Livermore scientists achieve first full mapping of phonons in plutonium
Making a landmark event in the history of the experimental investigation of plutonium, scientists from the Lawrence Livermore National Laboratory for the first time have fully mapped the phonons in gallium-stabilized delta plutonium.
The experiment promises to reveal much about the physics and material properties of plutonium and its alloys.
The research, conducted in collaboration with researchers at the European Synchrotron Radiation Facility in Grenoble, France, and the University of Illinois at Champaign- Urbana- and led by Livermore physical chemist Joe Wong will be published in the Aug. 22 edition of Science.
Other Livermore researchers include Daniel Farber, Florent Occelli, Adam Schwartz, Mark Wall and Carl Boro.
Wongs team took the first measurements of the complete phonon dispersions in a delta plutonium-gallium alloy, using a unique high-resolution inelastic X-ray scattering technique developed at the European Synchrotron Radiation Facility.
Since its discovery in 1941, many technical and safety issues have made experimental observations of plutonium extremely difficult. Measuring the phonon dispersion curves is key to understanding the properties of plutonium materials such as force constants, sound velocities, elasticity, phase stability and thermodynamics.
But for years, scientists have been plagued trying to measure these phonon dispersion curves in plutonium because they were unable to grow the large single crystals necessary for inelastic neutron scattering.
Instead, Wong and his colleagues used an inelastic X-ray scattering technique to impinge a micro-beam from a highly brilliant X-ray synchrotron source on a single grain in a polycrystalline plutonium alloy to make their measurements.
"The phonon dispersions are very fundamental to the understanding of the properties and behavior of plutonium and its alloys," Wong said. "The new phonon data will greatly enhance scientists understanding of the transformations and phases plutonium undergoes in different environments and over time. Basic knowledge of this sort is much needed and contributes greatly to the Laboratorys science-based stockpile stewardship mission to ensure the safety and reliability of the nations aging nuclear weapons without testing."
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energys National Nuclear Security Administration.
Anne Stark | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...