Speaker
Description
In nuclear structure studies, the nucleon-nucleon correlations are known to play a crucial role in determining the low-energy spectra and ground-state properties of nuclei.
Heavy ion reactions are considered a promising tool for investigating such correlations, as they allow for the exchange of multiple nucleon pairs, both neutrons and protons, among the reaction partners [1-6].
We will present preliminary results of the data analysis from an experiment conducted in March 2023 at LNL using the PRISMA + AGATA set-up, which aims to probe 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.
In this selected system, both neutron and proton stripping and pick-up processes are open, providing the opportunity to investigate nucleon-nucleon correlations simultaneously for a complete set of transfer channels.
The PRISMA magnetic spectrometer [7] was used to identify the light reaction products with excellent charge and mass resolution, allowing for the clear separation of multiple transfer channels.
Up to five proton pick-up channels were observed, as well as proton stripping up to two.
The Q-value distribution for the different transfer channels displays, at least for a few neutron transfers, a well-defined peak centred around the ground-to-ground-state transitions, as expected in a regime where quasi-elastic processes are dominant.
As more nucleons are transferred, a tail toward larger energy losses starts to develop, indicating that secondary processes may contribute.
For all channels, AGATA [8] will provide crucial information about the populated excited states and will allow to extract both the intensities of these excited states and, using also the information measured with PRISMA, the intensities of the ground-state populations.
[1] R. A. Broglia and A. Winther, Heavy Ion Reactions (Addison-Wesley, Redwood City, CA, 1991).
[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)