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Los Alamos National Laboratory

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Science, Technology & Engineering Highlights, July 2019

Awards and Recognition

Mandie Gehring recognized as a distinguished young alumna by alma mater

Mandie Gehring

Mandie Gehring

Mandie Gehring (Neutron Science and Technology, P-23) was recognized by her undergraduate alma mater, Rose-Hulman Institute of Technology (RHIT) in Indiana, with a 2018 Distinguished Young Alumni Award. The award identifies alumni who have graduated within the last 10 years that have pursued notable endeavors in career achievement, continued education, community service, and/or commitment to their alma mater.

Gehring, P-23’s National Security Science team leader, analyzes historical data from full-size nuclear tests and, in support of the Laboratory’s Stockpile Stewardship mission, is principal investigator of x-ray diagnostics for subcritical experiments. She is the recipient of two NNSA Defense Programs Awards of Excellence and a LANL Large Team Distinguished Performance Award. She is involved with the RHIT alumni network and co-organized her 10-year class reunion. In Los Alamos, she is active with her church’s outreach efforts. 

Gehring, who completed her Ph.D. in chemistry at Michigan State University in 2013, joined the Laboratory as a postdoctoral researcher later that year. She became a Laboratory staff member in 2015. Technical contact: Mandie Gehring

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Spendelow recognized for leadership by DOE’s Hydrogen and Fuel Cells Program

Jacob Spendelow

Jacob Spendelow (MPA-11), left, receives his award from Dimitrios Papageorgopoulos, Program Manager of the Fuel Cells program, at the Annual Merit Review and Peer Evaluation Meeting held in Annapolis, MD.

Jacob Spendelow (Materials Synthesis and Integrated Devices, MPA-11) received a 2019 Annual Merit Review Award for his work in fuel cell research and development from the Department of Energy’s Hydrogen and Fuel Cells Program.

The award committee cited Spendelow for outstanding leadership demonstrated in conducting the fuel cell project “Advanced electrocatalysts through crystallographic enhancement.” Spendelow led a large team of scientists from Los Alamos National Laboratory, State University of New York Buffalo, Brown University, University of Pennsylvania, and EWII Fuel Cells.

Spendelow and his team developed new intermetallic platinum–cobalt (PtCo) catalysts with atomic-level ordering that stabilizes Co atoms within the catalyst nanoparticles. This reduced the leaching rate of Co and maintained high Co content even after durability testing. The key innovation in 2018 was the development of a new synthetic method that enables simultaneous achievement of small nanoparticle size (< 4 nm) and a high degree of ordering. Previous efforts to develop intermetallic PtCo nanoparticles were limited by excessive particle growth that occurs during the ordering process. By avoiding this particle growth, the Los Alamos catalysts maintain high surface area and high catalytic activity while also exhibiting improved durability. The catalysts achieved a mass activity of 0.6 A/mgPGM after 30,000 voltage cycles, with a loss of only 40% after 30,000 cycles, exceeding DOE targets for catalyst performance and durability.

Spendelow joined the Laboratory as a Director’s Postdoctoral Fellow in 2006 and became a staff member in 2008. He received his Ph.D. from the University of Illinois at Urbana-Champaign in chemical engineering. In addition to his research, Spendelow served for several years as a science advisor and as a program manager at the DOE Fuel Cell Technologies Office in Washington D.C., where he managed R&D projects related to polymer electrolyte membranes, catalysts and supports, and reversible fuel cells. Technical contact: Jacob Spendelow

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Mary Anne With receives NPA’s 2019 Distinguished Service Award

Mary Anne With

Mary Anne With

Since she joined the postdoc program at the Lab in 1991, Mary Anne With (Office of Partnerships & Pipeline, PPO) has influenced the careers of more than 10,000 postdoctoral students. Citing that significant achievement, the National Postdoctoral Association (NPA) honored her with its 2019 Distinguished Service Award. The NPA also cited her strong work ethic, positive influence on the postdoc experience at local and national levels, and the opportunities she has helped create for postdocs in research and career advancement.

The NPA published an article in its March 2019 POSTDOCket issue, headlined “The Heart and Soul of Los Alamos National Laboratory," highlighting With’s impact on the postdoc world at the Lab.

She positioned the Lab’s postdoctoral program as a science-based organization, leading a committee in a rigorous review to select only the best and brightest candidates to join the more than 400 postdocs working at the Lab. Once selected, With hones these postdocs with CV writing, behavioral interviewing, seminar training, and a “Science in 3” initiative (a Scientific American-level three-minute elevator pitch).

The award was presented to With at the NPA 2019 Annual Conference in April. Technical contact: Blas Pedro Uberuaga

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Postdocs present their research in 3 minutes or less

Postdoc logo

The Science in “3” event offers the Laboratory’s postdocs a forum to present their research. In three minutes or less, LANL postdocs must concisely deliver their keys points and project impact in a dialogue fit for a general audience.

The program was created by Mary Anne With, program manager of the Postdoc Program, Partnerships & Pipeline Office, back in 2015. At that time, it was part of the Annual Research Day, but it branched off in 2017 as its own event. This year, 30 postdocs presented, of which three were recognized with Outstanding Presentation Awards and three with Honorable Mention Awards.

