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Los Alamos National Laboratory

Los Alamos National Laboratory

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Science Highlights, Sept. 26, 2018

Awards and Recognition

LALP 18-001

Awards and Recognition

High-impact innovations honored as R&D 100 Award Finalists

R&D 100

Ten Los Alamos National Laboratory innovations are Finalists for the 2018 R&D 100 Awards, which honor the top 100 proven technological advances of the past year as determined by a panel selected by R&D Magazine.

The Finalists, with projects covering energy, modeling and simulation, health, materials, and engineering, demonstrate the continued success of Laboratory researchers in technical innovation for national security science.

ACCObeam

ACCObeam: Acoustic Collimated Beam

Laboratory scientists have created the Acoustic Collimated Beam, a novel high-power, low-frequency, collimated sound beam that penetrates deeply and in high resolution. The invention provides precise, inexpensive imaging of fractured rock, cement, mud, and metal for borehole imaging, explosives threat evaluation, and other applications.

Click here to watch a video on the ACCObeam technology.

Cristian Pantea led the team of Dipen Sinha and Vamshi Chillara (Materials Synthesis and Integrated Devices, MPA-11).

Charliecloud R&D 100

Charliecloud: Lightweight Container Software

 Charliecloud enables software containers – packages of custom code, software, or software environments – on high performance computing resources. The invention achieves portability, consistency, usability, and security in 1000 lines of open-source code. It runs on existing high performance computing systems with zero configuration, servers, or extra processes. 

Reid Priedhorsky (HPC Environments, HPC-ENV) and Tim Randles (HPC Design, PCS-DES) led the team of Michael Jennings and J. Lowell Wofford (HPC Systems, HPC-SYS), Jordan Ogas (HPC-ENV), and Peter Wienemann and Oliver Freyermuth (University of Bonn), and Matthew Vernon (Wellcome Trust Sanger Institute).

GUFI

GUFI: Grand Unified File Index

The Grand Unified File Index is the fastest software for searching metadata at the scale used by supercomputer and enterprise datacenters. It is open-source software that allows simultaneous secure queries of ultrascale metadata by multiple users and system administrators. Users can search billions of files in the file system trees and receive query results in seconds, without sacrificing the performance of the file system itself or impacting security.

Gary Grider (High Performance Computing, HPC-DO) led the team of David Bonnie (HPC Design, HPC-DES), Jeff Inman (HPC-Environment, HPC-ENV), Dominic Manno (HPC-Systems), and Wendy Poole (HPC-ENV).

Insight R&D 100

Insight: Sample-to-Result Microbiome Analysis

Insight provides automated metatranscriptomic sequencing and bioinformatic analysis of an individual’s gut microbiome with the goal of improving health. In addition to identifying and quantifying the microbes, Insight determines what microbes are currently active in the gut. Viome has combined this technology with a simple in-home collection kit and smartphone app to provide personalized wellness and nutrition recommendations.

Los Alamos submitted the joint entry with Viome, Inc. Jason Gans and Patrick Chain (Biosecurity and Public Health, B-10) and Momchilo Vuyisich (Viome) led the team of Andrew Hatch, Po-E Li, and Chien-Chi Lo (B-10).

R&D 100

Lighthouse Directional Radiation Detectors

The detectors precisely determine the location, amount, and movement of a radioactive source in the presence of multiple sources. Gamma, fast-neutron, and thermal-neutron detectors are small, lightweight, portable, high resolution, and fast. Applications include environmental and geological surveys, emergency response, materials accountability and control, and situational awareness.

Click here to watch a video on the Lighthouse Directional Radiation Detector technology.

The Laboratory submitted the joint entry with Questa Instruments LLC, Phoenix International Holdings Inc., and Sexton Corp. L. Jonathan Dowell (International Threat Reduction, NEN-3) and Dale Talbott (Technology Development, Q-18) led the team of Rick Rasmussen, Rick Rothrock, Sam Salazar, and Theresa Cutler (Advanced Nuclear Technology, NEN-2); Mark Wald-Hopkins (NEN-3); Kris Hyatt (Weapons Test Engineering, Q-14); Don Hyatt (High Explosives & Weapons Engineering Tritium Facility, WFO-WETF); Larry Bronisz and James Thompson (Mechanical and Thermal Engineering, AET-1); Chris Chen (Fabrication Manufacturing Science, SIGMA-1); David Fontaine (Laboratory Fabrication Services, PF-LFS); Adam Kingsley and Thomas Barks (Q-18); Damien Milazzo (Earth System Observations, EES-14); James Hemsing (former student in NEN-2); Gary Sundby and David Allen (retired from the Lab); Paul Agyapong (U.S. Army); Pete Shifflett, Steve Hamann, Gary Womack, Kristopher Savage, and Aaron Clark (Quaesta Instruments, LLC); Peter McKibbin, Dan Pol, Gino Gonzalvez, Robert Lohe, John McCosker, and Juan Sevillano (Phoenix International Holdings, Inc.); Jeremy Childress and Kent Fletcher (Sexton Corporation).

R&D 100

Long-range Wireless Sensor Network

The Long-range Wireless Sensor Network grew out of the Lab’s decades of experience developing satellite components for the harsh space environment. The turnkey low-power sensor network is self-forming, self-healing, and scales to hundreds of nodes for unattended operation. It can affordably collect, process, and transmit data over long distances (19 km point-to-point) in rugged, extreme, and remote outdoor environments.

Click here to watch a video on the Long-range Wireless Sensor Network.

The Laboratory submitted the joint entry with West Virginia University. Janette Frigo (Space Data Science and Systems, ISR-3) led the team of Tracy Gambill, James Krone, Hudson Ayers, Shawn Hinzey, Kari Sentz, and Xiaoguang Yang (ISR-3); Terra Shepherd (ISR-4); Richard Dutch, Louis Borges, Bobby Quintana, and Ryan Hemphill (ISR-5); Michael Cai (ISR-DO); Sanna Sevanto, Cathy Wilson, Joel Rowland, and Thom Rahn (Earth System Observations, EES-14); Kevin McCabe, Don Enemark, Michael Proicou, David Guenther, and Stephen Judd (X-Theoretical Design, XTD-DO); Armand Groffman, Alexandra Saari, Steven Veenis, Allison Chan, and Bobbie Rappe (formerly ER Environmental Services, currently N3B); Tom Dufresne (formerly Lab); and Vinod Kulathumani (West Virginia University).

R&D 100

Rad-Hard Single-Board Computer for Space

The lightweight, low-cost single board computer has radiation- and mechanically-hardened electronics for satellites and other space applications. It is smaller and uses less power than any other space-grade computer currently available. Industry standard MicroTelecommunication Computing Architecture expands compatibility and interoperability. The invention leverages the Lab’s more than 50 years designing instruments for satellites and deep space missions.

Robert Merl (Space Electronics and Signal Processing, ISR-4) and Paul Graham (Space Data Science and Systems, ISR-3) led the team of Zachary Baker and Justin Tripp (Applied Computer Science, CCS-7), John Michel (ISR-3), and Richard Dutch (Space Instrumentation Realization, ISR-5).

R&D 100

Silicon Strip Cosmic Muon Detectors for Homeland Security

Naturally occurring cosmic particles called muons “rain down” from the atmosphere and scatter significantly when they interact with high-atomic-number materials. Muon trackers use the scattering trajectory signature to detect shielded clandestine materials, such as nuclear materials, explosives, and other items of interest. The slim profile and light weight of silicon strip muon detectors provides versatility and enables stealthy deployment into walls, ceilings and portable devices. The detectors quickly distinguish a potential threat from a non-threat.

Nevada National Security Site Mission Support and Test Services, LLC submitted the joint entry with Fermi National Accelerator Laboratory and Los Alamos National Laboratory. The Los Alamos team included Chris Morris, J. Matthew Durham, and Elena Guardincerri (Subatomic Physics, P-25).

R&D 100

Universal Bacterial Sensor

The human immune system inspired the development of the Universal Bacterial Sensor — a unique technology that mimics biological recognition of bacterial pathogens. Like the immune system, the sensor recognizes all bacterial infections as early as before the onset of symptoms. The method uses only a small volume of sample and requires no prior knowledge of what the bacteria might be. It is inexpensive, field-ready, can be performed by a nonexpert, and provides reliable answers within 30 minutes.

Click here to watch a video on the Universal Bacterial Sensor technology.

Harshini Mukundan (Physical Chemistry and Applied Spectroscopy, C-PCS) led the team of Basil Swanson (Biosecurity and Public Health, B-10), Aaron Anderson, Jessica Kubicek-Sutherland, Ramamurthy Sakamuri, and Loreen Stromberg (C-PCS).

R&D 100

ViDeoMAgic: Video-Based Dynamic Measurement & Analysis

ViDeoMAgic analyzes digital video of a vibrating structure to extract high-spatial-resolution structural dynamics response information. Unsupervised machine learning algorithms then analyze those dynamic responses and extract the structure’s dynamics properties (resonant frequencies, damping and mode shapes) from the video data, which in turn can be used to assess the system’s health (with respect to damage and defects). High fidelity, in situ damage detection of civil, mechanical, and aerospace structures enables identification and remedy of incipient damage before it reaches the critical level.

