Negative-parity states near the yrast line inNd144

New high-spin states of 142 58Ce and 140 56Ba from fusion-fission reactions: Proton excitations in the N = 84 isotones

“…Moreover as such coupled configurations contain both particles and holes, strong M1 transitions are expected between the members of the multiplets. In 148 Gd and 144 Nd, the negative-parity structures displaying the strong ∆I = 1 sequence identified above 4 MeV excitation energy have been interpreted in terms of such couplings [2,4]. Then the configurations, (πg 7/2 ) −1 (πh 11/2 ) 1 ⊗ (νf 7/2 ) 2 or (νf 7/2 ) 1 (νh 9/2 ) 1 , can be also assigned to the states of 142 Ce identified above 4.5 MeV excitation energy (see fig.2).…”

“…Furthermore negative-parity states from octupole correlations are known to be located at low energy in this mass region. The energies of the first fully-aligned states coming from one neutron-pair breaking in the N = 84 isotones with 50 ≤ Z ≤ 64 [1][2][3][4][5][6] are drawn in the right part of fig. 4.…”

“…The yrast structures of the N = 84 isotones from 134 50 Sn to 148 64 Gd are the result of the competition between the excitations from the two neutrons outside the neutron shell closure and the proton excitations, which are expected to change progressively as the proton Fermi level moves within the πg 7/2 and πd 5/2 orbits. The high-spin levels of the heaviest isotones, 148 64 Gd, 146 62 Sm, and 144 60 Nd, have been well studied using fusionevaporation reactions [1][2][3][4], while spontaneous fission has been used to populate the yrast states in the lightest isotones, 140 56 Ba, 138 54 Xe, 136 52 Te, and 134 50 Sn [5,6]. On the other hand the knowledge of 142 58 Ce is very fragmentary.…”