Date of Award

5-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Robert Grzywacz

Committee Members

Carrol Bingham, Lee Riedinger, Thomas Papenbrock, Jason Hayward

Abstract

The experimental study of exotic nuclei is very important for our understanding of nuclear structure. In this work the nuclei near doubly magic nuclei 100Sn and 78Ni were studied in two separate experiments. The first one was performed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. This experiment searched for the alpha decay of 112Cs, in order to establish the proton separation energy of 104Sb. Although the alpha decay of 112Cs was not observed, the upper limit of the alpha branching ratio was set at 0.26%. The improved statistics enabled an improved half-lives measurement of 112Cs, with the result of 506(55) microseconds. From these measurements and systematics arguments new limits for the proton separation energies of 104Sb and 108I were established. These estimates were compared to shell model calculations. The decay properties of 111Xe, the proton decay daughter of 112Cs, were also re-investigated. The alpha branching ratio for 111Xe was measured as 10.4(1.9)%.

The second experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. It was aimed to measure the half-life of excited states in two neutron-rich isotopes of nickel: 70Ni and 72Ni. These isotopes of Ni are close to doubly magic 78Ni, and therefore particularly interesting for the investigation of shell closure effects. The experiment attempted to measure the lifetimes of electromagnetic transitions from 4+ to 2+, and from 2+ to ground state. The results for the 2+ transition in 70Ni show a lifetime of the order of 10ps, significantly longer than expected from a previous experiment.

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