Doctor of Philosophy (PhD)
Physics and Astronomy
New collective coordinates that describe the deformation of atomic nuclei in terms of solitary waves (rotons) that are solutions of an underlying nonlinear liquid drop dynamics are introduced. The rotons, which are highly localized surface excitations, are shown to be intelligent states of an underlying angular momentum algebra, and furthermore, to adiabatically decouple from the rotational motion of the nucleus. An expansion of the roton profile in terms of surface multipoles shows that although the quadrupole mode (&lambda= 2) dominates, there are significant contributions from other even multipoles with &lambda= 4, 6, 8, etc. The picture of nuclear deformation that emerges is that of a smooth transition from vibrational motion to rotations, signaled by the increasing amplitude of the surface oscillations. The proposed model incorporates two features: Shell effects, with only particles (holes) above (below) the core participating in the dynamics. Collective modes, governed through nonlinear terms in the interaction governing the system. The theory offers a different interpretation of the Bohr-Mottelson picture of collective motion, one that integrates in a natural way the concept of shell closures.
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Stoitcheva, Guergana Stoianova, "Nonlinear dynamics in nuclear structure" (2002). LSU Doctoral Dissertations. 3392.
Jerry P. Draayer