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Ryan Debolt

Publications and source records attributed to Ryan Debolt.

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Braneworlds in Constant and Accelerated Motion and Their Causal Characteristics

We generalize prior work on the signatures of bulk signals detected by brane-based observers in a spacetime with a compactified dimension. When such braneworlds move with constant velocities or constant proper accelerations in the extra dimension, the observers may witness apparent superluminal signaling. Our analysis includes tilted branes that are partially wrapped along the compact dimension. We identify parameters that help characterize various scenarios. Despite the apparent superluminality of bulk signals, we show that anisotropies in their propagation relative to the brane-based observer preserve causality. Some of the effects studied here could be the basis for alternative cosmological models, as well as observable signatures of braneworld scenarios.

hep-th

Evolving Antennas for Ultra-High Energy Neutrino Detection

Evolutionary algorithms are a type of artificial intelligence that utilize principles of evolution to efficiently determine solutions to defined problems. These algorithms are particularly powerful at finding solutions that are too complex to solve with traditional techniques and at improving solutions found with simplified methods. The GENETIS collaboration is developing genetic algorithms to design antennas that are more sensitive to ultra high energy neutrino induced radio pulses than current detectors. Improving antenna sensitivity is critical because UHE neutrinos are rare and require massive detector volumes with stations dispersed over hundreds of km squared. The GENETIS algorithm evolves antenna designs using simulated neutrino sensitivity as a measure of fitness by integrating with XFdtd, a finite difference time domain modeling program, and with simulations of neutrino experiments. The best antennas will then be deployed in ice for initial testing. The genetic algorithm's aim is to create antennas that improve on the designs used in the existing ARA experiment by more than a factor of 2 in neutrino sensitivities. This research could improve antenna sensitivities in future experiments and thus accelerate the discovery of UHE neutrinos. This is the first time that antennas have been designed using genetic algorithms with a fitness score based on a physics outcome, which will motivate the continued use of genetic algorithm designed instrumentation in astrophysics and beyond. This proceeding will report on advancements to the algorithm, steps taken to improve the genetic algorithm performance, the latest results from our evolutions, and the manufacturing road map.

astro-ph.IM