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Los Alamos National Laboratory

Los Alamos National Laboratory

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STE Highlights, September 2019

Awards and Recognition

LA-UR-19-29715

Awards and Recognition

Five LANL scientists elected 2019 APS Fellows

Hans Herrmann, Scott Hsu, Alan Hurd, Katherine Prestridge, Richard Van de Water

Top row, from left: Hans Herrmann, Scott Hsu, and Alan Hurd. Bottom row, from left: Katherine Prestridge and Richard Van de Water

On Sept. 18, 2019, five LANL scientists were elected Fellows of the American Physical Society (APS). Scott Hsu, Alan Hurd, Katherine Prestridge, Richard Van de Water, and Hans Herrmann were chosen for their “exceptional contributions to the physics enterprise.” Fewer than one half of one percent of APS members are elected as Fellows each year.

These five scientists represent the breadth of physics contributions made at the Laboratory. Van de Water said of the award, “The thrill of doing science is an award itself, an APS Fellowship honor makes it that much better.”

Hans Herrmann (Engineered Materials, MST-7) was cited for “pioneering the use of Cherenkov radiation techniques for high energy gamma spectroscopy applications at the National Ignition and Omega Laser Facility.”

Scott Hsu (Physics, P-DO) was cited for “seminal experiments elucidating the physics of merging plasmas and jets spanning hydrodynamic to magnetized, self-organized behavior, thus impacting basic plasma physics, plasma astrophysics, and innovative fusion concept development.”

Alan Hurd (National Security Education Center, NSEC) was cited for “seminal advances in the physics of soft matter and applications of neutron scattering, and for advancing international science diplomacy.”

Katherine Prestridge (Neutron Science and Technology, P-23) was cited for “thoughtfully designed experiments on shock-driven mixing and turbulence, and for developing advanced flow diagnostics that bring insights to the understanding of mixing in extreme flows.”

Richard Van de Water (Subatomic Physics, P-25) was cited for “outstanding contributions to solar-neutrino and short-baseline accelerator-neutrino physics experiments that have shed new light on neutrino properties and have provided evidence for physics beyond the Standard Model.”

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Hunter and Mosby receive Presidential Early Career Awards

Abigail Hunter, left, and Shea Mosby

Abigail Hunter, left, and Shea Mosby

Abigail Hunter, of the Laboratory’s Computational Physics Division, and Shea Mosby, of the Laboratory’s Physics Division, have received the Presidential Early Career Award for Scientists and Engineers.

The Presidential Early Career Award is the highest honor bestowed by the U.S. government on outstanding scientists and engineers in the early stages of their independent research careers.

Abigail Hunter

Hunter received her doctorate in Mechanical Engineering from Purdue University in 2011, and her bachelor’s degree in Mechanical Engineering from the University of Utah in 2006. She became a postdoctoral research associate at Los Alamos in 2011 and converted to a staff scientist the following year.

"Abigail has become a technical thought leader within the Laboratory’s weapons program and our materials modeling community, as well as an internationally recognized expert in materials science and the physics of solid-state materials,” said Mark Schraad, Computational Physics Division leader. “She has established a critical skill set that serves her in a unique position at the intersection of Los Alamos’ physics modeling, software development and supporting science endeavors.”

Hunter’s research focuses on understanding and modeling nanoscale deformation mechanisms in metals. She is a leading expert in phase field modeling of dislocation-based deformation behaviors. A primary goal of her work is to better understand defect physics at the mesoscale and then use this information to develop more physically informed continuum-scale material models that must integrate into large-scale, parallel codes used for predictive science at Los Alamos.

Shea Mosby

Mosby earned his doctorate in experimental nuclear physics from Michigan State University in 2011. He came to Los Alamos in 2012 as a postdoctoral researcher to study neutron capture reactions for nuclear technology applications. In 2014, Mosby became a technical staff member,focusing on nuclear reactions relevant for applications using a variety of detector systems at LANSCE.

"Shea is a deep-thinking early career scientist who has contributed to many of the nuclear reaction measurements done at the Los Alamos Neutron Science Center. He is currently developing a novel concept to measure nuclear reactions in radioactive isotopes," said David Meyerhofer, Physics Division leader.

Mosby recently began investigating novel approaches to measuring neutron-induced reactions for radioactive isotopes, which preclude traditional measurement techniques. 

About the Award

Established in 1996, the Presidential Early Career Award for Scientists and Engineers acknowledges the contributions scientists and engineers have made to the advancement of science, technology, education, and mathematics education and to community service as demonstrated through scientific leadership, public education, and community outreach. The White House Office of Science and Technology Policy coordinates the award with participating departments and agencies.

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Avers, Chien, Curole, and Kovach receive 2019 DOE Office of Science Graduate Student Research Award

Keenan Avers, Abraham Chien, Jonathan Curole, and Yao Kovach

Top row, from left: Keenan Avers and Abraham Chien. Bottom row, from left: Jonathan Curole and Yao Kovach

Four Los Alamos graduate students—Keenan Avers, Abraham Chien, Jonathan Curole, and Yao Kovach — were honored with Department of Energy (DOE) Office of Science awards. Working with LANL mentors, each Ph.D. student submitted a proposal for thesis research relevant to DOE-targeted areas to be carried out at a DOE laboratory.

Students, mentors and research areas

Keenan Avers: mentored by Eric Bauer (MPA), proposal title “Quantum criticality in anisotropic ferromagnets and 1-D lanthanide and actinide materials.”

Abraham Chien: mentored by William Daughton (XTD), proposal title “PIC Study of Particle Acceleration from Magnetically Driven Reconnection in Different Plasma Regimes Using Laser-Powered Capacitor Coils.”

Jonathan Curole: mentored by Zhaowen Tang (pRad), proposal title “A Proposal to Measure and Search for Parity Violation in Heavy Nuclei at LANSCE for the NOPTREX Collaboration.”

Yao Kovach: mentored by Zhehui (Jeph) Wang (P-25), proposal title “Understanding nanoparticle emission from 1 atm DC glow discharge with liquid anode.”

