New Vistas of the Structure of Neutron-Rich Nuclei - Single Particle States and g-FACTORS
Abstract
Prompt γ-γ-γ coincidence studies of neutron-rich nuclei populated in the spontaneous fission of 252Cf led to the discoveries of many important processes like neutron-less binary and ternary fragmentation in spontaneous fission, binary and ternary hot fission modes, hyper-deformation, cluster radioactivity and quasi-molecular states in ternary fission. The high statistics data, 5.7 × 1011 triples and higher folds, opened up discoveries of new band structures and significant extensions of previously known bands. These data were used to measure the angular correlations of cascades of γ-rays from the excited states of neutron-rich fission fragments stopped in an unmagnetized iron foil. By using this γ-γ angular correlation technique, the single particle configurations of the known rotational bands were assigned and confirmed in the present work. In other words, the multipole mixing ratios of ΔI=1 transitions in the rotational bands were measured. These experimental mixing ratios are compred with the theoretical ones of particle and axial-rotor model. The configuration of the ground states in 109,111Ru were, for the first time, assigned. And magnetic g-factors of excited states in even-even neutron-rich nuclei were meaured, too. Two sets of ΔI=1 alternating parity doublets with opposite parities were observed in Ba and Ce isotopes. The B(E1)/B(E2) branching ratios and D0 values may indicate that the octupole correlations are strong in Ba and Ce isotopes because of the Z=56 and N=88 octupole shell gaps. High-spin, even-parity bands in neutron-rich 108,110,112Ru nuclei indicate two-phonon quasi-gamma bands in 110,112Ru.
- Publication:
-
Exploring Fundamental Issues in Nuclear Physics: Nuclear Clusters -- Superheavy, Superneutronic, Superstrange, of Anti-Matter
- Pub Date:
- January 2012
- DOI:
- 10.1142/9789814355766_0003
- Bibcode:
- 2012efin.conf...22R