To fulfill the mission of Brigham Young University, graduate students will be required to engage in scholarly research for which the student may be paid as a Research Assistant or by some other method such as a scholarship, internship, fellowship, or tuition waiver. Students have substantial freedom in the selection of research projects, and will elect to participate in the various entities within the University to enhance their educational experience.
All rights (including rights to income from sale or licensing), ownership, and title to research conducted at the University leading to the student's thesis or dissertation will reside with Brigham Young University. In some cases, as specified by University policy, a division of income from the sale of intellectual property will be made with contributing students.
A graduate student will work with his/her Advisory Committee or with other faculty on researching a topic. Both student and faculty must be very clear as to the contribution of each. Proper recognition must be given to all who contribute on any published results from the collaboration. This agreement on contribution and recognition is to be obtained from each contributor before the paper is submitted for publication.
Science is only possible if high standards of honesty are adhered to. These standards are part of the honor code to which one commits as part of a yearly ecclesiastical endorsement. The Department of Physics and Astronomy takes seriously this commitment to integrity in research. Plagiarism and falsified results will not be tolerated.
The Physics and Astronomy Department has six general areas of research available for students to choose from. A selection of possible research topics is listed below
- Defect Imaging in Steel Using Time Reversal Nonlinear Acoustics
We are developing new techniques to locate and characterize cracking in stainless steel structures using ultrasonics. In the United States, spent nuclear fuel is being stored inside stainless steel storage casks. We wish to prevent leaks of these casks by detecting cracks before they penetrate through the walls of the container. We use a sound focusing technique called time reversal to focus energy to inspection points. We then analyze the focus of energy to determine whether that location exhibits nonlinear acoustic behavior, indicative of cracking.
We will be using modifications to the traditional time reversal process to redo some nondestructive evaluation experiments that a recent graduate student did in order to determine whether they improve the ability to detect and locate cracks in steel. Preliminary experiments show this has a high chance of success.
- Numerical Modeling of Time Reversal in RoomsA recent graduate student completed a project on this and there are extensions of his work I'd like a student to work on. These models explored the use of time reversal in various different rooms to see how the room affects the possible quality of the time reversal focusing. One specific aspect to be done is to apply signal processing modifications to the time reversal process and see if the same conclusions hold as for the traditional time reversal process.
- Remote Whispering Applying Time Reversal AcousticsWe are developing new techniques to target an individual in a room and communicate with them without the need for that individual to have any equipment. Time reversal is a sound focusing technique that allows remotely placed loudspeakers to focus sound to a selected point in a room. We use time reversal as the carrier signal to deliver signals to a target location so that the individual at that location can understand the signal but others in the room cannot understand it.
- Time Reversal for Exploding Balloons with Scattering
This project will explore the impact of placing objects next to a sound source to change how the sound radiates away from the source. Time reversal has been shown to improve when objects are placed next to a source. This project would likely involve exploding balloons and lots of time reversal experiments.
- Ultrasonic Time Reversal Focusing in Air
This project will explore the use of time reversal to focus ultrasonic sound in air to create a high amplitude impulse of energy. We want to explore the limitations of doing this and what amplitudes are possible to achieve. If the sound levels are high enough then we can explore some nonlinear acoustic phenomena that may create audible sound due to known nonlinear acoustic effects. This would create a phantom sound source.
- Research in shock waves and high-amplitude acoustics
Come analyze F-22, F-35, rocket, or explosion data for NASA and the U.S. military. Other possibilities exist - email me to set up an appointment. Numerous publication opportunities are likely.
- Machine learning in Underwater AcousticsLarge arrays of hydrophones in the ocean can be used to locate acoustic sources. The reliability of these localization algorithms depends on the degree to which the ocean environment is correctly parameterized in the models. Machine learning is needed to correctly tackle this problem in real-time.
- Acoustic Resonator DesignThis work focuses on developing improved models of acoustic resonators.
- Active Structural Acoustic Control of ShellsThis project focuses on minimizing the acoustic sound power radiated from cylindrical shells.
- Measuring Acoustic Sound Power Using SLDV MeasurementsScanning Laser Doppler Vibrometer (SLDV) measurements provide vibration measurements of a structure in a noncontact manner. This data can be used to determine the sound radiated from the structure, and this project looks at trying to use the information to come up with an accurate estimate of the radiated sound power.