Award specifics

The Office of Science Graduate Student Research (SCGSR) award provides funding for exceptional graduate students in science, technology, engineering, and math (STEM) fields. The research projects are expected to advance the graduate awardees’ overall doctoral work while providing access to the expertise, resources, and capabilities available at DOE laboratories. Technical contact: Liz Sturgeon

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Randolph receives 2019 Larry Foreman award for innovation and excellence in target fabrication

Carlos Castro, left, and Blaine Randolph

Carlos Castro, left, and Blaine Randolph

Randall (Blaine) Randolph (Engineered Materials, MST-7) was honored as the co-recipient of the Larry Foreman award for his substantive contributions toward innovation and excellence in target fabrication for inertial confinement fusion (ICF). Randolph shares the award with Carlos Castro, a Senior Engineering Associate at Lawrence Livermore National Laboratory.

This is the first time the Larry Foreman award has been given to machinists. Randolph is specifically a precision micro-machinist, making essential contributions for more than 30 years to the ICF and High Energy Density Physics programs at Los Alamos. He is internationally known for his unconventional and innovative machining methods, custom precision tooling, and programming.

Randolph fabricates custom target components for pulsed power, laser, and high explosive facilities, including the Argonne Tandem Linear Accelerator System (Argonne National Laboratory), Proton Radiography and Trident Laser Facility (Los Alamos), Nova and the National Ignition Facility (Lawrence Livermore National Laboratory), OMEGA (University of Rochester), and Orion (Atomic Weapons Establishment). Technical contact: Blaine Randolph

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Accelerator Operations and Technology

Copper-weld breakthrough on the LANSCE accelerator

Jason Burkhart (Accelerator Operations and Technology, AOT-MDE) “saved” the Los Alamos Neutron Science Center (LANSCE) 2019 run cycle by welding a crack in the copper surface of the 1-m-diameter Drift Tube Linac (DTL) tank in July. The weld was particularly difficult because the crack was located 23 feet down inside the tank and the methodology to fix it required a very specific copper welding certification.

Jason Burkhart in the LANSCE accelerator drift tube.

Jason Burkhart in the LANSCE accelerator drift tube.

LANSCE is mission critical

LANSCE is a national user facility. Its operation is vital to national security research as well as to the production of medical isotopes. Therefore, when something breaks on the accelerator, it must be remedied quickly.

Burkhart was aware of the crack in the DTL tank and knew it would require copper welding, a specialized and somewhat unusual skill. No one at LANL was certified to make the needed repair, but without it, LANSCE would not run at full power.

Copper certification

To become certified to weld the crack, Burkhart had to qualify in a Gas Tungsten Arc Weld (GTAW) process for copper alloys. This meant that Burkhart needed to complete a weld “coupon” of copper plate and filler following LANL welding procedure to prove mastery of the process. The coupon was visually inspected to ensure weld quality and destructively tested. 

David Bingham, a LANL welding SME who helped and advised Burkhart in preparation for the repair, stated that welding copper is different from welding other materials. Loss of cover gas (even for a moment) can cause complete failure of the weld. Heat input, which can be as simple as moving too fast or too slow, can also cause complete failure. Despite the challenges, Burkhart successfully completed the certification without issue, becoming the only copper-certified welder at LANL.

Tank constraints

The skill required to fix this particular crack also involved welding in a confined space, face down, with only 14 inches of clearance to maneuver within. At 360 amps of current, an arc was created only 6 inches from Burkhart’s face to melt the copper and weld the crack. Burkhart’s progress and safety were monitored by a support team throughout the 11-hour repair process.

The weld was successful—LANSCE will run at full power for the next cycle. This repair has caught the attention of other accelerator facilities around the country concerned with similar problems affecting their accelerators. Technical contact: Jason Burkhart

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Chemistry

First single-crystal structure determination of organometallic americium molecule

Scientists from Los Alamos National Laboratory and the University of California at Irvine, along with collaborators, synthesized and gathered the first structural data on an organometallic cyclopentadienyl (Cp) complex of americium (Am): [Am(C5Me4H)3]. This compound was achieved from microgram quantities of Am-243.

Left: Molecular structure of the americium complex studied. Right: Crystals grown to help determine the structure of the molecule.

Left: Molecular structure of the americium complex studied. Right: Crystals grown to help determine the structure of the molecule.

Why Am-243?

The most commonly known isotope of Am is Am-241, as it is ubiquitously used in household smoke detectors in tiny (sub-microgram) quantities. It is also known—in much larger quantities—as a byproduct of commercial nuclear reactors and plutonium processing activities. Despite its relative abundance, Am-241 is not ideal for R&D chemistry on the milligram scale—the smallest scale generally required to synthesize and isolate molecules.

However, the Am-243 isotope is practical to handle on a milligram scale. Americium-243 is still considered to be highly radioactive, with a half-life of about 7,370 years; for context, this is more radioactive than plutonium-239, which has an approximate half-life of 24,000 years. But Am-243 is less radioactive than Am-241 and therefore less likely to cause radiation damage to synthesized molecules before full characterization can be completed.

This research was featured on the back cover of the journal. The americium complex is shown, with the Am–C bonds highlighted in the structure.

This research was featured on the back cover of the journal. The americium complex is shown, with the Am–C bonds highlighted in the structure.

Overcoming Am obstacles

Americium-243 is rarer and more expensive than Am-241, which limits its opportunities for chemical research advancements. Often, surrogates for americium are used in research where the reaction pathway has not yet been optimized. These obstacles have left scientists with a limited picture of the chemical bonding and electronic structure properties of americium in molecular compounds. That is why Los Alamos scientists and their collaborators worked to gain a better understanding of these properties, which can ultimately be harnessed to control chemical behavior in areas such as development of actinide waste remediation strategies.

Their research included small-scale optimization performed on lanthanide and actinide analogues, which allowed the scientists to successfully work with only 5 mg of Am-243. Their high product yield allowed a suite of analytical data to be gathered, which is often absent with transuranium molecular characterization.

Findings

The researchers reported a combined experimental and theoretical description of actinide f- and d-orbital energies and bonding as the actinide series is traversed toward Am. X-ray characterization comprised the first metrical quantification of an americium–carbon molecular bonding interaction. The metal–(Cp)n motif is a cornerstone of organometallic chemistry across the periodic table, and this research begins to define subtle bonding and electronic changes in homologous f-element molecules into the rarely studied realm beyond plutonium, providing important benchmark data and direct comparisons.

This cutting-edge research on Am and broader actinide science is made possible by Los Alamos’ niche expertise along with its specialty facilities for handling these types of materials.

