Lawrence Livermore National Laboratory

Marginal Soil Can Make for Good Biofuel Crops

New research by Lawrence Livermore, the University of California at Berkeley, the University of Oklahoma, Lawrence Berkeley National Laboratory, and the Samuel Roberts Noble Foundation is studying whether cultivation of switchgrass (Panicum virgatum)—a native North American prairie grass with broad adaptability and minimal nutritional needs—could enhance key ecosystem services such as carbon sequestration, soil fertility, and biodiversity. Switchgrass is one of the most promising bioenergy crops in the United States, with potential to provide high-yield biomass on marginal soils unsuitable for traditional agricultural crops.

According to Jennifer Pett-Ridge, co-principal investigator of the project, roughly 11 percent of the U.S. mainland is composed of “marginal lands” and represents an untapped agronomic resource well suited to switchgrass’ deep, extensive root-growth architecture. “This project will provide unprecedented insight into plant–microbial interactions that enable success under environmental stress, and will provide a model for other biology studies of plant–microbial interactions,” says Pett-Ridge.

Understanding the biochemical and genomic basis of beneficial plant–microbial interactions is a challenge for agriculture, forestry, and invasive species management. The Laboratory will receive approximately $1.6 million over five years from the Department of Energy’s Office of Biological and Environmental Research to conduct the study. To understand the relationships between switchgrass productivity and environmental effects in marginal soils, the team will analyze plant—microbial interactions within cultivated switchgrass growing under a range of resource limitations, and will document how these interactions contribute to desired ecosystem services.
Contact: Jennifer Pett-Ridge (925) 424-2882 (

Rare-Earth Elements Advance Unified Theory

A team of scientists from the Laboratory and the School of Physics at the University of New South Wales in Australia recently demonstrated that the properties that make rare-earth elements useful for a variety of applications also make them great probes of physics beyond the Standard Model. The research appeared in the October 14, 2015, edition of Physical Review A.

The 17 rare-earth elements occupy the row above the actinides in the periodic table. Despite their name, rare-earth elements (with the exception of promethium) are found in relatively high concentrations across the globe. However, because of their geochemical properties, they seldom occur in easily exploitable deposits. These elements are essential for American competitiveness in the clean-energy industry because they are used in many devices important to a high-tech economy and national security, including computer components, high-power magnets, wind turbines, mobile phones, solar panels, superconductors, and the National Ignition Facility’s neodymium-glass laser amplifiers.

According to Livermore’s Michael Hohensee, who led the research team, rare-earth elements make great magnets in part because they have an incompletely filled 4f orbital that can hold a large number of unpaired electrons, which have larger orbital angular momentum than in other atomic orbitals. At the same time, these electrons are protected from their surroundings by other, paired electrons, that form a shield around them. Consequently, rare-earth elements maintain the unusual properties of their 4f orbitals when mixed into a piece of glass or crystal that can then be used in laser applications. “Thanks to their shielded status, and large orbital angular momentum, electrons in the 4f orbital can also be used to perform the electronic equivalent of a Michelson–Morley experiment that would be more sensitive than any other yet performed, helping to validate or rule out proposed theories that unify gravity and particle physics,” says Hohensee. The Michelson–Morley experiment forms one of the fundamental test of special relativity theory.
Contact: Michael Hohensee (925) 423-2209 (

Laboratory Scientists Discover Five New Nuclei

In a paper published in the September 2, 2015, edition of Physics Letters B, Lawrence Livermore scientists, in conjunction with international researchers, detail five newly discovered atomic nuclei to be added to the chart of nuclides. These exotic nuclei are one isotope each of heavy elements berkelium, neptunium, and uranium and two isotopes of the element americium. The study focuses on developing new methods of synthesis for superheavy elements.

For the experiment, the scientists, who included Livermore’s Dawn Shaughnessy, Ken Moody, Roger Henderson, and Mark Stoyer, shot accelerated calcium nuclei at a 300-nanometer-thick foil of curium. In the collisions studied, the atomic nuclei of the two elements touched and formed a compound system for an extremely short time. Before the compound system could break apart again, after about a sextillionth of a second, the two nuclei exchanged a number of their nuclear building blocks—protons and neutrons.

The isotopes of berkelium, neptunium, uranium, and americium discovered were created as the end products of such collisions. They are unstable and decay after a few milliseconds or seconds, depending on the isotope. All of the resulting decay products can be separated and analyzed using special filters composed of electrical and magnetic fields. The scientists used all of the decay products detected to identify the new isotopes, which have fewer neutrons and are lighter than the previously known isotopes of the respective elements. “These results push what we know about nuclear structure to the extreme, neutron-deficient end of the chart of the nuclides,” says Shaughnessy. “When you realize that naturally occurring uranium has 146 neutrons and this new isotope only has 124 neutrons, it shows how much more we still have yet to learn about nuclear structure and the forces that hold the nucleus together.”
Contact: Dawn Shaughnessy (925) 422-9574 (