- Astronomy Education
I'm currently working on a number of projects to do with astronomy education.
1) We are also examining our constellation quiz to provide a baseline level and determine which constellations and bright stars students know when they start the class. What to test difference between Digistar and Zeiss projectors.
2) Development of a core set of test questions for descriptive astronomy class.
3) Will likely do a modified project on teaching moon phases to improve on a past MS project.
4) Work on bring robotic telescopes into the Phscs 127 class.
- Impact of Cadence on Variable Classifcation by Machine Learning
This is a project to examine how little data is needed to determine an accurate period in the pulsations of a short period variable star. There are many large survey programs running, or soon to be running, that find new variable stars. Through machine learning they try to classify these objects. However, for short period variables the classifications and periods determined, are found to often be wrong.
We are also examining the impact of space velocity on the measurements, phase jumps in the pulsation curve, and measurement errors.
We do observational work to follow-up on these new variables and modeling work to show the limits.
This is a program that is currently very active and where students are needed.
- Period Changes in Medium Amplitude delta Scuti Variables
In general, researchers consider there to be two groups of delta Scuti variables; the High Amplitude delta Scuti (HADS) and the Low Amplitude delta Scuti (LADS). However, the in between realm is interesting. The Medium Amplitide delta Scuti stars seems to show a range of changes in both amplitude and period. This makes them a very interesting group to monitor. Often we participate with astronomers from around the world in taking data for these projects.
We are now adding some computer modeling to try to better understand these changes.
- Spectrophotometic Comparison of H-alpha and H-beta IndexTraditionally the H-beta index has been used as a reddening free index to measure the surface temperature of stars. Prof. Joner in the department has developed a new H-alpha index that has great promise. We are working together to spectrophotometrically compare the two systems.
- Spectroscopic Survey of Northern Sky delta Scuti VariablesTo understand the nature of the delta Scuti variables in the instability strip one needs as much information as possible about the stars. However, an examination of the catalog of delta Scuti variables shows a lack of basic information on many of the group. Of the 247 delta Scuti stars visible in the northern hemisphere we currently have spectra of 242 of them. These need to be reduced to provide estimates of some basic stellar properties like [Fe/H], radial velocity, rotational velocity, and perhaps information on any binary companions.
- Variable Star Search in Open ClustersWe are currently searching for new low amplitude variable stars in a large sample of open clusters. The clusters cover a wide range of ages and will provide a evolutionary test of how the variable stars change with age. We are also looking for very small eclipses that might be the sign of a planet.
- Photometric Reverberation MappingTraditional reverberation mapping to estimate AGN black hole masses uses a combination of photometry and spectroscopy to determine the time lag between variations that occur at the accretion disk and then later in the broad line region. With such techniques, there is a need for a large amount of moderate to large telescope time in order to secure the spectroscopic data with an observing cadence suitable for a determination of the time lag. Photometric reverberation mapping uses a single epoch spectroscopic determination of the broad line region velocity and a time lag determination based on photometric observations that include predominantly continuum features or broad line components that can be seen to vary at a later time. This technique is still being tested but hold promise for the determination of black hole masses in the age of several large scale surveys.
- Testing the standard model of active galactic nuclei through automated multi-color broadband CCD imagingRemote Observatory for Variable Object Research is a 16" RC Optical telescope on a Paramount pier sited near Delta Utah. Operational since 2008, it is used to remotely monitor active galactic nuclei (AGNs) which includes blazars, quasars, Seyfert nuclei and Low Ionization Nuclear Emission Regions, or LINERS. The standard model of AGNs assumes each is a supermassive black hole surrounded by an accretion disk. The disk is fed by a more extensive lower-density region surrounding it. The disk brightens and dims as gas falls upon it and as dusty clouds orbiting around it obscure it from our view. Optical variability measures these effects providing data that can be used to model the specific nature of different AGNs.
