BYU physics researchers use some of the world's brightest x-ray and neutron sources to study the atomic structure and dynamics of advanced materials like superconductors and piezoelectrics. At the Advanced Photon Source at Argonne National Laboratory, electrons travel around a one-kilometer synchrotron ring at nearly the speed of light, emitting high-energy tangential Bremsstrahlung x-rays that are collimated into beams and scattered from material samples.
When an electron is born through ionization in a strong laser field, the wavepacket can be very large. As this large wavepacket continues to experience the laser field, different parts of the packet are accelerated in different directions. How will such a system radiate light? Contradicting predictions have been published in the literature, and Professors Justin Peatross and Michael Ware are looking to solve the issue with theory and experiment.
Wave-like modulations with non-lattice periodicities accompany a variety of important physical phenomena (e.g. magnetism and superconductivity). Though such a material is not properly crystalline in three dimensions, it does have a regular crystal lattice in a higher dimensional superspace. The superspace symmetry groups in (3+1), (3+2) and (3+3) dimensions have now been exhaustively tabulated, which will make it easier to solve modulated structure and understand their properties.
Wave-like modulations with non-lattice periodicities accompany a variety of important physical phenomena (e.g. magnetism and superconductivity) and dramatically complicate any quantitative crystal-structure analysis. An exhaustive group-theoretical enumeration of the order parameters that can arise from 1D incommensurate modulations now make it much easier to characterize crystals that behave this way. Figure: Short-range modulation in La1.8Sr2.2Mn2O7.
To uniquely identify the superspace-group (SSG) symmetry of a modulated crystal, one needs a way to test the equivalence of two distinct sets of superspace-group operators. A highly efficient and robust algorithm, which was recently developed for tabulating SSGs, has now been employed to identify the symmetries of each of the (3+2)D and (3+3)D modulated structures published in the literature to date.
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Mark Transtrum et al. recently published an article titled "Shielding Superconductors with Thin Films as Applied to rf Cavities for Particle Accelerators" in Physical Review Applied. Click on the image above to read it.
In the Center of Spiral Galaxy NGC 3521 : This huge swirling mass of stars, gas, and dust occurs near the center of a nearby spiral galaxy. Gorgeous spiral NGC 3521 is a mere 35 million light-years distant, toward the constellation Leo....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.