Click here to watch a video on the ViDeoMAgic technology.

Yongchao Yang (National Security Education Center-Engineering Institute, NSEC-EI) led the team of David Mascareñas, Charles Dorn, and Charles Farrar (NSEC-EI); and Garrett Kenyon (Information Sciences, CCS-3).

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Rusty Gray selected for new National Academy of Sciences board on Army R&D

Rusty Gray

Rusty Gray

The National Academy of Sciences appointed George T. “Rusty” Gray III (Materials Science in Radiation & Dynamics Extremes, MST-8) to its new Board of Army Research and Development (BOARD). Tom Russell, the Deputy Assistant Secretary of the Army for Research and Technology, requested the establishment of this organization. BOARD’s goal is to provide a forum to discuss science and technology options for addressing emerging threats and to recommend actionable items to the U.S. Army technology community.

For more than 30 years, Gray has made essential contributions to the Laboratory’s national security science mission through his work here and his participation in Army projects. He conducted his master’s thesis research on iron shock loading for the Army. He served two two-year terms as chair of the National Academy of Sciences Panel on Ballistics Science and Engineering at the U.S. Army Research Laboratory (ARL). This panel annually reviews the scientific and technical quality of ARL ballistics science and engineering research and development programs, providing input to the ARL Technical Assessment Board for its biennial assessment report on the overall quality of ARL scientific and engineering research.

Gray has a Ph.D. in metallurgical engineering from Carnegie Mellon University. He leads critical science projects for the Lab’s Stockpile Stewardship efforts and publishes materials science research. Gray advises institutions on materials dynamics in defense and manufacturing areas, acting as a liaison for the Laboratory. He is the only active Los Alamos scientist elected to the National Academy of Engineering. Gray is a fellow of the American Physical Society, ASM International, Los Alamos National Laboratory, and the Minerals, Metals and Materials Society, having served as the organization’s president in 2010. Technical contact: Rusty Gray

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Claudia Mora named Distinguished Alumna for the University of Wisconsin – Madison

Claudia Mora

Claudia Mora

The Department of Geoscience at the University of Wisconsin – Madison has honored Claudia Mora (Chemistry Deputy Division Leader, C-DO) as a Distinguished Alumnus. The award cited her “For innovative research in paleoclimatology and leadership in Earth Sciences.”

Mora completed her Ph.D. in Geoscience at the University of Wisconsin. She taught one year at the University of Texas-El Paso before moving to the University of Tennessee where she was the first woman on the faculty in geology. In 18 years, she rose from Assistant Professor to Carden Distinguished Professor and Department Head. At the University of Tennessee, Mora built a stable isotope research group and laboratory, initially to study metamorphic fluid flow. Her interests soon expanded to isotope proxy records of paleoclimate. Her pioneering papers reached across disciplines to develop the first soil carbonate proxy record of Paleozoic atmospheric carbon dioxide levels and a new paleo-hurricane proxy, based on the oxygen isotope compositions of wood cellulose from tree rings, and extending the record of hurricane occurrences along the Gulf and Atlantic coasts to more than 400 years ago.

Mora joined the Lab in 2007, where she was Group Leader of Earth Systems Observations (EES-14). She is now the Deputy Division Leader of the Chemistry (C) Division. Mora has served on the National Research Council Board on Earth Sciences and Resources, the National Academy of Sciences National Committees on Soil Science and Geology, the National Science Foundation Geosciences Advisory Committee, and the University of Wisconsin – Madison Geosciences Board of Visitors. She is a recent past-president of the Geological Society of America (GSA). The University of Wisconsin-Madison has fielded eight Geological Society of America Presidents over its 130-year history, more than any other university. As GSA President, she enthusiastically promoted strong science, GSA journals, public service, and the careers of young scientists. Technical contact: Claudia Mora

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Jaqueline Kiplinger invited to serve on the American Chemical Society Committee of Ethics

Jaqueline L. Kiplinger

Jaqueline L. Kiplinger

The American Chemical Society (ACS) has selected Jaqueline L. Kiplinger (Inorganic, Isotope and Actinide Chemistry, C-IIAC) to serve on the ACS Committee on Ethics (ETHX). The ACS President makes the appointments. During her two-year term, Kiplinger will attend biannual ETHX meetings held during the National ACS Meetings. She is the only National Laboratory representative on the committee.

Kiplinger came to Los Alamos as the first Frederick Reines Postdoctoral Fellow in 1999 and became a Technical Staff Member in 2002. She is an internationally recognized leader in f-element chemistry. Kiplinger is a Fellow of the American Association for the Advancement of Science, the Royal Society of Chemistry, the American Institute of Chemists, the American Chemical Society, and Los Alamos National Laboratory. She was selected as the first woman to receive the F. Albert Cotton Award in Synthetic Inorganic Chemistry from the ACS, the Violet Diller National Award for Professional Excellence in Chemistry (Iota Sigma Pi), the IUPAC International Distinguished Women in Chemistry award, and two R&D 100 Awards. She has received a Los Alamos Fellows Prize for Research, three mentoring awards, and several Los Alamos/NNSA Best-in-Class Pollution Prevention Awards.

With more than 161,000 members, the ACS is the world’s largest scientific society and the premier professional home for chemists, chemical engineers, and related professions worldwide. The Committee on Ethics (ETHX) was established in 2006 to promote and support high standards of ethical conduct and integrity in the community of chemistry and related disciplines for the benefit of science and society. ETHX also coordinates the ethics-related activities of the ACS and serves as an educational resource and clearinghouse. Its membership comprises Councilors and non-Councilors who have an interest in ethics, particularly in ethics education, professionalism, and responsible conduct of research. ETHX has the vision that “ethics will permeate the culture of chemistry.” Technical contact: Jaqueline Kiplinger

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Grossiord, He, Moore, Poudel win Lab’s Distinguished Postdoctoral Performance Awards

The Laboratory Distinguished Postdoctoral Performance Awards recognize individual or teams of no more than three who were major contributors towards outstanding and unique research resulting in a positive, significant impact on the Lab’s programmatic efforts, or status in the scientific community. Technical contact: Mary Anne With
Charlotte Grossiord

Charlotte Grossiord

Charlotte Grossiord (Earth System Observations, EES-14) is recognized for outstanding research and leadership to understand the ability of vegetation to adjust in response to changes in environment. Her work could potentially have a large impact on predictions of how vegetation responses to these changes. Until now, the acclimation capacity of plants to environmental changes has been completely absent from dynamic vegetation models. Despite the challenges in quantifying these changes due to the longevity of trees compared to the human lifetime, Grossiord has invented several clever ways to use the Los Alamos Plant Survival and Mortality (SUMO) experiment. This research has addressed plant acclimation capacity and the time frames of acclimation, as well as testing for interactions between different pressures resulting from drought and warming that could alter plant responses to environmental change.

In 2017, she published seven peer-reviewed articles, with seven other papers in review. Grossiord also planned and performed the world’s first experiment where changes in soil nitrogen availability and plant nitrogen use were linked to plant acclimation capacity to warming and drought at an ecosystem-scale. Her work builds a basis to model plant acclimation and testing that supports the Lab’s ability to predict impacts of climate on vegetation and the environment. Grossiord received a Ph.D. in Biology from the University of Lorraine. Chonggang Xu, Brent Newman, and Sanna Sevanto (EES-14) mentor her.

Xiaowei He

Xiaowei He

Xiaowei He (Center for Integrated Nanotechnologies, MPA-CINT) is recognized for his outstanding research and leadership in developing a new class of carbon nanotubes. These carbon nanotubes are the first material ever to act as a single photon source operating at room temperature, and emit light at the infrared wavelength compatible with telecommunications infrastructure.

This breakthrough development is of tremendous importance for advancing nanotubes as quantum light sources required for quantum information processing, quantum cryptography, quantum metrology, and fundamental studies of quantum photonics. He demonstrated outstanding spectroscopic characterization of nanomaterials, nanomaterials chemical modification, processing, and device development, combined with an exceptional work ethic. His research opens new directions in the fields of nanoscience, solitary dopant optoelectronics, and quantum information technologies. He earned a Ph.D. in Applied Physics from Rice University. Stephen Doorn and Han Htoon (MPA-CINT) mentor him.

Cameron Moore

Cameron Moore

Cameron Moore (Inorganic, Isotope and Actinide Chemistry, C-IIAC ) is recognized for his combination of experimental and theoretical strategies studying molecules and catalysts to perform transformations for sustainable energy applications, particularly with relevance to biomass conversions. He was the sole driving force behind the development of a new and highly promising research area to use bio-derived building blocks to rationally construct more complex molecules. Moore experimentally validated his approach and performed scale-up experiments. He extended his scientific approach to ethanol, enabling the dehydrogenation of the molecule without the need for external hydrogen – which has often been considered the Achilles Heel of biomass conversion.

