Chiral vibrations and collective bands in Mo104,106

Abstract

High spin states of the neutron-rich $^{104}\mathrm{Mo}$ nucleus have been reinvestigated by analyzing the $\ensuremath{\gamma}$ rays in the spontaneous fission of $^{252}\mathrm{Cf}$ with Gammasphere. Both $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence data were analyzed. A new $\mathrm{\ensuremath{\Delta}}I=1$ band has been discovered with a tentative ${5}^{\ensuremath{-}}$ band head, and is proposed to form a class of chiral vibrational doublets with another ${4}^{\ensuremath{-}}$ band previously found. Angular correlation measurements have been performed to determine the spins and parities. A new ${3}^{\ensuremath{-}}$ level has been added to one of the chiral doublet bands in $^{106}\mathrm{Mo}$. The origin of the chiral doublet bands in $^{104,106}\mathrm{Mo}$ is interpreted as a neutron ${h}_{11/2}$ particle and mixed ${d}_{5/2}, {g}_{7/2}$ hole coupled to the short and long axis, respectively. Triaxial projected shell model calculations have been performed for the chiral doublet bands in $^{104,106}\mathrm{Mo}$. The results show reasonably good agreement with the experimental data.