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Thursday's Colloquium: Vern Hart
Please join us for a colloquium titled “Cellular Multi-Scattering and the Quest for Early Cancer Detection” at 11:00 AM online, or in online.
APOD: Recycling Cassiopeia A
Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After a few million years, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the explosion which created this supernova remnant would have been first seen in planet Earth's sky about 350 years ago, although it took that light about 11,000 years to reach us. This false-color image, composed of X-ray and optical image data from the Chandra X-ray Observatory and Hubble Space Telescope, shows the still hot filaments and knots in the remnant. It spans about 30 light-years at the estimated distance of Cassiopeia A. High-energy X-ray emission from specific elements has been color coded, silicon in red, sulfur in yellow, calcium in green and iron in purple, to help astronomers explore the recycling of our galaxy's star stuff. Still expanding, the outer blast wave is seen in blue hues. The bright speck near the center is a neutron star, the incredibly dense, collapsed remains of the massive stellar core.
Weather at the Eyring Science Center
Check current conditions and historical weather data at the ESC.
Professor Receives Early Career Award
Physics professor Ben Frandsen recently received an Early Career Award from the United States Department of Energy
BYU Physics Student Highlighted by APS
Liz Finlayson, who is graduating from the Physics Teaching program, was recently highlighted in the APS Spring 2020 newsletter
New Campus 0.6-m Telescope
New telescope installed in the campus dome on February 22, 2020

Selected Publications

Techniques for the rapid calculation of the excitation pattern in the time varying extensions to ANSI S3.4-2007
BYU Authors: S. Hales Swift and Kent L. Gee, published in Proc. Meet. Acoust.

The ANSI S3.4-2007 standard gives a method for calculating the predicted loudness of stationary sounds for an average listener. Glasberg and Moore (2002) provide an extension of the method to time-varying sounds. The mathematical structure of the excitation in the loudness calculation is amenable to significant acceleration in MATLAB by expressing the entirety of the calculation representing the cochlear filtering process in terms of matrices and array operations. Thus, procedures to achieve rapid processing of loudness are set forth. The procedures explained here are also applicable to other metrics in this family including those in ISO 532-2 and the upcoming ISO 532-3. Further steps for obtaining faster than real-time processing of loudness employing approximation are explained.

Observation of a C -type short-range antiferromagnetic order in layer spacing expanded FeS
BYU Authors: Benjamin A. Frandsen, published in Phys. Rev. Materials

We report neutron diffraction studies of FeS single crystals obtained from RbxFe2−yS2 single crystals via a hydrothermal method. While no √5×√5 iron vacancy order or block antiferromagnetic order typical of RbxFe2−yS2 is found in our samples, we observe C-type short range antiferromagnetic order with moments pointed along the c-axis hosted by a new phase of FeS with an expanded inter-layer spacing. The N'{e}el temperature for this magnetic order is determined to be 170±4 K. Our finding of a variant FeS structure hosting this C-type antiferromagnetic order demonstrates that the known FeS phase synthesized in this method is in the vicinity of a magnetically ordered ground state, providing insights into understanding a variety of phenomena observed in FeS and the related FeSe1−xSx iron chalcogenide system.

DNA origami mediated electrically connected metal—semiconductor junctions
BYU Authors: Basu R. Aryal, Dulashani R. Ranasinghe, Tyler R. Westover, Diana G. Calvopiña, Robert C. Davis, John N. Harb, and Adam T. Woolley, published in Nano Res.

DNA-based nanofabrication of inorganic nanostructures has potential application in electronics, catalysis, and plasmonics. Previous DNA metallization has generated conductive DNA-assembled nanostructures; however, the use of semiconductors and the development of well-connected nanoscale metal—semiconductor junctions on DNA nanostructures are still at an early stage. Herein, we report the first fabrication of multiple electrically connected metal—semiconductor junctions on individual DNA origami by location-specific binding of gold and tellurium nanorods. Nanorod attachment to DNA origami was via DNA hybridization for Au and by electrostatic interaction for Te. Electroless gold plating was used to create nanoscale metal—semiconductor interfaces by filling the gaps between Au and Te nanorods. Two-point electrical characterization indicated that the Au—Te—Au junctions were electrically connected, with current—voltage properties consistent with a Schottky junction. DNA-based nanofabrication of metal—semiconductor junctions opens up potential opportunities in nanoelectronics, demonstrating the power of this bottom-up approach.