Moore also contributed to the development of new catalysts for the hydrodeoxygenation reaction, which is the most energy-intensive step in biomass conversion. He incorporated new catalytic schemes, resulting in a one hundred-fold improvement over the initial process. Moore has contributed to energy programs funded by the DOE Office of Energy Efficiency and Renewable Energy (EERE), DOE Bioenergy Technologies Office (BETO), and other sponsors. He earned a Ph.D. in Chemistry from the University of Michigan. Andrew Sutton (C-IIAC) mentors him.

Deepesh Poudel

Deepesh Poudel

Deepesh Poudel (Radiation Protection Services, RP-SVS), received an Honorable Mention for his outstanding research and leadership in developing biokinetic models of actinides in humans. His research addresses the important topic of modeling the transport of radioactive materials within wounds, an area at the Lab with historical relevance to past Laboratory activities.

He has made substantial contributions to the field of internal dosimetry, and has established himself as a leading expert in the larger field of radioactively contaminated wounds, as evidenced by his extensive collaborations at the Laboratory, around the country, and in Europe. Poudel earned a Ph.D. in Nuclear Science and Engineering from Idaho State University. John Klumpp and Tom Waters (RP-SVS) mentor him.

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Marc Kippen recognized with Laboratory’s Inaugural Laboratory Global Security Medal

Marc Kippen

Marc Kippen

Los Alamos National Laboratory has awarded R. Marc Kippen (Nuclear Nonproliferation and Security, GS-NNS) the inaugural Los Alamos Global Security Medal. The medal recognizes innovative, professional, and scientific excellence for the Laboratory’s Global Security mission area. Kippen is honored for his distinguished and enduring leadership and significant achievements in developing, promoting, and sustaining national security capabilities and programs in space-based sensing and nuclear detonation detection.

Kippen earned a Ph.D. in physics from the University of New Hampshire and joined the Lab in 2002. He has more than 25 years’ experience in space science, astrophysics, energetic radiation and particle sensing, and applied R&D leadership. Kippen has published more than 200 articles in science journals and conference proceedings.

He has held crucial leadership roles and has led the Lab to success in the DOE’s Space-based Nuclear Detonation Detection (SNDD) program, a core Laboratory program for over 50 years and a significant part of the Lab’s national security mission. Kippen currently serves as the Nuclear Detonation and Test Detection Program Manager for the Nuclear Nonproliferation and Security Program, leading and managing research and development in science and national security. He represents and promotes Laboratory capabilities that are a foundation for nuclear treaty verification, including programs for detecting and monitoring underground testing and post-detonation forensics.

Kippen coordinates the Lab’s efforts and strategy with other national laboratories, NNSA, U.S. Air Force Space Command, U.S. Strategic Command, the Aerospace, Boeing, and Lockheed-Martin Corporations, and other stakeholders to build a broad R&D program to meet the formidable challenges of monitoring future underground detonations. An award ceremony will be held in October 2018. Technical contact: Marc Kippen

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Accelerator Operations and Technology

State-of-the-art photocathodes grown on atomically thin layers of graphene

Figure. Advanced Materials Interfaces back cover featured the article. The grey spheres represent carbon atoms in the graphene.

Figure. Advanced Materials Interfaces back cover featured the article. The grey spheres represent carbon atoms in the graphene.

Future coherent x-ray sources and advanced colliders could provide insight into improved access and control of matter on the timescale of electronic motion and the spatial scale of atomic bonds. Such capabilities require increasingly high-performance electron beams that far exceed present state-of-the-art technologies. DOE-commissioned studies have repeatedly pointed to electron sources as one of the highest accelerator R&D priorities for the next decade, requiring a transformational advance in cold cathode performance in particular. However, these cold cathodes degrade when exposed to air.

Los Alamos researchers and their collaborators have created a unique approach that decouples two competing physical mechanisms that have prevented researchers from improving cold cathode efficiency and lifetime. The team integrated atomically thin materials with high-performing existing photocathode technologies for better protection. The journal Advanced Materials Interfaces reported the research.

The study relied on the bialkali antimonide semiconductor K2CsSb, which has one of the highest quantum efficiencies of any photocathode, combined with thin protective layers of graphene, a form of carbon possessing an exceptionally high gas barrier property to protect the photocathode from air, ultrahigh electrical and thermal conductivity, optical transparency, high charge mobility, and the ability to sustain extreme current densities.

Figure. Quantum efficiency (QE) maps obtained by rastering a 405 nm (approximately 3.1 eV) light emitting diode (LED) with spot size of ~0.2 mm over the ~3 mm diameter sample areas.

Figure. Quantum efficiency (QE) maps obtained by rastering a 405 nm (approximately 3.1 eV) light emitting diode (LED) with spot size of ~0.2 mm over the ~3 mm diameter sample areas. Gr is graphene, and Ni is nickel.

The team obtained quantum efficiency (QE) maps by rastering a 405 nm light emitting diode (LED) over the sample. The researchers characterized the samples in reflection mode, i.e. illuminated from photocathode sides with photoemission current collected from the same side. They observed notably high QE approaching 17% over a large area from the K2CsSb photocathode on graphene substrates. As a comparison, the photocathode was simultaneously deposited on a pure nickel foil. The QE on nickel had a mean value of 14.2%, which is slightly lower than that on the graphene samples. Moreover, the QE was less uniform for the nickel substrate.

The research demonstrated significant progress in growing state-of-the-art photocathodes (traditionally grown on thick substrates) on super thin, transparent graphene substrates that have a quantum efficiency comparable to those deposited on rigid substrates. This configuration marks progress toward encapsulating high performance, environmentally susceptible photocathodes using graphene as a passivating barrier. It is a promising step toward fabricating photocathodes with enhanced lifetimes and on the optically transparent yet electrically conductive substrates needed for new light sources.

Los Alamos capabilities that were critical to the project’s success included chemical vapor deposition to synthesize high quality graphene and nanomaterial processing to transfer graphene onto challenging substrates. The progress provides several advances to MaRIE, the Laboratory’s proposed matter-radiation interactions in extremes capability, including the option to switch from metal cathodes to higher performance semiconductor cathodes that reduce emittance by 50%. This development reduces risk by creating “headroom” throughout the design and would decrease system complexity and beam energy for immediate cost savings.

Reference: “Free-standing Bialkali Photocathodes using Atomically-thin Substrates,” Advanced Materials Interfaces 5, 1800249 (2018); DOI: 10.1002/admi.201800249. Authors: Hisato Yamaguchi, Fangze Liu, Claudia W. Narvaez Villarrubia, and Aditya D. Mohite (Materials Synthesis and Integrated Devices, MPA-11); Jeffrey DeFazio (Photonis USA Pennsylvania Inc.); Menglia Gaowei, John Sinsheimer, and J. Smedley (Brookhaven National Laboratory); Junqui Xie (Argonne National Laboratory); Derek Strom (Max Planck Institute for Physics); Vitaly Pavlenko and Nathan A. Moody (Accelerators and Electrodynamics, AOT-AE); and Kevin L. Jensen (Naval Research Laboratory).

Perspectives on Designer Photocathodes for X-ray Free-Electron Lasers: Influencing Emission Properties with Heterostructures and Nanoengineered Electronic States,” Physical Review Applied 10, 047002 (2018); DOI: https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.10.047002 - abstract  . Authors: Nathan A. Moody, Petr M. Anisimov, Vitaly Pavlenko, and John W. Lewellen (Accelerators and Electrodynamics, AOT-AE), Kevin L. Jensen, Andrew Shabaev, and Samuel G. Lambrakos (Naval Research Laboratory); John Smedley (Brookhaven National Laboratory); Daniel Finkenstadt (United States Naval Academy); Jeffrey M. Pietryga (Inorganic, Isotope and Actinide Chemistry, C-IIAC); Enrique R. Batista (Center for Nonlinear Studies, T-CNLS); Fangze Liu, Gautam Gupta, Aditya Mohite, and Hisato Yamaguchi (Materials Synthesis and Integrated Devices, MPA-11); Mark A. Hoffbauer (Chemical Diagnostics and Engineering, C-CDE); and István Robel (Physical Chemistry and Applied Spectroscopy, C-PCS).

Los Alamos National Laboratory hosted the Photocathode Physics for Photoinjectors 2018 Conference: https://indico.cern.ch/event/759878/overview.

N. A. Moody owns the patent US 8,823,259 on a concept of graphene protection of chemically reactive films.

The Laboratory Directed Research and Development (LDRD) program funded the Los Alamos work, which was partially conducted at the Center for Integrated Nanotechnologies, a DOE Office of Science User Facility operated by Los Alamos and Sandia national laboratories. The research supports the Lab’s Energy Security mission area and its Materials for the Future science pillar, including its defects and interfaces and emergent phenomena science themes, by developing materials with controlled functionality and predictive performance. Technical contacts: Nathan Moody and Hisato Yamaguchi

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Bioscience

Laboratory uses cavity-nesting bird eggs to monitor for environmental pollution

Environmental monitoring at Los Alamos National Laboratory is extensive, and site-wide monitoring programs began in the 1970s. Operations and management of the site since it was established in 1943 as part of the Manhattan Project have resulted in the historical release of nonradioactive chemicals such as organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and inorganic metals. In two publications in the Journal of Environmental Protection, Lab scientists have reported their analysis of chemicals found in western bluebird and ash-throated flycatcher unhatched eggs in areas within the current and historic Laboratory boundary relative to a developed but non-industrial nearby reference area.

