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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

SciDAC GSEP: Gyrokinetic Simulation of Energetic Particle Turbulence and Transport

Energetic particle (EP) confinement is a key physics issue for burning plasma experiment ITER, the crucial next step in the quest for clean and abundant energy, since ignition relies on self-heating by energetic fusion products (α-particles). Due to the strong coupling of EP with burning thermal plasmas, plasma confinement property in the ignition regime is one of the most uncertain factors when extrapolating from existing fusion devices to the ITER tokamak. EP population in current tokamaks are mostly produced by auxiliary heating such as neutral beam injection (NBI) and radio frequency (RF) heating. Remarkable progress in developing comprehensive EP simulation codes and understanding basic EP physics has been made by two concurrent SciDAC EP projects GSEP funded by the Department of Energy (DOE) Office of Fusion Energy Science (OFES), which have successfully established gyrokinetic turbulence simulation as a necessary paradigm shift for studying the EP confinement in burning plasmas. Verification and validation have rapidly advanced through close collaborations between simulation, theory, and experiment. Furthermore, productive collaborations with computational scientists have enabled EP simulation codes to effectively utilize current petascale computers and emerging exascale computers. We review here key physics progress in the GSEP projects regarding verification and validation of gyrokinetic simulations, nonlinear EP physics, EP coupling with thermal plasmas, and reduced EP transport models. Advances in high performance computing through collaborations with computational scientists that enable these large scale electromagnetic simulations are also highlighted. These results have been widely disseminated in numerous peer-reviewed publications including many Phys. Rev. Lett. papers and many invited presentations at prominent fusion conferences such as the biennial International Atomic Energy Agency (IAEA) Fusion Energy Conference and the annual meeting of the American Physics Society, Division of Plasma Physics (APS-DPP).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

ARM Lead Mentor Selection Process

The Atmospheric Radiation Measurement (ARM) Program was created in 1989 with funding from the U.S. Department of Energy (DOE) to develop several highly instrumented ground stations to study cloud-formation processes and their influence on radiative transfer. This scientific infrastructure provides for fixed sites, mobile facilities, an aerial facility, and a data archive available for use by scientists worldwide through the ARM Climate Research Facility—a scientific user facility. The ARM Climate Research Facility currently operates more than 300 instrument systems that provide ground-based observations of the atmospheric column. To keep ARM at the forefront of climate observations, the ARM infrastructure depends heavily on instrument scientists and engineers, known as Mentors. Mentors must have an excellent understanding of instrumentation theory and operation for their instrument areas and have comprehensive knowledge of critical scale-dependent atmospheric processes. They must also possess the technical and analytical skills to develop new data retrievals that provide innovative approaches for creating research-quality data sets. The ARM Facility seeks the best overall qualified candidate, or team when appropriate, that can fulfill Mentor requirements in a timely manner. The roles and responsibilities of the ARM Instrument Operations Manager are provided in Appendix A. The key role and responsibilities and detailed responsibilities of ARM Lead Mentors are provided in Appendix B and Appendix C, respectively.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

2017 LLNL Nuclear Forensics Summer Internship Program

The Lawrence Livermore National Laboratory (LLNL) Nuclear Forensics Summer Internship Program (NFSIP) is designed to give graduate students an opportunity to come to LLNL for 8-10 weeks of hands-on research. Students conduct research under the supervision of a staff scientist, attend a weekly lecture series, interact with other students, and present their work in poster format at the end of the program. Students can also meet staff scientists one-on-one, participate in LLNL facility tours (e.g., the National Ignition Facility and Center for Accelerator Mass Spectrometry), and gain a better understanding of the various science programs at LLNL.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Final Technique Report of SMIRTP

Positron emission tomography (PET) imaging agents play significantly roles in detection and management of diseases. There are urgent needs to increase output and translate probes more rapidly for clinical use. Moreover, there is a crucial lack of trained radiochemists and nuclear medicine physician scientists to meet the increasing demand of developing novel PET imaging probes for clinical use. With strong support and commitment from Office of Science, Department of Energy, coupled with an expanding interest in the benefits of molecular and biomedical imaging, Stanford Molecular Imaging Research and Training Program (SMIRT) has advanced generalizable strategies to develop PET agents and multimodality radiotracers that can target most cell surface receptors. These radioactive imaging agents have been based on novel protein scaffolds such as knottins and Affibodies, and newly developed gold nanoparticles and organic nanoparticles. The projects yielded several new classes of knottin-based imaging probes that target α v b 6 , α v b 3 , EGFR, melanin, etc. as single or multimodal imaging agents. More importantly, the projects firmly established the development of knottins based PET probes as a generalizable approach for many tumor targets. Three novel PET probes have been successfully developed from research lab and translated into pilot clinical patient imaging studies during the course of the funding period. We also increased the number of trained radiochemists/nuclear medicine physician-scientists and provided them with comprehensive training regarding probe development and the clinical translational process. The research opportunities of this SMIRT engaged trainees in cutting-edge projects with experienced mentors and improve cross-training between radiochemists and nuclear medicine physicians. The training enabled an overall understanding of the complete probe development and clinical translation process, and encouraged trainees to pursue rewarding careers in radionuclide based imaging.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Integrating Distributed-Memory Machine Learning into Large-Scale HPC Simulations

