Intrinsic structures and associated rotational bands in deformed even-even nuclei of the actinide region

Experimental investigation of vibrational excitations in230Th

“…But the 0 + excitations in the thorium isotopes are observed to be strongly populated in e-decay and in the (p, t) reaction, which excludes their intepretation as B-vibrations [2]. The usual fl band has not yet been identified experimentally in the very heavy nuclei, and the importance of its location was emphasized [3,41. Another unexpected excitation is a second K ~ =2 + band observed in both zeaTh and 23~ ~200 keV above the )~-vibrational band, strongly decaying to the ),-band by E0 transitions.…”

“…Experimental information on higherlying collective excitations exists for 228Th and 23~ with some interesting but not yet fully understood features [2]. The lowest positive-parity excited bands are K ~ = 0 + and 2 + bands, with bandhead energies of E(O+)/E(2+) = 832/969 keV in 228Th and 635/781 keV in 23~…”

Quadrupole deformed and octupole collective bands in 228Ra

“…The pure E0 character of the 259.9-keV line implies that it connects two 0 + states. The possibilitites that it feeds the ground state or de-excites the 721.2 keV state, must be rejected, since a l o w lying 0 + state would mean a dramatic departure from the systematics of the 0 + states in the region [19,20], and also: (even if weakly populated) it would have been likely found in the 232 Th(d, 6 Li) 228 Ra reaction [8,20]. Furthermore, in the case of a 0 Further experimental studies are needed to clarify the placement of this transition.…”

Enhanced and quenched B(E1) transition rates between parity doublet bands in 227Ra

“…Fermi energies for proton and neutron systems were chosen in order to give the correct number of particles in each of these systems and were p = 42.760 MeV, n = 49.750 MeV for 227 Ra and p = 43.220 MeV, n = 48.985 MeV for 223 Ra. All parameters involved in the long-range residual interactions of H QPM were determined by the energies of quadrupole and octupole core vibrational energies, which in the case of 227 Ra were taken from 226 Ra [36,37]: E 0+ = 650 keV, E 2+ = 846 keV (E 2+ is not available in 226 Ra, thus it was taken from 228 Ra), E 0 = 254 keV, and E 1 = 1049 keV. In the case of 223 Ra they were taken as an average of the available data for 222 Ra and 224 Ra [37]: E 0+ = 914 keV, E 2+ = 966 keV, E 0 = 234 keV, and E 1 = 1054 keV.…”

“…All parameters involved in the long-range residual interactions of H QPM were determined by the energies of quadrupole and octupole core vibrational energies, which in the case of 227 Ra were taken from 226 Ra [36,37]: E 0+ = 650 keV, E 2+ = 846 keV (E 2+ is not available in 226 Ra, thus it was taken from 228 Ra), E 0 = 254 keV, and E 1 = 1049 keV. In the case of 223 Ra they were taken as an average of the available data for 222 Ra and 224 Ra [37]: E 0+ = 914 keV, E 2+ = 966 keV, E 0 = 234 keV, and E 1 = 1054 keV. The results of the QPM calculations are presented in Tables 7 and 8 for 227 Ra and 223 Ra, respectively.…”