News and Events

Gustavo Marques Tavares
Wed, Dec 3, 4:00 PM (C215 ESC, and online)
Searching for dark forces with cosmology The Standard Model of particle physics provides an exceptionally effective and precise description of experimental results across a wide range of energy scales. However, astrophysical and cosmological observations have revealed that the particles described by the Standard Model account for only around 5% of the energy in our Universe. The remaining 95% exists in the mysterious forms of dark matter and dark energy, about which very little is currently known.
In this talk, I will discuss how current and future cosmological observations can be leveraged to search for new forces within this "dark sector" and to determine whether dark matter is composed of a single particle type or a more complex assortment of constituents. By probing the dark side of our Universe, we may uncover fundamental insights that extend beyond the successful Standard Model of particle physics.
Thumbnail of M77: Spiral Galaxy with an Active Center
What's happening in the center of nearby spiral galaxy M77? The face-on galaxy lies a mere 47 million light-years away toward the constellation of the Sea Monster (Cetus). At that estimated distance, this gorgeous island universe is about 100 thousand light-years across. Also known as NGC 1068, its compact and very bright core is well studied by astronomers exploring the mysteries of supermassive black holes in active Seyfert galaxies. M77's active core glows bright at x-ray, ultraviolet, visible, infrared, and radio wavelengths. The featured sharp image of M77 was taken by the Hubble Space Telescope. The image shows details of the spiral's winding spiral arms as traced by obscuring red dust clouds and blue star clusters, all circling the galaxy's bright white luminous center. Free APOD Lecture in Phoenix: Wednesday, December 10 at 7 pm
Mount Timpanogos with sky above
Temp:  40 °FN2 Boiling:75.9 K
Humidity: 52%H2O Boiling:   368.3 K
Pressure:85 kPaSunrise:7:31 AM
Wind:2 m/s   Sunset:5:01 PM
Precip:0 mm   Sunlight:1 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 New Acoustics Major
The BYU Physics & Astronomy department recently introduced the Applied Physics: Acoustics degree.

Selected Publications

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Jared Roth, Jared Logan, James Harkness, Richard Vanfleet, Robert Davis, William Pitt, and Tyler Westover

The effects of physiologically relevant glucose concentrations on the optical properties of whole blood were measured in-vitro. A concentration increase of +400 mg/dL caused a decrease in the scattering coefficient by 10% over all wavelengths studied. To determine potential mechanisms for the change in the scattering coefficient, we employed optical microscopy to quantify the change in erythrocyte geometry. A 15% change in cell thickness was observed following a glucose increase of +500 mg/dL.

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Karen A. Della Corte, Tyler Bosler, Cole McClure, James D. LeCheminant, and Dennis Della Corte (et al.)

Objective

To investigate the dose-response relationship between dietary sugar and T2D risk.

Methods

MEDLINE, Embase, CINAHL, Web of Science and Cochrane databases were searched through July 9, 2024 for prospective cohorts reporting relative measures of incident T2D risk by categories of dietary sugar (total, free, added, fructose, sucrose) or two beverage sources (non-diet SSB, fruit juice) in healthy adults (Prospero ID: CRD42023401800). Linear and restricted cubic spline dose-response models were fitted for each exposure and study-specific slopes and confidence intervals (CIs) were calculated. Heterogeneity was evaluated using Q-statistics. Risk of bias was evaluated using ROBINS-E tool GRADE approach was applied to assess the certainty of evidence.

Results

Of 10,384 studies, 29 cohorts were included: SSB:18 (n = 541,288); fruit juice:14 (n = 490,413); sucrose: 7 (n = 223,238); total sugar: 4 (n = 109,858); fructose: 5 (n = 158,136); and added sugar: 2 (n = 31,004). Studies were conducted in Europe (13), USA (11), Asia (6), Australia (4), and Latin America (3). Each additional serving of SSB and fruit juice was associated with a higher risk of T2D (RR: 1.25; 95% CI: 1.17–1.35 and RR: 1.05; 95% CI: >1.00–1.11, respectively; moderate certainty). In contrast, 20 g/d intakes of total sugar and sucrose were inversely associated with T2D (RR: 0.96; 95% CI: 0.94–0.98; low certainty; and RR: 0.95; 95% CI: 0.91– <1.00; moderate certainty, respectively). No associations for added sugar (RR: 0.99; 95% CI: 0.96–1.01; low certainty) or fructose (RR: 0.98; 95% CI: 0.83–1.15; very low certainty).

Conclusion

These findings suggest that dietary sugar consumed as a beverage (SSB and fruit juice) is associated with incident T2D risk. The results do not support the common assumption that dietary sugar (i.e., total sugar and sucrose), irrespective of type and amount, is consistently associated with increased T2D risk.

