Structure of 0+ excitations in the mass A≈100 region: 02+ bands in Sr98 and Zr100

Abstract

${0}_{2}^{+}$ bands in $^{98}\mathrm{Sr}$ and $^{100}\mathrm{Zr}$, populated in spontaneous fission of $^{248}\mathrm{Cm}$ and $^{252}\mathrm{Cf}$, have been studied using the Eurogam2 and Gammasphere arrays. Phenomenological classification of excited ${0}^{+}$ levels in even-even nuclei of the $A\ensuremath{\approx}100$ region into four categories is presented and an interpretation for each category is proposed. Highly deformed ${0}_{1}^{+}$ ground states and low-energy ${0}_{2}^{+}$ levels in both nuclei are probably due to the 2p-2h excitation of two neutrons from the $9/{2}^{+}[404]$ extruder to the low-$\mathrm{\ensuremath{\Omega}}$ prolate and the $11/{2}^{\ensuremath{-}}[505]$ oblate orbitals originating from the ${h}_{11/2}$ shell, respectively. Candidates for ${0}^{+}, \ensuremath{\beta}$ vibrational states in $A\ensuremath{\approx}100$ region are suggested at $\mathrm{N}g60$.