Speaker
Description
Understanding the evolution of nuclear shells with increasing nucleon number provides insight into how the fundamental interactions governing nuclear properties manifest at the scale of nuclear observables. One such region where this is particularly apparent is the $N=20$ island of inversion, where the nominally higher-lying $\nu(f_{7/2})$ shell falls below the $\nu(d_{3/2})$ and dominates the ground state configuration of $^{32}$Mg. Neutron rich Si isotopes lying at the northwestern boundary of the island of inversion have been of significant interest recently, as they represent a region where the evolution between the ''normal'' and ''intruder'' configurations are dominant. Specifically, the ground state of $^{32}$Si is predicted to have a pure $sd$-shell configuration with little-to-no $fp$-shell contributions to the low-energy states, while $^{34}$Si has been described as a ''transitional'' nucleus with dominant $sd$-shell ground state but significant $fp$-shell contributions in low-energy states. In this talk I will discuss the results of neutron-adding $^{31}$Si($d,p$)$^{32}$Si experiments recently performed using the HELIOS solenoidal spectrometer at ATLAS, as well as planned future experiments for the analogous $^{33}$Si($d,p$)$^{34}$Si reaction using SOLARIS at FRIB. The results and implications of these measurements will be addressed.
This work is supported in part by the U.S. Department of Energy Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 and with resources of ANL's ATLAS facility, a Department of Energy, Office of Science User Facility.