Particle-Hole Multiplets inY88and the Mechanism of the (He3,t) Reaction

Abstract

The reactions ${\mathrm{Sr}}^{87}({\mathrm{He}}^3,d){\mathrm{Y}}^{88}$, ${\mathrm{Sr}}^{87}(\alpha ,t){\mathrm{Y}}^{88}$, ${\mathrm{Sr}}^{88}({\mathrm{He}}^3,t){\mathrm{Y}}^{88}$, and ${\mathrm{Y}}^{89}({\mathrm{He}}^3,\alpha ){\mathrm{Y}}^{88}$ were studied and the data were used to construct a level scheme of ${\mathrm{Y}}^{88}$. Spin and parity assignments are suggested for many new states below 2.5 MeV. The principal components of their wave functions are interpreted in terms of particle-hole multiplets. The angular distributions from the (${\mathrm{He}}^3,t$) reaction are not well fitted by distorted-wave calculations. Some systematic patterns of the (${\mathrm{He}}^3,t$) reaction mechanism are noted, but the exceptions indicate that the conventional treatment of the (${\mathrm{He}}^3,t$) reaction may be far from adequate.