• 4 December 2025
• 11:00 EST

The nuclear matter equation of state (EOS) is poorly known at the limit of high density and temperature. While this limit is not currently reached in laboratory settings, it is in neutron star interiors. In this talk, I will discuss two approaches to probing the EOS using neutron star measurements, and how laboratory experiments, such as those performed at FRIB, can complement these approaches. The first approach consists of constraining the EOS with observations of neutron star mass, radius and tidal deformability. I will describe how data from the NICER telescope and the LIGO-VIRGO interferometers are used for this purpose, as well as how constraints from ab initio calculations - such as chiral effective field theory (cEFT) and perturbative QCD (pQCD) – are incorporated to perform EOS inference. I will also discuss how experiments currently running at FRIB will provide additional constraints that can be incorporated into this framework. The second approach to constraining the EOS is related to neutron star cooling by the emission of photons and neutrinos. I will explain how one can use x-ray astrophysical observations to infer the evolution of neutron star luminosity over time, and constrain other EOS quantities, such as particle composition and nuclear pairing. In this case, I will discuss how the measurements of beta-decay and electron capture rates of selected nuclei at FRIB will help in this effort.

• 5 December 2025
• 11:00 EST

Understanding how the same nuclear interactions govern systems ranging from ordinary nuclei to neutron-star matter is central to nuclear astrophysics. These interactions not only determine nuclear stability but also shape the reaction pathways that produce the elements and influence the behavior of extreme stellar environments. Addressing these questions requires ab initio methods that can capture strong correlations, large particle numbers, and sensitivities to the underlying nuclear forces. In this talk, I will present recent advances in neural-network quantum states (NQS) as a scalable variational framework for strongly correlated quantum systems. I will discuss the development of permutation-equivariant neural architectures and Pfaffian pairing ansätze, which enable accurate simulations of large systems of ultracold Fermi gases and electron gases. Extensions of these tools to nuclear matter and medium-mass nuclei provide insight into clustering phenomena and many-body correlations relevant for neutron-star crusts. Complementary work on Bayesian uncertainty quantification connects microscopic theory to both astrophysical and experimental observables. This includes reduced-order models for nucleon-nucleon scattering and Gaussian-process-based strategies for constraining the neutron-star equation of state and propagating uncertainties to derived stellar properties. At the limits of stability, binding becomes delicate and resonances appear, regions that FRIB will explore in unprecedented detail. I will conclude by outlining future directions for extending NQS to describe low-lying excited states and resonances, including approaches based on Grassmannian geometry and complex scaling. Together, these developments aim to build a unified, scalable, and uncertainty-quantified ab initio framework capable of supporting FRIB's mission and advancing our understanding of nuclear structure and astrophysics.

• 5 December 2025
• 2:00 EST

The reaction 22Ne(alpha,neutron)25Mg is one of the main neutron source in stars, providing the neutron flux for the weak component of the s-process in massive stars and partially contributing to the main component in AGB stars. For these reasons, its reaction rate is crucial in nuclear astrophysics.

However, the limited availability of experimental data in the energy range of astrophysical interest still leads to significant uncertainties in the reaction rate and in nucleosynthesis predictions.

The SHADES project addresses this long-standing lack of data in the energy region relevant to stellar He-burning, which spans from the neutron threshold up to a strong resonance at Ecm ≈ 706 keV, which remains the only one accessible on surface.
The main novelty of SHADES is to directly study the 22Ne(𝛼,𝑛)25Mg in the deep underground environment provided by the Laboratori Nazionali del Gran Sasso (INFN-LNGS), thus exploiting the advantages of a highly reduced-background environment to enhance sensitivity to the weak neutron signals characteristic of this reaction.

In this seminar, I will describe the development and optimization of the SHADES experimental setup, the strategies adopted during the several data-taking phases, and the first results obtained from the exploration of the relevant energy region.