$^9$Be+$^{120}$Sn scattering at near-barrier energies within a four body model

TL;DR

This study measures elastic and inelastic scattering of weakly-bound $^9$Be on $^{120}$Sn near the Coulomb barrier, using a four-body CDCC model to analyze the importance of breakup processes at low energies.

Contribution

It introduces a four-body CDCC approach considering $^9$Be as a three-body projectile, providing improved analysis of scattering data near the Coulomb barrier.

Findings

Coupling to continuum states is crucial for matching experimental data.

Breakup processes are significant even at energies around the Coulomb barrier.

Inelastic peaks correspond to excitations in $^{120}$Sn, confirmed by coupled-channels calculations.

Abstract

Cross sections for elastic and inelastic scattering of the weakly-bound $^9$Be nucleus on a $^{120}$Sn target have been measured at seven bombarding energies around and above the Coulomb barrier. The elastic angular distributions are analyzed with a four-body continuum-discretized coupled-channels (CDCC) calculation, which considers $^9$Be as a three-body projectile ($\alpha$ + $\alpha$ + n). An optical model analysis using the S\~ao Paulo potential is also shown for comparison. The CDCC analysis shows that the coupling to the continuum part of the spectrum is important for the agreement with experimental data even at energies around the Coulomb barrier, suggesting that breakup is an important process at low energies. At the highest incident energies, two inelastic peaks are observed at 1.19(5) and 2.41(5) MeV. Coupled-channels (CC) calculations using a rotational model confirm that the first inelastic peak corresponds to the excitation of the 2$_1^+$ state in $^{120}$Sn, while the second one likely corresponds to the excitation of the 3$_1^-$ state.