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Thumbnail of Jupiter and Ring in Infrared from Webb
Why does Jupiter have rings? Jupiter's main ring was discovered in 1979 by NASA's passing Voyager 1 spacecraft, but its origin was then a mystery. Data from NASA's Galileo spacecraft that orbited Jupiter from 1995 to 2003, however, confirmed the hypothesis that this ring was created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Metis, for example, it will bore into the moon, vaporize, and explode dirt and dust off into a Jovian orbit. The featured image of Jupiter in infrared light by the James Webb Space Telescope shows not only Jupiter and its clouds, but this ring as well. Jupiter's Great Red Spot (GRS) -- in comparatively light color on the right, Jupiter's large moon Europa -- in the center of diffraction spikes on the left, and Europa's shadow -- next to the GRS -- are also visible. Several features in the image are not yet well understood, including the seemingly separated cloud layer on Jupiter's right limb. Celestial Surprise: What picture did APOD feature on your birthday? (post 1995)
Mount Timpanogos with sky above
Temperature: F
Rel. Humidity: %
Pressure: Inches Hg
Image for Dr. Stephens’ Sabbatical to University of Arizona
Dr. Stephens participated in a research project at the University of Arizona focused on studying brown dwarfs using the James Webb Space Telescope (JWST).
Image for BYU Women Represent at CUWiP 2024
21 women student attend conference at Montana State University, where students engaged in keynote speeches, panels, and research presentations.
Image for Dr. John Colton’s Sabbatical to the National Renewable Energy Laboratory
Dr. John Colton embarked on a six-month sabbatical at the National Renewable Energy Laboratory (NREL) in Colorado to explore the use of terahertz radiation in probing the chiral properties of hybrid perovskite materials, a research area previously unfamiliar to him.
Image for Nathan Powers, Updated labs and AAPT lab committee work
Dr. Powers initiated the effort to update BYU’s physics undergraduate lab curriculum in 2015. The revamped curriculum, aimed at teaching students how to construct knowledge from experiments.

Selected Publications

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By S. C. Olsen, D. D. Allred, and R. R. Vanfleet
Abstract:

Hollow cathodes are a common type of vacuum ultraviolet (VUV) light source with a wide range of design and application. We determined the VUV (58.4 nm) intensity distribution of a hollow cathode as a function of current and pressure. Our model describes the intensity distribution of a McPherson 629-like hollow cathode helium plasma within the range of 0.50–1.00 A and 0.50–1.00 Torr as a ring with a center peak. We found that for all pressures and currents considered, the ring emits more VUV light than the center peak. We also found that the center peak has a minimum VUV light emission near 0.9 Torr.

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By Christiana Z. Suggs, Emma Zappala, and Benjamin A. Frandsen (et al.)
Abstract:

Manganese telluride (MnTe) is a prospective platform for ultrafast carrier dynamics, spin-based thermoelectrics, and magnon-drag transport due to its unique electronic and magnetic properties. We use inelastic neutron scattering to study both pure and lithium-doped MnTe, focusing on the influence of doping in opening a magnon gap. We use neutron powder diffraction to determine critical exponents for the phase transition in both pure and Li-doped MnTe and complement this information with muon spin rotation/relaxation. The opening of the magnon gap and spin reorientation in Li-doped MnTe is mainly due to increased magnetic anisotropy along the [001] axis, a feature not present in pure MnTe.

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By Curtis Garner, Jonathan Blotter, and Scott Sommerfeldt
Abstract:

Presented in this paper is a method for determining the optimal microphone positions for a two-dimensional (2D) beamforming array, which will be referred to as the average-gain microphone placement (AMP) method. The AMP method is specifically intended for applications where an undesired sound (noise) is expected to come from a single direction and desired sound is expected to come from a range of directions. The optimum placement determined by the algorithm yields the best average performance over the range of anticipated directions of arrival, rather than the best performance in any single direction. The AMP method notably includes a procedure for reducing the performance characteristics of an array to a single-valued performance metric, which allows for a definitive optimum to be located. A typical application would be for filtering speech with a large noise source in a single direction, such as machinery or HVAC equipment. Both the optimization routine and the method for predicting performance can be applied to 2D microphone arrays of any size. Results that demonstrate the validity of both the optimization and performance predictive methods are shown and discussed.

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By Chao Pang, Benjamin T. Karlinsey, Megan Ward, Roger G. Harrison, Robert C. Davis, and Adam T. Woolley
Abstract:

DNA-templated nanofabrication presents an innovative approach to creating self-assembled nanoscale metal–semiconductor-based Schottky contacts, which can advance nanoelectronics. Herein, we report the successful fabrication of metal–semiconductor Schottky contacts using a DNA origami scaffold. The scaffold, consisting of DNA strands organized into a specific linear architecture, facilitates the competitive arrangement of Au and CdS nanorods, forming heterojunctions, and addresses previous limitations in low electrical conductance making DNA-templated electronics with semiconductor nanomaterials. Electroless gold plating extends the Au nanorods and makes the necessary electrical contacts. Tungsten electrical connection lines are further created by electron beam-induced deposition. Electrical characterization reveals nonlinear Schottky barrier behavior, with electrical conductance ranging from 0.5 × 10–4 to 1.7 × 10–4 S. The conductance of these DNA-templated junctions is several million times higher than with our prior Schottky contacts. Our research establishes an innovative self-assembly approach with applicable metal and semiconductor materials for making highly conductive nanoscale Schottky contacts, paving the way for the future development of DNA-based nanoscale electronics.

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By Jay C. Spendlove, Tracianne B. Neilsen, and Mark K. Transtrum
Abstract:

The model manifold, an information geometry tool, is a geometric representation of a model that can quantify the expected information content of modeling parameters. For a normal-mode sound propagation model in a shallow ocean environment, transmission loss (TL) is calculated for a vertical line array and model manifolds are constructed for both absolute and relative TL. For the example presented in this paper, relative TL yields more compact model manifolds with seabed environments that are less statistically distinguishable than manifolds of absolute TL. This example illustrates how model manifolds can be used to improve experimental design for inverse problems.

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By Darin Ragozzine (et al.)
Abstract:

We present a new catalog of Kepler planet candidates that prioritizes accuracy of planetary dispositions and properties over uniformity. This catalog contains 4376 transiting planet candidates, including 1791 residing within 709 multiplanet systems, and provides the best parameters available for a large sample of Kepler planet candidates. We also provide a second set of stellar and planetary properties for transiting candidates that are uniformly derived for use in occurrence rate studies. Estimates of orbital periods have been improved, but as in previous catalogs, our tabulated values for period uncertainties do not fully account for transit timing variations (TTVs). We show that many planets are likely to have TTVs with long periodicities caused by various processes, including orbital precession, and that such TTVs imply that ephemerides of Kepler planets are not as accurate on multidecadal timescales as predicted by the small formal errors (typically 1 part in 10(6) and rarely >10(-5)) in the planets' measured mean orbital periods during the Kepler epoch. Analysis of normalized transit durations implies that eccentricities of planets are anticorrelated with the number of companion transiting planets. Our primary catalog lists all known Kepler planet candidates that orbit and transit only one star; for completeness, we also provide an abbreviated listing of the properties of the two dozen nontransiting planets that have been identified around stars that host transiting planets discovered by Kepler.