Alpha+²⁸Si cluster structure as solitons on the nuclear surface

Abstract

The characteristic alpha-particle spectra from the decay of intermediate states in α+ 28 Si (32 S) to the silicon ground state have been measured during the bombardment of thick targets. The α-spectra were measured in backward angles for the determination of the spins of the states formed in elastic alpha scattering. The level spectra have been investigated in terms of a nonlinear Lagrangean which gives a quantum analogue to the classical large amplitude collective motion in nuclei, succesfully used for the evaluation of the preformation factor in alpha and cluster decays. The corresponding Hamiltonian becomes diagonal with a spectrum similar to a sum of harmonic oscillator spectra. In this way new quantum numbers are introduced. The present model not only reproduces the observed levels but predicts also positions and spins of other levels of the quasimolecular spectra. Both even and odd parities are reproduced using the same parameters.

Thermo-optical distortions in second-harmonic generation in nonlinear crystals

“…We have shown that by assuming a travelling wave profile this equation becomes a MKdV equation which, by a nonlinear Miura transformation, yields finally a KdV equation. Consequently, a full correspondence with the previous classical description is obtained [26]. The quantum fluctuations around the classical solutions (i.e.…”

“…In this way we introduced a new coexistence model consisting of the usual shell model and a cluster-like model describing a soliton moving on the nuclear surface. This model has already been shown to excellently describe the experimental preformation factors for or and cluster [26] decays. A similar model was introduced microscopically in [U] and, earlier, by Konnecke etol [30].…”

“…Microscopically, in order to explain such effects, one has to introduce in the shell model a cluster-like component [U] or many-body correlations. We consider that a collective description, in which the outside nucleons of a rigid core join together to form a cluster, could also represent an appropriate frame for the evaluation of cluster preformation factors [26].…”

Observation techniques and properties of α-cluster states at high excitation inA = 16-40 nuclei

“…-A soliton approach is, indeed, the only description so far that can give a suffiently large number of states [20]. It has, however, problems with a physical interpretation because of the non-linear approach and because of the excitation of the soliton ("orbiting alpha particle") itself.…”

Similarity Analysis of Nonlinear Equations and Bases of Finite Wavelength Solitons

“…3 Other notable features of the theory include its description of solitons and breather modes, features in quantum optics, 4 molecular and solid state physics phenomena, 5 and solitons in nuclear and particle physics. 6 In contrast with linear theories which exhibit smooth regular motion, nonlinear models require nonlinear partial differential equations (NPDE) and show strong couplings between different mechanisms and parts of the system. Also, the nonlinear interactions involve multiple scales 7 and are related with self-similar patterns or fractals.…”