High-spin states inAl.

TheMg( α, p γ) reaction has been studied at α-particle energies of 13, 15, and 15.2 MeV. Using method II of Litherland and Ferguson spin assignments or restrictions thereof could be made to theAl levels at E=5500 keV ( I=11/2, 7/2), 6950 keV ( I=11/2, 7/2), 7226 keV ( I=9/2), 7286 keV ( I=9/2-13/2), 7399 keV ( I=11/2, 7/2) and 7443 keV ( I=13/2, 9/2). Using the Doppler-shift attenuation method a lifetime τ=20-50 fs was obtained for the E=7399 keV level and a limit τ<20 fs for the levels at E=7443, 7286, 7226, 6950, 6718, and 6287 keV, respectively. Further spin assignments inAl were obtained by a study of theMg( p, γ) reaction at the E=2174 keV resonance. From γ-ray angular distributions the resonance spin was determined as I=9/2 (previous assignment I=7/2) and the spin of the E=5959 keV level was determined as I=7/2. Tentative spin assignments were made to the levels at E=6537 keV ( I=7/2) and 6718 keV ( I=9/2). From the combined evidence of theMg( α, p) andMg( p, γ) reactions the spin of the 6287 keV level was found to be I=7/2. The results are compared with shell model calculations and the Nilsson model. [ABSTRACT FROM AUTHOR]