Laser Spectroscopy and $$\beta$$-NMR Measurements of Short-Lived Mg Isotopes

The feasibility of studying the neutron-rich 29Mg, 31Mg, and 33Mg isotopes has been demonstrated with the laser and β-NMR spectroscopy setup at ISOLDE/CERN. The values of the magnetic moment and the nuclear spin of 31Mg are reported and reveal an intruder ground state. This proves the weakening of N = 20 shell gap and places this nucleus inside the so-called ‘island of inversion.’ The experimental setup and technique, as well as the results, are presented.