New beta level mixing and nuclear magnetic resonance method for measuring magnetic dipole and electric quadrupole moments of short-lived nuclei

The level-mixing resonance technique applied to beta-decaying nuclei (beta- LMR) is a well-established tool for measuring the ground state quadrupole m oments of nuclei away from stability. These experiments yield the quadrupol e to magnetic moment ratio, provided the electric field gradient (EFG) of t he implanted nuclei in the crystal is known. By combining beta-LMR with bet a nuclear magnetic resonance (beta-NMR), both the quadrupole moment Q and t he magnetic moment mu can be simultaneously extracted in a single experimen t. A major advantage of this technique is that the initial nuclei need only to be aligned, and not necessarily polarized. Alignment is generally easie r to produce than polarization, and occurs at the highest yield point in th e nuclear reaction mechanism. This is an especially important consideration in the study of dipole and quadrupole moments of nuclei in the region of t he drip lines. We report here the successful application of this combined t echnique to the known case of B-12(Mg). The main features of the LMR-NMR te chnique are described. [S0556-2813(99)01204-2].