The event is open for all LANL postdocs to apply, with the final list of presenters selected by the Associate Laboratory Directors (ALDs). Each applicant delivers a preliminary presentation to their managers and associated ALD. This first round determines who will qualify to present at “Science in 3.”

On June 11, 2019, the 30 postdocs selected made their presentations to a prestigious Review Panel of seven members, which included LANL Emeritus Director Terry Wallace and New Mexico State Representative Christine Chandler. The Science in “3” event is open to all badge holders to attend. The Review Panel selected the top six presenters, those who received Outstanding Presentation Awards as well as Honorable Mention.

Science in 3 winners

Left to Right: Carol Burns DDSTE Executive Officer, Honorable Mention Awardees Kim Schultz (J-5), John Greenhall (MPA-11), Deborah Shutt (A-1), Outstanding Presentation Awardees Derrick Kaseman (B-11), Christina Hanson (MST-7), Eric Davis (MPA-11), & Nan Sauer Partnerships & Pipeline Office Director

Eric Davis (MPA-11), Christina Hanson (MST-7), and Derrick Kaseman (B-11/E-6) were selected as the Outstanding Presentation awardees. Davis presented on a portable explosives characterization system based on time-of-flight acoustics. Hanson presented on new polyimide aerogel materials that can reduce the weight of components, such as military gear and airplane parts. Kaseman presented on a fieldable spectrometer that can identify thousands of unique structures from organophosphorus chemical warfare agents.

John Greenhall (MPA-11), Kim Schultz (J-5), and Deborah Shutt (A-1/CCS-6) were selected as the Honorable Mention awardees. Greenhall presented a new acoustic source for underwater detection that offers a narrow, collimated, low-frequency beam. Schultz presented on new diagnostic capabilities for the DARHT 2 axis beam. Shutt presented statistical and mechanistic models on infectious disease to inform public health policy.

These presenters represent the breadth of research at LANL and the cutting-edge technology that is being produced. The format of three minutes or less presenting to a general audience develops the postdocs’ communication skills that will be needed throughout their careers and for collaboration with industries.

Science in “3” supports Lab-wide science in all three mission areas (Nuclear Deterrence, Global Security, and Energy Security) as well as all four science pillars (Information Science and Technology, Materials of the Future, Nuclear and Particle Futures, and Science of Signatures).

Technical Contact: Mary Anne With

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Fensin receives TMS American Institute of Mining, Metallurgical, and Petroleum Engineers Hardy Award

Saryu Fensin

Saryu Fensin

Saryu Fensin of LANL’s Materials Science in Radiation and Dynamics Extremes (MST-8) is a co-recipient of the 2019 American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Robert Lansing Hardy Award. This award recognizes talented scientists under the age of 35 in the fields of metallurgy and materials science. The Minerals, Metals, and Materials Society (TMS) gives this award in recognition of the scientist for their “exceptional promise of a successful career.”

Fensin earned her Ph.D. in materials science and engineering from the University of California, Davis, and joined the Laboratory in 2010 as a postdoctoral researcher. She is currently a staff member on MST-8’s Dynamic and Quasistatic Loading Experimental Team.

Fensin was presented with the award at the 2019 TMS-AIME Annual Awards Ceremony in San Antonio, Texas. She was cited for “innovative and scientifically groundbreaking modeling research quantifying the role of grain boundary structure on the dynamic mechanical response of materials.” Technical contact: Saryu Fensin

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Lockhart and Gerez Awarded Barry Goldwater Scholarships

The Barry Goldwater scholarship is the most prestigious undergraduate scholarship in the United States in the natural sciences, mathematics, and engineering. This year, Los Alamos’ Nuclear Engineering and Nonproliferation (NEN-1) group boasts two Goldwater scholars: Kyzer Gerez and Madeline Lockhart.

Madeline Lockhart

Madeline Lockhart

Kyzer Gerez

Kyzer Gerez

Madeline Lockhart (NEN-1)

Lockhart is an undergraduate student at Texas Tech University double majoring in physics and math and a fourth-year intern in NEN. A Los Alamos-native, Lockhart attended Los Alamos High School and began interning with the Lab after her junior year.

Her goal is to receive a doctorate in nuclear physics and further the fields of nuclear safeguards and peaceful uses of nuclear energy. Technical contact: Daniela Henzlova

Kyzer Gerez (NEN-1)

Gerez is an undergraduate student at Oregon State University majoring in nuclear engineering and minoring in political science with a focus on international affairs. He is a second-year summer intern in NEN.

His career goal is to carry out research in support of national and global security, specifically at a national laboratory, and he is well on his way. With publications in Analytical Chemistry and Progress in Nuclear Energy, and Transactions of the American Nuclear Society, Gerez has shown initiative and aptitude. Technical contact: Garrett McMath

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Matthews recognized with DOE Fuel Cycle R&D Excellence award

Christopher (Topher) Matthews

Topher Matthews

Christopher (Topher) Matthews of LANL’s Materials Science in Radiation and Dynamics Extremes (MST-8) was recognized with a Department of Energy Fuel Cycle R&D Excellence award for his work developing advanced BISON simulations for nuclear fuels at the engineering scale. Matthews was presented with the award at the American Nuclear Society technical session, and to commemorate the moment, Matthews was presented with a piece of graphite used in the CP-1 (the world’s first nuclear reactor).

