Octupole strength in the neutron-rich calcium isotopes

TL;DR

This study investigates the octupole excitations in neutron-rich calcium isotopes using gamma-ray spectroscopy, revealing consistent energies and strengths that suggest proton-dominated states.

Contribution

The paper provides new experimental data on octupole states in calcium isotopes, highlighting their proton excitation dominance and stability across isotopes.

Findings

Octupole state energies are remarkably constant across isotopes.

Octupole strengths indicate proton excitation dominance.

States are consistent with previous theoretical predictions.

Abstract

Low-lying excited states of the neutron-rich calcium isotopes $^{48-52}$Ca have been studied via $\gamma$-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA $\gamma$-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.