Mg through 2-proton knockout

In the Island of Inversion at N = 20, ground states are dominated by intruder configurations with particle-hole excitations across the shell gap instead of normal 0p0h configurations. For example in ³²Mg the yrast band appears to be deformed instead of spherical, indicating that intruder configurations are preferred compared to the normal closed-shell configuration. Until recently, ³²Mg had been understood in terms of the competition between the 0p0h and 2p2h configurations but this picture predicts a higher energy and lower (t, p) cross section for the isomeric 0⁺₂ state than was observed. To understand the importance of including the 4p4h configuration we performed reaction and lifetime studies of ³²Mg by means of 2p knockout from ³⁴Si at the NSCL. Gamma-ray energy and position information measured by GRETINA was used along with various lifetime measurement techniques that cover a range of possible lifetimes. New results are presented and discussed in the context of competition between normal and intruder configurations.