Recent data on fusion far below the barrier for ¹²C + ²⁸Si

¹ Univ. of Padova, Italy
² INFN-Padova, Italy
³ Univ. of Ferrara, Italy
⁴ INFN-Lab. Naz. di Legnaro, Padova, Italy
⁵ Univ. Complutense de Madrid, Spain
⁶ IPHC/CNRS Strasbourg, France
⁷ HIL, Univ. Warsaw, Poland
⁸ Univ. of Milano, Italy
⁹ INFN-Milano, Italy
¹⁰ INFN-Firenze, Italy
¹¹ Ruder Bošković Institute, Zagreb, Croatia
¹² Univ. of Stockholm, Sweden

^* e-mail: giovanna.montagnoli@unipd.it

Published online: 11 April 2025

Abstract

Heavy-ion fusion reactions are essential to investigate the fundamental problem of quantum tunnelling of many-body systems in the presence of intrinsic degrees of freedom. Studying the fusion of light systems with Q > 0 and possibly identifying the hindrance phenomenon, requires challenging measurements. Investigating slightly heavier cases allows a reliable extrapolation towards the lighter astrophysical systems. We measured the fusion excitation function of ¹²C + ²⁸Si down to hundreds of nanobarns, using ²⁸Si beams from the XTU Tandem accelerator of LNL. The charged particles evaporated after the fusion process were detected by two DSSDs around the target. The prompt γ-rays emitted by the evaporation residues (ER) were detected by the γ-spectrometer AGATA. The fusion cross-sections are obtained from the coincident events between γ-rays and charged particles. The light-charged particles have been identified through pulse shape analysis, using the rise time, vs their energy E_part. The main transitions from the ER have been identified, and the fusion cross section is obtained by the number of coincident γ-particle events for all observed evaporation channels. Neutron evaporation is calculated to be limited to a few per cent for this system in the measured energy range. Preliminary analyses provide promising results in studying fusion cross sections for light systems at deep sub-barrier energies.