Steve Hayes, Idaho National Laboratory (INL) scientist and National Technical Director for the Advanced Fuels Campaign, nominated Matthews for the award. The two scientists collaborate on the project as the leads for INL and LANL, respectively. This research project will drive the advancement of fission energy and fast reactors, contributing to the progress of nuclear energy as a “green” technology.

Matthews received his Ph.D. in nuclear engineering from Oregon State University and joined the Laboratory in 2015. His work supports the Lab’s Energy Security mission and Materials of the Future science pillar. Technical contact: Topher Matthews

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Trugman wins international High Performance Computing Innovation Award

Daniel Trugman

Daniel Trugman

Earth and Environmental Sciences (EES) Division’s Richard P. Feynman Postdoctoral Research Fellow Daniel Trugman won an HPC Innovation Excellence Award for his recent Quake Template Matching (QTM) project. Trugman shares the award with his collaborators on the recent Southern California earthquake big data analysis (published in Science) that resulted in the most comprehensive earthquake catalog to date that may help researchers detect and locate quakes more precisely.

Trugman and collaborators from the California Institute of Technology and Scripps Institution of Oceanography performed a massive data mining operation, computing 10 years’ worth of Southern California seismic data to identify tiny earthquakes. They identified 1.81 million quakes—10 times more earthquakes occurring 10 times more frequently than previously identified using traditional seismology methods. They also found small quakes hidden in the noise and provided a more precise picture about stress in the Earth's crust. The team developed a publicly available earthquake library for the entire Southern California region called the QTM Catalog and are using it to create a more complete map of California earthquake faults and behavior.

In June at the International Supercomputing Conference in Frankfurt, Germany, Hyperion Research presented the HPC User Forum’s HPC Innovation Excellence Award to Trugman and collaborators. Trugman earned his bachelor’s, master’s, and doctoral degrees in geophysics from the University of California, San Diego, and Stanford University. He joined Los Alamos National Laboratory in 2008 as an undergraduate student researcher and was named a Feynman Postdoctoral Research Fellow in January of 2018. Technical contact: Daniel Trugman

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Bioscience

The role of sequence data in global threat reduction

For the past 14 years, the Laboratory’s Bioscience Division has co-hosted the annual Sequencing, Finishing, and Analysis in the Future (SFAF) meeting to bring together experts in the sequencing community. This collaborative information sharing spurs health security and threat reduction questions that lead to researching advances in sequencing relevant to national security.

Scientists from Ethiopia came to Los Alamos to participate in an annual sequencing and bioinformatics training as part of Bioscience Division’s on-going bioengagement programs. The 2019 training was held in May (a week prior to the Sequencing, Finishing, and Analysis in the Future [SFAF] meeting) and included 28 participants from 11 countries.

Scientists from Ethiopia came to Los Alamos to participate in an annual sequencing and bioinformatics training as part of Bioscience Division’s on-going bioengagement programs. The 2019 training was held in May (a week prior to the SFAF meeting) and included 28 participants from 11 countries.

The product of the 2018 SFAF conference panel was a recent 2019 publication in Tropical Medicine and Infectious Disease, which included authors Jeanne Fair and Helen Cui (B-10) along with collaborators from eight other institutions. This article highlights international collaborations based on genomics that can improve the timeliness and accuracy of disease surveillance to mitigate infectious disease outbreaks.

In particular, three major U.S. assistance programs that focus on countering biological threats through bioengagement with other countries are highlighted: the Defense Threat Reduction Agency’s Biological Threat Reduction Program, the Department of State’s Biosecurity Engagement Program, and the U.S. Agency for International Development Global Health Security/Emerging Pandemic Threats programs. This article and the SFAF panel discussed the benefits of widespread sequencing-based diagnostics and how it can reduce the time required (from weeks to hours) to characterize and identify the causative agents of outbreaks. With greater collaboration and exchange of sequencing data among countries, greater advancements in global health security can be achieved.

However, there challenges still exist, such as the need to standardize sequencing protocols in order to improve data sharing as well as the issue of sustainability, as sequencing centers need to maintain both the technical expertise of their personnel and the specialized sequencing equipment. Los Alamos’ Bioscience Division is helping meet these challenges by providing a Genomics and Sequencing training workshop once a year for country partners of the Biological Threat Reduction Program.

Reference: “Achieving Health Security and Threat Reduction through Sharing Sequence Data.” Kenneth Yeh (MRIGlobal), Jeanne Fair (B-10), Helen Cui (B-10), Carl Newman , Gavin Braunstein, Gvantsa Chanturia (Defense Threat Reduction Agency), Sapana Vora (Dept. of State), Kendra Chittenden (USAID), Ashley Tseng (Columbia University), Corina Monagin (Univ. of California, Davis), and Jacqueline Fletcher (Oklahoma State University). Tropical Medicine and Infectious Disease 2019, 4(2), 78; https://doi.org/10.3390/tropicalmed4020078

This work supports the Laboratory’s Global Security mission area and the Information Science and Technology pillar. Technical contact: Jeanne Fair

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Chemistry

Characterizing nuclear material out of regulatory control: Testing Los Alamos’ nuclear forensics capabilities

Nuclear forensics is an essential component of national and international nuclear security response. To encourage collaboration and advance the scientific discipline of nuclear forensics, a multi-national association was created in 1995, called the Nuclear Forensics International Technical Working Group (ITWG). This year marks the sixth Collaborative Materials Exercise (CMX-6) organized by ITWG, and 38 staff members from Los Alamos National Laboratory (LANL) participated.

