First evidence of an octupole rotational band in Ge isotopes
C. G. Wang, Rui Han, C. Xu, H. Hua, R. A. Bark, Shuangquan Zhang, S. Y. Wang, T. M. Shneidman, Shan-Gui Zhou, Jie Meng, S. Wyngaardt, A. C. Dai, F. R. Xu, X. Q. Li, Z. H. Li, Y. L. Ye, D. Jiang, C. G. Li, C. Y. Niu, Z. Q. Chen, H. y. Wu, D. W. Luo, S. Wang, D. P. Sun, C. Liu, Z. Q. Li, N. B. Zhang, R. J. Guo, Peter G. Jones, E. A. Lawrie, J. J. Lawrie, J. F. Sharpey‐Schafer, M. Wiedeking, S. N. T. Majola, T. D. Bucher, T. S. Dinoko, B. Maqabuka, L. Makhathini, L. Mdletshe, O. Shirinda, K. Sowazi
Abstract
The spectroscopy of $^{71}\mathrm{Ge}$ has been investigated via the fusion-evaporation reaction $^{74}\mathrm{Ge}(\ensuremath{\alpha},\ensuremath{\alpha}3n)^{71}\mathrm{Ge}$. Collective structures including a rotational band built on the $15/{2}^{\ensuremath{-}}$ octupole state in $^{71}\mathrm{Ge}$ have been established. The observation of strong $E1$ transitions and the well-behaved rotational sequence built on the $15/{2}^{\ensuremath{-}}$ octupole state provide the first experimental evidence of an octupole rotational band in Ge isotopes, suggesting an enhanced octupole correlation around $N=40$ in the $A\ensuremath{\approx}70$ region. A newly developed semimicroscopic cluster model provides a good description of the octupole characteristics of $^{71}\mathrm{Ge}$.