Level structure in the transitional nucleus ${}^{195}$Au

Excited states in ${}^{195}$Au have been studied experimentally via the ${}^{192}$Os(${}^7$Li, 4$n$) reaction at a beam energy of 44 MeV. Based on the $\gamma$-$\gamma$-$t$ coincidence measurement, a level scheme consisting of 15 new transitions and 10 new levels is established for ${}^{195}$Au. The triaxial shape-polarizing effect of the high-$j$ $h_{11/2}$ proton hole was studied by total Routhian surface calculations. By comparing with the level structures in the odd-$A$ Au isotopes and the even-even core Hg nuclei, configurations are proposed to the rotational bands and three-quasiparticle states observed in ${}^{195}$Au.

Figure 1

The $\gamma$-ray spectra gated by (a) the 388.0-, (b) 208.3-, and (c) 260.5-keV transitions.

Figure 2

Level scheme of ${}^{195}$Au deduced from the present work. The widths of the arrows indicate the relative transition intensities.

Figure 3

Total Routhian surfaces at $\hslash \omega =0.127$ MeV calculated for the lowest ($\pi ,\alpha )=(-,-1/2$) configurations in ${}^{189–197}$Au. The energy difference between neighboring contours is 100 keV.

Figure 4

Partial level schemes of ${}^{189}$Au, ${}^{191}$Au, ${}^{193}$Au, and ${}^{195}$Au. Data are taken from Refs. [3, 5, 6] and the present work.