CMX-6 exercise sample of a depleted uranium block (F) packaged within a rusty pipe (B).

CMX-6 exercise sample of a depleted uranium block (F) packaged within a rusty pipe (B).

Through a realistic, illicit radiological material scenario, CMX-6 participants employed their destructive and non-destructive nuclear forensic capabilities to characterize nuclear material found out of regulatory control to support an investigation.

In 2019, CMX-6 participants (including LANL) received two radioactive material samples—a cerium metal block and a depleted uranium metal block—seized from a fictional metal recycling plant. Both samples were contaminated with plutonium fluoride and hidden within multiple layers of plastic bags in rusty pipes (see figure). This was the second time in ITWG CMX history in which test samples included a plutonium component, making shipping, handling, and analysis considerably more challenging.

The United States tasked three of its national laboratories (LANL, Lawrence Livermore, and Savannah River) with contributing their expertise to CMX-6. Savannah River handled the 24-hour reporting, which included traditional forensic evidence (e.g., fingerprinting) and basic characterization. From there, the samples went to Livermore and LANL for more in-depth nuclear forensics, delivering 1-week and 2-month data along with a final analytical assessment of results.

LANL received the samples on March 6 and proceeded with non-destructive and destructive analyses. Expertise was contributed by four groups: C-NR, C-AAC, C-IIAC, and A-2.

Non-Destructive Nuclear Forensics

The non-destructive analyses conducted at LANL included photography, gamma-ray spectrometry, autoradiography, physical characterization (mass, dimensions, etc.), optical microscopy, elemental mapping by micro-XRF, scanning-electron microscopy (SEM), x-ray diffraction, and LIBS.

Optical images and physical characterization for both samples were performed inside a radiologically contained open-front box in LANL’s Chemistry and Metallurgy Research (CMR) facility. This was followed by surface morphology analysis using SEM and elemental mapping using micro-XRF (see figure). These analyses provided important information related to sample processing.

Destructive Nuclear Forensics

The destructive analyses conducted at LANL included secondary ion mass spectrometry; element concentration analysis by ICP-OES and ICP-MS; uranium assay by Davies and Gray titration; mass spectrometry for assay and isotope composition measurements of U, Pu, Th, Am, and Np; and radiochronometry.

The samples were dissolved with acids, and elements of interest were purified using radiochemical techniques for mass spectrometry. Plutonium analyses at the Nuclear and Radiochemistry (C-NR) facility confirmed the presence of weapons-grade plutonium, which was identical in isotopic composition between the two samples. The purities of the uranium and cerium metals, as well as the impurities, were determined using C-AAC’s coulometry techniques and ICP-OES/MS methods. Radiochronometry (age dating) was performed at C-NR by measuring the following daughter/parent pairs: 230Th/234U, 241Am/241Pu, and 237Np/241Am.

Left – optical image of depleted uranium with colored arrows denoting dimensions measured; Middle – micro-XRF map of composition (blue = uranium, red = cerium, green = yttrium); Right – SEM of morphology, including saw cuts, oxidation, and etch pits.

Left: Optical image of depleted uranium with colored arrows denoting dimensions measured; Middle: Micro-XRF map of composition (blue = uranium, red = cerium, green = yttrium); Right: SEM of morphology, including saw cuts, oxidation, and etch pits.

Assessing the Results

From the destructive analysis, a critical nuclear forensic signature was determined. The uranium metal block contained cerium and yttrium (a major impurity in the cerium metal block). This indicated that the two metal blocks were related.

The radiochronometry data helped determine the production history of the samples. The depleted uranium block had a model 230Th/234U production date of April 14, 2018 ± 6 days. The plutonium surface contamination on each sample was found to have considerably older model production dates of July 13, 1965 ± 132 days (cerium block) and July 18, 1965 ± 106 days (depleted uranium metal), based on 241Am/241Pu. Measured 237Np/241Am production dates of the plutonium agreed with the 241Am/241Pu production dates, supporting the conclusion that the plutonium was last purified approximately 54 years before the CMX-6 exercise.

CMX-6 culminated in a data review meeting in Warsaw, Poland, in early June 2019 for all international participants. Both LANL and Livermore as well as the European Commission Joint Research Centre were awarded for excellence in radiochronometry.

