Reduced transition probabilities have been measured for the neutron-rich ${}^{73,74,75}$Ni nuclei with relativistic Coulomb excitation performed at the RIKEN Nishina Center. For the even-even Ni isotope the determined $B(E2;0^{+}\to 2^{+})$ value is compatible within errors with the result of a previous intermediate energy Coulomb excitation experiment, although being somewhat larger. For the odd Ni isotopes $B(E2)$ values have been determined for the first time. In the middle $\nu g_{9/2}$ shell nucleus ${}^{73}$Ni three peak candidates have been observed and tentatively assigned to the (5/2${}^{+}$), (13/2${}^{+}$) and (11/2${}^{+}$) excitations. Two peak candidates have been observed in ${}^{75}$Ni and tentatively assigned to the (13/2${}^{+}$) and (11/2${}^{+}$) levels. The measured $B(E2)$ values are in line with the large $B(E2)$ reported in ${}^{70}$Ni and at variance with the small strength measured in ${}^{72}$Ni. Excitation energies compare well with the result of large-scale shell-model calculations, while $B(E2)$ values are larger than predicted. This could indicate an increasing contribution of proton excitations across the $Z=28$ shell closure when approaching ${}^{78}$Ni.

中文翻译：

---

富含中子的73、74、75Ni同位素的跃迁强度

已经测量了富中子的降低的跃迁概率 ${}^{73，74，75}$在理研西那中心进行了具有相对论库仑激发的镍核。对于均匀的Ni同位素，$乙（Ë2;0^{+}\to 2^{+}）$尽管该值较大，但在误差范围内与先前的中间能库仑激发实验的结果兼容。对于奇数的Ni同位素$乙（Ë2）$值是第一次确定。在中间$\nu G_{9/2}$ 壳核 ${}^{73}$已观察到Ni个三个候选峰，并暂时将其分配给（5/2${}^{+}$），（13/2${}^{+}$）和（11/2${}^{+}$）激励。已经观察到两个峰值候选者${}^{75}$Ni，并暂时分配给（13/2${}^{+}$）和（11/2${}^{+}$）级别。实测$乙（Ë2）$ 值与大 $乙（Ë2）$ 报告于 ${}^{70}$镍和与在 ${}^{72}$你。激发能与大规模壳模型计算的结果相比较，而$乙（Ë2）$值大于预期。这可能表明质子激发在整个过程中的贡献越来越大。$ž=28$ 接近时关闭外壳 ${}^{78}$你。