Properties of unbound high-spin states in 27 Al

Selectively excited high-spin states in27Al have been located by the reaction12C(16O,p)27Al. The excitation functions of these states have been measured at incident energiesEcm=18.7 to 30.1 MeV at intervals of 150 keV. They exhibit maxima of presumably non-statistical origin. At four different energies the subsequent decay of the27Al states has been studied by detecting the final heavy recoils with the Munich recoil spectrometer in coincidence with the proton emitted in the first stage of the reaction. Using this new method branching ratios of theγ-, α-, andn-decay have been measured. Based on angular correlation arguments spins up to 27/2ħ have been determined within the experimental accuracy of 1–2ħ. The observations suggest a superdeformed shape of27Al at least in some of the states.