Participation in CMX-6 and other forensic examinations provides the opportunity to exercise LANL’s nuclear forensics capabilities and ensure LANL scientists are prepared to support nuclear smuggling investigations and other incidents of nuclear or radioactive material found outside of regulatory control. This research supports the Global Security mission and the Science of Signatures science pillar. The U.S. DOE National Nuclear Security Administration (NNSA) sponsored this research.Technical contact: Theresa Kayzar-Boggs

In-glovebox discrimination of uranium hydride/uranium oxide using laser-induced breakdown spectroscopy

The ability to distinguish between uranium hydride and uranium oxide and to provide relative abundance measurements of these co-existing materials is important during weapons surveillance activities. A complicating factor is that any chemical characterization methodology to provide this analysis must be robust, have a small footprint, and be deployable in an inert environment glovebox. Currently available analytical techniques for hydrogen and/or oxygen detection in uranium materials are too complex, infrastructure-intensive, and time-consuming for deployment in weapons disassembly and inspection applications.

Relative intensity of oxygen to uranium (O/U) and hydrogen to uranium (H/U) LIBS peaks during instrument parametric studies. Circled data show regions of high discrimination between uranium corrosion products.

Relative intensity of oxygen to uranium (O/U) and hydrogen to uranium (H/U) LIBS peaks during instrument parametric studies. Circled data show regions of high discrimination between uranium corrosion products.

Chemistry Division researchers are addressing this dearth by developing new instrumentation and methods to rapidly distinguish between uranium oxide and uranium hydride in a glovebox. The method is based on a commercially available handheld laser-induced breakdown spectroscopy (LIBS) instrument that is modified for the unique application of uranium corrosion product characterization.

The Chemistry researchers have proven the method can detect and distinguish between nanogram to microgram quantities of powder and monolithic solid samples of UH3, U3O8, and mixed uranium oxide/hydride. Relative abundances of oxide and hydride are measured by evaluating atomic emission peaks for hydrogen at 656 nm and oxygen at 777 nm to neighboring uranium peaks.

Handheld LIBS unit being developed for use in gloveboxes to quickly distinguish between uranium hydride and uranium oxide.

Handheld LIBS unit being developed for use in gloveboxes to quickly distinguish between uranium hydride and uranium oxide.

One of their recent studies shows that oxygen and hydrogen LIBS peak intensities, relative to uranium, have a higher degree of discrimination at shorter delay times after the LIBS plasma is formed.

The Chemistry researchers are optimizing hardware and methods as well as developing an on-board calibration and sample evaluation app to load onto the handheld instrument. This app will enable “Yes/No” determination of the presence of uranium oxide or uranium hydride, along with an evaluation of their relative abundances. The prototype unit will be handed off to the Laboratory’s Core Surveillance program in October 2019. 

This work is funded by LANL's Aging and Lifetimes Program within the Engineering, Stockpile Assessment, and Responsiveness (ESAR) Program Office, which supports the Lab’s nuclear deterrence mission and the Science of Signatures pillar. Technical contacts: Beth Judge and Dan Kelly.

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Earth and Environmental Sciences

Uranium migrates under conditions previously assumed to be immobilizing

Uranium, as the source of fuel for nuclear power plants, is one of the premier energy sources of the modern era. Though extensive research has focused on characterizing the ore bodies supplying uranium for power plants, this research has relied on the assumption that uranium is immobile under reducing conditions.

In a major upset to this dogma, Los Alamos researchers in the Earth and Environmental Science (EES) and Materials Science and Technology (MST) divisions, in collaboration with colleagues at McGill University, identified and characterized a new uranium chloride species that in aqueous solutions can trigger higher mobility of uranium under reducing as compared to oxidizing conditions, demonstrating that reducing conditions can no longer be considered a guarantee of uranium immobility. These findings have profound implications for our understanding of uranium behavior and are crucial for evaluating the safety of uranium power production and waste disposal.

Uranium activity increases as a function of chloride activity under high temperatures.

Uranium activity increases as a function of chloride activity under high temperatures. (a) Uranium activity as a function of chloride activity under reducing conditions. Circles, diamonds, and triangles indicate results obtained at 250, 300, and 350 °C, respectively. The slope of all trendlines is 4. (b) Uranium activity as a function of chloride activity for specified temperature (circles = 250 °C, diamonds = 300 °C, triangles = 350 °C) under oxidizing (blue) or reducing (brown) conditions. The slope of the fit under oxidizing conditions is 2 and under reducing conditions is 4.

The accepted model of uranium transport under oxidizing conditions only allows for deposition of uranium at low to moderate temperatures, despite the known formation of certain types of deposits at high temperatures. To explain the formation of these high-temperature uranium ore deposits, LANL researchers investigated a means of transporting uranium under reducing conditions. Since chloride (Cl) is the most abundant ligand in seawater, most ore-forming fluids, and many waters surrounding underground waste repositories, they chose to explore speciation of uranium chlorides.

To assess the stability of uranium chloride complexes, researchers conducted uranium oxide solubility experiments at variable NaCl concentrations, at temperatures ranging from 250–350 °C, and with buffers to maintain either oxidizing or reducing conditions. Changes in dissolved uranium concentrations with increases in chloride activity were used to identify corresponding uranium chloride species. Under reducing conditions, they found that an order of magnitude increase in chloride activity or decrease in pH caused uranium solubility to increase by four orders of magnitude, whereas increasing the temperature from 250 to 350 °C caused uranium activity to increase by five orders of magnitude.