- Orbits in the Outer Solar SystemBeyond the orbit of Neptune lies a population of icy bodies whose orbits can reveal unique information about how our solar system formed. This region of the solar system is called the Kuiper Belt and these small icy bodies are called Kuiper Belt Objects (KBOs or sometimes Trans-Neptunian Objects or TNOs), though some are large enough to also qualify as "dwarf planets" like Pluto and Haumea. There are multiple projects available in my research group to study KBO satellites (e.g., Haumea's moons) and KBO orbits (e.g., the Haumea and other collisional families). There are a variety of projects available at a variety of levels. Please contact me for more information.
- Studying the Architectures of Exoplanetary Systems
Like our Sun, other stars are known to host planetary systems. As we continued to discover many more exoplanetary systems, we learn about how these systems are put together. The "architecture" of these systems (are small planets on the inside or outside? how close are the planets to each other? etc.) gives us invaluable clues to the formation of planetary systems. I used state-of-the-art statistical and computational techniques to discovery new exoplanetary systems, study existing systems, and remove the biases on their properties from our limited observational methods. I have many projects at different levels and durations available for students. Please contact me for more information.
- Brown Dwarf Binary SystemsLooking at peculiarities in the spectra of known binary brown dwarfs. Trying to understand the large number of L/T transition binaries, and why the spectra of these objects change so quickly over a constant temperature range. We want to determine binary statistics with spectral type, and how many of the L/T objects are truly single objects. We want to understand which spectral features vary the most between a single brown dwarf and an unresolved binary system, so we can use these spectral features as a way to identify binaries from existing spectra. Eventually we will use high resolution photometry and psf fitting to identify marginally resolved and unresolved binaries.
- High resoluion spectra of T dwarfsAnalyze and reduce high resolution spectra of late T dwarfs to look for evidence and measure the abundance of ammonia bands in the near-infrared.
- Transiting ExoplanetsTake data with the 16" telescope on the roof of the Eyring Science Center of stars that may have transiting planets. Reduce this data using IRAF and AstroimageJ software. Characterize the radius of the planet (if we see a transit) by fitting the transit light curve. Return results to the team so that we can either obtain further observations of a possible planet candidate or expire the target as spurious or an eclipsing binary star system.
- Variability in Brown DwarfsReduce Spitzer observations of 3 brown dwarfs taken sequentially in time to look for evidence of variability. If variability exists, the amplitude is very low. The evidence of variability would suggest that cloud features or holes in the clouds are not homogeneously distributed across the surface.
- Advanced Materials for Nuclear Energy
We are able to produce as thin films existing and novel materials for nuclear energy that cannot easily made at other universities.
- Advanced Mirror Coatings for Hubble's successorIn 1999 the IMAGE spacecraft was successfully launched and functioned for over 6 years studying the various plasma filled regions surrounding the earth (ionosphere to magnetosphere) in wavelengths from radio through EUV. We designed and coated mirrors for the Extreme Ultraviolet Imager (EUVI) instrument, which was one of about four observational components of the IMAGE Mission. IMAGE, which stands for Imager for Magnetopause to Aurora Global Exploration, was a NASA funded Medium Explorer (MIDEX) program) .
We are now working with NASA scientist and engineers in the process of designing, fabricating and testing novel mirror coatings for the next generation space observatory. The flag-ship mission that comes after the James Web Telescope and WFIRST.
- Atomic layer & chemical vapor infiltration of C nanotube forests.Atomic layer and chemical vapor infiltration of carbon nanotube forests with metals such as tungsten to make three-dimensional microstructures for MEMS applications. This work is closely aligned with that of Prof. Robert C. Davis and Richard R. Vanfleet.
- Heavily doped p-type zinc oxide for UV optoelectronic devicesZinc oxide- especially heavily doped p-type material. This is a promising material for UV optoelectronics applications including UV lasers, light emitting diodes, and visible light-blind detectors. It also has applications in piezoelectricity, spintronics, transparent electronics, and as a substrate for the growth of other materials.
- optical constants of metals, semiconductors & insulators
1. we use ellipsometer in Chemistry C387 BNSN
2. we measure Optical Constants in VUV in U161 with R. Steven Turley
- Ultra-cold Plasmas
We are making ultra-cold plasma by photo-ionizing laser-cooled calcium atoms in a Magneto-Optical Trap (MOT). The trap size is about 1 mm and it holds about 10 million calcium atoms at a temperature of 0.001 K above absolute zero. The ultracold plasma is formed when we shine in two laser pulses that ionize all of the atoms.
