Collective quadrupole behavior in ${}^{106}\mathrm{Pd}$

Excited states in ${}^{106}\mathrm{Pd}$ were studied with the $\left(n,n^{\prime }\gamma \right)$ reaction, and comprehensive information for excitations with spin $\le 6\hslash$ was obtained. The data include level lifetimes in the femtosecond regime, spins and parities, transition multipolarities, and multipole mixing ratios, which allow the determination of reduced transition probabilities. The $E2$ decay strength to the low-lying states is mapped up to $\approx 2.4$ MeV in excitation energy. The structures associated with quadrupole collectivity are elucidated and organized into bands.

Figure 1

(a) Angular distribution of the 1397.6 keV $\gamma$ ray from the 1909.5 keV level measured at $E_n=2.2$ MeV and (b) plot of ${\chi }^2$ vs mixing ratio, $\delta$, for the fit of the angular distribution in panel (a) with statistical model calculations.

Figure 2

Lifetimes from the Doppler-shift data for the (a) 1909.5 and (b) 1397.6 keV $\gamma$ rays from the 1909.5 keV level, (c) the 1796.9 keV $\gamma$ ray from the 2308.8 keV level, and (d) the 2193.3 keV $\gamma$ ray from the 2705.2 keV level.

Figure 3

Spectrum obtained by summing the $\gamma$-ray spectra for all angles for the $E_n=2.7$ MeV angular distribution. Some prominent peaks are labeled with the $\gamma$-ray energy, and level spin and parity.

Figure 4

$\gamma \mathrm{-}\gamma$ coincidence spectra gated on the (a) $0_2^{+}\to 2_1^{+}622$, (b) $2_2^{+}\to 2_1^{+}616$, and (c) $4_1^{+}\to 2_1^{+}717$ keV $\gamma$ rays. The value of $J_i^{\pi }$ is given above the labeled $\gamma$-ray energies only for the most intense $\gamma$ rays with firm spin assignments. New $\gamma$ rays from this work are marked with *. The right-hand section of panel (c), (II), has an expanded $y$ axis compared to the left-hand section, (I).

Figure 5

Levels, spins and parities, and $E2$ transition probabilities in W.u. (given in boxes) in ${}^{106}\mathrm{Pd}$. See Table 2 for more detailed information.

Figure 6

Levels in ${}^{106}\mathrm{Pd}$ shown as $K=0$, 2, and 4 bands.