Photo. Top: Ash-throated flycatcher eggs. Bottom: Western bluebird eggs.

Photo. Top: Ash-throated flycatcher eggs. Bottom: Western bluebird eggs.

Biomonitoring is an important tool to assess environmental contamination by analyzing chemicals or their metabolites from biological tissues. Bird eggs are useful as bioindicators because 1) different species occupy many levels in the ecosystem, 2) collection of unhatched or abandoned eggs is relatively noninvasive and nondestructive to populations, and 3) collection is relatively easy. The composition of eggs is consistent, and eggs can be preserved for long periods of time. Studies suggest that avian eggs reflect local contaminant exposure where the female was feeding during the time of egg formation. However, migratory species may also accumulate constituents during migration or on wintering grounds. Birds can be exposed through a variety of routes to both anthropogenic and natural sources of inorganic metals. Both types of contaminants can pose risks of adverse effects to birds if they receive sufficiently high exposure.

The western bluebird (Sialia mexicana) and the ash-throated flycatcher (Myiarchus cinerascens) are common secondary cavity-nesting species on the Pajarito Plateau and readily nest in artificial nestboxes. Ash-throated flycatchers migrate to a winter range spanning from Mexico to Costa Rica. Western bluebirds are year-round residents, although some migration into Mexico may occur. During the breeding season, both species feed primarily on insects. Both species rely on fruits during the winter. Western bluebirds also consume seeds, and they pick up small amounts of grit for their gizzards.

The avian nestbox network for the study contains more than 500 boxes. Nestbox placements within the study area included two canyons (Cañada del Buey and Mortandad). To obtain reference values at a developed but non-industrial site, the team placed nestboxes approximately 3 km upgradient of the study area in the Los Alamos townsite at a golf course and a cemetery. Nonviable, unhatched eggs were collected from 1997 to 2012 and analyzed. The Laboratory Institutional Animal Care and Use Committee approved all protocols, and unhatched egg collection was permitted under federal and state permits.

Figure. Study region showing where western bluebird and ash-throated eggs were collected.

Figure. Study region showing where western bluebird and ash-throated eggs were collected.

The two publications of chemical analysis documented limited impacts to the birds. Chemicals were below detection limits in the majority of samples. Western bluebird eggs collected from the study area had significantly lower concentrations of the pesticides dieldrin, oxychlordane, and trans-nonachlor than eggs from the non-industrial reference site. Concentrations of many inorganic elements in eggs were below reporting limits. No statistically significant differences were observed in concentrations of inorganic elements in western bluebird eggs collected from the study area (which consists of areas within the current and historic Lab boundary) and from a non-industrial reference site. No statistically significant differences were observed between the two canyons that were known to have received effluents and storm water runoff from Laboratory facilities, and the non-industrial reference site. These results indicate that the Lab operations are not impacting chemical contaminant concentrations in eggs. Organic and inorganic element levels detected in western bluebirds were typically within the range measured in eggs of other related birds in the published literature. The data suggest that concentrations of organic and inorganic elements in eggs collected from the study area appear to be at levels causing negligible risks to local bird populations. Reporting low-level chemical concentrations in areas with potential environmental contamination is important because it will contribute to the understanding of the dynamics and behavior of chemicals in the environment as well as the bioavailability to avian wildlife.

References:

“Organic Chemical Concentrations in Eggs and Nestlings of Cavity Nesting Birds at and around Los Alamos National Laboratory,” Journal of Environmental & Analytical Toxicology 8, 1 (2018); doi: 10.4172/2161-0525.1000549. Authors: Shannon Marie Gaukler and Charles Dean Hathcock (Environmental Stewardship, EPC-ES), and Jeanne Marie Fair (Biosecurity and Public Health, B-10).

“Inorganic Elements in Eggs of Two Cavity-Nesting Passerine Species at and around Los Alamos National Laboratory, Los Alamos, New Mexico,” Journal of Environmental Protection 9, 932 (2018); doi: 10.4236/jep.2018.99058;. Authors: Shannon Marie Gaukler and Charles Dean Hathcock (EPC-ES), and Jeanne Marie Fair (B-10).

The Laboratory’s Environmental Stewardship and Environmental Restoration Program funded the work, which supports the Lab’s mission areas and the Science of Signatures science pillar through the ongoing assessment of site-related ecological risk at the Lab. Technical contact: Jeanne Fair and Shannon Gaukler

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Capability Enhancement

LANSCE detectors enable previously unattainable measurements with neutron beams

State-of-the-art detector technologies at the Los Alamos Neutron Science Center (LANSCE) are being used with the LANSCE fast-pulsed and intense neutron beams to perform previously unattainable measurements of element and isotope specific imaging by gating on specific nuclear resonances. A special issue of the Journal of Imaging devoted to neutron imaging highlighted LANSCE’s recent advances, applications, and future prospects in a cover article.
Figure. The journal cover depicts thermal neutron images of a 62.3 million-year-old Tetraclaenodon puercensis. (Left) surface and (right) internal reconstruction.

Figure. The journal cover depicts thermal neutron images of a 62.3 million-year-old Tetraclaenodon puercensis. (Left) surface and (right) internal reconstruction.

Neutron radiography and tomography covering a wide neutron energy range have been applied at several beam lines at LANSCE. Researchers have made substantial developments in energy-resolved neutron imaging with epi-thermal neutrons, using neutron absorption resonances for contrast as well as quantitative density measurements, at the Target 1 (Lujan Center) flight path 5 beam line. Only three facilities worldwide (J-PARC in Japan, ISIS at the Rutherford Appleton Laboratory in England, and LANSCE) have demonstrated the capability to make such measurements. Applications include imaging of metallic and ceramic nuclear fuels, fission gas measurements, tomography of fossils, and studies of dopants in scintillators. The technique enables the characterization of materials opaque to thermal neutrons and the use of neutron resonance analysis codes to quantify isotopes to within 0.1 atom %. The latter also allows measuring fuel enrichment levels or the pressure of fission gas remotely.

Researchers used the cold neutron spectrum at the ASTERIX beam line, also located at Target 1, to demonstrate phase contrast imaging with pulsed neutrons. This result extends the capabilities for imaging of thin and transparent materials at LANSCE. Cold neutrons have enabled the study water uptake in plants and the observation of small cracks in a variety of materials.

Unmoderated fast spallation neutrons from Target 4 in the Weapons Neutron Research (WNR) facility have enabled high-energy neutron imaging of dense, thick objects. Scientists imaged an aluminum “chili pepper”, iron pyrite crystals, and a pewter trinket inside a 7.5 cm thick uranium annular cylinder. Fast (ns), time-of-flight imaging allows development of imaging at specific, selected MeV neutron energies, and testing and characterization of fast scintillators. Researchers have reconfigured the 4FP-60R beam line with increased shielding and new, larger collimation dedicated to fast neutron imaging. Investigators are exploring ways in which pulsed neutron beams and the time-of-flight method can provide additional benefits.

Reference: “Neutron Imaging at LANSCE – from Cold to Ultrafast,” Journal of Imaging 4 (2), 45 (2018); doi: 10.3390/jimaging4020045. Authors: Ron Nelson and Shea Mosby (LANSCE Weapons Physics, P-27), Sven Vogel, Kenneth McClellan, and Adrian Losko (Materials Science in Radiation and Dynamics Extremes, MST-8); James Hunter (Applied Engineering Technology, AET-6); Erik Watkins (Materials Synthesis and Integrated Devices, MPA-11); Anton Tremsin (University of California – Berkeley); Nicholas Borges (MST-8 and Worcester Polytechnic Institute); Theresa Cutler and Nicola Winch (Advanced Nuclear Technology, NEN-2); Lee Dickman and Sanna Sevanto (Earth System Observations, EES-14); Michelle Espy and Cort Gautier (AET-6); Amanda Madden and Richard Schirato (Space Science and Applications, ISR-1); Jaroslaw Majewski (Center for Integrated Nanotechnologies and MPA-CINT and National Science Foundation); Michael Malone (Applied Modern Physics, P-21); Douglas Mayo (Monte Carlo Codes, XCP-3); David Montgomery (Plasma Physics, P-24); Andrew Nelson (Engineered Materials, MST-7); Kyle Ramos (HE Science and Technology, M-7); Katlin Schroeder (University of New Mexico); Alicia Swift (Y-12 National Security Complex); Long Vo (MST-8 and Kansas State University); and Thomas Williamson (New Mexico Museum of National History and Science).