These results indicate that, contrary to expectations, considerable uranium transport can take place under reducing conditions. Hot, chloride-rich, and highly acidic fluid turns out to be the ideal solution for moving uranium, while deposition can be accomplished by cooling the temperature, decreasing the chloride concentration, or increasing the pH.

These findings have important implications for management of nuclear waste repositories and catastrophic incident cleanup. For instance, these data suggest that seawater used to cool fuel assemblies after the Fukushima nuclear accident, which likely remained at temperatures near or above boiling for months following the event, had the potential to dissolve and mobilize significant concentrations of uranium. In addition, these results necessitate a re-evaluation of reducing conditions as a cure-all method for halting uranium transport in nuclear waste repositories given a breach of containment. Given the major impact of these findings, further investigation is essential to determine whether the new uranium chloride species identified here is just the first of many, as ligands other than chloride may also play an important role in reduced-uranium transport.

 Reference: “Uranium transport in acidic brines under reducing conditions” 2018. Nature Communications, doi:10.1038/s41467-018-03564-7. LA-UR-18-23473. Alexander Timofeev (McGill University), Artaches A. Migdissov (Earth System Observations, EES-14), Anthony E. Williams-Jones (McGill University), Robert Roback (EES-14), Andrew Nelson (Materials Science in Radiation & Dynamics Extremes, MST-8), and Hongwu Xu (EES-14).

This research was supported by Los Alamos National Laboratory’s (LANL) Laboratory Directed Research and Development (LDRD) program and a Summer Research Fellowship from the Seaborg Institute. The work supports the Laboratory’s Global Security and Energy Security mission areas and Science of Signatures science pillar. Technical contact: Artas Migdissov

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Educational Outreach

2019 Summer Physics Camp for young women of Northern New Mexico is a success

In June, Anna Llobet of LANL’s P-23 Neutron Science and Technology group lead the third annual Summer Physics Camp for Young Women of Northern New Mexico. The two-week-long camp for 8th through 12th-grade young women provides an interactive learning experience and career exploration in STEM fields. Ninety-four volunteers participated under the educational leadership of Megan Rains of Los Alamos Public Schools and Pascale Pinner (a DOE Albert Einstein Distinguished Educator Fellow), who served as lead educators, to make the camp a success. Two-thirds of the volunteers were female role models in STEM and the vast majority were enthusiastic LANL employees.

The 22 young women selected to participate in the 2019 Summer Physics Camp along with some of the volunteers who participated in the LANL tour.

The 22 young women selected to participate in the 2019 Summer Physics Camp along with some of the volunteers who participated in the LANL tour.

The camp showcases STEM careers through a multitude of hands-on activities, demonstrations, and lectures on topics that range from basic electromagnetism, particle physics, and radioactivity to rocket engineering, space exploration, and materials science; the curriculum included professional development activities such as resume writing and interviewing skills. The camp also offered a unique opportunity for the young women—a day-long tour to LANL’s LANSCE accelerator and experimental areas, NHMFL-Pulsed Field Facility and LIBS Lab, as well as the New Mexico Consortium Biolaboratory.

To attend the camp, the 22 young participants went through an application and selection process, which specifically targeted students who would benefit the most from such an opportunity. Applications were received from 17 different schools within nine school districts. Those selected largely represented students who lacked STEM role models in their family environment.

Upon completion of the camp, the participants recounted that it was an amazing experience. It answered questions, sparked interest, and forged relationships that will help shape their future careers. “Now, I am very sure I want to go to college to study physics,” one participant said. “Thank you so much for putting hard work into this camp and making it possible for me to learn more about the STEM fields. Please continue to do this camp for future generations,” said another participant.

This camp strengthens the Laboratory’s community outreach footprint in Northern New Mexico, fostering higher education pursuits and inspiring careers in STEM.

The Summer Physics Camp was sponsored by Triad, New Mexico Consortium, Pojoaque Valley and Los Alamos Public Schools, and LANL Foundation. Technical contact: Anna Llobet

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Materials Physics and Applications

Using light to “listen” to electron scattering for the nascent field of valleytronics

The insets depict a single monolayer of the 2D semiconductor WSe2 and its corresponding band structure, with +K/−K valleys (blue/red) that couple to right/left circularly polarized light. Spontaneous fluctuations of electrons between valleys are detected optically. The main graph shows the frequency spectrum of this measured “valley noise”; its narrow width indicates very long valley scattering timescales.

The insets depict a single monolayer of the 2D semiconductor WSe2 and its corresponding band structure, with +K/−K valleys (blue/red) that couple to right/left circularly polarized light. Spontaneous fluctuations of electrons between valleys are detected optically. The main graph shows the frequency spectrum of this measured “valley noise”; its narrow width indicates very long valley scattering timescales.

Conventional electronics use a binary system based on voltage and an electron’s charge to store and transmit information, but scientists have long wanted to improve upon this methodology. The addition of other physical parameters, or degrees of freedom, could improve computational speeds, efficiency, and information security.

One alternative approach, called “spintronics,” has been studied over the past two decades and exploits an electron’s spin degree of freedom: storing information in whether an electron is oriented “spin-up” or “spin-down” (or indeed, in some quantum-mechanical superposition thereof).

