News and Events

Arianna Gleason
Wed, Nov 5, 4:00 PM (C215 ESC, and online)
Frontier of Matter at Extremes – Habitable Exoplanets to Harnessing Star-Power

The study of matter under extreme conditions is a highly interdisciplinary subject with broad applications to materials science, plasma physics, geophysics and astrophysics. Understanding the processes which dictate physical properties in warm dense plasmas and condensed matter, requires studies at the relevant length-scales (e.g., interatomic spacing) and time-scales (e.g., phonon period). Experiments performed at XFEL lightsources across the world, combined with dynamic compression, provide ever-improving spatial- and temporal-fidelity to push the frontier. This talk will cover a very broad range of conditions, intended to present an overview of important recent developments in how we generate and probe extreme environments – providing an atom-eye view of transformations and the fundamental physics dictating materials properties. 


We will take a planetary tour from a high-pressure/shock mineral physics perspective – peering into Earth’s mantle to exoplanet interiors to ask how dynamos form and evolve as a precursor for habitability. Recent advances in experimental capabilities for reaching high pressures and temperatures coupled with in situ characterization tools make this an exciting time for mineral physics studies of planetary deep interiors. Turning our attention to the stars, we will examine the technical hurdles to harnessing star-power as fusion energy on Earth for delivering reliable power to the grid. One crucial area of study is in designing and validating target materials performance for inertial fusion energy –using low density polymer-based nanofoams to hold deuterium/tritium fuels. Critical benchmarking experiments will be discussed and compared to hydrodynamic codes to improve predictive capabilities and inform the future path of inertial fusion energy concepts. 


Thumbnail of NGC 6960: The Witch's Broom Nebula
Ten thousand years ago, before the dawn of recorded human history, a new light would suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. This sharp telescopic view is centered on a western segment of the Veil Nebula cataloged as NGC 6960 but less formally known as the Witch's Broom Nebula. Blasted out in the cataclysmic explosion, an interstellar shock wave plows through space sweeping up and exciting interstellar material. Imaged with narrow band filters, the glowing filaments are like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. The complete supernova remnant lies about 1400 light-years away towards the constellation Cygnus. This Witch's Broom actually spans about 35 light-years. The bright star in the frame is 52 Cygni, visible with the unaided eye from a dark location but unrelated to the ancient supernova remnant.
Mount Timpanogos with sky above
Temp:  63 °FN2 Boiling:76.0 K
Humidity: 27%H2O Boiling:   368.7 K
Pressure:86 kPaSunrise:7:57 AM
Wind:1 m/s   Sunset:6:23 PM
Precip:0 mm   Sunlight:571 W/m²  
Image for The Physics of Life
BYU's new Biological Physics course introduces students to the physics behind biological processes, fostering interdisciplinary skills to tackle complex biological questions.
Image for Dr. Kent Gee Receives Top faculty Award
Dr. Kent Gee has been named the recipient of the Karl G. Maeser Distinguished Faculty Lecturer Award
Image for Drs. Davis and Vanfleet Receive Technology Transfer Award
BYU Physics and Astronomy Professors Dr. Davis and Dr. Vanfleet recently received the 2024 award for outstanding achievement in technology transfer from the BYU Technology Transfer Office.

Selected Publications

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Grant W. Hart, Kent L. Gee, Eric G. Hintz, Nathan F. Carlston, and Giovanna G. Nuccitelli (et al.)

At 7:30 AM on October 6, 2020 Space-X launched a Falcon-9 rocket from Kennedy Space Center. Photographer Trevor Mahlmann had positioned his camera in the location where the rocket would pass in front of the rising sun and took a series of images of that encounter. The high-intensity sound and shock waves originating in the plume are imaged by passing in front of the sun, particularly near the edge of the sun. This can be considered as a type of schlieren imaging system. The sound emitted from a supersonic rocket plume is thought to be due to Mach wave radiation. The images were processed to enhance the visibility of the propagating shock waves, and the propagation of those shock waves was traced back to the plume. This allowed the source location and emission direction of the sound to be determined. The measured shocks were found to be consistent with the predictions of Mach wave radiation from the plume, originating about 15-20 nozzle diameters down the plume, and radiating in a wide lobe peaking at about 70° from the plume direction. There are also indications that lower frequency waves are preferentially emitted at smaller angles relative to the plume.

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Tyce W. Olaveson, Kent L. Gee, Logan T. Mathews, and Hunter J. Pratt (et al.)

This paper presents a comprehensive overview of the operation and spectral performance of a novel lab-scale afterburning jet noise rig at Virginia Tech. The study involved steady-state operation at relevant Total Temperature Ratios (TTR) of approximately 6, typical for afterburning jets. The flow was discharged through a scaled-down GE F-404 supersonic nozzle, and far-field noise measurements were acquired using ground microphones positioned at 27 angular locations on a concrete pad. A key focus of the study is to benchmark the rig's performance by comparing its far-field Overall Sound Pressure Level (OASPL) with that of T-7A and F-35B aircraft operating at afterburner power. The investigation revealed that Nozzle Pressure Ratio (NPR) exerts a significant influence on OASPL at relatively close TTRs. Furthermore, the effects of varying TTR and NPR on OASPL were compared with trends observed in F-35A and F-35B operating at two distinct afterburner power levels. Acoustic efficiency in the presented cases lies in the range 0.41% to 0.51%. Phenomena only observed in full scale afterburning jet engine tests were reproduced for the first time in a laboratory scaled rig. This allowed the identification that engine combustion instabilities can convect downstream through the nozzle and impact the far-field noise spectrum. These instabilities manifest as distinct 'instability streaks' in a spatio-spectral map. The present study highlights the importance of conducting high TTR jet noise experiments in a controlled environment with known operating parameters (total pressure, total temperature, mass flow rate, dynamic pressure, etc.) to enhance the understanding of afterburning jet noise phenomena.