Funding and mission

This research was funded by a Laboratory Directed Research and Development (LDRD) Exploratory Research award, a J.R. Oppenheimer postdoctoral fellowship, the DOE  Office of Science Basic Energy Sciences, and the Heavy Element Chemistry Program.

This research supports the Laboratory’s Energy Security mission area by enhancing its reputation as an actinide/plutonium center of excellence. It also supports the Lab’s Science of Signatures and Nuclear and Particle Futures science pillars.

Reference: Conrad Goodwin, Andrew Gaunt, Stosh Kozimor (C-IIAC); Jing Su, Ping Yang (T-1); Enrique Batista (T-CNLS); Brian Scott (MPA-11); Thomas Schmitt (Florida State); Anastasia Blake (MPA-CINT/Univ. of Iowa); Scott Daly (Univ. of Iowa); Stefanie Dehnen (Marburg); Niels Lichtenberger (LANL Chemistry Division/Marburg); William J. Evans (UC Irvine). “[Am(C5Me4H)3]: An Organometallic Americium Complex.” Angew. Chem. Int. Ed. 2019, 58, 11695–11699 (featured on back cover). https://doi.org/10.1002/anie.201905225

Technical contact: Andrew Gaunt

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Earth and Environmental Sciences

Tackling the multifaceted impacts of increasing temperatures on forests

Forests cover one third of Earth’s total land area and contain more carbon in biomass and soils than is stored in the atmosphere. Every forested continent has undergone widespread, drought-induced forest mortality over the last two decades, and climate change is expected to cause even greater stress on forests by superimposing longer periods of low precipitation on elevated evaporative demand (vapor pressure deficit, VPD) due to warming. These environmental changes are also expected to impact populations of insect pathogens, causing further uncertainty regarding the fate of forests and projections of future carbon balance. Earth & Environmental Sciences Division (EES) researchers tackled this problem through a multiscale model-experiment (ModEx) approach from cell to ecosystem to globe. Experimentalists implemented one of the world’s first ecosystem-scale drought and heat experiments, the Los Alamos Survival Mortality experiment (SUMO), subjecting mature pinon and juniper trees to five years of artificial drought and heat to evaluate physiological response to projected environmental changes. In tandem, modelers evaluated a series of insect phenology models to improve prediction of pest outbreaks, and implemented a leaf-level plant biophysics model to understand the effects of forest canopy architecture on water, carbon, and energy balance. This work supports the Lab’s Energy Security mission area and Science of Signatures science pillar.

 

Relative humidity in the intercellular air spaces inside the leaves of two semiarid conifer species plotted as a function of the air vapor pressure deficit to which the leaves were exposed. A relative humidity of one indicates saturation, and is denoted by the horizontal line within each panel. The analysis demonstrates clear evidence of unsaturation of the internal humidity, even at rather modest air vapour pressure deficits, for these semiarid conifers.

Relative humidity in the intercellular air spaces inside the leaves of two semiarid conifer species plotted as a function of the air vapor pressure deficit to which the leaves were exposed. A relative humidity of one indicates saturation, and is denoted by the horizontal line within each panel. The analysis demonstrates clear evidence of unsaturation of the internal humidity, even at rather modest air vapour pressure deficits, for these semiarid conifers.

Universal assumptions about photosynthesis collapse under hot drought

Global carbon and water cycles, food production, and ecosystem services are dependent on the fundamental plant physiological functions of photosynthesis and transpiration. These processes are impacted by stomatal conductance, or the diffusion of CO2 and water vapor through leaf pores.  Mathematical models, the primary means of analyzing and predicting this important leaf gas exchange, universally assume that relative humidity inside leaves (ei) remains saturated under all conditions. The validity of this assumption has not been well tested, because ei has not been measured directly, and resolving it indirectly is challenging. LANL experimentalists and colleagues used the SUMO experiment to test this assumption using a novel technique, based on coupled measurements of leaf gas exchange and the stable isotope compositions of CO2 and water vapor passing over the leaf. In both mature conifer species measured at the site, relative humidity routinely dropped below saturation when leaves were exposed to moderate to high air vapor pressure deficits (evaporative demand, VPD), which increase exponentially with increasing temperature. These departures caused significant biases in calculations of stomatal conductance and the intercellular CO2 concentration, and show that the longstanding assumption of saturated relative humidity in plant leaves under all conditions is incorrect. Correcting this bias will allow for improved prediction of plant function and contribution to global carbon and water cycles under future high temperatures.

Reference: “Unsaturation of vapor pressure inside leaves of two conifer species.” Nature, Scientific Reports. 2018. DOI 10.1038/s41598-018-25838-2. Lucas A. Cernusak (James Cook University), Nerea Ubierna (The Australian National University), Michael W. Jenkins (University of California), Steven R. Garrity (METER Group, Inc.), Thom Rahn (EES-14), Heath H. Powers (EES-14), David T. Hanson (University of New Mexico), Sanna A. Sevanto (EES-14), Suan Chin Wong (The Australian National University), Nate G. McDowell (Pacific Northwest National Laboratory) & Graham D. Farquhar (The Australian National University). Technical contact: Sanna Sevanto

First 3D plant tissue imaging to reveal important links between structure and drought response

Plants close their stomata during drought to avoid excessive water loss, but species differ with respect to the drought severity at which stomata close. The stomatal closure point is related to the structure of the woody water-transport tissue (xylem) and its vulnerability to blockage (embolism). However, there may also be links between stomatal closure and structure of the soft, sugar-transport tissue (phloem), allowing for sugar translocation under varying degrees of drought. Since reduced water availability increases the viscosity of phloem sap, desiccation tolerant plants would have more phloem tissue and larger phloem conduits compared to plants that avoid desiccation by stomatal closure under moderate drought. To test these hypotheses, EES researchers colleagues conducted the world’s first experiment using tridimensional synchroton X-ray microtomography and light microscopy to image xylem and phloem tissues and evaluate changes in their anatomy with respect to plant desiccation tolerance. Their subjects were two coniferous species (piñon pine and one-seed juniper) exposed to experimental drought and irrigation treatments. Their findings confirm that desiccation tolerant plants require higher phloem transport capacity than desiccation avoiding plants.

