Coulomb excitation of Kr80,82 and a change in structure approaching N=Z=40

Background: Nuclei approaching N = Z = 40 are known to exhibit strongly deformed structures and are thought to be candidates for shape coexistence. In the krypton isotopes, Kr-80,Kr-82 are poorly characterized, preventing an understanding of evolving deformation approaching N = 40. Purpose: The present work aims to determine electric quadrupole transition strengths and quadrupole moments of Kr-80,Kr-82 in order to better characterize their deformation. Methods: Sub-barrier Coulomb excitation was employed, impinging the isotopes of krypton on Pt-196 and Pb-208 targets. Utilizing a semiclassical description of the safe Coulomb-excitation process E2 matrix elements could then be determined. Results: Eleven new or improved matrix elements are determined in Kr-80 and seven in Kr-82. The new B(E2; 0(1)(+) -> 2(1)(+) ) value in Kr-82 disagrees with the evaluated value by 3 sigma, which can be explained in terms of deficiencies in a previous Coulomb-excitation analysis. Conclusions: Comparison of measured Q(s)(2(1)(+)) and B(E2; 0(1)(+) -> 2(1)(+)) values indicates that neutron-deficient (N less than or similar to 42) isotopes of krypton are closer to axial deformation than other isotopic chains in the mass region. A continuation of this trend to higher Z may result in Sr and Zr isotopes exhibiting near-axial prolate deformation.