Direct Reactions with Exotic Beams (DREB2016)

Competing particle-hole excitations in $^{30}$Na: constraining state-of-the-art effective interactions (Invited)

11 Jul 2016, 10:35

20m

Scotiabank Theatre (St. Mary's University)

Invited

Speaker

Marina Petri (Technical University Darmstadt)

Description

Light neutron-rich nuclei around N=20 show properties that are not in line with their expected magicity but rather imply a deformed shape. These nuclei lie in the so-called ''Island of Inversion'' where the deformation is due to neutron cross-shell excitations dominating their ground and low-lying states. Recently, there has been much interest in studying the transition towards this region to determine the evolution of the sd-pf shell gap around N=20 and to provide a stringent test for nuclear models. In this work the odd-odd nucleus $^{30}$Na is studied via 1p, 1p1n and 1n knockout reactions at the NSCL using $^{31}$Mg, $^{32}$Mg and $^{31}$Na radioactive beams, respectively. Combining high-resolution $\gamma$-ray spectroscopy with the selectivity of the various reaction mechanisms we are able to distinguish multiple particle-hole configurations. Negative parity states in $^{30}$Na are observed for the first time, providing an important measure of the excitation of the 1p1h configuration and hence the sd-pf shell gap. Extracted band structures and level energies are compared with state-of-the-art shell model calculations.