Reference: “Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two co-existing arid-zone coniferous trees?” 2018. Plant, Cell and Environment. DOI 10.1111/pce.13198. Sanna Sevanto (EES-14), Max Ryan (EES-14), L. Turin Dickman (EES-14), Dominique Derome (Swiss Federal Laboratories for Material Science and Technology (Empa), Switzerland), Alessandra Patera (Paul Scherrer Institute, Switzerland; Ecole Polytechnique Federale de Lausanne, Switzerland), Thijs Defraeye (Empa; ETH Zurich, Switzerland), Robert E. Pangle (University of New Mexico), Patrick J. Hudson (University of New Mexico), William T. Pockman (University of New Mexico). Technical contact: Sanna Sevanto

Hydraulic adjustment to high temperature partially mitigates negative impacts of warming and drought on trees

Precipitation reduction and increased evaporative demand (vapor pressure deficit, VPD) due to temperature increase can have additive or opposing effects on plant function. Disentangling the relative impacts of these environmental changes on plant water dynamics, and determining whether acclimation influences these patterns in the future, is important for understanding feedbacks to the climate system. EES experimentalists used the SUMO experiment to evaluate the impacts of five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects on several metrics of hydraulic function in mature piñon pine and juniper trees. No acclimation occurred under precipitation reduction, while warming reduced the sensitivity of leaf pores, or stomata, to VPD for both species but resulted in the maintenance of stomatal conductance (Gs) at ambient levels in piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced Gs. Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs were similar to reductions under single stresses for both species. These results show that stomatal adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi-arid regions.

Reference: “Tree water dynamics in a drying and warming world,” Plant, Cell & Environment, DOI 10.1111/pce.12991.  Charlotte Grossiord (Formerly EES-14), Sanna Sevanto (EES-14), Isaac Borrego (EES-14), Allison M. Chan (Environmental Remediation – Field Services, ER-FS), Adam D. Collins (EES-14), Lee T. Dickman (EES-14), Patrick J. Hudson (University of New Mexico), Natalie McBranch (EES-14), Sean T. Michaletz (University of Arizona), William T. Pockman (University of New Mexico), Max Ryan (EES-14), Alberto Vilagrosa (University of Alicante) & Nate G. McDowell (Pacific Northwest National Laboratory). Technical contact: Sanna Sevanto

Competition for dying trees counteracts the positive effect of warmer temperatures on bark beetle populations

Bark beetles cause extensive forest mortality, and warmer climates are predicted to increase outbreak frequency, severity, and range. However, even in favorable climates, resource limitation can cause outbreaks to decelerate. Analyses of climatic effects on populations need to consider competition for limited resources. EES researchers evaluated how climate can impact mountain pine beetle reproduction, using an extensive 9-year dataset sampling 10,000 beetle-invaded trees across a 22-million-acre Canadian region. Their analysis supports the hypothesis of a positive effect of warmer winter temperatures on beetle survival and provides evidence that the increasing trend in North American minimum winter temperatures is an important driver of increased reproduction. Although they demonstrate the temperatures impact reproduction (at landscape and regional scales), this effect is overwhelmed resource competition. The study confirms that increasing minimum winter temperatures allow beetles to expand their range but reveals that overcrowding halts population growth.

Reference: “The effect of warmer winters on the demography of an outbreak insect is hidden by intraspecific competition.” 2018. Global Change Biology. DOI: 10.1111/gcb.14284. Devin W. Goodsman (Formerly EES-14), Guenchik Grosklos (Utah State University), Brian H. Aukema (University of Minnesota), Caroline Whitehouse (Alberta Agriculture and Forestry), Katherine P. Bleiker (Canadian Forest Service) Nate G. McDowell (Pacific Northwest National Laboratory), Richard S. Middleton (EES-16) & Chonggang Xu (EES-14). Technical contact: Chonggang Xu

These EES projects were funded by the Los Alamos National Laboratory Laboratory Directed Research and Development program (LDRD), an LDRD Director’s fellowship, and the Lab’s Center of Space and Earth Sciences (CSES) Chick Keller postdoctoral fellowship. Funding was also provided by the Department of Energy Office of Science Biology and Environmental Research program, the National Science Foundation, the Sevilleta Long Term Ecological Research program, and the Australian Research Council’s Discovery Grants.

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Educational Outreach

Joint Science and Technology Institute comes to Albuquerque with help from LANL

Ramesh Jha (B-11), standing on right, helps students analyze data at the JSTI–ABQ workshop this summer.

Ramesh Jha (B-11), standing on right, helps students analyze data at the JSTI–ABQ workshop this summer.

Los Alamos scientists from Bioscience, LANSCE, the HAZMAT team, the Student Programs Office, and the Bradbury Science Museum helped inspire and educate New Mexico high school students at a Department of Defense STEM program. The Joint Science and Technology Institute, which was held for a number of years at Aberdeen Proving Ground in Maryland, came to Albuquerque for the first time this June. JSTI–ABQ included two weeks of fully funded residential STEM research.

More STEM for NM

The purpose of JSTI is to inspire and encourage students to pursue careers in science, technology, engineering, and math fields; increase STEM literacy; and expose students to the importance of STEM through hands-on, relevant research.

According to JSTI–ABQ organizer Ricardo Marti-Arbona (B-11, now MPA-DO) it is important for New Mexico students to have new learning opportunities in STEM areas. “The JSTI program not only benefits New Mexico students but also revitalizes our scientists by feeding their insatiable hunger to share their knowledge and prepare future generations to carry on.”

Elizabeth Hong-Geller (B-DO), left, talks with JSTI students during their visit to the Bradbury Museum.

Elizabeth Hong-Geller (B-DO), left, talks with JSTI students during their visit to the Bradbury Museum.

In real life

At the end of the first week, the New Mexico students took a break from their hands-on science experiments and data analysis led by LANL and Sandia National Laboratories scientists to field trip to Los Alamos. Their stops included LANSCE and Bradbury Science Museum. More than 35 LANL staff members participated in the outreach program this year.

Marti-Arbona’s goal is to continue working with the Department of Defense team to ensure the program will take place again next year and double the number of instructors/courses from four to eight. If you would like to participate in the JSTI 2020 workshop, please contact Ricardo Marti-Arbona. Funding for JSTI–ABQ was provided by the Department of Defense, DTRA. Technical contact: Ricardo Marti-Arbona

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Experimental Capability Enhancement

Proton Radiography Facility improvements boost safety, maximize experiment time

The Proton Radiography Facility’s two quadrupole magnets, the Identity Lens (left) and the x3 Magnifier (right), are now mounted on rails for simplified experimental setup.

