Octupole correlations in neutron rich, odd-Alanthanum nuclei

New level schemes and octupole correlations of light neutron-rich lanthanum isotopes 143,144La

“…Intensive investigations have shown strong evidence of octupole deformation and/or correlations in [142][143][144][145][146]148 Ba (Z = 56, N = 86-92) and 144,146 Ce (Z = 58, N = 86, 88) [5][6][7][8][9][10][11][12][13]. The neutron-rich La isotopes with Z = 57 lie between the Ba and Ce nuclei, and evidence for octupole correlations were reported in 145,147 La (N = 88, 90) by our collaboration [14] and by Urban et al [15] as found in the Ba cores. The 143 La (Z = 57, N = 86) was first studied by our collaboration, and octupole correlations were proposed in the nucleus [16].…”

“…[29,30] and the references therein). Thus 7/2 + , instead of 5/2 + as assigned to 145 La [14,15], is assigned to the ground state of 143 La as in [18]. While the spin/parity assignment for the ground state of 143 La is not the same as that for 145 La [14,15], the latter is consistent with its neighboring N = 86 isotones.…”

“…Thus 7/2 + , instead of 5/2 + as assigned to 145 La [14,15], is assigned to the ground state of 143 La as in [18]. While the spin/parity assignment for the ground state of 143 La is not the same as that for 145 La [14,15], the latter is consistent with its neighboring N = 86 isotones. However, the spin/parity of the bandhead at 291.3 keV of band 3 of 143 La is the same as that of the neighboring isotope 145 La ground state, as discussed below.…”

“…In the present work, an alternative parity assignment for side band 4 of 143 La was facilitated by the observation of the new band 5 in the nucleus, and by comparison of the level systematics of the new level scheme of 143 La to that of the neighboring 145 La [14]. In [14,15], the spin/parity assignments for 145 La were based on measurements of internal conversion coefficients, branching ratios and triple angular correlations. For 143 La, however, since the related transition cascade is not strong enough for angular correlation measurements, we re-determined the multipolarity of the 128.1-keV transition linking bands 3 and 4 (see Fig.…”

“…The 93.9-keV transition between bands 1 and 3 is too weak to deduce an α T for this transition, and the 569.8-498.1-291.3-keV cascade is not strong enough for angular correlation measurements. However, based on the systematics of the yrast levels of 145 La reported in [14,15], the spins/parities of which were assigned based on internal conversion coefficients and angular correlation measurements, as mentioned above, it is reasonable to assign odd-parity to band 1 and to the newly observed band 5 in 143 La. The obvious rotational character of the bands of 143 La suggests stretched E2 for the in-band transitions and | I | = 1 for the linking transitions of the observed bands.…”