Fractal Electromagnetic Showers

We study the self-similar structure of electromagnetic showers and introduce the notion of the fractal dimension of a shower. Studies underway of showers in various materials and at various energies are presented, and the range over which the fractal scaling behaviour is observed is discussed. Applications to fast shower simulations and identification, particularly in the context of extensive air showers, are also discussed.Comment: Talk to be presented at the XI International Symposium on Very High Energy Cosmic Ray Interaction

Variable Step Random Walks and Self-Similar Distributions

We study a scenario under which variable step random walks give anomalous statistics. We begin by analyzing the Martingale Central Limit Theorem to find a sufficient condition for the limit distribution to be non-Gaussian. We note that the theorem implies that the scaling index $\zeta$ is 1/2. For corresponding continuous time processes, it is shown that the probability density function $W(x;t)$ satisfies the Fokker-Planck equation. Possible forms for the diffusion coefficient are given, and related to $W(x,t)$. Finally, we show how a time-series can be used to distinguish between these variable diffusion processes and L\'evy dynamics.Comment: 13pages, 2 figure

Modeling near-field radiative heat transfer from sharp objects using a general 3d numerical scattering technique

We examine the non-equilibrium radiative heat transfer between a plate and finite cylinders and cones, making the first accurate theoretical predictions for the total heat transfer and the spatial heat flux profile for three-dimensional compact objects including corners or tips. We find qualitatively different scaling laws for conical shapes at small separations, and in contrast to a flat/slightly-curved object, a sharp cone exhibits a local \emph{minimum} in the spatially resolved heat flux directly below the tip. The method we develop, in which a scattering-theory formulation of thermal transfer is combined with a boundary-element method for computing scattering matrices, can be applied to three-dimensional objects of arbitrary shape.Comment: 5 pages, 4 figures. Corrected background information in the introduction, results and discussion unchange

Using {\sc top-c} for Commodity Parallel Computing in Cosmic Ray Physics Simulations

{\sc top-c} (Task Oriented Parallel C) is a freely available package for parallel computing. It is designed to be easy to learn and to have good tolerance for the high latencies that are common in commodity networks of computers. It has been successfully used in a wide range of examples, providing linear speedup with the number of computers. A brief overview of {\sc top-c} is provided, along with recent experience with cosmic ray physics simulations.Comment: Talk to be presented at the XI International Symposium on Very High Energy Cosmic Ray Interaction

Exotic and not-so-exotic candidates for ultrahigh energy cosmic rays

Ultrahigh energy cosmic rays present a major unsolved puzzle. Not only do we not know their origin, but we also have no really solid evidence that they are protons or iron nuclei—the two most popular candidates. We examine briefly a couple of “nonstandard” possibilities: light magnetic monopoles, which are rather exotic, and nuclei heavier than iron, which are perhaps less exotic, but have many attractive features.Facultad de Ciencias Exacta

Kansas environmental and resource study: A Great Plains model, tasks 1-6

There are no author identified significant results in this report. Environmental and resources investigations in Kansas utilizing ERTS-1 imagery are summarized for the following areas: (1) use of feature extraction techniqued for texture context information in ERTS imagery; (2) interpretation and automatic image enhancement; (3) water use, production, and disease detection and predictions for wheat; (4) ERTS-1 agricultural statistics; (5) monitoring fresh water resources; and (6) ground pattern analysis in the Great Plains

Simulation of Water Cerenkov Detectors Using {\sc geant4}

We present a detailed simulation of the performance of water Cerenkov detectors suitable for use in the Pierre Auger Observatory. Using {\sc geant4}, a flexible object-oriented simulation program, including all known physics processes, has been developed. The program also allows interactive visualization, and can easily be modified for any experimental setup.Comment: Talk to be presented at the XI Symposium on Very High Energy Cosmic Ray Interaction