The Proton Radiography Facility’s two quadrupole magnets, the Identity Lens (left) and the x3 Magnifier (right), are now mounted on rails for simplified experimental setup.

Recent improvements at the Proton Radiography Facility (or pRad) streamlined the process for switching magnification systems. This enhancement reduced the time required for system changes from days to hours.

pRad serves users

pRad is a state-of-the-art facility located at LANL’s Los Alamos Neutron Science Center (LANSCE). Open to national users, pRad offers scientists insights into a wide range of materials under extreme pressures, strains, and strain rates using the penetrating power of high-energy protons. Although the demand for pRad is high, the availability for users is limited. That is why this current enhancement is so beneficial—it allows for quick experimental setup, making the most of available beam time during the LANSCE run cycle. Previously, changing the magnet configuration required a forklift, necessitating additional safety checks and caution to avoid jostling and potentially damaging the magnets. Connecting power to the magnets required specially trained operators from Accelerator Operations (AOT-OPS). 

Medina brings the idea

The enhancement for switching magnification systems came in the form of new rail tracks, installed by members of Subatomic Physics (P-25). The rail racks allow the magnets to be safely, gently, and quickly rolled into position. A new quick-disconnect power cable system (which was proposed by Jason Medina of Subatomic Physics) eliminates the previously intricate process and features several integrated safety mechanisms.

Jason Medina’s (P-25) proposed concept for a new quick-disconnect power cable system is brought to life.

Jason Medina’s (P-25) proposed concept for a new quick-disconnect power cable system is brought to life.

Funding and mission

These experimental facility improvements exemplify excellence in mission operations supporting excellence in mission-focused science, technology, and engineering. It was funded by the pRad Capability LANSCE High-resolution Spectrometer Deactivating and Decommissioning Project. The Laboratory’s Weapons Program made this capability investment in support of national and international weapons science and stockpile stewardship programs. The improvements are part of an ongoing effort to restart dynamic experiments using plutonium. As a complement to the large-scale experiments at Nevada National Security Site, Pu@pRad will provide tomographic imaging and small-scale dynamic response studies on plutonium systems—resolving features as small as a human hair. 

The work benefits research supporting the Laboratory’s Nuclear Deterrence mission area and its Materials of the Future and Nuclear and Particle Futures science pillars. As a user facility, the Proton Radiography Facility is used by Los Alamos, other national laboratories, and academic institutions for unclassified and classified experiments.

Upgrade team members include Jason Medina, Julian Lopez, Levi Neukirch, Amy Tainter, Steve Greene, Fesseha Mariam, William Meijer, Andy Saunders, Tamsen Schurman, Zhaowen Tang, Dale Tupa, David Archuleta, Nicholas Lovato, Rayann Mora, Emily Rivera, Anthony Sanchez, Alexis Trujillo (all P-25).

Technical contact: Kathy Prestridge

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Intelligence and Space Research

New technique for understanding extreme lightning and changing climate

Lightning has far-reaching consequences beyond its immediate hazard of a strike. Electrified weather around the world drives electrical connections in the Earth–atmosphere system, and we can use this electrical heartbeat of the planet to track long-term changes in storminess as the climate evolves. Science with this breadth of impact offers great value to policymakers, researchers, and humanity. That’s why when Los Alamos’ Michael Peterson of Intelligence and Space Research (ISR-2) submitted his latest work to the Journal of Geophysical Research Atmospheres in early August, it was immediately published online and reported in National Geographic.

Peterson’s work provides new insights into lightning data used by forecasters. For example, Peterson reprocessed the 2018 Geostationary Lightning Mapper (GLM) data that was produced in real-time by the Lightning Cluster Filter Algorithm (LCFA). LCFA was designed to get lightning data into the hands of forecasters quickly in order to protect lives and property. But LCFA’s speed comes at a cost—taking computational shortcuts that limit the utility of its data for scientific research. Most notably, complex cases of horizontal “spider” lightning that were mapped by previous space-based instruments (including the LANL/Sandia FORTE satellite, which was launched to space in 1997) are split into many pieces by LCFA. Data issues like this lead to inaccurate thunderstorm flash rates and incorrect assessments of what lightning is actually doing in a given storm.

The largest lightning flash measured by the Geostationary Lightning Mapper in 2018. This monster flash encompassed parts of Texas, Louisiana, Missouri, and Mississippi. Lines trace the horizontal development of the flash in time from first light (dark gray) to the final pulse (light gray). The top and right panels show the latitude/longitude extents of every pulse in the flash over time, while the bottom time series documents changes in pulse energy (top) and area (bottom) over the course of the flash.

The largest lightning flash measured by the Geostationary Lightning Mapper in 2018. This monster flash encompassed parts of Texas, Louisiana, Missouri, and Mississippi. Lines trace the horizontal development of the flash in time from first light (dark gray) to the final pulse (light gray). The top and right panels show the latitude/longitude extents of every pulse in the flash over time, while the bottom time series documents changes in pulse energy (top) and area (bottom) over the course of the flash.

Old data, new perspective

Fortunately, the underlying data was preserved, and this means the LCFA can be corrected. Peterson developed a new technique for reprocessing the GLM data to mitigate the shortcomings of the LCFA. His results document all lightning across America during 2018 (not just the simple flashes) and provide statistics describing the characteristics and frequencies of GLM lightning flash and thunderstorm features. Peterson shows how often lightning and thunderstorms occur, documents what the flashes look like, and identifies extreme examples of lightning across the Americas.

The new technique offers more information about lightning than the standard NASA/National Oceanic Atmospheric Administration (NOAA) products, and the new technique requires less computational cost to produce compared to other approaches that have been considered for constructing a GLM “science” dataset. This is an important consideration when dealing with large datasets and limited computing power. “The biggest challenge is also the biggest benefit,” Peterson says. “It’s just the sheer amount of data.”

Findings and future

Science-grade GLM data will be necessary for monitoring global change. In order to track long-term lightning trends starting from the FORTE satellite era and continuing into the future, it is necessary that all of the NASA, NOAA, and LANL/Sandia instruments agree on the definition of a lightning flash and how that will be measured.