The plasma is "strongly coupled", meaning that the average "nearest-neighbor" Coulomb energy is orders of magnitude larger than the mean thermal energy of particles in the plasma. A strongly coupled plasma behaves in some ways more like a solid than a gas. One of our major research goals is to understand how strong coupling changes basic processes like recombination and collisional ionization.
We use calcium to create this plasma because the energy level scheme in Ca is favorable for laser cooling and trapping. The blue wavelengths for both Ca and Ca+ are easily generated with standard laser technology. So when plasma is created we can measure the ion temperature and plasma density in a straightforward manner.
Our newest two projects are using lasers to cool the ions in the plasma, and also generating a plasma with both Ca and Yb ions at the same time. This last project will allow us to study the approach to thermal equilibrium in a two-temperature and two-mass system.
- Effects of Roughness of ReflectanceSimple calculations of optical reflection and transmission from surfaces assume flat surfaces with abrupt interfaces. These assumptions are often sufficiently incorrect to lead to significant errors in computing the optical properties of mirrors and coatings in the extreme ultraviolet. We have several projects which involve computing the of surface roughness on the optical properties of thin films. The projects involve numerically solving Maxwell's equations from first principles on representative surfaces and developing algorithms to apply the results to general surfaces.
- Extreme Ultraviolet OpticsI am working on a project with Prof. David Allred and a group of undergraduate and graduate students that began with designing and testing a mirror for the Medium Exploror (MIDEX) Program. The research involves computer-aided optical design, multilayer mirror fabrication, measurement of optical properties of materials, and design and fabrication of test and measurement components. Measurements are made both at our facilities at BYU and at the Advanced Light Source at the Lawrence Berkeley National Laboratory.
- Computing electron behavior in high-intensity laser interactions
When high-intensity lasers interact with materials, they rip electrons from atoms and pull them around at nearly the speed of light. We study electrons under these extreme conditions using MATLAB coding.
- Measuring Nuclear Decay Rates
- Single photon radiation from relativistic electronsWe are building an experiment to measure the radiation produced by an accelerated electron with a large quantum-mechanical wave packet. This experiment uses extremely high intensity lasers along with single-photon detectors to study the behavior of matter at the most fundamental level.
- Binary alloysMy group collaborates with Professor Gus Hart the discovery of novel alloys of Pt that have been predicted from first principles calculations, but never observed in nature. This work involves sample preparation, x-ray and neutron diffraction experiments, and extensive data analysis.
- Magnetic structures from neutron diffractionWe are exploring the use of symmetry principles to simplify the discovery and characterization of novel magnetic structures in solid-state materials. This work involves experimental (neutron diffraction), theoretical (group theory) and computational (ultimate curve fitting) aspects.
- Structural phase transitionsWe are currently collaborating with Professor Harold Stokes to develop interactive software tools for computing and visualizing structural distortions in crystalline materials.
Student researchers have the opportunity to apply these state-of-the-art tools to solve materials physics problems in advanced materials like superconductors, piezoelectrics and magnetoresistors.
- X-ray scattering from embedded nanostructuresI am currently applying state-of-the-art x-ray and neutron scattering techniques to study the local and intermediate-range structure of solid-state materials. Systems of interest include the fast-ion conductors, ferroelectric relaxors, and colossal magnetoresistive manganites, where nanoscale structural features can be manipulated to determine the macroscopic physical properties.
- Magnetic properties in nanomaterialsWe study magnetic properties in matter at the nanoscopic scale. Tools we use include magnetometry techniques (VSM, EHE, SMOKE), magnetic microscopy (MFM) and synchrotron techniques (XMCD, XMRS, magnetic speckles...). Types of systems we study vary from thin films (ferromagnetic, exchange bias), superparamagnetic nanoparticles, magnetically dopped materials with interesting electronic and optical properties...
