Quadrupole collectivity beyond N = 50 in neutron- rich Se and Kr isotopes

We will present results on measuring the $B(E2; 0^+_1 \rightarrow 2^+_n)$ strength for the neutron-rich $^{88,90}$Kr and $^{86}$Se isotopes from intermediate-energy Coulomb excitation. The electric quadrupole transition strengths to the first 2+ state complete, with considerably improved uncertainties, the evolution of quadrupole collectivity in the Kr and Se isotopes approaching $N = 60$, for which $^{90}$Kr and $^{86}$Se had previously been the most uncertain. We also report significant excitation strength to several higher lying 2+ states in the krypton isotopes. The results confirm shell model calculations in the $\pi(fpg)-\nu(sdg)$ shell with only a minimally tuned shell model setup that is based on a nucleon-nucleon interaction derived from effective field theory with effective charges adjusted to $^{86}$Kr.