Magnetic moment and electric quadrupole moment of the 18N ground state

The magnetic moment and electric quadrupole moment of a neutron-rich nucleus 18N have been determined by the β-NMR method, taking advantage of the fragment spin polarization induced in the intermediate-energy projectile fragmentation reaction. To assure the existence of a sufficient polarization prior to the resonance search, a scheme of polarization measurement by means of an adiabatic field rotation has been developed and successfully incorporated in the β-NMR experiment. From the observed resonance in a Pt stopper the magnetic moment for the 18N ground state has been determined to be |μ|=0.3279±0.0013μN. The 18N fragments have also been implanted in a single crystal Mg stopper, and from the observed quadrupole frequency |eqQ/h|=73.2±1.4 kHz, the electric quadrupole moment |Q|=12.3±1.2 mb has been deduced. The obtained μ and Q are compared with shell model calculations.