- Nanoparticles as temperature sensorsWe're working with a mechanical engineering professor (Troy Munro) to use semiconductor nanoparticles as temperature sensors. The wavelengths of light present in the nanoparticles' photoluminescence (aka fluorescence), and the time it takes for the luminescence to be emitted after the electrons have been excited both depend on the temperature. By characterizing the nanoparticles’ photoluminescence spectrum in both wavelength and time as a function of temperature, we hope to be able to use the nanoparticles as non-invasive temperature sensors in e.g. medical applications. For example, one could use the optical emission from nanoparticles injected into tissue to monitor temperatures as focused ultrasound is used to heat up and destroy tumors.
- Platinum nanoparticlesFerritin semiconductor nanoparticles can be used to help metallic platinum nanoparticles form. Platinum is well known as a catalyst, and nanoparticles are great catalysts because of the extremely high surface area to volume ratio. We've been making these nanoparticles and are looking to use them as photocatalysts for using optical energy to produce hydrogen gas... initially via a UV light-catalyzed reaction using a chemical called "methyl viologen" but hopefully eventually by using solar energy to split water molecules.
- Semiconductor nanoparticles in ferritinFerritin is a hollow protein about 10 nm in diameter, and can be used as a template for creating semiconductor nanoparticles. The particles form inside the protein shell. We're investigating ways to synthesize the nanoparticles, and their properties once synthesized, especially for solar cell applications. There's also a cool possible application for fighting cancer that we may be pursuing, binding fluorescent nanoparticles to cancerous cells and using them to image the tumor. This research is done in collaboration with Richard Watt, a BYU chemistry professor
- ZnO thin filmsZinc oxide is a semiconductor that potentially has good optical properties that should allow it to be used to make semiconductor devices such as LEDs and lasers. However, to make such devices you need both “n-type” and “p-type” material. (N-type has extra electrons compared to what is needing for bonding; p-type has an electron deficit.) ZnO tends to naturally form as n-type and it's traditionally been very hard to make good quality p-type ZnO, but we're working with faculty member David Allred and visiting professor Gary Renlund to develop a new synthesis technique. We've been doing film growth on substrates coated with ZnAs using a sputtering technique, and optical investigations of the resulting material. For that matter, we plan to publish a paper on the ZnAs coating that we’ve produced along the way.
- Biological SeparationsThis work is focused on capture of cells and molecules using precision filters for the detection of cancer and antibiotic resistant bacteria.
- Biomolecular ElectronicsCarbon nanotubes, proteins and nucleic acids are candidate structures for self assembled molecular electronic materials for sensing and the internet of things. .
- Nanostructures and MicromachinesWe are developing three dimensional microscale structures from vertically grown nanotube forests. We are using films of carbon atoms, few atoms thick, to make ultrastrong materials.
- ProSPr - Protein Structure Prediction
A cross divisional team of physicists, computer scientists, biologists and chemists implements a novel protein structure prediction pipeline to solve one of the oldest challenges in computational biophysics: The Protein Folding Problem.
We will apply our pipeline to a global community wide blind test in 2020 called CASP14.
The work entails:
- training of convolutional neural networks
- design of simulation algorithms
- high performance super computer usage
- chemical and biological evaluation of results
- Radical SAM Engineering
Together with the Chemistry department at BYU, we are developing algorithms that aid the systematic design of novel enzymes.
These enzymes can be applied to a variety of use cases, such as fertilizer production, detergent production, or drug production.
- Atomic and magnetic structure investigations of complex materialsOne of the first steps toward understanding any given material of interest (a new superconductor, an unusual magnetic material, an energy-related compound, etc) is determining its atomic and magnetic structure. We utilize beams of x-rays, neutrons, and muons at large-scale accelerator facilities to do just that. Our primary experimental techniques include atomic and magnetic pair distribution function (PDF) analysis, conventional x-ray and neutron scattering, and muon spin relaxation/rotation. A few times a year, we visit these types of facilities to collect data, and then we come back home to analyze and make sense of it all. Through this process, we hope to shed light on the origin of the material's properties by gaining a detailed understanding of the local and average atomic and magnetic structure.
- Open source, python-based software for atomic and magnetic structureData are only useful if we can understand them, and to understand them, we often need specialized tools. We are currently developing open source, python-based software tools to analyze experimental data collected from condensed matter experiments using x-ray, neutron, and muon beams. The software will maximize research effectiveness and enable new methods of analysis not only for our own research group, but also for the wider community of condensed matter physicists using similar types of experimental methods.
