Two-Hole and Two-Particle-Four-Hole States inSr88and the Decay of 17.8-minRb88

The population of levels of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ from the decay of 17.8-min ${}_{}{}^{88}{}_{}{}^{}\mathrm{Rb}$ has been investigated by studying the ${}_{}{}^{88}{}_{}{}^{}\mathrm{Rb}$ $\gamma$ rays with a Ge (Li) Compton-suppression spectrometer and with largevolume Ge(Li) detectors. 42 $\gamma$ rays are identified as originating from ${}_{}{}^{88}{}_{}{}^{}\mathrm{Rb}$, and 31 of them are assigned to 18 levels of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$. Discrepancies which existed among previous Ge (Li) $\gamma$-ray studies are resolved. The levels populated from ${}_{}{}^{88}{}_{}{}^{}\mathrm{Rb}$ decay are compared with the levels of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ populated by other reactions. The nature of the levels is discussed in terms of two-hole and two-particle-four-hole excitations and collective modes of excitations.