Gamma-Ray Spectroscopy onAl28

Abstract

Properties of levels of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ with $E_{\mathrm{ex}}<2.7\mathrm{}$ MeV have been studied by means of the reactions ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(d,p\gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}({}_{}{}^3{}_{}{}^{}\mathrm{He},p\gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$, and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}(d,\alpha \gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$. The decay schemes of the first 12 excited states were determined. The known level at 1.62 MeV was found to consist of a doublet with a separation of 2.5 ± 1 keV. Particle-$\gamma$ angular-correlation measurements using an annular silicon diode and a Ge(Li) detector led to spin-parity assignments of $3^{+}$, ($2^{+}$) for the third level, and $1^{+}$ for the fourth level. For a number of $\gamma$-ray transitions the $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratio was determined. A new method was applied to the measurement and analysis of the angular correlations. The results obtained are compared with the predictions of a simple shell model.