High-spin states in Al 29 and Mg 27

The structure of Al-29 and Mg-27 was investigated using the reactions O-18(C-14, p2n) and O-18(C-14, alpha n) at 40 MeV. The charged particles were detected and identified with a Delta E-E telescope in coincidence with. radiation detected in the Florida State University Compton suppressed. detector array. The level and decay schemes of both nuclei have been expanded at higher spins and excitation energies. The positive-parity states up to 3.5-4.5 MeV agree well with shell model calculations using the USDA interaction. The negative-parity states in Mg-27 are reproduced relatively well by one-particle-one-hole calculations with the WBP-a interaction. Three Mg-27 states unbound by 0.4-1.4 MeV to neutron decay were observed to decay radiatively. One of these states had been previously observed to. decay in a (d, p gamma) experiment along with a surprising 16 other neutron unbound states. The competition between neutron and gamma decay in these states is discussed in terms of angular momentum barriers and spectroscopic factors.