- Machine Learning for Discovering New MaterialsWe are developing mathematics, algorithms, and software to discover the new materials that will define the next age of human civilization. Stone, Bronze, Iron, Steel, Silcon,...what material will define the next age? We are building a "virtual laboratory" so that artificially intelligent computers can discover the materials of tomorrow.
- Materials simulation: Algorithm development and applicationsOur group focuses on computer simulation of materials for the purpose of discovering new materials that have exceptional properties. There are two aspects of the research: 1) developing new approaches, algorithms, and mathematics that can be used in simulation, and 2) applying existing and new approaches to find new materials. Both aspects are challenging and require participating students to move far outside their comfort zone and learn things that won't be part of a regular physics or CS degree.
- Computational methods for exploring high-dimensional parameter spacesModern computers enable large models of complex processes. These models often involve a large number of parameters and a relevant question is often how the model's behavior depends on the parameter values. Because the parameter space is high-dimensional, a brute force search will never be possible for models with more than a few parameters. We are developing novel computational methods for efficiently and intelligently exploring these high-dimensional parameter spaces. This project uses theoretical insights based on information theory and applies sophisticated techniques in computational differential geometry, automatic differentiation, and topology with high-performance computing. Our goal is to improve algorithms for fitting models to data, performing statistical sampling, and classifying regimes of distinct model behaviors.
- Information theory of multi-parameter modelsMathematical modeling is a central component of nearly all scientific inquiry. Parsimonious representations of physical systems, together with robust methods for interacting with them, is one of the primary engines of scientific progress. Much of the work in our group involves developing new methods, both theoretical and computational, for improving the predictive performance of complex multi-parameter models. Our research explores the mathematical structures that enable predictive modeling. We use information theory, statistics, differential geometry, and topology, as well as relevant physical laws from a variety of fields to better understand data, models, and the relationship between reductionism and emergence.
- Machine Learning on Acoustic data setsSound is one of the fundamental ways we observe our environment. In collaboration with acousticians at BYU and Blue Ridge Research and Consulting, we use machine learning techniques to predict ambient sound levels from environmental parameters (such as the distance to a road or local population densities). Our models will ultimately be useful for a variety of applications including military mission planning, public health, urban development, and ecology. We also use machine learning to predict crowd dynamics from acoustic data sets. Can analysis of acoustic data collected at sporting events be used to infer the shifting mood of a diverse crowd? If so, can acoustic monitoring be used to improve law enforcement responses to crowds before they become violent?
- Modeling Complex Biological SystemsBiological systems are rich in the types of behavior they can exhibit. This is enabled through a complex web of components. In the case of development biology, the relevant components are networks of chemical reactions while in neuroscience, it is a combination of electrical and biochemical signals. In both cases, the complex system responds to external stimuli and performs calculations to formulate an appropriate response. The complexity of these systems is overwhelming. New theoretical and computational tools are needed to organize our knowledge of these processes and compress it into a coherent theory. Our research tries to develop minimal models from these "parts lists" in order to summarize and organize our understanding of biological and neurological processes.
- Modeling Complex Energy SystemsModels of energy systems involve a large number of heterogeneous components connected in complex networks. Detailed models of these systems constructed from physical first principles are similarly complicated and involve a large number of unknown parameters. In spite of their detail and complexity, models often have limited predictive capability because it is difficult to identify the model, i.e., find accurate values for all of the parameters. Our goals it develop models that are sufficiently complex to capture the rich behavior of real power systems, but simple enough so that all the parameters can be learned from data.
- Superconducting Materials for next generation particle acceleratorsParticle accelerators are are foundational technology in modern science, enabling fundamental research in facilities such as the Large Hadron Collider (LHC), as well as providing some of our best sources of coherent x-rays for probing nanoscale structure in materials. The same physical principles underly other technologies such as electron microscopy. Superconducting resonance cavities are the enabling technology that allows subatomic particles to be accelerated to near light speeds. In collaboration with researchers at the Center for Bright Beams (cbb.cornell.edu), we are working to better understand materials properties of superconductors in order to lay the foundation for the next generation of particle accelerators. Our work uses high performance computing to solve equations that describe how specific materials respond to applied magnetic fields, accounting for details such as surface roughness, grain boundaries, and material inhomogeneities.
