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Physics & Astronomy

Department Features

Department Features

Current research and activities in the Department of Physics and Astronomy.

2009 International Year of Astronomy

 In 2009 it will be 400 years since Galileo turned his telescope on the heavens. To celebrate this event there will be a wide variety of activities all around the world. Many events are being planned for the BYU community as well. Currently we are planning a book display in the special collections area of the library, a space art exhibit, special planetarium shows, and public star parties. Stay tuned for more information as we get each event finalized.

Advanced Scattering Probes of Material Structure

 BYU physics researchers use some of the world's brightest x-ray and neutron sources to study a variety of useful materials, such as superconductors, piezoelectrics and solid electrolytes. At the Advanced Photon Source at Argonne National Laboratory, 7 GeV electrons travel around a one-kilometer synchrotron ring at nearly the speed of light, emitting tangential Bremsstrahlung x-rays (much like the tangential spray from a leaky pail of water swung in a wide circle with a rope). At the newly-constructed Spallation Neutron Source at Oak Ridge National Laboratory, accelerator-driven proton pulses bombard a liquid-mercury target, knocking (i.e. spalling) neutrons from the target nuclei, which are then cooled in a moderator and collimated into beams.

Advanced Scattering Probes of Material Structure

 BYU physics researchers use some of the world's brightest x-ray and neutron sources to study a variety of useful materials, such as superconductors, piezoelectrics and solid electrolytes. At the Advanced Photon Source at Argonne National Laboratory, 7 GeV electrons travel around a one-kilometer synchrotron ring at nearly the speed of light, emitting tangential Bremsstrahlung x-rays (much like the tangential spray from a leaky pail of water swung in a wide circle with a rope). At the newly-constructed Spallation Neutron Source at Oak Ridge National Laboratory, accelerator-driven proton pulses bombard a liquid-mercury target, knocking (i.e. spalling) neutrons from the target nuclei, which are then cooled in a moderator and collimated into beams.

BYU ARG at Acoustical Society Meeting

 12 BYU students and 6 faculty went to Portland, Oregon in May 2009 for the 157th meeting of the Acoustical Society of America. BYU students gave 10 presentations and a couple posters, faculty gave an additional 7 presentations (including one on proposing a Sound and Audio merit badge for the Boy Scouts of America), and former BYU students gave another 5 presentations. The picture above includes many of the current BYU ARG members that attended the meeting. The BYU ARG has a reputation of providing a strong showing of quality and quantity at these meetings.

Defect-Free Superconductors

 A long-standing mystery surrounding the electron-doped superconducting cuprates has been solved. Unlike their hole-doped cousins, these crystals do not superconduct when newly grown, but only after a high-temperature treatment in a reducing environment. Using a combination of x-ray diffuse scattering and neutron powder diffraction, Branton Campbell and collaborators have demonstrated that the copper-oxide sheets are initially riddled with copper-vacancy defects, but are effectively repaired by copper-ion migrations during the heat treatments. Nature Materials 6, 224-229 (2007).

Eclipse in the Pacific

 July 22 2009 brought a spectacular solar eclipse. Totality was 6 minutes 39 seconds making it the longest solar eclipse of the 21st century. The path of totality cut through India, Nepal, Burma, China, Japan and several pacific islands. The H alpha picture above is of the maximum eclipse in Saipan. It was obtained by friends of Dr. J. Ward Moody using a digital camera through an 8" telescope.

Group theory aids the study of crystal distortions

 In crystalline solids, phase transitions that result in the loss of part (but not all) of the crystallographic symmetry, are known as distortions. ISODISPLACE is a group-theoretical tool that can be used to generate and interactively visualize virtually any crystal distortion involving atomic displacements or lattice strains. It also provides a unique and exhaustive classification of the distortion modes available to any three-dimensional crystal structure. ISODISPLACE was introduced in 2005 by Branton Campbell, Harold Stokes, and undergraduate student David Tanner at the triennial IUCr Congress in Florence Italy in 2005. J. Appl. Cryst. 39, 607-614 (2006).

How loud is the sound we can't hear?

