Structure of Mg28 and influence of the neutron pf shell

Abstract

Gamma-ray spectroscopy and lifetime measurements using the Doppler Shift Attenuation Method (DSAM) were performed on the nucleus 28 Mg near the N = 20 'island of inversion', which was populated using a 12 C(18 O,2p) 28 Mg fusion-evaporation reaction to investigate the impact of shell evolution on its high-lying structure. Three new levels were identified at 7203(3), 7747(2), and 7929.3(12) keV along with several new gamma rays. A newly extracted B(E2; 4 + 1 → 2 + 1) of 42(7) e 2 fm 4 indicates reduced collectivity in the yrast band at high spin, consistent with ab initio SA-NCSM calculations. At high excitation energy, evidence for the population of intruder orbitals was obtained through identification of negative parity levels (I π = (0, 4) − , (4, 5) −). Calculations using the SDPF-MU interaction indicate that these levels arise from single neutron excitation to the pf shell and provides evidence for the lowering of these intruder orbitals approaching the 'island of inversion'.

Configuration mixing in Mg28 and the Mg26(t,p)MgMcNeel1, Wuosmaa2, Kuvin3 et al. 2021Phys. Rev. C3000View full textAdd to dashboardCite

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