However, in the recently discovered family of atomically thin transition-metal dichalcogenide semiconductors (e.g., a single monolayer of MoS2 or WSe2) it is also possible to store information in an electron’s momentum state. This new approach uses a binary system based on where the electron resides in terms of energy minima, or “valleys,” in the material’s band structure—the so-called +K or –K points of the material’s Brillouin zone in reciprocal space. Of particular importance in these new 2D semiconductors is easy access to specific valleys using circularly polarized light. This new valley-based degree of freedom forms the basis for the nascent field of “valleytronics.” 

In a recent report published in Science Advances, Los Alamos researchers and their external collaborators measured an important valleytronics parameter: the time it takes for an electron to scatter from one valley to another. This time scale will be a limiting factor for future device applications based on valley degrees of freedom. Importantly, these data were collected through an innovative means of an optical probe to passively “listen” to the intrinsic fluctuations of the electrons as they scatter back and forth between the two valleys, a random process that always occurs, even under conditions of strict thermal equilibrium. This is in contrast to conventional pump-probe optical methods, which are necessarily perturbative and therefore associated with various fundamental limitations. Thanks to the Fluctuation–Dissipation Theorem, this spontaneous “valley noise” can be used to infer the truly intrinsic valley scattering and relaxation time scales.

The work was performed as part of an ongoing Laboratory Directed Research and Development (LDRD) Exploratory Research program. Lead author Mateusz Goryca (MPA-MAG) is a LANL Director’s-funded postdoc, and all data were acquired at the National High Magnetic Field Laboratory at Los Alamos, using structures assembled in the group of longtime collaborator Xiaodong Xu at the University of Washington.

The work supports the Laboratory’s Energy Security mission and its Materials for the Future science pillar by uncovering the parameters essential to designing next-generation devices.

Researchers: M. Goryca (MPA-MAG), N. P. Wilson (University of Washington), P. Dey (MPA-MAG), X. Xu (University of Washington), S. A. Crooker (MPA-MAG).

Reference: “Detection of thermodynamic “valley noise” in monolayer semiconductors: Access to intrinsic valley relaxation time scales.” Science Advances 5, eaau4899 (2019). DOI: 10.1126/sciadv.eaau4899  Technical contact: Scott Crooker

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Materials Science and Technology

Integrating complex functional materials with additive manufacturing

Illustration and digital/scanning electron microscope images of a hierarchical nested-network porous silver monolithic produced via additive manufacturing. The bi-modal porosity is engineered across two widely separated length scales.

Illustration and digital/scanning electron microscope images of a hierarchical nested-network porous silver monolithic produced via additive manufacturing. The bi-modal porosity is engineered across two widely separated length scales.

Engineering materials (MST-7) researchers developed a new three-dimensional printing technology to manufacture advanced materials with controlled material chemistry and engineered architectures spanning multiple length scales. These new materials possess “tunable” porosity—pores of known and predictable size—that exist in nested networks throughout a fully three-dimensional material.

Their research combines the benefits of both stereolithographic additive manufacturing technology and nanomaterials chemistry to engineer new generations of “designer” materials for catalysis, weapons systems, separations, heat transfer, and beyond.

The work, for which two patents have recently been applied, upgrades traditional stereolithography, which produces solid parts from photo-reactive liquid precursors, by incorporating self-assembly processes within the printed objects, enabling nanoscale casting of metals, ceramics, oxides, and multi-phase composites (e.g., conductive polymers).

The technique also opens up stereolithography to new classes of polymers, including silicones, epoxies, and bioplastics that until now were not compatible with photo-chemical additive manufacturing techniques such as vat polymerization. The goal is to capitalize on the advantages of stereolithography (speed, high resolution, and scalability) while producing complex and high-performance materials for an array of applications across multiple length scales.

The research comprises several embodiments of an overarching R&D concept, which is to use polymerization-induced phase separation within a 3D-printed object to generate micro/meso-structures within its walls.

At this point, a multitude of simple processing steps can be used to transform or modulate the material chemistry upon removal of fugitive components. These transformations can be achieved by in situ ion reduction, crosslinking of miscible monomers, or sol-gel chemistry, among other techniques.

Scanning electron microscopy images of a nested-network gold material with three levels of engineered porosity.

Scanning electron microscopy images of a nested-network gold material with three levels of engineered porosity.

The work supports the Laboratory’s Energy Security mission area and its Materials for the Future science pillar by developing materials with a specific function and predictable performance, the key focus of the Lab’s materials strategy.

Facets of this research have been funded by several Laboratory Directed Research and Development (LDRD) Program Exploratory and Mission Foundation research projects, the Science Programs, the Stockpile Responsiveness Program, and the Enhanced Surveillance Program. This technology is being continually developed by Matt Lee, Nicholas Parra-Vasquez, and Kyle Cluff (MST-7).

