Speaker
Description
Halo nuclei have served as benchmarks for understanding weakly-bound and continuum effects on the evolution of single-particle energies and particle correlations at and beyond the dripline. However, direct evidence of halo structures in nuclear excited states has remained elusive due to experimental challenges, thus limiting the number of cases available for investigating halo formation near the threshold.
A new technique, based on a combination of gamma-ray spectroscopy and the transmission method, has been developed to probe the presence or absence of halos in excited states. This novel approach, termed the Gamma-decay Transmission Method, quantifies gamma-ray yields with and without a reaction target to extract the interaction cross section of excited states.
The 1/2$^{+}$ excited state of $^{17}$C, characterized by a small one-neutron separation energy of 0.5 MeV and a significant s-wave component, is a strong halo candidate and therefore well suited to demonstrate the new method. An experimental study using this technique was performed at FRIB utilizing GRETINA, the S800 spectrograph, and a dedicated target assembly to produce $^{17}$C. This talk will describe the new methodology and provide an overview of preliminary results.