- Atomic and near atomic scale studies of materials by Transmission Electron Microscopy.We attempt to determine in as direct observational way as possible the way materials actually chose to arrange themselves. This is often in contrast to how man has attempted to arrange them. We are interested in the structural arrangement of atoms as well as the elemental and bonding arrangements of atoms within nanometer scale features of the sample. An undergraduate would learn to prepare samples for TEM analysis as well as learn the basics of TEM operation to analyze their samples in the TEM.
- Lensless imaging to study nanometer-scale material dynamics
We have positions opened for undergraduates and upwards of three graduate students in the Physics and Astronomy Department starting immediately or for 2020. Our new lab is developing lensless or coherent diffraction imaging to study materials dynamics. We use coherent light sources (x-ray, XUV, and optical), Fourier Optics, and computer algorithms to produce nanometer scale images of materials lenslessly.
Graduate and undergraduate student position projects available:
- Imaging atomic strain in structural materials
- Nanoscale 3D few nanometer imaging
- Single shot imaging of materials in extreme conditions
For more information, contact Dr. Sandberg at email@example.com, 801-422-1497 or N261 ESC
- Charged black holes in higher dimensionsThe Kerr-Newman black hole is the charged, rotating black hole in 4 dimensions. The 5 dimensional version is not known. Using numerical techniques we are trying to construct it.
- General relativisitic equilibrium models of magnetars
We would like to construct axisymmetric, general relativistic, equilibrium models of neutron stars with ultra-strong magnetic fields (magnetars). Physics inputs include poloidal and toroidal magnetic fields, realistic equations of state for the matter, differential rotation and convective motions.
- General relativistic compact binaries
We are interested in all aspects of compact object binary mergers (black holes and neutron stars). This includes predicting the gravitational and electromagnetic radiation from such systems as well as constraining the properties of dense matter in such mergers.
This work involves large scale computation and necessitates developing numerical algorithms for solving the nonlinear partial differential equations of general relativity and radiation magnetohydrodynamics.
- Relativistic magnetohydrodynamics
Past, present and future projects include
- Establishing the characteristic structure of the equations of general relativistic magnetohydrodynamics (GRMHD) in different formulations.
- Studying the instabilities and waves associated with this system in different geometries.
- Developing constraint preserving boundary conditions for GRMHD.
- Developing simulations in 1D, 2D and 3D for flat space MHD.
- General RelativityGeneral relativity describes gravitational phenomena geometrically as curvature in spacetime: Matter curves space, and the spacetime curvature affects matter. General relativity predicts that accelerating objects can emit gravitational radiation. While this radiation is typically extremely weak, some astrophysical systems, such as colliding black holes or neutron stars, may emit gravitational waves that we can detect on Earth. Large, kilometer scale laser interferometers, such as LIGO, are being constructed to study gravitational wave signals from these events. Unfortunately, we currently know very little about the radiation expected from the regions of spacetime with the strongest (nonlinear) gravitational fields. I study computational methods for solving the Einstein equations for these strong-field gravitational wave sources. Various projects are available to investigate black hole spacetimes, black hole formation, and properties of the Einstein equations. All projects require writing, testing, and running computer codes to investigate nonlinear gravitational phenomena.
- Numerical methodsResearch with the Einstein equations and RFD requires sophisticated numerical methods and techniques (as well as cheats and tricks). Some techniques include adaptive mesh refinement (AMR), parallel computing, high-resolution shock-capturing methods for fluid equations. Some systems, such as moving black holes, may naturally be solved in multiple reference frames simultaneously. I am investigating the use of overlapping computational grids for these problems. One particular interest is combining modern fluid methods with overlapping grids.
- Relativistic fluid dynamics (RFD)Neutron star collapse, supernovae, gamma-ray sources, etc., are some of the exciting topics in relativistic astrophysics, and the perfect fluid is the fundamental model for all of these. I study relativistic perfect fluids near black holes using computational methods. In particular, Eric Hirschmann, Steven Millward and I at BYU are studying a magnetized fluid around a black hole with computational Magneto-Hydrodynamics (MHD). Various computational projects are available in RFD and MHD, which require writing, testing and running computer programs to model relativistic fluids.