Typescript (photocopy). / Digitized by Kansas Correctional Industries

No description available.

Gamma decays from high-spin states in the A=51 mirror-pair "'Mn and "Fe, and the A=53 mirror pair 53Fe and 53 Co have been observed up to, and in one nucleus beyond, the fä band terminating states. For "Fe and 53Co, this represents the first observation of states of this type. The nuclei were studied in two GAMMASPHERE experiments with the addition of the FRAGMENT MASS ANALYSER recoil separator and an ion chamber at Argonne National Laboratory in Chicago, Illinois; and the MICROBALL light charged particle detector and the NEUTRON SHELL neutron detector system at Lawrence Berkeley National Laboratory in Berkeley, California. The observation of these isobaric analogue states allowed a detailed comparison of the level energies in each mirror pair. The mirror nuclei have the same mass number, but differing numbers of protons and neutrons. Thus, any difference in excitation energies can be interpreted as being due mainly to the Coulomb interaction, leading to a Coulomb Energy Difference (CED) plot as a function of angular momentum. The changes of the CED with spin have been interpreted in terms of the spatial arrangement of the valence protons, from rotational alignments and the effects of proton-proton recoupling. The observed level energies and the CED have been compared with the results of full pf shell-model calculations, with the Coulomb interaction included via the Coulomb Matrix Elements (CME). This comparison has allowed a detailed understanding of the microscopic mechanisms behind the changes in the CED. The CME were investigated in a fit to the A=53 CED, which revealed an anomalously high and counter-intuitive J=2 component. Extensive results from the study of these CME have been presented, including their role in the evolution of the CED, the physical meaning of the matrix elements themselves, and in particular the origin of the J=2 anomaly.

No description available.

Break up processes involving a three body system in the Coulomb field are studied. A method is developed for the realistic treatment of such a system, and is applied to the break up of the nucleus, ⁷Li. The Simple Cluster Model of ⁷Li and the Coulomb excitation code COULVAR are used for the calculations. The continuum states of the α + t system are treated as a set of discrete states, by confining the relative motion of the clusters to a spherical box. The infinite set of states is then truncated by imposing an energy cutoff so that only the states below this energy are considered. The density of these states varies according to the box radius and the energy cutoff. The stability of the model is tested by varying these two parameters. The corresponding calculated probability of excitation of ⁷Li has converged for a box radius of 20 fm and an energy cutoff of 20 MeV. The level energies and the wavefunctions of the continuum states are then easily obtained and are used to calculate the important matrix elements for the electromagnetic transitions between the bound states and the continuum states of ⁷Li. The method is used to calculate the probability of excitation of ⁷Li to its first excited state in the inelastic scattering experiments. It successfully reproduces a range of available data. An approximation is then developed to calculate the nuclear-Coulomb interference at low energies (well below the Coulomb barrier). The results of its application supports the need for renormalisation of the nuclear potentials suggested by inverse scattering calculations. The method closely reproduces The ⁷Li data in this region with the refitted nuclear potentials. The application of the three body model to the break up of ⁷Li on heavy targets at high energies produces very interesting results. It predicts reasonably good cross sections in the regions of pure Coulomb interaction. It also shows that at high energies the nuclear forces become very strong and affect the classical Rutherford orbit of the projectile. These effects are enhanced for heavier targets and the observed small scattering angle should not be taken as the angle of a classical orbit. Finally improvements towards the generalisation of the method are suggested so that it will be capable of coping with any three body system in a strong Coulomb field.

No description available.

This dissertation analyzes the Wigner-Poisson system in the presence of an external Coulomb potential. In the first part, the Weyl transform is defined and used to derive an exact quantum mechanical equation for the Weyl transform of the density function ρw (the Wigner function) known as the Wigner equation. This equation holds for any Hamiltonian which is a function of the position and momentum operators. The Wigner-Poisson system is then formally derived by imposing various assumptions on the structure of the Hamiltonian. This system describes the behaviour of an effective one-particle distribution in the presence of a large ensemble of particles. Furthermore, it allows the particles to either attract or repel each other as well as attract or repel as a whole from a fixed Coulomb source located at the origin. The second part details the question of existence and uniqueness for the Wigner-Poisson system. It is shown that provided the initial Wigner function is sufficiently regular [special characters omitted] and is a valid Wigner distribution, then the Wigner-Poisson system has a unique global mild solution [special characters omitted]. This result is independent of both the nature of the external Coulomb potential as well as the interparticle interaction.The proof of this result is accomplished by first transforming the Wigner-Poisson system into a countably infinite set of Schrödinger equations which results in what is referred to as the Schrödinger Poisson system. Using standard semigroup theory arguments, existence and uniqueness of the Schrödinger-Poisson system is established. The properties of the Wigner-Poisson system are then obtained by reversing the transformation step. Regularity results for both the Schrödinger-Poisson and the Wigner-Poisson systems are compared to the case with no external Coulomb potential. In addition, the known regularity results are extended when there is no external field. The results illustrate that the introduction of an external Coulomb potential slightly reduces the regularity of the solution. This confirms a conjecture of Brezzi and Markowich. The third part analyzes the asymptotic behaviour of the Wigner-Poisson system. If the configurational energy Εₐ,ᵦ(t) is positive for all times then by considering the Schrödinger-Poisson system, solutions will decay in the sense of Lᵖ for 2 < p < 6. This generalizes a result of Illner, Lange and Zweifel. Moreover, If the total energy is negative then the solutions will not decay in the sense of Lᵖ for any 2 < p ≤ ∞. This generalizes a result of Chadam and Glassey. Decay estimates for both the Schrödinger-Poisson and the Wigner-Poisson systems are compared to the case with no external Coulomb field. As with the regularity results, the introduction of an external Coulomb field degrades the reported decay rates of the solution. / Graduate

No description available.

No description available.

No description available.