Zakopane 2026 Conference on Nuclear Physics

In nuclear structure studies, the nucleon-nucleon correlations are recognised as crucial in determining the low-energy spectra and ground-state properties of nuclei. Heavy ion reactions are considered a valuable tool for investigating such correlations, since they enable the transfer of multiple nucleon pairs, both neutrons and protons, between the interacting nuclei [1-6].
We will present preliminary results of the analysis of data collected in an experiment conducted at LNL using the PRISMA + AGATA set-up, aimed at probing nucleon-nucleon correlations in the $^{48}$Ca + $^{208}$Pb, measuring the transfer probabilities for multi-neutron and multi-proton transfer channels at energies close to and below the Coulomb barrier.
The experiment was carried out in inverse kinematics, using a $^{208}$Pb beam directed at a $^{48}$Ca target, employing the superconducting PIAVE-ALPI accelerator complex.
The experimental setup consists of the PRISMA magnetic spectrometer [7], which was used to identify the light reaction products with high charge and mass resolution, enabling clear separation of multiple transfer channels;
and the AGATA $\gamma$-spectrometer [8], which allowed us to identify the gamma-transitions for each transfer channel. This will provide crucial information about the populated excited states and enable the extraction of both the intensities of these excited states and, using the information measured with PRISMA, the intensities of the ground-state populations.
In this selected system, both neutron and proton stripping and pick-up processes are open, offering a unique opportunity to investigate nucleon-nucleon correlations across a complete set of transfer channels within a single experiment. These preliminary results will help to better understand the relative importance of single-nucleon transfer and more complex processes involving correlated nucleon pairs, as well as the role of correlations in the dynamics of the collision. The present work is particularly timely in view of forthcoming experiments with radioactive beams in both proton-rich and neutron-rich regions, where a wealth of interesting new effects is predicted.

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[2] R. A. Broglia and V. Zelevinsky, Fifty Years of Nuclear BCS—Pairing in Finite Systems (World Scientific, Singapore,2013).
[3] D. Montanari et al., Phys. Rev. Lett. 113 (2014) 052501.
[4] D. Montanari et al., Phys. Rev. C 93 (2016) 054623.
[5] L. Corradi et al., Phys. Lett. B 834 (2022) 137477.
[6] S. Szilner, et al., Phys. Rev. Lett. 133 (2024) 202501.
[7] A. M. Stefanini, et al., Nucl. Phys. A701, 217c (2002).
[8] J.J. Valiente-Dobón et al., Nuc. Instr. Meth. A1049, 168040 (2023)