Peterson’s work ensures that the GLM flashes are clustered correctly and are compatible with the legacy datasets. It has also led to the discovery of some truly extraordinary cases of lightning. Peterson identified one lightning flash that was 673 km across, another that developed horizontally over a 114,997-km2 area, and a third that lasted for nearly 13.5 s. For comparison, the most exceptional flashes measured from satellites in low Earth orbit (including FORTE) were 89 km in length, 10,000 km2 in area, and 7.5 s in duration.

GLM can measure even the rarest types of lightning, wherever they occur on the continent, but GLM will not be alone up in orbit for very long. The upcoming Space and Endo-Atmospheric Nuclear denotation detection Surveillance Experiment and Risk Reduction (SENSER) payload is an NNSA/LANL/Sandia collaboration that will join GLM in geosynchronous orbit over the Western hemisphere to provide FORTE-like radio frequency and optical measurements of lightning within the GLM field of view. Data fusion between SENSER’s unique capabilities and Peterson’s repaired GLM data will enable new and exciting opportunities for space-based lightning research.

Funding and mission

This study was supported by a NASA grant. The research supports the Laboratory’s Global Security mission area and the Information Science and Technology science pillar.

Reference: Michael Peterson (ISR-2). “Research Applications for the Geostationary Lightning Mapper (GLM) Operational Lightning Flash Data Product.” J. Geophysical Research Atmospheres (Accepted, unedited articles published online and citable) DOI: https://doi.org/10.1029/2019JD031054   Technical contact: Michael Peterson

Milestone launch for space-based nuclear detonation detection

On Aug. 22, 2019, a new Global Positioning System (GPS) satellite carrying Los Alamos-designed, -developed, and -produced sensing instruments was successfully launched into orbit aboard an Air Force rocket. This satellite—officially named GPS-III 02 Magellan—marks the second of its kind to launch to space.

This launch is part of an effort that began more than 14 years ago to maintain U.S. national security through the detection of nuclear detonations. The Global Burst Detector (GBD) payload, a collaborative effort between Los Alamos and Sandia National Laboratories, senses nuclear detonations anywhere in the atmosphere or space around the world, offering timely information about potential activity to U.S. policymakers. Pairing this GBD technology with GPS is particularly advantageous because GPS offers position, navigation, and timing capabilities that enable pinpointing the location and time of a nuclear explosion.

“This milestone is a testament to the Lab’s strong and long-term dedication to the nuclear detonation detection mission,” said Marc Kippen, Los Alamos Program Manager for Nuclear Detonation & Test Detection.

The Magellan satellite rode to space on a U.S. Air Force Delta IV rocket.

The Magellan satellite rode to space on a U.S. Air Force Delta IV rocket.

For Magellan, the GBD payload was integrated with the GPS satellite starting in 2013, and the completed satellite was shipped to Cape Canaveral, Florida in March 2019 for integration with the launch vehicle. There are a few different sensing systems incorporated into the GBD payload aboard Magellan that can detect nuclear explosions: electromagnetic pulse and X-ray sensors developed by Los Alamos and optical sensors developed by Sandia.

This launch marks the second deployment of an ongoing payload design, development, and production effort of the GPS-III series of satellites and GBD payloads. Following final orbital insertion and spacecraft activation, Los Alamos and Sandia personnel will support the activation and on-orbit testing of the GBD payload systems in the coming weeks.

Funding and mission

Another six GPS-III satellites with GBD payloads are in various stages of production and testing, and they will be launched in the coming few years. These activities support the Laboratory’s Nuclear Deterrence mission area and the Science of Signatures and Information Science and Technology science pillars. Funding for this work is through the National Nuclear Security Administration and the United States Air Force. Technical contact: Marc Kippen

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Materials Science and Technology

Evidence that electrons can help study materials under extreme conditions

In June 2019, LANL researchers in Materials Science & Technology and Engineering Technology & Design, in collaboration with the Naval Research Laboratory (NRL), made a first step in demonstrating that electrons can be used as surrogates for rapid heating of materials. This was accomplished using Gamble II—a pulsed-power electron beam line at NRL.

Gamble II beam line and residual gas analyzer used for these experiments.

Gamble II beam line and residual gas analyzer used for these experiments.

Built in 1970, Gamble II was the first water-dielectric machine in the West. Now, it is commonly used as an inexpensive “pre-test” for novel materials. Many successful Gamble II experiments move on to more expensive testing at the National Ignition Facility at Lawrence Livermore National Laboratory or the Z Machine at Sandia National Laboratories.

A first for Gamble II

The most recent use of Gamble II illustrated that electron beam irradiation can imitate extreme conditions for materials, and those results can be quantified. The Los Alamos and NRL researchers irradiated foam material and measured the gas decomposition products with a residual gas analyzer (RGA; see figure). The residual gas spectra showed evidence of the chemical changes the sample underwent, and visual inspection of the samples showed the physical damage (e.g., charring) caused by the electron beam irradiation.  

This was the first time in situ information was acquired on the chemical and physical changes that materials undergo under extreme conditions. Ex situ characterization of the materials before and after electron beam irradiation demonstrated significant material property changes, which is in agreement with the residual gas data obtained during the experiments. Preliminary Density Functional Theory (DFT) studies of the fragmentation of this material was also in agreement with the RGA data: multiple bonds break at once, with carbon monoxide (CO) and ethylene (C2H4) being the first ones emitted during rapid heating. This evidence will allow more materials under extreme conditions to be studied and understood. This research was recently submitted for peer review for the 2020 Weapons Engineering Symposium at LANL.

Residual gas spectra of foam material before and during electron beam irradiation.  The data show gases produced due to rapid heating of the sample to and beyond its decomposition temperature. The inset image illustrates the physical changes: vaporization and charring are observed as well as evidence of ablation.

Residual gas spectra of foam material before and during electron beam irradiation. The data show gases produced due to rapid heating of the sample to and beyond its decomposition temperature. The inset image illustrates the physical changes: vaporization and charring are observed as well as evidence of ablation.

Funding and mission

Science Campaign 7 (LANL Program Manager Steve McCready) funded this research, which was performed at LANL and NRL. LANL scientists and engineers performed material characterization (such as surface profiling, TGA, DSC, and density functional theory analysis) before and after electron irradiation. The experiments were performed at NRL. This work supports the Laboratory’s Nuclear Deterrence mission and Materials of the Future science pillar.