This work benefited from use of the Laboratory’s LANSCE accelerator facility. The DOE, Office of Nuclear Energy Nuclear Technology Research and Development program, the National Nuclear Security Administration’s Nonproliferation Research and Development program (NA-22), the Laboratory Directed Research and Development (LDRD) program, the New Mexico Consortium, a summer research fellowship from the Lab’s Seaborg Institute for Plutonium and Actinide Science, and a Principal Associate Directorate for Science, Technology, and Engineering (PADSTE) small equipment grant funded different portions of the work. Technical contacts: Ron Nelson and Sven Vogel

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Chemistry

Handheld LIBS instrument rapidly analyzes rare earth elements in uranium

Figure. Schematic of the handheld LIBS instrument used for the analysis of nuclear materials.

Figure. Schematic of the handheld LIBS instrument used for the analysis of nuclear materials.

Laser induced breakdown spectroscopy (LIBS) is an analytical technique traditionally employed to perform rapid chemical analysis on solid materials. LIBS analysis focuses a high-energy pulsed laser onto the sample surface to form a plasma. The emitted photons from the plasma are then collected, focused, and analyzed spectroscopically. The recent availability of handheld (HH) LIBS instruments as commercial off-the-shelf (COTS) enables LIBS analysis to be performed in situ. The Los Alamos Materials Recycle and Recovery program has investigated a HH LIBS unit to perform a rapid, at-line chemical analysis of nuclear materials. The journal Applied Spectroscopy published the results of the study.

The team developed a methodology with a SciAps HH LIBS instrument that emphasized sensitivity, accuracy, and analysis time. The researchers used a uranium oxide (U3O8) standard with minimal impurities to develop a spectral database for uranium emission with the instrument. Next, the HH LIBS analyzed a near pure uranium sample. The Figure shows the analysis. The HH LIBS unit completely identified the uranium emission lines. Carbon was also detected as the uranium powder was deposited onto a carbon-rich tape, but was “disabled” due to the known occurrence. Then the researchers spiked the rare earth elements europium, neodymium, and ytterbium (1-20%) gravimetrically into a uranium oxide powder and analyzed the sample by HH LIBS. The team determined the preliminary limits of detection for the rare earth elements in U3O8 powder to be on the order of hundredths of a percent. The data within the concentration range (1-20%) demonstrated excellent correlation. The investigators also examined two certified reference materials, which contained rare earth elements in a glass matrix. They concluded that the HH LIBS method clearly discerned the rare earth elements in the glass or uranium matrices.

Figure. Sample uranium emission spectrum depicted using the SciAps Profile Builder software (top) along with an analysis of the sample (bottom).

Figure. Sample uranium emission spectrum depicted using the SciAps Profile Builder software (top) along with an analysis of the sample (bottom).

The researchers envision that this technique could provide a rapid first pass analysis to assist in the chemical characterization of both actinide and non-actinide content in a sample. This pre-screening would help determine what additional actions or measurements are warranted and would minimize the handling and transport of radiological/nuclear materials. The speed with which these determinations can be made could save many hours of labor by enabling the down selection of materials requiring a full chemical analysis by more sensitive and costly techniques. Moreover, the small footprint of the instrument enables its use in confined environments such as glove boxes and fume hoods. Therefore, the team concluded that the technique shows great promise for sample pre-screening in the Materials Recycle and Recovery program.

Reference: “Analysis of Rare Earth Elements in Uranium by Handheld Laser Induced Breakdown Spectroscopy (HH LIBS),” Applied Spectroscopy, (2018); doi: 10.1177/0003702818775431. Authors: Benjamin T. Manard, E. Miller Wylie, and Stephen P. Willson (Actinide Analytical Chemistry, C-AAC).

The NNSA Materials Recycle and Recovery program funded the work, which supports the Lab’s Nuclear Deterrence mission area and the Science of Signatures science pillar through rapid chemical analysis of samples. Technical contact: Benjamin T. Manard

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Intelligence and Space Research

Radiation Hardened Single-Board Computer developed for space applications

Figure. Artist’s rendition of the Radiation Hardened Single-Board Computer. In the background a satellite and image of Earth portray the space environment.

Figure. Artist’s rendition of the Radiation Hardened Single-Board Computer. In the background a satellite and image of Earth portray the space environment.

In 1957 the world watched the first successful launch of a satellite into Low-Earth Orbit (LEO). Five years later Telstar 1 was launched into Medium-Earth Orbit (MEO) to facilitate high-speed telephone signals, and two years following Syncom 2 became the first operational satellite sent into Geosynchronous Orbit (GEO). These activities began the satellite era. Since then the higher orbits of MEO and GEO (where more natural radiation occurs) have been primarily occupied by large satellites used for weather, communications, earth observations, and defense. Although small satellites (SmallSats) are widely used today, they have been primarily limited to LEO for a several reasons including the high cost of space-hardened parts. Higher orbits may soon be accessible to small satellite vendors thanks to a novel Laboratory technology, the Radiation Hardened Single-Board Computer (Rad-Hard SBC) for Command and Data Handling. Los Alamos engineers and scientists have developed this technology, which leverages the Lab’s legacy of designing instruments for satellites and deep space missions for over fifty years.

The Earth’s atmosphere and magnetic field protect inhabitants from most of the harsh radiation from space. Satellites must be properly shielded and designed to withstand the space radiation environment. Designing a satellite able to withstand the shock, vibration and stress of a launch, the ensuing rocket separation, and the high levels of radiation in space is complex and costly. Industry and government satellites that occupy MEO and GEO are built with space-grade components designed and hardened for use in the high-radiation environment of upper orbits. Due to their size, SmallSats have less room, a lower weight budget, and lower weight bearing capability than larger satellites. To achieve the same level of quality and hardening necessary for large satellites, the cost of a space-ready single board computer would cost $250K or higher. SmallSat users are often small businesses or universities that operate under lower budgets. Therefore, SmallSats often use less costly automotive-, industrial-, or consumer-grade parts that have a higher likelihood of failing due to the extreme conditions of launch, and generally have a shorter lifespan in the radiation and temperature environments of space. Due to these increased risks, SmallSat companies frequently mitigate these risks by sending up multiple SmallSats to increase the probability of success. The SmallSats often require a significant amount of additional engineering time and resources to identify design techniques and non-space-grade components that are more robust to launch and space environment – both of which add cost.

Photo. (Left): Paul Graham (Space Data Science & Systems, ISR-3) and Robert Merl (Space Electronics and Signal Processing, ISR-4) work on the Rad-Hard SBC for Command and Data Handling.

Photo. (Left): Paul Graham (Space Data Science & Systems, ISR-3) and Robert Merl (Space Electronics and Signal Processing, ISR-4) work on the Rad-Hard SBC for Command and Data Handling.

The Lab researchers designed the Rad-Hard SBC to meet the command- and data-handling requirements for missions requiring true space-grade radiation hardness and fault tolerance. The Rad-Hard SBC provides a space-hardened, affordable single-board computer to a market segment that is not currently represented. The technology is smaller in size (measuring less than 7 inches x 6 inches), weight, cost, and lower power (consuming just 6.6 Watts) than encountered in the current space-grade solution space available from the large aerospace manufacturers. The Rad-Hard SBC is designed with space-grade integrated circuits, is conduction cooled for operation outside the atmosphere, and is mechanically hardened to withstand the shock and vibration encountered during a satellite launch.

A dual-core fault-tolerant LEON3 processor supplies the processing horsepower, and a field programmable gate array (FPGA) adds hardware co-processing capability. The SBC complies with the popular MicroTCA industrial computing standard, which makes it compatible with commercial systems. The Lab’s next iteration of the Radiation Hardened Single-Board Computer for space applications includes a quad-core LEON4 processor and a gigabyte of main memory. It will be compliant with the SpaceVPX and OpenVPX standards used for commercial, military, and space purposes. This compatibility will allow the new design to inter-operate with both low cost-commercial hardware and more expensive flight-grade hardware.

This Lab technology could provide a high level of reliability through space-hardened parts at a fraction of the current cost. The Rad-Hard SBC would enable small satellite companies to improve their small satellites’ performance, reliability, and longevity in space orbits that were not previously available to them. This, in turn, may enable long-term deployment in MEO and/or GEO for SmallSats, increasing the competitive advantage of companies that use this technology. SmallSat missions might have longer lifetimes lasting many years in MEO and GEO orbits because these orbits do not decay the way a LEO orbit would.

The team included Robert Merl and Nikolai Mondragon (Space Electronics and Signal Processing, ISR-4), Paul Graham and John Michel (Space Data Science & Systems, ISR-3), Zachary Baker and Justin Tripp (Applied Computer Science, CCS-7), and Richard Dutch (Space Instrumentation Realization, ISR-5).

References:

“Radiation-Hardened SpaceVPX System Controller”, IEEE Aerospace Conference, Big Sky, Montana, March 2018; doi: 10.1109/AERO.2018.8396380.

A Low-Cost, Radiation-Hardened Single-Board Computer for Command and Data Handling, IEEE Aerospace Conference, Big Sky, Montana, March 2016.

