“Stapler” mechanism for a dipole band in Se79

The spectroscopy of( 79)Se is studied via the Se-82(alpha, alpha 3n)Se-79 fusion-evaporation reaction. A negative-parity magnetic dipole band in Se-79 is established for the first time. Based on the calculations by the self-consistent tilted axis cranking covariant density functional theory, this new dipole band can be classified as a "stapler" band, which has a relatively stable symmetric prolate deformation as a function of rotational frequency. Hence, it is demonstrated that the stapler bands exist not only in the oblate and triaxial nuclei, but also in prolate nuclei. By examining the angular momentum coupling, it is found that the five valence nucleons in the high-j orbitals play a major role in the closing of the stapler.