Doctoral Dissertations

Abstract

"The work presented in this dissertation was performed in order to obtain additional information on the level schemes and decay properties of several nuclei in an attempt to explain the observations in terms of an applicable nuclear model. Various nuclear models are discussed in Section II. A general review from the classical point of view of the Coulomb excitation reaction is discussed in Section III and the thermal-neutron-capture reaction is outlined in Section IV. The experimental equipment and procedure is discussed in Section V in which the ramper method of energy determination is outlined. This method allows the measurement of y-ray energies to an accuracy of [approximately] 0.1 keV in many cases and therefore increases the chances for an unambiguous placement of the γ-ray in a level scheme. A method for the accurate determination of the analyzing system dead time is also presented. The exclusive use of Ge(Li) detectors is made in both singles and coincidence γ-ray studies. A series of measurements on the singles and coincidence γ-ray spectra as well as the conversion electron spectra following the decay of ⁶⁶Ge is presented in Section VI. This nucleus decays primarily by allowed beta transitions permitting the determination of the quantum mechanical parameters of many of the states in ⁶⁶Ge. This nuclide is expected to exhibit excited states being primarily single-particle in nature. The shell model structure of these states could lead to the occurrence of forbidden M1 transitions and indeed the first excited state of ⁶⁶Ge does exhibit a retarded M1 transition as reflected in its 21 nsec lifetime. Measurements of the de-excitation γ-rays following Coulomb excitation of the low-lying levels in ¹⁰⁵Pd are presented in Section VII. Attempts to describe this nucleus in terms of Nilsson orbitals have been largely unsuccessful. A description of the low-lying levels in terms of the core-excitation model is presented. The agreement between the experimental observations and the predictions of the core-excitation model is somewhat less than satisfying. However, accurate B(E2)[up arrow] transition probabilities are presented which may be compared to a more extensive theoretical treatment. Section VIII discusses the thermal-neutron-capture reaction ¹⁸⁶W ([nu, gamma])¹⁸⁷W]. Both high-energy and low-energy γ-rays have been observed using both singles and coincidence γ-ray spectroscopic techniques in an attempt to construct an unambiguous level scheme. The resulting low-lying energy levels are discussed in terms of the Nilsson model including the Coriolis band mixing terms. Evidence is presented for the existence of Coriolis mixed states built on the [512]3/2̄⁻, and [510]1/2⁻ intrinsic states . The results of the model-predicted energy level sequence and γ-ray branching ratios are discussed"--Abstract, pages ii-iii.

Advisor(s)

Hotz, Henry P.

Committee Member(s)

Wesley, James Paul
Bolotin, H. H.
Zenor, Hughes M.
Lund, Louis H.

Department(s)

Physics

Degree Name

Ph. D. in Physics

Sponsor(s)

Argonne National Laboratory

Comments

Published later by Argonne Physics Division, Argonne National Laboratory, as Informal Report PHY-1969-E in August 1969.

Publisher

University of Missouri--Rolla

Publication Date

1969

Pagination

ix, 131 pages

Note about bibliography

Includes bibliographical references (pages 125-130).

Rights

© 1969 Donald A. McClure, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

NuclidesThermal neutronsCoulomb excitationNuclear physics

Thesis Number

T 2354

Print OCLC #

6019494

Electronic OCLC #

857789976

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