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V. 1. Single particle motion -- v. 2. Nuclear deformations. / Originally published as 2 separate volumes. Title from ebook title screen. Includes bibliographical references (v. 2, p. 693-730) and index.

This work covers spectroscopic studies of nuclei from different regions of the Segré chart whose properties illustrate the delicate balance between the forces in the atomic nucleus. Studies of nuclei far from stability offer new insights into the complex nucleon many-body problem. In nuclei with equal neutron and proton numbers (N = Z), the unique nature of the atomic nucleus as an object composed of two distinct types of fermions can be expressed as enhanced correlations arising between neutrons and protons occupying orbitals with the same quantum numbers. The bound N = Z nuclei with mass number A &gt; 90 can only be produced in the laboratory at very low cross sections. The related problems of identifying and distinguishing such reaction products and their associated gamma rays have prevented a firm interpretation of their structure even for the lowest excited states until recently. In the present work the experimental difficulties of observation of excited states in the N = Z = 46 nucleus 92Pd have been overcome through the use of a highly efficient, state-of-the-art detector system; the EXOGAM-Neutron Wall-DIAMANT setup, and a prolonged experimental running period. The level spacings in the ground state band of 92Pd give the first experimental evidence for a new spin-aligned neutron-proton (np) paired phase, an unexpected effect of enhanced np correlations for N = Z nuclei in the immediate vicinity of the doubly magic nucleus 100Sn. Excited states in 94Ru and 95Rh nuclei close to the double magic shell  Z = N = 50 have been studied in order to untangle the ambiguity of the spin and the parity of the lowest-lying states. The observed yrast structures are compared to results of large-scale shell model (LSSM) calculations and the strengths of hindered E1 transitions are used as a sensitive test of the LSSM parameters. The effect of single-particle-hole excitations is discussed in terms of the strength of hindered E1 transitions. Excited states of the odd-odd nucleus 162Ta have been observed using the JUROGAM/RITU experimental set-up. This nucleus is located in a transitional region in the nuclide chart which is between near-spherical nuclei and well-deformed nuclei, offering the possibility to study the emergence of collective phenomena and nuclear deformation (in particular the degree of triaxiality). The results, which are interpreted in the framework of the cranked shell model with total Routhian surface calculations, suggest an almost axially symmetric nuclear shape. The energy staggering between the signature partners of the yrast rotational bands has been deduced for eight odd-odd isotopes in the neighborhood of 162Ta nucleus and the special observed feature of signature inversion for these nuclei is discussed. / <p>QC 20140217</p>

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A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / This investigation involves a survey of the fine structure phenomenon of the Isovector Giant Dipole Resonance (IVGDR) over a wide mass range of nuclei, from 27Al, 40Ca, 56Fe, 58Ni to 208Pb, using inelastic proton scattering at 200 MeV. Proton detection is accomplished using the recently commissioned zero-degree facility of the K600 magnetic spectrometer at iThemba LABS. Inelastic proton experiments at zero degrees are very selective to excitations with low angular momentum transfer, and therefore ideal for studies of the IVGDR. This is because such experiments simplify the analysis of the many contributions to the spectra due to the complex nature of the nuclear interaction. The ability to make precise measurements of the properties of the IVGDR demonstrated by this work opens up new challenges to both experimental and theoretical work in nuclear structure. This is a survey of the (p,p′) reaction at zero degrees as a probe to study properties of the GDR and also the low energy E1 strength with high energy-resolution. Such a data base will provide more stringent tests of nuclear theory and the progress is seen in the details obtained. These tests can only be described by microscopic models including complex degrees-of-freedom. This should lead to new insights into the underlying interactions responsible for the nature of the electric dipole strength in nuclei. In the present study, double-differential cross-sections were converted to equivalent photo-absorption cross-sections and their results compared to previously published photo-absorption data. An excellent correspondence in the excitation-energy region of the Giant Dipole Resonance (GDR) was noticed between the two data sets. The fine structure observed can be described using characteristic energy scales, arising mainly from Landau damping (even though the spreading width may also play a role). The extraction of these characteristic energy scales which are a signature for the decay process was achieved through the use of wavelet analysis. Furthermore, thanks to the recent advances in computational power and techniques, microscopic shell model-based calculations lead to new insights into the underlying properties of the nuclear interaction which are responsible for the collective behaviour evidenced by the existence and properties of the IVGDR. In addition to the extraction of characteristic energy scales, this study also provides level densities of J = 1− states. In order to extract nuclear level densities, there is need to eliminate instrumental background and other contributions to the spectra from (p,p′) scattering using the model-independent Discrete Wavelet Transform (DWT) method. Level densities of J = 1− states are determined using the fluctuation analysis technique and comparisons are made with the phenomenological Back Shifted Fermi Gas (BSFG) model predictions, calculations of the Hartree Fock- Bogoluibov (HFB) microscopic model and Hartree Fock-Bardeen-Cooper-Schrieffer (HF-BCS) predictions. Finally, this survey will simultaneously provide bench-marks on the capabilities and limitations of the new zero-degree facility important for planning of the future experimental work.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / This study investigates the e ect of nuclear deformation on both the broad and ne structure of the Isovector Giant Dipole Resonance (IVGDR) in the rareearth region. The IVGDR is strongly excited at and close to zero degrees by virtual-photon Coulomb excitation. As such, the Zero-degree Facility of the K600 magnetic spectrometer of iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) was used with an incident proton beam energy of 200 MeV to measure high energy-resolution (p,p0) scattering on a range of neodymium isotopes from spherical 142 60Nd82 to the permanently deformed 150 60Nd90 and the correspondingly deformed 152 62Sm90 in the region of the IVGDR. It is important to note that for nuclei with 88 N 92, a detailed study of the IVGDR is of speci c interest since it is here that a transition from spherical to permanently deformed nuclei occurs. An extensive data analysis procedure was performed, which included cross section extraction and conversion to equivalent photo-absorption spectra for comparison with existing photo-absorption data and theoretical predictions. For the more deformed 150Nd and 152Sm nuclei, however, the data from this study lack the expected double-peaked structure resulting from the splitting of the IVGDR into K = 0 and K = 1 components, and display a signi cant reduction in the strength of the K = 0 component of the IVGDR in comparison to previously published photo-absorption spectra. This reduced strength near the neutron threshold agrees very well with recent photo-neutron experiments. A ne structure analysis was performed on all of the measured isotopes, that is, 142;144;146;148;150Nd and 152Sm through the use of techniques associated with ii the continuous wavelet transform. Characteristic energy scales for the present high energy-resolution data are extracted using the complex Morlet motherwavelet and compared to those obtained for the theoretically predicted B(E1) strength functions. Finally, conclusions regarding the suitability of the model predictions to the current data are drawn. / GR 2016

