Lifetime measurement of the yrast 8$^{+}$ state in $^{70}$As

In the A $\sim $ 70 region of the nuclear chart, the structure of excited nuclear states is sensitive to the occupation of the g$_{9/2}$ orbital. In particular, the excited states of the odd-odd nucleus $^{70}$As have been discussed in terms of the coupling of the valence proton and neutron to form two-particle configurations of $\pi $g$_{9/2}\nu $g$_{9/2}$ orbitals. To examine this, the lifetime of the 8$^{+}$ yrast state in $^{70}$As was measured using the gamma-ray line shape technique at the NSCL. Gamma-rays emitted at the reaction target position were measured with the SeGA HPGe array in coincidence with reaction residues detected in the S800 spectrometer. The transition strength of the lowest 8$^{+}$ level, which is among the excited states suggested to be part of these two-particle configurations, was obtained from the measured lifetimes. The validity of this assignment to a $\pi $g$_{9/2}\nu $g$_{9/2}$ configuration and the possible evolution of such high-spin orbitals in neutron-deficient As nuclei will be discussed in light of the present results.