Date of Award

Summer 7-1998

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics

First Advisor

Pui-Man Lam

Second Advisor

Diola Bagayoko

Third Advisor

Ali Fazely

Abstract

Random deposition represents the simplest growth model. From a randomly chosen site over the surface, a particle falls vertically until it reaches the top of the interface, whereupon it sticks irreversibly. To include surface relaxation, we allow the deposited particle to diffuse along the surface up to a finite distance, stopping when it finds the position with the lowest height. As a result of the relaxation process, the final interface will be smooth, compared to the model without relaxation. In this research we investigate two types of randomness in the relaxation of sandpile models when the slop at some point becomes over-critical. In one type of randomness, the number of particles, nr, falling to its nearest neighbors in the resulting relaxation, is not constant but random, even though an equal number fall in each direction. We find that this kind of randomness does not change the universality class of the models. Another type of randomness is introduced by having all nr particles to fall in one single direction, but with the direction chosen randomly. We find that this type of randomness has a strong effect on the universality of the models.

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