Background: The $\gamma$ softness of ${}^{136}\mathrm{Nd}$ makes it possible to study the shape changes induced by two-proton or two-neutron excitation.

Purpose: We measure the lifetimes of two-quasiparticle states of the bands based on the ${10}^{+}$ states at 3296 and 3279 keV to investigate the shape change induced by the alignment of two protons or two neutrons in the $h_{11/2}$ orbital.

Methods: The recoil-distance Doppler shift method was used for the study of ${}^{136}\mathrm{Nd}$ studies, which was formed by the fusion reaction ${}^{120}\mathrm{Sn}({}^{20}\mathrm{Ne},4n){}^{136}\mathrm{Nd}$, at $E_{beam}=85$ MeV. Calculations were performed within the microscopic-macroscopic approach, based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy.

Results: The lifetime of the ${10}^{+}$ state at 3279 keV of ${}^{136}\mathrm{Nd}$ was measured to be $T_{1/2}^{{10}^{+}}=1.63\left(9\right)$ ns. The lifetimes of the $2^{+}$ state at 374 keV and of the ${12}^{+}$ state at 3686 keV of the ground band were also measured to be $T_{1/2}^{2^{+}}=26.5\left(14\right)$ ps and $T_{1/2}^{{12}^{+}}=22.5\left(14\right)$ ps.

Conclusions: The measured lifetime of ${10}^{+}$ the state at 3279 keV together with other observables confirm the structure change in ${}^{136}\mathrm{Nd}$. A rather small reduced hindrance of the electromagnetic decay of the ${10}^{+}$ state at 3279 keV would be consistent with its $K$-mixed character.

• Received 6 June 2019

DOI:https://doi.org/10.1103/PhysRevC.100.014330