Signature splitting, shape evolution, and nearly degenerate bands in ${}^{108}$Ag

High spin states in ${}^{108}$Ag have been studied via in-beam $\gamma$ spectroscopy techniques using the ${}^{104}$Ru(${}^7$Li, $3n$) reaction. The previously known level scheme has been extended, and a new band structure has been established. The configurations have been tentatively assigned to all observed rotational bands. The signature splitting behavior of the $\pi g_{9/2}\otimes \nu g_{7/2}$ band has been discussed and interpreted as a change in shape from near-oblate to prolate. A systematic study of the nearly degenerate negative-parity bands in the $A\sim 110$ mass region has been performed and it is found that the yrast band in ${}^{108}$Ag and its side band show different behaviors with those expected from a pair of chiral bands.

Figure 1

Level scheme of ${}^{108}$Ag deduced from the present work. Transition energies are given in keV, while the widths of the arrows indicate their relative intensities.

Figure 2

Typical samples of $\gamma$-ray coincidence spectra in ${}^{108}$Ag. The peaks labeled C indicate contaminations.

Figure 3

$S\left(I\right)=E\left(I\right)-E(I-1)-\left[E\right(I+1)-E(I)+E(I-1)-E(I-2\left)\right]/2$ for band 4 in ${}^{108}$Ag (present work) compared to the band with the same configuration in ${}^{106}$Ag.

Figure 4

TRS calculations for the $\pi g_{9/2}\otimes \nu g_{7/2}$ configuration in ${}^{108}$Ag at rotational frequencies of 0.25 MeV and 0.35 MeV.

Figure 5

Excitation energies (a), the energy staggering parameter $S\left(I\right)=\left[E\right(I)-E(I-1\left)\right]/2I$ (b), experimental alignments (c), the kinematic moments of inertia (d), and experimental $B\left(M1\right)/B\left(E2\right)$ ratios (e) as a function of spin for the nearly degenerate bands in ${}^{98,100}$Tc [16, 17], ${}^{104,106}$Rh [18, 19], ${}^{106}$Ag [8, 10], and ${}^{108}$Ag (present work).

Figure 6

TRS calculations for the $\pi g_{9/2}\otimes \nu h_{11/2}$ configuration in ${}^{108}$Ag at rotational frequencies of 0.25 and 0.35 MeV.