Neste trabalho nós propomos uma extensão da teoria Hadrodinâmica Quântica (QHD) para o estudo do emparelhamento nucleônico na matéria nuclear. O trabalho segue a formulação usual da QHD, descrevendo a interação-NN em termos de campos médios, tanto para a auto-energia usual, E, como para a energia de emparelhamento, A. As equações dos campos são obtidas em termos dos propagadores nucleônicos exatos, os quais são expandidos até a primeira ordem na interação-NN, definindo a aproxirnação auto-consistente Hartree-Fock-Bogoliubov (HFB) para E e A. Esta abordagem representa um avanço sobre as tradicionais formulações não-relativísticas, no sentido de que ela permite uma descrição simultânea de muitas propriedades da matéria nuclear como o ponto de saturação, a massa efetiva do nucleon, o gap de energia no espectro de partícula única, etc., de uma maneira consistente considerando apenas os graus de liberdade hadrônicos, ou seja, os nucleons interagindo na matéria nuclear através da troca de mésons. Os campos médios resultantes E e A, tem grandes componentes no espaço de Lorentz, que adequadamente se cancelam nas expressões tanto da energia de ligação por nucleon como no parâmetro de gap\", de forma que os valores resultantes dessas quantidades concordam com os resultados experimentais. Embora o parâmetro de gap possa ser adequadamente estimado com modelos não-relativísticos, em termos de interações de dois nucleons, o ponto de saturação da matéria nuclear não pode. O aspecto atraente do presente modelo é sua formulação fundamental bastante simples em termos de graus de liberdade hadrônicos e da aproximação HFB usual à teoria de muitos corpos, o que aponta para avanços futuros como poderiam ser obtidos com a aproximação Brueckner-HF auto-consistente. / In this work we propose an extension of the relativistic Quantum Hadrodynamic theory (QHD) to the study of nucleonic pairing in nuclear matter. The work follows the usual formulation of QHD by describing the NN-interaction in terms of mean fields either for the usual self-energy, E, or the pairing energy, A. The equations of the fields are obtained in terms of the exact nucleon propagators which are expanded up to the first order in the NN-interaction, defining the self-consistent Hartree-Fock-Bogoliubov (HPB) approximation E for A and .This approach represents an improvement over the old non-relativistic formulations in the sense that it allows for a simultaneous description of many nuclear matter properties as the saturation point, the effective mass or the nucleon, the energy gap in the sp-spectrum, etc., in a consistent fashion, by considering only the hadronic degrees of freedom, that is, the nucleons interacting in nuclear matter through the exchange of mesons. The resulting mean field energies, E and A, have large components in the Lorentz space, which adequately cancel each other in the expressions of either the energy per nucleon or the gap parameter\", so that the resulting values of these quantities agree with the experimental data. Although the gap parameter can be adequately estimated with non-relativistic models, in terms of two nucleon interactions, the saturation point of nuclear matter cannot be. The appealing feature of the present model is its rather simple fundamental formulation in terms of hadronic degrees of freedom and the usual HFB approximation to the many-body field theory, which points toward future improvements as would be obtained with a self-consistent Brueckner-HF approximation.

Abstract The Projected Shell Model has been applied to the Isotones even (odd -odd) mass nuclei La; odd (odd - even)mass Ce, and odd (odd - even)mass Nd nuclei, to investigate the high-spin superdeformed phenomena. The theoretical calculated transition energy E£^, kinetic moment of inertia J(1) ,and dynamic moment of inertia J(2) are compared with experimental data. High-spin superdeformed nuclei behave like rigidbody ,the physical meaning .show a large gap at N=73¡BZ=58 and Z=60.