Researchers: Loren I Espada Castillo (MST-7), Erwin Schwegler (Advanced Engineering Analysis, E-13), Martin Perraglio (Mechanical and Thermal Engineering, E-1), Isaac Herrera (MST-7), Paul Peterson (MST-7), Kin Lam (E-13), and David Hinshelwood (NRL). Technical contact: Loren I Espada Castillo

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Mesoscale Materials Science on the Roadmap to MaRIE

Machine learning for scintillator design: learning to predict novel material performance

Los Alamos scientists combined expertise in radiation detection and high-performance computing to create a two-pronged, machine-learning approach to scintillator design. The researchers used only a limited dataset to train their computer model and identify previously unknown characteristics that contribute to scintillator performance.

The research was selected as the June 2019 finalist for the Journal of Materials Science Robert W. Cahn Best Paper Prize. (One article is selected each month as a Cahn Prize finalist, with the award presented in December.)

a) Data-enabled science as a fourth paradigm in materials science. (b) Schematic depiction of the conventional and ML-based routes from materials to properties. Two essential ingredients of the ML approach, namely fingerprinting and statistical learning, are highlighted.

a) Data-enabled science as a fourth paradigm in materials science. (b) Schematic depiction of the conventional and ML-based routes from materials to properties. Two essential ingredients of the ML approach, namely fingerprinting and statistical learning, are highlighted.

For DMMSC and beyond

Scintillators—materials that fluoresce when struck by a charged particle or high-energy photon—are used to detect radiation (including light) for scientific, medical, and industrial applications. For LANL, bright, very-fast scintillators will image high-repetition-rate experiments in extreme environments for the DOE’s currently unmet Dynamic Mesoscale Material Science Capability (DMMSC; formerly known as MaRIE).

Historically, developing a new scintillator material has been a resource-intensive process of trial and error, taking nearly a decade from discovery to deployment. This technique has had some success, but it is limited in the number of materials that can be evaluated. A new technique was needed for the discovery of next-generation scintillators.

Next-gen materials need machine learning

That is why LANL researchers turned to machine learning (ML). Thus far, ML techniques have required hundreds-to-thousands of samples for initial model training, but few scintillator materials exist to serve as the basis for such training. These researchers were able to overcome this hurdle by incorporating known physics phenomena (or expert knowledge) into the computer’s learning process along with their limited dataset: 25 known lanthanide-doped scintillator materials with reliable data on desirable characteristics of light output and decay time.

The model was based on standard learning algorithms, such as kernel ridge regression and AdaBoost algorithm, applied on top of a decision tree regression to learn the design rules and make accurate predictions for novel scintillator materials. This data-enabled science is dubbed the fourth paradigm in materials science (see figure).

Their ML technique identified characteristics that were not previously linked to scintillation. For example, they found that the lattice component of the dielectric constant is a highly relevant predictor for light yield, irrespective of the specific chemistry of the compound. This work also proved that the ML technique is applicable to relatively small training sets, provided one can effectively integrate known physics of the problem into the learning process.

Funding and missions

Funding for this technology maturation work came from the Laboratory’s MaRIE project (Capture Manager: Cris Barnes) through the Campaign 2 program (LANL Program Manager: Dana Dattelbaum). Computational support for this work was provided by LANL’s high performance computing clusters. 

This work supports the Laboratory’s Nuclear Deterrence mission and the Materials of the Future and Nuclear and Particle Futures science pillars by enabling the informed design of materials for future radiation detection devices. It supports the Information Science and Technology science pillar by using Los Alamos’ high-performance computational capabilities to accelerate the predictive capability of the scientific method.

Reference: Ghanshyam Pilania and Xiang-Yang Liu (Materials Science in Radiation and Dynamics Extremes, MST-8) and Zhehui Wang (Subatomic Physics, P-25). “Data-enabled structure–property mappings for lanthanide-activated inorganic scintillators,” J. Mater. Sci. 54, 8361–8380 (2019). DOI: https://doi.org/10.1007/s10853-019-03434-7 Technical contact: Ghanshyam Pilania

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Physics

NIFFTE measures angular anisotropy of U-235 with unprecedented precision

Verena Geppert-Kleinrath and the fully assembled fission time projection chamber at LANSCE—the only detector of its kind.

Verena Geppert-Kleinrath and the fully assembled fission time projection chamber at LANSCE—the only detector of its kind.

After 75 years of fission research, a great deal is still left to discover. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration is helping to uncover some of those fission mysteries.

New measurement by NIFFTE

NIFFTE operates a novel time projection chamber for measuring fission cross sections of major actinides. NIFFTE’s latest discovery, led by Verena Geppert-Kleinrath of Los Alamos’ Physics Division (P-23), uncovered fission fragment angular distributions and anisotropy values for fission of uranium-235. LANL researchers involved in the measurement include Dana Duke (P-23), Elena Guardincerri (P-25), and Kyle Schmitt (ISR-1).

Uranium-235 is a particularly relevant isotope because it is fissile, making it ideal as a key component in nuclear energy and nuclear weapons. Using NIFFTE’s unique time projection chamber for 3D tracking of charged particles produced in the fission process led to the measurement of complete angular distributions and anisotropy in fission fragments—marking a first in the field. This data will aid in fission theory and modeling, and the technique is now being applied to other actinides, such as plutonium-239.

Anisotropy aids fission understanding

In this experiment, incident neutron energies from 180 keV to 200 MeV were used to induce fission at the Los Alamos Neutron Science Center (LANSCE). The collected data corresponds with previous datasets while adding information about the structure of anisotropy, which was found to closely follow the fission cross section. A detailed study of systematic uncertainties in anisotropy and angular measurements also marks a first in the field.

The NIFFTE anisotropy measurement is the first in the field to be derived from complete 3D tracking of fission fragments and the first to study systematic uncertainties in great detail. These results conclusively showed a relation between anisotropy and fission cross section related to the energy levels in the excited fissioning nucleus.

The NIFFTE anisotropy measurement is the first in the field to be derived from complete 3D tracking of fission fragments and the first to study systematic uncertainties in great detail. These results conclusively showed a relation between anisotropy and fission cross section related to the energy levels in the excited fissioning nucleus.

