Positive-Parity States in Odd-Even As Isotopes

The (${}_{}{}^3{}_{}{}^{}\mathrm{He}$,$d$) reaction on ${}_{}{}^{70,72,74,76}{}_{}{}^{}\mathrm{Ge}$ has been studied at 17-MeV incident energy. In all four isotopes, a ${\mathrm{½}}^{+}$ state is observed about 600 keV above the low-lying ${\frac{9}{2}}^{+}$ isomeric state. The presence of these ${\mathrm{½}}^{+}$ states provides a convincing argument in favor of the validity of the rotational model with prolate deformation and with strong Coriolis coupling in this region of the periodic table.