Reflection asymmetric shell model for octupole-deformed nuclei

Abstract

The reflection asymmetric shell model has been established by means of the variational procedure and the projection method to describe the high spin states of octupole deformed nuclei. The Q•Q forces of quadrupole, octupole, and hexadecapole as well as the monopole and quadrupole pairings are included in the Hamiltonian. The shell model space is spanned by a selected set of the simultaneous angular momentum-and parityprojected BCS multiquasiparticle states which are intrinsically deformed. The general features of rotational octupole bands in even-even nuclei can be interpreted and reproduced by the present model, and the calculated results for the Ra isotopes are in good agreement with the experimental data.

Reflection symmetry of the near-yrast excitations in145Ba

“…[9]. Similarly, the α K coefficient of 0.67 (13) for the 109.7-keV transition in 147 Ba, calculated in this work, agrees with the result of Ref. [9].…”

“…The obtained value, α K (109.5) = 0.85(11), compared against theoretical α K values of 0.15, 0.65 and 0.92 [22], calculated at 109.5 keV for pure E1, M1, and E2 multipolarities, respectively, indicates an E2 multipolarity for the 109.5-keV transition. Similarly, using the α tot (112.5) = 0.76(7) value obtained from Fig.9 and γ intensities from 8 we estimated the total conversion coefficient for the 109.5-keV transition to be α tot (109.5) = 1.18 (13). This value is closest to the E2 solution, considering the theoretical values of 0.18, 0.76 and 1.39 calculated at 109.5 keV for pure E1, M1, and E2 multipolarities.…”

“…[10] into simplex s = +i and s = −i branches of the I=5/2 parity doublets. These results were analyzed theoretically by Chen et al [12], using their model [13], which has been well tested in octupole-deformed actinides. The Authors concluded that while the s = −i branch of the I=5/2 parity doublet can be reproduced by calculations (though no 7/2 + level is known), the proposed s = +i branch includes levels which probably belong to reflection-symmetric configurations.…”

Reinvestigation of high spin states and proposed octupole correlations inCe147

“…The details about RASM can be found in Refs. [25][26][27]. For 147 Ce, the deformation parameters used in the calculations are as follows: ε 2 = 0.173, ε 3 = 0.082 and ε 4 = -0.04, which are close to the values presented in Ref.…”

“…This model was first developed to describe octupole deformation of the even-even Ra isotopes in the A = 220 region [25]. Then it was successfully adapted to describe the octupole deformation and octupole correlations in the Z = 56, N = 88 region, for example, in some Ce and Ba isotopes [11,26,27].…”