Extreme Prolate Deformation in Light Strontium Isotopes

Abstract

Multiple-particle, $\gamma$-ray coincidence techniques have been used to study neutron-deficient isotopes near $N=Z=40\mathrm{}$. Results are presented for ${}_{}{}^{77-80}{}_{}{}^{}\mathrm{Sr}$. Levels in ${}_{}{}^{78}{}_{}{}^{}\mathrm{Sr}$ were seen to $J=10\mathrm{}$ with $E\left(2^{+}\right)=278\mathrm{}$ keV and $T_{\frac{1}{2}}=155\mathrm{}\pm 19$ ps. The results suggest that this region contains some of the most deformed nuclei known, with quadrupole deformations ${\epsilon }_2\approx 0.4$. These data resolve conflicting theoretical predictions of nuclear shapes and emphasize the important contribution of hexadecapole deformation in determining the most stable shape.