6533b82dfe1ef96bd1291bc9

RESEARCH PRODUCT

Nuclear ground-state spins and magnetic moments ofMg27,Mg29, andMg31

subject

description

The ground-state spins and magnetic moments of neutron-rich {sup 27}Mg, {sup 29}Mg, and {sup 31}Mg were measured for the first time with laser and {beta}-NMR spectroscopy at ISOLDE/CERN. The hyperfine structure of {sup 27}Mg--observed in fluorescence--confirms previous assignments of the spin I=1/2 and reveals the magnetic moment {mu}{sub I}({sup 27}Mg)=-0.4107(15){mu}{sub N}. The hyperfine structure and nuclear magnetic resonance of optically polarized {sup 29}Mg--observed in the asymmetry of its {beta} decay after implantation in a cubic crystal--give I=3/2 and {mu}{sub I}({sup 29}Mg)=+0.9780(6){mu}{sub N}. For {sup 31}Mg they yield together I=1/2 and {mu}{sub I}({sup 31}Mg)=-0.88355(15){mu}{sub N}, where the negative magnetic moment provides evidence for a positive parity. The results for {sup 27}Mg and {sup 29}Mg agree well with shell-model calculations confined only to the sd model space, whereas the ground state of {sup 31}Mg involves large contributions from neutrons in the pf shell, which places this nucleus inside the ''island of inversion.''.