Shape changes inN=Znuclei from germanium to zirconium

The first experimental results are reported on excited states in the N=Z nuclei ${}_{}{}^{68}{}_{}{}^{}\mathrm{Se}$ and ${}_{}{}^{76}{}_{}{}^{}\mathrm{Sr}$. These data, combined with recent results on germanium, krypton, and zirconium show the importance of deformed shell gaps in stabilizing nuclear shapes in this region, initially polarizing towards oblate then towards prolate shapes with increasing mass. The results present direct tests of a variety of nuclear models, and a clearer picture of the structure of the region now emerges.