NNSA’s Office of Defense Nuclear Nonproliferation Research and Development funded the work, which supports the Laboratory’s Global Security mission area and the Science of Signatures and Information Science and Technology pillars. The technology underlying the single board computer is used as part of the Lab’s mission responsibility for treaty verification. Technical contact: Robert Merl

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Materials Physics and Applications

Gold melting at the atomic scale reveals first observation of heterogeneous melting

Understanding the fast melting of metals is important for welding and micromachining in many applications, including the engineering of fusion power reactors. However, melting happens so quickly that it has historically only been probed on the atomic scale through simulations. Molecular dynamics simulations of gold films have predicted the existence of distinct melting regimes that have been excited by ultrafast lasers at different energy densities, but experimental data on the phenomenon has not been recorded. In a study published in Science, an international team that included Los Alamos National Laboratory researchers performed ultrafast electron diffraction experiments on laser-pulsed gold films.
Figure. Schematic of the experiment. SC is single crystalline, and PC is polycrystalline.

Figure. Schematic of the experiment. SC is single crystalline, and PC is polycrystalline.

The researchers used a high-speed electron camera at SLAC National Accelerator Laboratory to make the first visualizations of the ultrafast melting of gold on the atomic length scale. The camera provided time-resolved electron diffraction with MeV electrons, enabling measurements with extremely high signal-to-noise ratios that resulted in detailed maps of melting gold. The team determined the ion and electron temperature evolution and found superheated conditions.

Energy density dependence of ultrafast laser–induced melting mechanisms in gold

Figure. Energy density dependence of ultrafast laser–induced melting mechanisms in gold. The measured melting time of SC (single crystalline) gold and PC (polycrystalline) gold are compared with two-temperature modeling coupled with molecular dynamics (TTM-MD) simulations by Lin and Mazevet.

The data showed that gold melting happens through two distinct regimes while the bonding behavior changes in unexpected ways. For energy densities approaching the irreversible melting regime, the research team observed heterogeneous melting on time scales of 100–1000 ps. This transitioned to homogeneous melting that occurred catastrophically within 10–20 ps at higher energy densities. At intermediate energy densities, the team showed evidence for both solid and liquid coexisting heterogeneously. This was the first observation of heterogeneous melting. The observation enabled direct comparison with molecular dynamics simulations and revealed the sensitivity to nucleation seeds for melting. Watch the movies here.

The results provide critical information to test and improve the kinetic theories of melting and help advance the material processing related to solid-liquid phase transition to atomic-level precision. The discovery also reveals missing physical phenomena that should be included in high-energy melting models. The observation of heterogeneous coexistence reveals a new method for addressing important questions related to the determination of nucleation seeds for melting. This will provide critical information to test and improve the kinetic theories of melting and advance the material processing related to solid-liquid phase transition to atomic-level precision. The knowledge may aid development of inertial confinement fusion experiments and other applications that require materials to endure extreme conditions for long periods of time.

Reference: “Heterogeneous to Homogeneous Melting Transition Visualized with Ultrafast Electron Diffraction,” Science 360, 1451 (2018); doi: 10.1126/science.aar2058. Authors: M. Z. Mo, Z. Chen, R. K. Li, and M. Dunning (SLAC National Accelerator Laboratory); B. Witte (SLAC and University of Rostock in Germany); J. K. Baldwin (Center for Integrated Nanotechnologies, MPA-CINT); L. Fletcher and J. Kim (SLAC); A. Ng (University of British Columbia in Canada); R. Redmer (University of Rostock in Germany); A. H. Reid (SLAC); P. Shekhar (University of Alberta in Canada); X. Z. Shen (SLAC); M. Shen (University of Alberta in Canada); K. Sokolowski-Tinten (University of Duisburg-Essen in Germany); Y. Y. Tsui (University of Alberta in Canada); Y. Q. Wang (Materials Science in Radiation and Dynamics Extremes, MST-8); Q. Zheng, X. J. Wang, and S. H. Glenzer (SLAC).

The Department of Energy, the DOE Fusion Energy Sciences Program, and the DOE Basic Energy Sciences’ Accelerator and Detector program funded the Los Alamos portion of the work. Lab researchers synthesized the samples in an ultra-high vacuum electron beam evaporation system located at the Center for Integrated Nanotechnologies (CINT), a DOE Office of Basic Energy Sciences user facility jointly operated by Sandia National Laboratories and Los Alamos National Laboratory. The work supports the Laboratory’s Nuclear Deterrence and Energy Security mission areas and its Materials for the Future science pillar. Technical contact: Kevin Baldwin

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Materials Science and Technology

First demonstration of an all-solid-state cryocooler

The ability to cool objects to cryogenic temperatures is essential to a wide range of scientific and national security applications. To date, mechanical refrigeration has been the only technology for cryocooling devices that operate continuously in remote locations such as in space. However, all mechanical cryocoolers have moving parts that not only limit their reliability but also introduce mechanical vibrations and microphonic noise that limit system performance. Markus Hehlen (Engineered Materials, MST-7) and collaborators have made the first demonstration of an all-solid-state optical refrigerator that operates at cryogenic temperatures and has no moving parts. Their work represents a breakthrough in cryogenics. The Nature journal Light: Science & Applications published the work, and Nature Photonics featured it in an article.

Photo. Solid-state optical cryocooler characterization at the University of New Mexico (UNM) collaborator laboratory. Pictured from left to right are Markus Hehlen (MST-7), and UNM collaborators Junwei Meng, Mansoor-Sheik Bahae, Alexander Albrecht, and Richard Epstein.

Photo. Solid-state optical cryocooler characterization at the University of New Mexico (UNM) collaborator laboratory. Pictured from left to right are Markus Hehlen (MST-7), and UNM collaborators Junwei Meng, Mansoor-Sheik Bahae, Alexander Albrecht, and Richard Epstein.

All-solid-state cryocooling is an optical effect that occurs in certain materials via anti-Stokes fluorescence. In this process, a solid is excited by a laser and subsequently fluoresces at a slightly greater mean energy (shorter wavelength) than that of the exciting laser. The corresponding energy difference is provided by phonon energy (heat) that is extracted from the solid and carried away as light, thus cooling the solid in the process. This effect was first observed by Richard Epstein at the Laboratory in 1995. Ultrapure rare-earth-doped crystals such as Yb3+-doped YLiF4 (YLF:Yb) developed by the project team over the past two decades are particularly suited because they offer the required spectrally narrow optical transitions and greater than 99% quantum yields.

Previous work had only cooled the YLF:Yb crystal itself. Cooling a useful payload such as a sensor or an electronic component by using a YLF:Yb crystal posed a range of additional engineering challenges. The primary challenges for advancing from a basic laser-cooling setup to a practical optical cryocooler device involve: 1) managing the numerous heat and radiation flows in the system and 2) providing a sturdy, thermally insulating support structure for the laser-cooled assembly.

Solid-state laser cooling of a HgCdTe sensor to 135 K using a YLF:Yb crystal.

Figure. Solid-state laser cooling of a HgCdTe sensor to 135 K using a YLF:Yb crystal. The solid curve shows the sensor temperature as a function of time after turning on the pump laser (47 W at 1020 nm). The inset is a picture of the optical cryocooler assembly developed in this project.

To achieve success, the team developed: 1) a custom-shaped thermal link that connected the YLF:Yb crystal to the sensor with good thermal conductivity while rejecting the intense crystal fluorescence, 2) an adhesives-free bond between the thermal link and the YLF:Yb crystal, and 3) silica aerogel supports that secured the cooled assembly inside the cryocooler with minimal conductive heat load. These advances have enabled laser-cooling of a HgCdTe infrared sensor to 135 K for the first time.

This work represents a breakthrough in the field of cryogenics and opens the door to use this technology for a variety of applications that benefit from a reliable cryogenic refrigerator having no moving parts and no associated vibrations. Optical cryocoolers could prove useful wherever there is a need for minimal or negligible vibration that precludes the use of traditional mechanical means, such as a Stirling or Gifford-McMahon refrigerator that features moving parts. Potential examples that may benefit include germanium gamma-ray detectors, cryogenic microscopy, and space-based sensors.

Reference: “First Demonstration of an All-Solid-State Optical Cryocooler,” Light: Science & Applications 7, 15 (2018); doi: 10.1038/s41377-018-0028-7. Markus Hehlen (Engineered Materials, MST-7) led the team, which included Christopher Hamilton and Tana Cardenas (MST-7), Steven Love (Space and Remote Sensing, ISR-2), Kevin Baldwin (Center for Integrated Nanotechnologies, MPA-CINT), Todd Williamson (Nuclear and Radiochemistry, C-NR), and University of New Mexico collaborators Junwei Meng, Alexander Albrecht, Eric Lee, Aram Gragossian, Richard Epstein, and Mansoor Sheik-Bahae.

The work leverages the Laboratory’s expertise in high-purity inorganic synthesis, halide crystal growth, thin-film deposition, silica aerogel fabrication, optical spectroscopy, high-power lasers, and thermal/optical system design. The work used the Lab’s capabilities such as the Target Fabrication Facility (TFF), Center for Integrated Nanotechnology (CINT), and the TA-46 clean room infrastructure to realize the first optical cryocooler prototype.

