Date of Award

8-2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Energy Science and Engineering

Major Professor

Robert Grzywacz

Committee Members

Lee Riedinger, Thomas Papenbrock, Ivan Maldonado, Krzysztof Rykaczewski

Abstract

Decay spectroscopy of neutron rich nuclei near doubly magic 78Ni [78-Nickel] is relevant to nuclear structure and astrophysics as well as reactor and neutrino physics. β-decay [beta-decay] calorimetry studies are essential to reconstruct the decay strength function and is used to overcome the problems arising from the high density of states leading to nuclear Pandemonium. The Modular Total Absorption Spectrometer, currently located in HRIBF at the Oak Ridge National Laboratory, collected data on 25 fission products of 238U [238-Uranium] during a run in March 2015. Analysis of the 84,85,86Br [84, 85 and 86-Bromine] data from the March 2015 run indicates a significant modification of the β-strength [beta-strength] function when compared with previous measurements for all three nuclei, including the introduction of new high energy states not previously detected. The cases of 84,85,86Br will be discussed in concert with shell model predictions. 85Br [85-Bromine] is a singly magic N=50 nucleus. Through the study of N=49,50,51 nuclei the decay properties around a neutron shell closure governed by the interplay between core and valence nucleon excitations and Gamow-Teller decay in a 78Ni [78-Nickel] core can be understood and provide a pinpoint for the study of more exotic nuclei.

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