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Kent L. Gee, Noah L. Pulsipher, Makayle S. Kellison, Grant W. Hart, Logan T. Mathews, and Mark C. Anderson

his Letter analyzes launch noise from Starship Super Heavy's Flights 5 and 6. While Flight-5 data covered 9.7-35.5 km, the stations during Flight 6 spanned 1.0-35.5 km. A comparison of A-weighted and unweighted maximum and exposure levels is made between flights and with an updated environmental assessment (EA). Key findings include: (a) the two flights' noise levels diverge beyond 10 km, (b) EA models overestimate A-weighted metrics, and (c) the acoustic energy from a Starship launch is equivalent to 2.2 Space Launch System launches or ∼11 Falcon 9 launches. These measurements help predict Starship's noise levels around Kennedy Space Center.

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Samuel D. Bellows, Joseph E. Avila, and Timothy W. Leishman

The directional radiation patterns of musical instruments have long been defining characteristics known to influence their perceived qualities. Technical understanding of musical instrument directivities is essential for applications such as concert hall design, auralizations, and recording microphone placements. Nonetheless, the difficulties in measuring sound radiation from musician-played instruments at numerous locations over a sphere have severely limited their directivity measurement resolutions compared to standardized loudspeaker resolutions. This work illustrates how a carefully implemented multiple-capture transfer-function method adapts well to played musical instrument directivities and achieves compatible resolutions. Comparisons between a musician-played and artificially excited trumpet attached to a mannikin validate the approach’s effectiveness. The results demonstrate the trumpet’s highly directional characteristics at high frequencies and underscore the crucial effects of musician diffraction. Spherical spectral analysis reveals that standardized resolutions may only be sufficient to produce valid complex-valued directivities up to nearly 4 kHz, emphasizing the need for high-resolution, played musical instrumentdirectivity measurements.

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Scott Bergeson, Matthew Schlitters, Matthew Miller, Ben Farley, and Devin Sieverts (et al.)

Understanding how plasmas thermalize when density gradients are steep remains a fundamental challenge in plasma physics, with direct implications for fusion experiments and astrophysical phenomena. Standard hydrodynamic models break down in these regimes, and kinetic theories make predictions that have never been directly tested. Here, we present the first detailed phase-space measurements of a strongly coupled plasma as it evolves from sharp density gradients to thermal equilibrium. Using laser-induced fluorescence imaging of an ultracold calcium plasma, we track the complete ion distribution function f(x,v,t)⁠. We discover that commonly used kinetic models (Bhatnagar–Gross–Krook and Lenard–Bernstein) overpredict thermalization rates, even while correctly capturing the initial counterstreaming plasma formation. Our measurements reveal that the initial ion acceleration response scales linearly with electron temperature, and that the simulations underpredict the initial ion response. In our geometry we demonstrate the formation of well-controlled counterpropagating plasma beams. This experimental platform enables precision tests of kinetic theories and opens new possibilities for studying plasma stopping power and flow-induced instabilities in strongly coupled systems.

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Maia A Nelsen, Darin Ragozzine, Benjamin C. N. Proudfoot, and William G. Giforos (et al.)

Dynamically studying trans-Neptunian object (TNO) binaries allows us to measure masses and orbits. Most of the known objects appear to have only two components, except (47171) Lempo, which is the single known hierarchical triple system with three similar-mass components. Though hundreds of TNOs have been imaged with high-resolution telescopes, no other hierarchical triples (or trinaries) have been found among solar system small bodies, even though they are predicted in planetesimal formation models such as gravitational collapse after the streaming instability. By going beyond the point-mass assumption and modeling TNO orbits as non-Keplerian, we open a new window into the shapes and spins of the components, including the possible presence of unresolved "inner" binaries. Here we present evidence for a new hierarchical triple, (148780) Altjira (2001 UQ18), based on non-Keplerian dynamical modeling of the two observed components. We incorporate two recent Hubble Space Telescope observations, leading to a 17 yr observational baseline. We present a new open-source Bayesian point-spread function fitting code called nPSF that provides precise relative astrometry and uncertainties for single images. Our non-Keplerian analysis measures a statistically significant (∼2.5σ) nonspherical shape for Altjira. The measured J2 is best explained as an unresolved inner binary, and an example hierarchical triple model gives the best fit to the observed astrometry. Using an updated non-Keplerian ephemeris (which is significantly different from the Keplerian predictions), we show that the predicted mutual event season for Altjira has already begun, with several excellent opportunities for observations through ∼2030.