References: U.S. Provisional Patent App. No. 16/265641 (2019); U.S. Provisional Patent App. No. 62/819243 (2019) Technical contact: Matt Lee

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Program Leadership

Laboratory managers attend Criticality Safety Training

A cross-section of Laboratory managers participated in a hands-on Criticality Safety Class recently held in April at the National Criticality Experiments Research Center (NCERC) located on the Nevada National Security Site (NNSS). The class, jointly organized by the Global Security and Weapons directorates, highlighted the physics of criticality using tangible demonstrations with real material. The three-day training included a tour of the NNSS complex and two intense days of classroom and laboratory instruction that provided an introduction to criticality safety fundamentals and hands-on experience building a critical system.

LANL managers visit the Sedan Crater, formed as a result of the Sedan nuclear test conducted in July 1962. Left to right: Stacy Mclaughlin, AMPP-DO; Alexei Klimenko, ISR-1; Suzanne Nowicki, ISR-1; Stephanie Archuleta, DESH-DO; Mark Chadwick, ALDX; Kim Obrey, MST-8; Cory Johnson, A-3; Charles Kelsey, P-27; Jeff Pietryga, C-IIAC; Morag Smith, NEN-3; Michelle Silva, NEN-3; Gowri Srinivasan, XCP-8; Jimmy Fung, XCP-1; Pat Fitch, ALDCELS; and Michael Cai, ISR-DO.

LANL managers visit the Sedan Crater, formed as a result of the Sedan nuclear test conducted in July 1962. Left to right: Stacy Mclaughlin, AMPP-DO; Alexei Klimenko, ISR-1; Suzanne Nowicki, ISR-1; Stephanie Archuleta, DESH-DO; Mark Chadwick, ALDX; Kim Obrey, MST-8; Cory Johnson, A-3; Charles Kelsey, P-27; Jeff Pietryga, C-IIAC; Morag Smith, NEN-3; Michelle Silva, NEN-3; Gowri Srinivasan, XCP-8; Jimmy Fung, XCP-1; Pat Fitch, ALDCELS; and Michael Cai, ISR-DO.

The objective of the training is to provide the Laboratory’s future leaders with solid working knowledge of nuclear criticality safety and material operations. Managers who attend this training gain a better understanding of nuclear experiments and an appreciation for the complexities of the NCERC facility and team of experts who support key mission areas of Global Security and the Laboratory at large.

On arriving at the NNSS complex, participants spent part of the first day touring the complex and visiting a few historic sites. Stops throughout the morning included Frenchman Flat, the site of the first nuclear test in NV, and the Tumbleweed Test Range. The group then headed to the Device Assembly Facility (DAF) and toured NCERC, home to the nation’s only general-purpose critical experiments facility and staffed with some of the most highly specialized individuals. NCERC is funded by the Nuclear Criticality Safety Program (NA-511), and its mission is to conduct experiments and training with critical assemblies and fissionable material, at or near the critical state, in order to explore reactivity phenomena. This focus is aimed at ensuring the safety and security of operations involving nuclear materials throughout the United States and the world.

The first day ended with a windshield tour of ICECAP-B, a modular tower built for a nuclear test that never occurred due to the Underground Nuclear Testing Moratorium, the Big Explosives Experimental Facility (BEEF), a hydrodynamic testing facility, and a stop at the Sedan Crater.

On day two, the managers moved into the classroom and learned criticality safety fundamentals including radiation safety versus nuclear criticality safety, neutron interactions, critical mass and volume, and safety margins. They were also introduced to the four critical assembly machines still in operation today. Planet, a general purpose, light-duty vertical lift assembly machine; Comet, a general purpose, heavy-duty vertical lift machine; Flattop, a fast benchmark critical assembly machine; and Godiva IV, a fast burst reactor, were all developed at LANL.

Managers were taught about Planet’s operations, including experiment methodology, hand-stacking, and remote approach to critical operations. Before any operation with fissile material begins throughout the DOE complex, the entire process must be determined, with extremely high fidelity, to be subcritical, under both normal and credible abnormal process conditions. In contrast, the experiments at NCERC intentionally take fissile material to and above the critical state but only under an extremely well-controlled environment. These experiments provide required data that allows operations with fissionable material to proceed throughout the DOE complex.

Mary Hockaday, NEN Division Leader, stacks polyethylene plates and uranium foils during a hands-on experiment used to demonstrate the effects of moderators and reflectors on fissile material operations.

Mary Hockaday, NEN Division Leader, stacks polyethylene plates and uranium foils during a hands-on experiment used to demonstrate the effects of moderators and reflectors on fissile material operations.

On the third day, participants learned about Flat-Top operations and participated in a hands-on demonstration of the BeRP Ball and Np Sphere, both essential components in nuclear experimentation. The day ended observing a Godiva IV burst operation (demonstrating the effects of a criticality accident) and touring a Fissionable Material Staging Vault. On both days of instruction, students learned about and discussed historical criticality accidents here in the United States and abroad. They analyzed what went wrong and how lessons learned from those incidents have influenced how operations are performed today. David Hayes, NEN-2 Advanced Nuclear Technology Group Leader and NCERC instructor, helps develop and teach the curriculum.

Participants for the April 2019 class were chosen through a nomination process, and then each submitted a write-up on the value the training would bring to their line of work. This training supports the Global Security mission area at the Laboratory and the Lab’s Nuclear and Particle Futures science pillar. Technical contact: David Hayes

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