nuclei formed through the surrogate reaction with unrivaled precision and indirectly determine the aforementioned cross sections.

In this talk, I will present our new methodology and the results of the two first surrogate-reaction experiments that we have performed at the ESR storage ring of the GSI/FAIR facility in Darmstadt, Germany. In these experiments we have achieved a significant breakthrough by measuring for the first time the fission, γ-ray, neutron and even two- and three-neutron emission probabilities simultaneously. The measurement of all competing decay channels enables the precise determination of fundamental quantities, including fission barriers, particle transmission coefficients, γ-ray strength functions, and nuclear level densities. These quantities are then employed to infer (n,f), (n,γ), (n,n'), (n,2n), and (n,3n) cross sections.

Speaker: Lucas Bégué--Guillou (LP2ib-Laboratoire de Physique des 2 infinis de Bordeaux)

09:50 MAJORANA-TYPE HEAVY ION DOUBLE CHARGE EXCHANGE REACTIONS

The Double Charge Exchange (DCE) reactions represent a special class of direct nuclear reactions suitable for spectroscopic research, as they provide valuable insight into nuclear isospin dynamics and offer a gateway to probe processes directly related to rank-2 isospin effects in bound nuclear systems. Moreover, the DCE reactions are a suitable tool for probing the quantities involved in double beta (0νββ) decay, namely the Nuclear Matrix Elements (NMEs) [1]. Currently, the NMEs for such a decay are affected by large uncertainties in their determination [2], representing a major challenge in the extraction of the effective Majorana neutrino mass as a signature for lepton number violation. In this context, the NUMEN project [1,3] aims to investigate a wide range of heavy-ion-induced DCE reactions in order to constrain NME calculations [1].
The DCE reaction mainly proceeds through three competing mechanisms: multi-nucleon Transfer Double Charge Exchange (TDCE) [4], Double Single Charge Exchange (DSCE) [5], and Majorana Double Charge Exchange (MDCE) [6]. The latter involves meson exchange and it is driven by an effective rank-2 isotensor interaction arising from off-shell pion-nucleon DCE scattering. This process is characterized by a strong short-range nature, with an interaction range on the order of 1 fm. Microscopic calculations of MDCE NMEs have been performed, where pion potentials act as the strong interaction counterparts to the 0νββ neutrino potentials. These pion-induced short-range correlations give rise to a novel class of two-body transition form factors, which are of key importance and particular interest in nuclear spectroscopy.
This contribution will introduce the MDCE mechanism and discuss its role in the 0νββ NME problem. Recent results highlighting its key features will be also presented.

References
[1] F. Cappuzzello et al., Prog. Part. Nucl. Phys. 128, 103999 (2023).
[2] M. Agostini et al., Rev. Mod. Phys 95, 025002 (2023).
[3] F. Cappuzzello et al., EPJ A 54, 72 (2018).
[4] J. L. Ferreira et al., PRC 105, 014630 (2022).
[5] J. I. Bellone et al., Phys. Lett. B 807, 135528 (2020).
[6] H. Lenske et al., Universe 10, 202 (2024).

Speaker: Caterina Garofalo

10:10 Dinuclear system description of capture, fusion and evaporation residues in superheavy element production

The formation of superheavy elements is governed by the interplay between capture, fusion, quasifission, and statistical deexcitation in heavy-ion collisions. In this work, the reaction mechanism of superheavy element production is investigated for the $^{50}\mathrm{Ti}+^{244}\mathrm{Pu}$ system within the dinuclear system (DNS) model. Capture cross sections, compound nucleus formation probabilities, and fusion cross sections are calculated by explicitly accounting for nuclear deformation, orientation effects, angular momentum, and shell corrections. The evolution of the dinuclear configuration along the mass asymmetry coordinate is analyzed to quantify fusion barriers and the competition with quasifission.

The survival of the hot compound nucleus against fission is evaluated using a statistical decay. Evaporation residue cross sections are predicted for several neutron emission channels. The calculated 4$n$ channel exhibits a maximum cross section in good agreement with recent experimental data, confirming the reliability of the DNS-based description.

These results demonstrate the critical role of dynamical fusion mechanisms and nuclear structure effects in optimizing reaction conditions for the synthesis of superheavy nuclei.