This research supports the Laboratory’s Energy Security and Global Security mission areas and the Science of Signatures and Materials for the Future science pillars through the development of an all-solid-state cryocooler. Technical contact: Markus Hehlen

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Mesoscale Materials Science on the Roadmap to MaRIE

Adaptive feedback automatically tunes electron beams in advanced x-ray free-electron lasers

Next-generation particle accelerators, such as the Linac Coherent Light Source (LCLS) at the SLAC National Acceleratory and future instruments such as the proposed MaRIE (Matter-Radiation Interactions at Extremes) x-ray free-electron laser at Los Alamos, support NNSA missions. Due to the complexity and uncertainty inherent in their beam generation, quickly and precisely tuning the sophisticated parameters required to accommodate various experimental setups is challenging. This causes valuable beam time lost between setups.

To mitigate this, a team led by Alexander Scheinker (RF Engineering, AOT-RFE) with collaborators from SLAC National Accelerator Laboratory is developing a novel hybrid tuning technique to combine machine-learning and adaptive feedback to enable fast, automated optical tuning of the particle beams and optimized beam maintenance over time. The team combined a neural network with adaptive feedback to achieve performance beyond what either method could reach on its own. Feedback alone can get stuck in a local minimum, and a neural network alone cannot make exact predictions due to interpolation between training points and the time variation of particle accelerator characteristics.

The team demonstrated proof-of-principle of this technique at the LCLS, training a neural network to map two-dimensional longitudinal phase space distributions of the electron beam. The neural network quickly searched for the desired phase space distribution and then used feedback to determine the correct settings for two different parameters. This network also tracked the correct settings as the accelerator varied over time.

An illustration of the neural network that provided proof-of-principle for this technique

Figure. An illustration of the neural network that provided proof-of-principle for this technique. This network was designed to map two-dimensional longitudinal phase space distributions of the LCLS electron beam to LCLS parameter settings. Acronyms: XTCAV = X-band radio frequency transverse deflecting cavity, NN = Neural Network, ES = Extremum Seeking.

For this initial study, the team focused on just two parameters of the LCLS, which control how much the electron beam is compressed. The researchers performed a 2D grid scan of the parameters and saved a 2D longitudinal phase space distribution at each point. The investigators used the data to train a neural network to predict parameter settings based on 2D phase space distributions. They created a target phase space distribution (not part of the training data) by making very large changes in parameter settings. The team used the neural network to make a prediction of what the machine parameter settings should be to achieve this target. Because the network must interpolate between training points and the machine characteristics drift with time, the predicted parameter settings resulted in a distribution close to the target, but not an exact match.

The researchers utilized model-independent feedback, which completed the tuning by zooming in on the actual correct parameter settings and continuously tracking them as they varied with time. In this demonstration, the target phase space was so dramatically different from the initial machine setup that local model-independent feedback alone became trapped in a local minimum, unable to converge to the correct settings. The team intends to create non-invasive diagnostics that account for the six dimensions of phase space and plans to apply the algorithm to tune about 20 parameters at once.

The core algorithm will benefit all particle accelerators, including the linear accelerator at the Los Alamos Neutron Science Center (LANSCE). The types of algorithm being developed would especially benefit the Lab’s proposed MaRIE x-ray free-electron laser for exploring matter-radiation interactions in extremes. Because MaRIE would be designed to produce extremely closely spaced electron bunches, it would face greater tuning, control, and optimization challenges than existing accelerators.

Reference: “Demonstration of Model-Independent Control of the Longitudinal Phase Space of Electron Beams in the Linac-Coherent Light Source with Femtosecond Resolution,” Physical Review Letters 121(4), 044801, 2018; doi: 10.1103/PhysRevLett.121.044801. Authors: Alexander Scheinker (RF Engineering, AOT-RFE), Auralee Edelen, Dorian Bohler, Claudio Emma, and Alberto Lutman SLAC National Acceleratory Laboratory).

The Laboratory Directed Research and Development (LDRD) program funded the work at Los Alamos through its 2018 Momentum Initiative, which aims to advance two capability thrusts: accelerator capability enhancement and development of advanced accelerators and exploration of mesoscale materials phenomena using state-of-the-art light source user facilities. The work supports the Laboratory’s Nuclear Deterrence mission area and its Nuclear and Particle Futures science pillar, especially its accelerators and electrodynamics thrust area. Technical contact: Alexander Scheinker

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Nuclear Engineering and Nonproliferation

National Criticality Experiments Research Center provides training and experiments

The Laboratory operates the National Criticality Experiments Research Center (NCERC) for the National Nuclear Security Administration (NNSA). NCERC’s mission is to conduct experiments and training with critical assemblies and fissionable material in order to explore reactivity phenomena. NCERC maintains an essential skill base of nuclear material handling and criticality safety expertise based on experimental capability. As part of the Nuclear Critical Safety Program (NCSP), it is the nation’s only general-purpose critical experiments facility. The facility supports the nuclear weapons enterprise, global security, space exploration, and clean energy solutions in addition to its core mission in the Nuclear Criticality Safety Program.

The safe handling of large quantities of plutonium and uranium relies on the data generated over past decades at NCERC and its predecessor facility. Many of these unique experiments are part of the Nuclear Criticality Safety Program, a program essential to the nuclear community. The program is designed to protect nuclear operations personnel, the public, and the environment from the consequences of a criticality incident using formality of operations, written operating procedures, criticality safety evaluations, criticality safety controls, training, and other programmatic features.

Photo. Students stack polyethylene plates and uranium foils under the instruction of David Hayes (Advanced Nuclear Technology, NEN-2, second from right) and Rene Sanchez (NEN-2, far right) at a criticality safety class.

Photo. Students stack polyethylene plates and uranium foils under the instruction of David Hayes (Advanced Nuclear Technology, NEN-2, second from right) and Rene Sanchez (NEN-2, far right) at a criticality safety class.

The training of specialists nationwide by NCERC personnel using the facility’s unique nuclear materials and capabilities enhances the criticality safety discipline. What began in the 1970s as a 2-day hands-on course for fissionable material operators has evolved to include one-week courses for managers and process supervisors, and a two-week course for criticality safety analysts. Personnel from DOE, other government agencies, the commercial nuclear community, and the military witness criticality demonstrations while attending the training. The training exercises are core requirements for criticality safety analysts, and support fissionable material operations across the DOE complex. 

Data from the experiments conducted at NCERC significantly reduce the margins of uncertainty for criticality safety evaluations by determining the exact point where a given system will attain the critical state. The confidence in the U.S. stockpile assessment, the accuracy of criticality safety guidance, and the cost of production operations depend on the NCERC.

Photo. Los Alamos and NASA engineers lower the vacuum chamber over the Kilopower test reactor during testing at NCERC.

Photo. Los Alamos and NASA engineers lower the vacuum chamber over the Kilopower test reactor during testing at NCERC.

The design and development of new nuclear reactor designs necessarily includes experimentation. The NCERC is the only place where critical experiments can be conducted to prototype new reactors. Nuclear energy may hold future benefits for energy production, power grid resilience, national security, and deep space exploration. One of the most novel technologies to be tested recently at NCERC is the Kilopower Reactor Using Stirling Technology experiment. A joint project with NASA, Kilopower is a power system that can operate in extremely harsh environments and is efficient, reliable, safe, low cost, and compact. The experiment demonstrated the efficiency of fission power for lunar and planetary exploration. This new nuclear power system might enable long-duration crewed missions to the Moon, Mars, and destinations beyond. 

NCERC also performs experiments to validate nuclear data and computer codes. Moreover, the experiments, demonstrations, and training conducted at NCERC support the Lab’s nuclear deterrence capability in the handling and processing of nuclear materials. This is achieved through scientific and engineering expertise in concert with highly advanced, state-of-the-art equipment also developed at Los Alamos. Many critical assembly machines have been developed, four of which are in operation today. These machines, and the experiments conducted using them, are essential to understand the phenomenology of criticality accidents.

As concerns have grown that rogue states and organizations might obtain and use nuclear materials to disrupt democracies, this specialized discipline has become part of the comprehensive training that nuclear incident response personnel receive. NCERC is the only place in the United States where nuclear incident responders can train and hone their diagnostic skills with nuclear material in quantities and configurations that they could encounter in realistic scenarios. In addition to criticality safety and nuclear emergency response, NCERC also supports arms control, nuclear nonproliferation, and national technical nuclear forensics applications.

The DOE Nuclear Criticality Safety Program funds the majority of NCERC’s operation. The works supports the Lab’s Nuclear Deterrence, Global Security, and Energy Security mission areas and the Nuclear and Particle Futures, Science of Signatures, and Materials for the Future science pillars. Technical contacts: David Hayes and Joetta Goda

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Physics

National Ignition Facility experiment explains a behavior of evolving supernovae

Nuclear fusion happens constantly in stars, which makes understanding the process key to enabling energy-efficient, controlled fusion power in a lab setting. One component of this natural fusion is Rayleigh-Taylor mixing, or instability caused by the acceleration of a heavy fluid into a light fluid (think water on top of oil). Rayleigh-Taylor has been extensively studied as scientists work to understand the inner working of stars, their supernovae and achieve fusion, but astrophysical simulations have never included radiation and heat conduction. For the first time, a team that included researchers from Los Alamos has replicated the evolution of supernovae in a way that factors in the effects of radiation and heat conduction. This experimental replication may help understand potential processes of laboratory fusion and may explain fundamental behaviors of the universe. Nature Communications published the research.

