Date of Award

12-2005

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Carrol R. Bingham

Committee Members

Lee Riedinger, Witold Nazarewicz, Lawrence Townsend, Krzysztof Rykaczewski

Abstract

In this dissertation, the systematics of the [pi]h₁₁/₂ [tensor] [nu]h₁₁/₂ and [pi]h₁₁/₂ [tensor] [nu]s₁/₂ isomeric configurations were studied for the odd-Z, N = 77 isotones near the proton drip line. The isomeric decays in ¹⁴⁰Eu, ¹⁴²Tb, ¹⁴⁴Ho and ¹⁴⁶Tm were measured by means of X-ray, [gamma]-ray and charged particle spectroscopy at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). The spin and parity of I[pi] = 8⁺ and 5⁻ were deduced for the isomers in ¹⁴⁰ Eu and ¹⁴²Tb. New decay schemes were established, and the half-lives of the 8⁺ isomers were measured to be 302(3) ns for ¹⁴⁰m²Eu and 25(1) [mu]s for ¹⁴²m²Tb. No evidence for the expected 1⁺ ground-state was found in the ¹⁴⁴Ho decay data.

The proton emission from ¹⁴⁶Tm was restudied. Five proton transitions were assigned to two proton emitting states. The half-lives of 198(3) ms and 68(3) ms and the spin and parity values of I[pi] = 10⁺ and 5⁻ were established for ¹⁴⁶mTm and ¹⁴⁶gsTm, respectively. For the first time for an odd-odd nucleus, the interpretation of the observed decay properties and structure of the proton-emitting states was made by accounting the deformation and proton and neutron coupling to the core excitations. A complex wave function structure was obtained, with dominating components of [pi]h₁₁/₂ [tensor] [nu]h₁₁/₂ for the10⁺ isomer and [pi]h₁₁/₂ [tensor] [nu]s₁/₂ for the 5⁻ ground state.

Details of the experimental setup and results as well as a brief description of the detectors used in the experiments and the HRIBF facility will be discussed in this dissertation.

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