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Daniel Hodge and Richard Sandberg (et al.)

The last decade has shown the great potential that X-ray Free Electron Lasers (FEL) have to study High Energy Density (HED) physics. Experiments at FELs have made significant breakthroughs in Shock Physics and Dynamic Diffraction, Dense Plasma Physics and Warm Dense Matter Science, using techniques such as isochoric heating, inelastic scattering, small angle scattering and X-ray diffraction. In addition, and complementary to these techniques, the coherent properties of the FEL beam can be used to image HED samples with high fidelity. We present new imaging diagnostics and techniques developed at the Matter in Extreme Conditions (MEC) instrument at Linac Coherent Light Source (LCLS) over the last few years. We show results in Phase Contrast Imaging geometry, where the X-ray beam propagates from the target to a camera revealing its phase, as well as in Direct Imaging geometry, where a real image of the sample plane is produced in the camera with a spatial resolution down to 200 nm. Last, we show an implementation of the Talbot Imaging method allowing both X-ray phase and intensity measurements change introduced by a target with sub-micron resolution.

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Trigg Randall, Levi Homer, Garrett Davis, and John S. Colton (et al.)

Hybrid perovskite dimensional engineering enables the creation of one- to three-dimensional (1D to 3D) networks of corner-sharing metal halide octahedra interspersed by organic cations, offering opportunities to tailor semiconducting properties through quantum- and dielectric-confinement effects. Beyond the discrete options, intermediate dimensionality has been introduced in the form of quasi-2D phases with inorganic layers of varying thickness. The current study extends this approach to quasi-1D lead-iodide systems with variable ribbon widths from 2 to 6 octahedra, stabilized by flexible molecular configurations, cation mixing of organic cations, or guest molecule selection. This family of quasi-1D structures adopts characteristic well-like configurations, with intraoctahedral distortion increasing from the core to the edges. First-principles density-functional theory (DFT) calculations and optical characterizations─i.e., temperature-dependent UV–visible absorption, electro-absorption, photoluminescence, and circular dichroism─collectively demonstrate lower bandgap and exciton binding energy with increased ribbon width due to tailorable quantum confinement and structural distortions. Access to two ribbon widths within a single well-ordered structure yields distinguishable bandgaps and excitonic properties, demonstrating a class of dual-quantum confinement materials within the perovskite family. Our study serves as a starting point, showcasing a paradigm to stabilize increased ribbon widths through further tuning of organic templating effects. This continuum between 2D and 1D structures offers promise for fine-tuning the dimensionality and optoelectronic properties of hybrid perovskites.

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Michael C. Mortenson, Tracianne B. Neilsen, and David F. Van Komen (et al.)

In shallow-water downward-refracting ocean environments, hydrophone measurements of shipping noise encode information about the seabed. In this study, neural networks are trained on synthetic data to predict seabed classes from multichannel hydrophone spectrograms of shipping noise. Specifically, ResNet-18 networks are trained on different combinations of synthetic inputs from one, two, four, and eight channels. The trained networks are then applied to measured ship spectrograms from the Seabed Characterization Experiment 2017 (SBCEX 2017) to obtain an effective seabed class for the area. Data preprocessing techniques and ensemble modeling are leveraged to improve performance over previous studies. The results showcase the predictive capability of the trained networks; the seabed predictions from the measured ship spectrograms tend towards two seabed classes that share similarities in the upper few meters of sediment and are consistent with geoacoustic inversion results from SBCEX 2017. This work also demonstrates how ensemble modeling yields a measure of precision and confidence in the predicted results. Furthermore, the impact of using data from multiple hydrophone channels is quantified. While the water sound speed in this experiment was only slightly upward refracting, we anticipate increased advantages of using multiple channels to train neural networks for more varied sound speed profiles.

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The coupling between structural, electronic and magnetic degrees of freedom across the metal-insulator transition in V2O3 makes it hard to determine the main driving mechanism behind the transition. Specifically, the role of magnetism is debated and its interplay with the other transitions has not been established. To address this issue, this work uses a combination of muon spin relaxation/rotation, electrical transport and reciprocal space mapping which allows to correlate magnetic, electronic and structural degrees of freedom in strain-engineered V2O3 thin films. Evidence is found for a magnetic instability in the vicinity of the structural transition. This is manifested as a decrease in the antiferromagnetic moment in proximity to the structural and electronic transitions. Moreover, this work finds evidence for an onset of antiferromagnetic (AF) fluctuations in the rhombohedral phase even without a structural transition to the monoclinic phase. In samples where the transition is most strongly suppressed by strain, a depth-dependent magnetic state is observed. These results reveal the importance of an AF instability in the paramagnetic phase in triggering the metal-insulator transition and the crucial role of the structural transition in allowing for the formation of an ordered AF state.