Evolution of Collective Structure in Odd-Odd $^{70}$As

Excited states in $^{70}$As were produced via the $^{23}$Na($^{54}$Fe, $\alpha 2pn)^{77}$Rb reaction at 80MeV. Gamma-ray transitions between the excited states were collected in coincidence using a high-resolution array of 10 Ge detectors. From the coincidence relationships, a candidate for the missing odd-spin negative-parity sequence was found, with spins and parities assigned tentatively using systematic arguments. All other high-spin level sequences found previously were confirmed. The kinematic moments of inertia for the new band and those observed previously, calculated within the context of the cranked-shell model, show that $^{70}$As is likely dominated by collective behavior at high spin, making it more similar in this regard to $^{72}$As than $^{68}$As. Collectivity and deformation also seem to increase with neutron number in the light proton-rich arsenic isotopes.