No evidence of reduced collectivity in Coulomb-excited Sn isotopes

Abstract

In a series of Coulomb excitation experiments the first excited ${2}^{+}$ states in semimagic $^{112,116,118,120,122,124}\mathrm{Sn}$ isotopes were excited using a $^{58}\mathrm{Ni}$ beam at safe Coulomb energy. The $B(E2$; ${0}^{+}\ensuremath{\rightarrow}{2}^{+})$ values were determined with high precision $(\ensuremath{\sim}3%)$ relative to $^{58}\mathrm{Ni}$ projectile excitation. These results disagree with previously reported $B(E2\ensuremath{\uparrow})$ values [A. Jungclaus et al., Phys. Lett. B 695, 110 (2011).] extracted from Doppler-shift attenuation lifetime measurements, whereas the reported mass dependence of $B(E2\ensuremath{\uparrow})$ values is very similar to a recent Coulomb excitation study [J. M. Allmond et al., Phys. Rev. C 92, 041303(R) (2015)]. The stable Sn isotopes, key nuclei in nuclear structure, show no evidence of reduced collectivity and we, thus, reconfirm the nonsymmetric behavior of reduced transition probabilities with respect to the midshell $A=116$.