Evolution of quadrupole collectivity in N=80 isotones toward the Z=64 subshell gap: The $B(E2;2_{1}^{+} \rightarrow 0_{1}^{+})$ value of $^{142}$Sm

It was shown that the evolution of the $B(E2;2_{1}^{+} \rightarrow 0_{1}^{+})$ values in $N$ = 80 isotones from Te to Nd is affected by the underlying subshell structure. This manifests itself in the observation of the local suppression of the $B(E2)$ value at $Z$ = 58 with respect to the neighboring nuclei $^{136}$Ba and $^{140}$Nd. To investigate this shell sensitivity toward the $Z$ = 64 subshell gap, the $B(E2;2_{1}^{+} \rightarrow 0_{1}^{+})$ value of the unstable nucleus $^{142}$Sm was measured utilizing the projectile Coulomb excitation technique. The radioactive ion beam (RIB) experiment was performed at the REX-ISOLDE facility at CERN. The $B(E2)$ value of 32(4) W.u. reflects the impact of the $\pi(1g_{7/2} 2d_{5/2})$ subshell closure at $Z$ = 64 with respect to a linear scaling of collectivity with valence proton number.