The researchers used the extreme heat and lasers at the National Ignition Facility (NIF) to recreate how natural fusion in supernovae can produce strong energy fluxes that affect evolution of an exploding star as it interacts with the interstellar medium. The team adopted the Lab’s Shear high energy-density turbulence experimental design from other NIF experiments for the new research. The Figure depicts a schematic of the experimental target. The laser beams impinge on the gold hohlraum (open cylinder) to create the x-ray drive and on the large-area backlighter to create the diagnostic x-ray source. A plastic shock tube is attached to the hohlraum. The soft x-rays from the hohlraum create a shock wave in the plastic layer inside the shock tube, which decays into a blast wave before crossing the unstable interface and entering the foam. The diagnostic x-ray source creates radiographs by being preferentially absorbed by a tracer layer in the center of the plastic. X-ray radiographs of the experiment reveal the plasma flow and the Rayleigh-Taylor instability growth.

Figure. a) NIF target schematic and b) the attached plastic shock tube. c) and d) x-ray radiographs of the experiment. Here, the plasma flows upward and the dark fingers are due to Rayleigh-Taylor instability growth. The color bar indicates the relative transmission for c) the high-flux case at t = 13 ns and d) the low-flux case taken at t = 34 ns.

Figure. a) NIF target schematic and b) the attached plastic shock tube. c) and d) x-ray radiographs of the experiment. Here, the plasma flows upward and the dark fingers are due to Rayleigh-Taylor instability growth. The color bar indicates the relative transmission for c) the high-flux case at t = 13 ns and d) the low-flux case taken at t = 34 ns.

The study suggests that models of Rayleigh-Taylor mixing in supernovae are not complete, given that hot shocked matter can produce significant radiative fluxes that may affect emissions from the supernovae remnants and alter Rayleigh-Taylor behavior. The study showed a 30 percent reduction in Rayleigh-Taylor growth, a decrease that continued over time. The analysis implies that thermal conduction has substantial consequences for the structure and stability of modeling supernova remnants. The results could influence future studies of evolving supernovae and may improve the scientific community’s understanding of laboratory fusion experiments under similar conditions.

Reference: “How High Energy Fluxes May Affect Rayleigh–Taylor Instability Growth in Young Supernova Remnants,” Nature Communications 9, Article 1564 (2018); doi: 10.1038/s41467-018-03548-7. Authors: C. C. Kuranz, M. R. Trantham, W. C. Wan, G. Malamud, T. A. Handy, S. R. Klein, D. C. Marion, and R. P. Drake (University of Michigan, Ann Arbor); H.-S. Park, C. M. Huntington, A. R. Miles, B. A. Remington, H. F. Robey, K. Raman, S. MacLaren, S. Prisbrey, R. Wallace, and D. Kalantar (Lawrence Livermore National Laboratory); T. Plewa (Florida State University, Tallahassee); D. Shvarts and A. Shimony (Ben Gurion University, Israel); D. Shvarts, A. Shimony, and G. Malamud (Nuclear Research Center Negev, Israel); Willow C. Wan and Kirk A. Flippo (Plasma Physics, P-24); F. W. Doss (XTD Integrated Design and Assessment, XTD-IA); John Kline (formerly P-24, currently Weapons Physics, ADX); C. M. Krauland and E. Giraldez (General Atomics); E. C. Harding (Sandia National Laboratories); and M. J. Grosskopf (Simon Fraser University, Canada).

The NNSA Defense Programs and DOE Office of Science’s Fusion Energy Sciences Joint Program in High-Energy-Density Laboratory Plasmas funded the Los Alamos portion of the research. The study supports the Laboratory’s Energy Security mission area and the Nuclear and Particle Futures science pillar, with a focus on the High Energy Density Plasma and Fluids thrust area. Los Alamos advances on the National Ignition Facility in generating and imaging hydrodynamic instabilities in radiation-driven shock tubes enabled the work. Technical contact: Kirk Flippo and Forrest Doss

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Theoretical

Magnetic particles discovered in rare earth magnets

Skyrmions are disklike objects that typically form triangular crystals in two-dimensional systems. Shi-Zeng Lin and Cristian Batista (Physics of Condensed Matter and Complex Systems, T-4) have demonstrated that different 3D Skyrmion crystals can be stabilized in centrosymmetric magnets by tuning the ratio between competing interlayer exchange interactions. The journal Physical Review Letters published the research. Ions or atoms condense into crystal with various symmetries, depending on the interacting force among them. For instance, salt is made of sodium and chloride, which form a face centered cubic lattice at room temperature. In magnetic materials, the magnetic polarization can organize into a particle-like texture in the mesoscale. An example is the swirling Skyrmion spin texture, which former Los Alamos scientist Tony Skyrme predicted. The swirling Skyrmion spin texture has been observed recently in magnets without an inversion center (panel a in the Figure). The Skyrmion is regarded as a particle-like excitation because the associated spin texture is well localized in space with a well-defined characteristic size. The size of a Skyrmion typically ranges from a few nanometers to hundreds of nanometers depending on the microscopic interactions that stabilize the Skyrmions. In bulk crystals Skyrmions become line-like objects and crystallize into a triangular line lattice (panel b in the Figure). In thin films the Skyrmions are pancake-like objects and form a triangular crystal.
Figure. (a) Spin profile at the cross-section of a Skyrmion line. (b) Triangular Skyrmion line lattice. (c) Face centered cubic Skyrmion crystal corresponding to the ABCABC stacking of pancake Skyrmions in different layers. Color represents the magnitude of the magnetization along the magnetic field direction.

Figure. (a) Spin profile at the cross-section of a Skyrmion line. (b) Triangular Skyrmion line lattice. (c) Face centered cubic Skyrmion crystal corresponding to the ABCABC stacking of pancake Skyrmions in different layers. Color represents the magnitude of the magnetization along the magnetic field direction.

Skyrmions are compact, robust against external perturbations, and can be manipulated by electric currents. Therefore, they could be prime candidates for next generation spintronic applications such as memory devices. Most Skyrmions systems discovered to date do not have an inversion center. According to theory, breaking the inversion symmetry of the crystals is necessary to host the Skyrmions. This limits the material choice for Skyrmions. Lin and Batista aimed to determine 1) if it is possible to stabilize Skyrmion crystals in magnets with inversion symmetry and 2) if Skyrmions organize into crystals with symmetries other than the hexagonal symmetry. Their research indicates that both are possible.

In inversion-symmetric rare earth magnets with layered structure, conduction electrons mediate the interaction of localized spins. The interaction is highly oscillatory as a function of the separation between spins. The interaction can be peaked at a nonzero momentum. As a consequence, the ground state configuration of spins is a helix, where spins rotate along a certain direction. This occurs in many rare earth magnets, such as holmium and erbium. Previous theory predicted that in the presence of a moderate easy axis anisotropy, a triangular lattice of Skyrmions could be achieved by applying magnetic field. Because the conditions for stabilization the Skyrmion lattice are very general, the Skyrmion lattice may exist in the rare earth magnets. The Skyrmions in rare-earth magnets could have novel properties that do not occur in magnets without an inversion center.

For a ferromagnetic interaction between layers, the Skyrmions in each layer stack uniformly along the crystal c axis and the magnetic field direction. Therefore, the triangular Skyrmion line crystal is stabilized. The researchers investigated the effect of competing magnetic interactions between layers. Generally, the competing interactions introduce modulation in the c axis, which tilts the Skyrmion lines away from the magnetic field direction. For strong competing interactions, such that the modulation period along the c axis is 3, which corresponds to the ABCABC… stacking of the pancake Skyrmions along the c axis, the pancake Skyrmions crystallize into a face-centered cubic lattice (panel c in the Figure). For an antiferromagnetic interlayer coupling, the pancake Skyrmions try to avoid piling up uniformly in the c axis. This creates an ABAB… stacking of the pancake Skyrmions, which corresponds to the hexagonal close packed lattice. Analogous to real atoms, Skyrmions can organize into multiple crystal structures with different responses to external stimuli. This phenomenon makes them suitable for potential technological applications.

Reference: “Face Centered Cubic and Hexagonal Close Packed Skyrmion Crystals in Centrosymmetric Magnets,” Physical Review Letters 120, 077201 (2018); doi: 10.1103/PhysRevLett.120.077202. Authors: Shi-Zeng Lin and Cristian D. Batista (Physics of Condensed Matter and Complex Systems, T-4).

The Laboratory Directed Research and Development (LDRD) program funded the work, and the Institutional Computing Program at the Lab provided computer resources for numerical calculations. The research supports the Lab’s Energy Security mission area and the Materials for the Future science pillar through the development of materials for spintronic applications. Technical contact: Shi-Zeng Lin

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