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The γ -ray spectroscopy of 25 Si and 29 S has been performed using single neutron knockout reactions with intermediate energy beams of the exotic isotopes 26 Si and 30 S. Two γ rays have been observed in 25 Si and three in 29 S. These are the first γ rays observed in these two isotopes. These two nuclei appear to be well deformed, and possible future intermediate-energy Coulomb excitation measurements would confirm their rotational nature.

Two-neutron knockout reactions from nuclei in the proximity of the proton dripline have been studied using intermediate-energy beams of neutron-deficient 34 Ar, 30 S, and 26 Si. The inclusive cross sections, and also the partial cross sections for the population of individual bound final states of the 32 Ar, 28 S and 24 Si knockout residues, have been determined using the combination of particle and γ -ray spectroscopy. Similar to the two-proton knockout mechanism on the neutron-rich side of the nuclear chart, these two-neutron removal reactions from already neutron-deficient nuclei are also shown to be consistent with a direct reaction mechanism.

We report on the observation of excited states in the neutron-deficient phosphorus isotopes 26,27,28 P via in-beam γ-ray spectroscopy with both high-efficiency and high-resolution detector arrays. In 26 P, a previously-unobserved level has been identified at 244(3) keV, two new measurements of the astrophysically-important 3/2 + resonance in 27 P have been performed, γ decays have been assigned to the proton-unbound levels at 2216 keV and 2483 keV in 28 P, and the γ-ray lineshape method has been used to make the first determination of the lifetimes of the two lowest-lying excited states in 28 P. The expected Thomas-Ehrman shifts were calculated and applied to levels in the mirror nuclei. The resulting level energies from this procedure were then compared with the energies of known states in 26,27,28 P.

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The first excited state in the neutron-rich Nϭ20 isotope 31 Na was observed at 350͑20͒ keV via intermediate energy heavy-ion scattering, which is dominated by the Coulomb excitation mechanism. This state appears to be a rotational excitation built on a strongly deformed ground state. The yield of the ␥ ray deexciting this state can be reproduced by a shell model calculation which takes ( f 7/2 ,p 3/2 ) intruder configurations into account.

The anharmonicity of octupole vibrations is deduced over a wide range of Z and A through the examination of summed B(E3) 1' values for all 3 states in a given nuclide versus the centroid energy for those states. Data obtained with the (p, p'), (d, d'), and (nn') , reactions are used, as opposed to an earlier study based on Coulomb excitation and lifetime data. Results of the new analysis support earlier observations of significant anharmonicity, but leave open the possibility of greater harmonicity than was previously supposed. Fits to the experimental data are discussed within the framework of the hydrodynamical model and possible mechanisms for the observed behavior are suggested. PACS number(s): 21.10.Re, 23.20.Js, 21.60.Ev