This work is both an improvement in terms of future accuracy of fission cross sections as well as guiding theoretical modeling of the fission process. Since anisotropy varies in magnitude between different isotopes, cross-section measurements need to correct for a difference in detection efficiency for differential measurements. The anisotropy and angular distributions of fission fragments are also used to extract information about nuclear levels on top of the fission barriers and are therefore important for advancing our understanding of the fission process.

Nuclear fission is complex, but NIFFTE researchers are unraveling the details and adding valuable data to solve the puzzle.

Funding and mission

The work was performed at the Los Alamos Neutron Science Center (LANSCE) and was funded by the Department of Energy. This research supports the Laboratory’s Energy Security mission area and the Nuclear and Particle Futures science pillar. Collaborative institutions include Oregon State University, Lawrence Livermore National Laboratory, Colorado School of Mines, University of California (Davis), Abilene Christian University, California Polytechnic State University, and Technische Universität Wien.

Reference: V. Geppert-Kleinrath et al. (NIFFTE Collaboration). “Fission fragment angular anisotropy in neutron-induced fission of U-235 measured with a time projection chamber.” Phys. Rev. C 99, 064619 (2019). DOI: 10.1103/PhysRevC.99.064619 Technical contact: Verena Geppert-Kleinrath

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Sigma

Resolving a long-standing debate on the hydrogen diffusion coefficient for α-uranium

The calculated low-barrier diffusion pathway of hydrogen (white spheres) through the α-U lattice (blue-gray spheres). The <100>-only pathway was determined to be the most likely.

The calculated low-barrier diffusion pathway of hydrogen (white spheres) through the α-U lattice (blue-gray spheres). The <100>-only pathway was determined to be the most likely.

Uranium is central to the Laboratory’s mission, but some uranium mysteries still remain, such as the room temperature hydrogen diffusion coefficient through bulk α-uranium (α-U).

The diffusion of hydrogen through α-U is a key kinetic step to forming uranium hydride. This transformation from orthorhombic α-U to uranium hydride involves structural reorganization and volume changes.

Without knowing the hydrogen diffusion coefficient, calculations and predictions are difficult to make. Until now, the only data on this diffusion coefficient came from experiments performed at temperatures near the α-U stability range (around 500 °C). The data from several independent experiments agree fairly well at these high temperatures, but once they are extrapolated to room temperature, their predictions differ by as much as three orders of magnitude.

Experimental and density functional theory-derived diffusion coefficients as a function of temperature.

Experimental and density functional theory-derived diffusion coefficients as a function of temperature.

Determining the coefficient

Edward F. Holby (Finishing Manufacturing Science, Sigma-2) decided to solve this mystery via a computational approach. Holby used density functional theory to model the way diffusion would occur in different crystallographic orientations of α-U, including relevant kinetic barriers and vibrational properties.

The calculations show that one proposed pathway captures the diffusion coefficient value at experimental temperatures and gives appropriate values at lower temperatures. This pathway for interstitial hydrogen diffusion through the bulk α-U lattice (depicted in the figure) shows that diffusion of hydrogen without additional defects is possible. This work proposes an answer to a long-standing dispute regarding the room temperature diffusion coefficient of hydrogen through α-U.

Published in the Journal of Nuclear Materials, this work relied on the Laboratory’s Institutional Computing Program resources to carry out density functional theory calculations of relaxed structures, diffusion barriers, and vibrational normal modes.

Funding and mission

This research was funded by LANL Enhanced Surveillance, formerly known as Campaign 8, (LANL Program Managers Thomas G. Zocco and Charles R. Hills). Computational support was provided by Los Alamos National Laboratory Institutional Computing.

The work supports the Laboratory’s Nuclear Deterrence mission and the Materials of the Future and Information Science and Technology science pillars. It also supports the Excellence in Nuclear Security strategic objective of the Laboratory Agenda by further developing the foundational materials science that underpins the fidelity of the Annual Assessment Reports.

Reference: Edward F. Holby. “Crystallographic orientation effects of hydrogen diffusion in α-uranium from DFT: Interpreting variations in experimental data,” Journal of Nuclear Materials 513, 293–296 (2019). DOI: https://doi.org/10.1016/j.jnucmat.2018.10.022  Technical contact: Edward Holby

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Theoretical

$3.25M awarded to LANL for quantum software and quantum algorithms

Contrasting the classical computing unit (bit) with the quantum computing unit (qubit). Qubits can be in a combination of states. Credit: APS Physics

Contrasting the classical computing unit (bit) with the quantum computing unit (qubit). Qubits can be in a combination of states. Credit: APS Physics

“We are on the threshold of a new era in Quantum Information Science,” said DOE Under Secretary of Science Paul Dabbar, “with potentially great promise for science and society.” This promise is backed by a total of $60.7M in funding from the DOE for the development of quantum computing and quantum networking.

The money is divided among nine DOE laboratories, 10 universities, and one non-profit. Most of the projects are multi-institutional, offering needed collaboration to solve a complex problem—boosting the range of quantum-based communications.

Two LANL scientists, Patrick Coles and Rolando Somma (Physics of Condensed Matter & Complex Sys, T-4), were awarded $3.25M over a five-year period from that funding pot. The projects for Cole and Somma, “Advancing Integrated Development Environments for Quantum Computing through Fundamental Research” and “Fundamental Algorithmic Research for Quantum Computing,” respectively, will help build the groundwork for extended quantum networking.

Coles and Somma submitted their applications for funding to the Office of Advanced Scientific Computing Research within the DOE’s Office of Science. The awardees were selected through competitive peer review.

Coles was highlighted in LANL’s August STE Highlights issue for his recent work on the quantum-to-classical transition, published in Nature Communications. Somma was recently published in APS Physical Review Letters for research on two quantum-computing algorithms, which emphasize the role of Hamiltonian-based models of quantum computing.

Quantum computing—the field both Coles and Somma will support—uses quantum phenomena to perform computations. Therefore, quantum computers are able to simulate things that current “classical” computers cannot. Using the unit of quantum bits, or qubits, problems can be solved that were previously impossible and speeds can be reached that were previously incomprehensible.

This research and funding will support the Laboratory’s Global Security mission and the Information Science and Technology science pillar. Technical contact: Patrick Coles and Rolando Somma

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