 Researchers in the BYU ARG are studying the high pitch noise that is above our hearing range, sponsored by the Los Alamos National Laboratory. Undergraduates Trevor Jenny and Jayrin Farley (both mentored by Dr. Brian Anderson) will be exploring ultrasonic noise in everyday environments and the transmission properties of ultrasonic sound through various wall materials. Pictured above are various devices designed to listen to ultrasonic frequencies that are emitted from various electronic devices such as cell phones and laptops, and to listen to the ultrasound that various animals emit, such as bats and rodents. One of the above devices is a toy that dials down the ultrasonic frequencies to our hearing range so we can hear what a bat's world sounds like. One fundamental question for future research is whether sound that is above (or below) our hearing range can be loud enough to damage our hearing?

It's not...wait, it IS rocket science!

 Members of the BYU Acoustics Research Group have been involved with multiple projects intended to characterize the noise radiated from large rocket plumes. The photo shown is from a GEM-60 test at ATK in Feb. 2009. For the sake of scale, the visible afterburning plume extends about 125 ft from the nozzle. (Photo credit, ATK). Undeterred by below-freezing temperatures prior to the test, BYU recorded the noise produced by the motor as close as 30 ft from the edge of the plume and as far away as 1000 ft.

In Aug. 2009, BYU ARG members will participate in the ARES DM-1 test at ATK. Various types of microphones will be placed near the rocket plume. The 5-stage solid rocket motor will provide greater thrust than the 3-million-lb-thrust Shuttle boosters and will eventually be used to propel NASA's new Crew Launch Vehicle during the first two minutes of flight.

M66 with ROVOR

 The ROVOR 16" telescope is now functioning in full research mode! Every clear night it operates under computer control, executing commands from an observing script downloaded from campus. The picture of M66 displayed above is the combination of nearly 400 one-minute blue, green, red, and clear images. We are observing objects like M66 to refine our data acquisition and analysis capability - and also to have a bit of fun! (Image courtesy of Cameron Pace)

Megapixel X-ray Camera

 When an x-ray beam strikes a material sample, the x-rays scatter in many directions at once. The often beautiful scattering patterns that arise contain a wealth of information about the sample's atomic structure. How are these patterns measured? With an x-ray camera! In this photo of BYU's single-crystal x-ray diffraction facility, x-rays arriving from the left scatter from a tiny crystal, and are detected by the 16-megapixel x-ray camera at the right. The speed and sensitivity of state-of-the-art instruments like this have revolutionized the study of material structure-property relationships.

Modulated Crystal Structures

 Harold Stokes, Branton Campbell, and Dorian Hatch recently announced an exhaustive group-theoretical enumeration and classification of the distortion symmetries that can arise from one-dimensional incommensurate modulations of three-dimensional crystal structures. Acta Cryst. A63, 365-373 (2007). Such wave-like modulations accompany a variety of important physical phenomena (e.g. magnetism and superconductivity) and dramatically complicate any quantitative structure analysis. This work will make it much easier to interpret basic experimental diffraction data. The figure illustrates a short-range displacive modulation observed in magnetoresistive La1.8Sr2.2Mn2O7.

Stellar X-ray Diffuse Scattering

 Diffuse x-ray scattering pattern from a single-crystal sample of zeolite mordenite, an important industrial isomerization catalyst. This image was reconstructed by Branton Campbell using portions of over 1000 CCD x-ray photos. The broad patches, open diamonds, and star-shaped distributions are clues that reveal a complex architecture of framework defects with implications for mordenite's unusual adsorptive and catalytic properties. J. Appl. Cryst. 37, 187-192 (2004).

Transient Defects Caught in the Act

 Anisotropic x-ray diffuse scattering pattern surrounding the (200) Bragg reflection of La1.8Sr2.2Mn2O7 at 125 K. This "butterfly" scattering is evidence that Jahn-Teller polarons (football-shaped lattice distortions that follow hopping electrons from site to site) play a role in this material's exotic phase transition from paramagnetic insulator to ferromagnetic metal. Branton Campbell and collaborators used this data to conduct the first quantitative three-dimensional structural analysis of a transient crystal defect. Phys. Rev. B 67, 020409(R) (2003).
 
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