Complementary decay spectroscopy of neutron-rich radium isotopes: experimental progress using the GRIFFIN spectrometer

Spectroscopy of nuclei near Z=90 and N=134 has previously revealed structures indicative of a reflection-asymmetric or "pear'' shaped deformation of the nuclear fluid. In even-even nuclei, the B(E3) transition strength measured following Coulomb excitation to the lowest-lying 3- state provides a sensitive method to probe the evolution of octupole collectivity across an isotopic chain. High-precision measurements of pertinent properties such as branching ratios and inter(intra)-band mixing ratios form a critical input to the experimental analysis of the transition strength and the extracted multipole moments and shape (deformation) parameters. Recent results from gamma and conversion electron spectroscopy of Ra-228 and Ra-230 are hereby presented following the beta-decay of neutron-rich francium beams delivered to the GRIFFIN spectrometer at the TRIUMF-ISAC facility. Collaborative efforts focused on the spectroscopy of actinide nuclei at TRIUMF and CERN-ISOLDE demonstrate a timely confluence of experiments aimed at examining the nature and onset of octupole collectivity in exotic nuclei.