Speaker: Dr Bakhodir Kayumov (New Uzbekistan University)

10:30 Investigation of the fusion process for 6Li + 196Pt at energies near the Coulomb barrier

The investigation of heavy-ion reactions involving weakly bound stable nuclei, such as 6,7Li, 9Be, and 10B, plays an important role in the study of the properties of radioactive nuclei. Nuclei of this nature exhibit a high probability of fragmentation (breakup) during the interaction with the target nucleus, giving rise to a complex three- or more-body problem. Owing to this characteristic, the reaction mechanisms associated with collisions involving weakly bound nuclei have been extensively studied at energies around and above the Coulomb barrier.
With the aim of investigating nuclear reaction mechanisms in systems involving weakly bound projectiles, fusion cross sections for the 6Li + 196Pt reaction were experimentally determined at the TANDAR Laboratory in Argentina through off-line measurements of characteristic gamma-ray decays. The cross sections corresponding to complete fusion, incomplete fusion, and transfer channels were obtained from off-line measurements of fusion-evaporation residues produced by the irradiation of the 196Pt target at several bombarding energies around the Coulomb barrier, ranging from 20 to 36 MeV. In addition, the production of 196Au, compatible with a charge-exchange process, was observed.

Speaker: Jessica Chaves (Dalva Sonia Lemos)

10:50 → 11:20 COFFEE BREAK

11:20 → 12:50 Modeling and Codes

Convener: Francesco Cerutti (CERN)

11:20 Antineutron and antideuteron as projectile in the INCL (IntraNuclear Cascade of Liège) code.

At the 16th edition of the Varenna conference, D. Zharevov presented the ability of the INCL (IntraNuclear Cascade of Liège) code to simulate interaction with an antiproton as a projectile from 0 to approximately 10 GeV. Over the past three years, two new antiparticles have been added: the antineutron and the antideuteron. These new capabilities are motivated in particular by the GAPS experiment, which aims to indirectly detect dark matter via the cosmological measurement of the antideuteron using a balloon in Antarctica.

We will present the assumptions and elements used to implement these antiparticles, as well as comparisons with the scarce experimental data available. If time permits, we will explain how certain elements could be improved through the use of Bayesian statistics.

Speaker: Jean-Christophe David

11:50 Model bias and parameter optimisation with the example of INCL/ABLA

The accuracy (the bias) and precision (the uncertainties) of high-energy spallation models is a key issue for the design and development of new applications and experiments. In the case of the combination of the IntraNuclear Cascade model of Liège (INCL) [1, 2] and the Ablation model (ABLA) [3, 4], we address the problem through two orthogonal approaches, both based on a Bayesian framework.

In the framework of the joined project NURBS, shared between the Swiss National Science Foundation (SNF) and the French National Agency for Research (ANR), we developed an approach to optimise the internal parameter of the model [5] and, on the other hand, we developed a method to estimate the bias of the model [6]. The first approach improve the accuracy and the second quantify the accuracy and the precision of model combination. This will be used to study observable ranging from the double differential neutron production to the hypernuclei fission cross section.

References
[1] A. Boudard et al., Phys. Rev. C 87, 014606 (2013).
[2] D. Mancusi et al., Phys. Rev. C 90, 054602 (2014).
[3] J. L. Rodrı́guez-Sánchez et al., Phys. Rev. C 105, 014623 (2022).
[4] J. L. Rodrı́guez-Sánchez et al., Phys. Rev. Lett. 130, 132501 (2023).
[5] J. Hirtz et al., EPJ A 60, 149 (2024).
[6] G. Schnabel, EPJ Nuclear Sci. Technol. 4, 33 (2018).

Speaker: Dr Jason Hirtz (CEA Saclay)

12:20 Recent Improvements and Educational use of the Particle and Heavy Ion Transport code System (PHITS)

An overview of the upgraded features of the general-purpose Monte Carlo radiation particle and Heavy Ion Transport code System PHITS for different applications, will be presented, together with an overview of given and planned PHITS courses. An example of a PHITS course given for international nuclear engineering MSc students, incl. from the EU supported Erasmus Mundus SARENA program, at IMT Atlantique, Nantes, France, will be presented.

Speaker: Lembit Sihver (The University of Rio Grande Texas)