Time-resolved and time-integral on-line nuclear orientation measurements of neutron-deficient Hg−Au−Pt−Ir nuclei

The methods of time-resolved and time-integral on-line nuclear orientation have been applied to study short lived nuclei with the NICOLE facility (Nuclear Implantation into Cold On-Line Equipment) at ISOLDE-3 in CERN using beams of^182–186Hg. The half-lives in these decay chains are of the order of seconds and therefore comparable to the spin-lattice relaxation times of the nuclei in iron. As the relaxation rate depends strongly on the g-factor, g-factors of nuclei in the decay chains can be deduced from the observation of the time evolution of γ-ray anisotropy. Using this technique the existence of an isomer in¹⁸⁴Au has been found and the g-factors of¹⁸⁴Au,^184mAu and¹⁸²Au have been determined. Accurate half-lives have been extracted from the data. Time-integral nuclear orientation has been observed for short lived as well as longer lived isotopes of the Hg decay chains. From these measurements, after proper correction for incomplete relaxation, the magnetic moments of^183mPt,¹⁸³Ir and¹⁸²Ir have been derived. The applicability of the time-resolved nuclear orientation technique for nuclei far from stability and its possible limitations is discussed.