High spin states in ${}_{}{}^{68}{}_{}{}^{}\mathrm{As}$: Experiment and theory

High spin states in ${}_{}{}^{68}{}_{}{}^{}\mathrm{As}$ have been studied using the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$${(}^{14}$N,2n${)}^{68}$As, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ ${(}^{12}$C,pn${)}^{68}$As, and ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$${(}^{25}$ Mg,p2n${)}^{68}$As reactions. New high spin states have been observed including a band structure above the known 2160 keV isomeric state. A microscopic description based on the EXCITED VAMPIR model for negative and positive parity states in ${}_{}{}^{68}{}_{}{}^{}\mathrm{As}$ is presented. A possible mechanism to populate the observed high spin isomeric state is proposed. The complex structure of the ${}_{}{}^{68}{}_{}{}^{}\mathrm{As}$ nucleus is caused essentially by specific shape coexistence effects. © 1996 The American Physical Society.