Ponente
Descripción
$^{64}$Ge is a self-conjugate nucleus with N = Z = 32, located at just above the doubly magic nucleus, $^{56}$Ni. This nucleus has a notable feature observed in the $2^{+}_{2}$ state and its band structure [P. J. Ennis et al., NPA 535, 392 (1991)]. This band structure does not represent the $\gamma$-band structure with $K = 2$ although the authors particularly focused on triaxial deformation. This structure has no odd-spin states and more intriguing feature is the excitation energies of the $4^{+}$, $6^{+}$, and $8^{+}$ states. Those excited states lie on almost identical excitation energies of those states belonging to the ground state, which show degeneracy. However, the origin of this anomalous structure has not yet been revealed.
In this presentation, we focus on the observation of the low-lying excited states to confirm this anomaly. We aim to measure the $3^{+}$ state and/or $0^{+}_{2}$ state. The successful measurement of the $3^{+}$ state provides decisive information on the $\gamma$-band structure. If this state is indeed missing, the $2^{+}_{2}$ band structure has a unique feature. On the other hand, the successful observation of the $0^{+}_{2}$ state locating below the $2^{+}_{2}$ state may explain this structure in terms of shape coexistence. Finding neither of these states will drive the feature to the degeneracy of first $4^{+}$, $6^{+}$, and $8^{+}$ states and advanced shell-model calculation needs to be developed.