Lawrence Livermore National Laboratory (LLNL) is a national lab based in Livermore, California. It was established in 1952 to meet increasing national security needs. They specialize in earth and atmospheric science, bioscience and bioengineering, lasers and optical science and technology, advanced materials and manufacturing, high-energy-density science, nuclear, chemical, and isotopic science and technology, and HPC, simulation and data science ((cor, 2018)). LLNL is also home to a number of large Linux clusters and supercomputers which are used to support research in their areas of specialization (mac, 2018). One purpose of the LLNL supercomputers is to run highly detailed and accurate physics simulations. These simulations allow scientists to get data on experiments that would be too expensive, difficult, or dangerous to perform in reality. With the help of simulations scientists at LLNL are able to study processes in more depth than they would be able to otherwise.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

It Takes a Village: Documenting the Contributions of Non-Scientific Staff to Scientific Research [Slides]

Science, especially large-scale basic research, is a collaborative endeavor, often drawing on the skills of people from a wide variety of disciplines. These people include not just scientists, but also administrators, engineers, and many others. Fermilab, a Department of Energy National Laboratory and the United States’ premier particle physics laboratory, exemplifies this kind of research; many of its high-energy physics experiments involve hundreds of collaborators from all over the world. The Fermilab Archives seeks to document the history of the lab and the unique scientific research its staff and visitors perform. Adequately documenting the lab’s work often requires us to go far beyond things like the writings and correspondence of scientists to also capture the administrative and social histories of the experiments and the context in which they were performed. At Fermilab, we have sought to capture these elements of the lab’s activities through an oral history program that focuses on support staff as well as physicists and collection development choices that recognize the importance of records documenting the cultural life of the lab. These materials are not merely supplementary, but rather essential documentation of the many types of labor that go into the planning and execution of an experiment or the construction of an accelerator and the context in which this work is performed. Any picture of these experiments and accelerators that did not include this type of information would be incomplete. While the importance and richness of this material is especially pronounced at Fermilab due to the massive size of its experiments and accelerator facilities and its vibrant cultural life, the fruitfulness of these collecting efforts at Fermilab suggests that other archives documenting modern STEM research should also make sure the contributions of non-technical and non-scientific staff are preserved and that researchers interested in this subject should not neglect such sources.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Crossroads Workflows

The Department of Energy (DOE) compute facilities operate as resources for the National Nuclear Security Administration (NNSA) and Office of Science. In this document we describe a subset of scientific work flows which are run on current platforms. There is significant commonality to how Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), Lawrence Liver- more National Laboratory (LLNL) and the National Energy Research Scientific Computing Center (NERSC) operate and conduct scienti c inquiry with supercomputers. In addition to presenting the commonality between the sites, we believe that opportunities exist to significantly optimize the operation of our facilities and more rapidly advance our scientific goals. In describing how our scientific work flows move from inception to realization we believe that we can enable significant improvements in how computer architectures support real scientific work flows. Briefly, in order for a team of scientists to access the large supercomputers at these facilities, the team must be granted an allocation. Allocations last for a fixed amount of time (usually 6 or 12 months), and a large number of teams will have overlapping allocations ensuring that a large amount of work is available in the scheduling queue. During the allocation, the scientists will construct work flows as described in this document. Many simultaneous allocations may use identical work flows with different data and scientific goals.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Changes in Interfacial Tension with Time in Two-Liquid-Phase Systems

Interfacial tension (IFT) is a thermodynamic property of the interface between two immiscible fluids. This property has been identified as an important factor in an advanced solvent extraction system because it correlates with settling time and miscibility. The IFT in a variety of two phase systems has been partially characterized by Los Alamos National Laboratory (LANL) scientists. Information about the change in IFT is gathered in this study to more fully characterize these two-phase systems. Metal loaded aqueous solutions are of particular interest, as they simulate a solvent extraction system. Based in part on this body of research, LANL scientists will select the appropriate organic solvent and aqueous pH to develop an advanced solvent extraction system which will remove heavy metals from acidic solutions. Previous studies show that the factor which has the greatest effect on discrete IFT measurements is the ratio of aqueous density to organic density1. It is expected that this density ratio will play an important role in time-dependent IFT measurements as well. The two phases will be brought into equilibrium before beginning the tests, so it is also expected that IFT will not drastically change over a two hour time period.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

High-Speed Shocks Induce a Phase Change in Calcium Fluoride Crystals

Placing a crystal under extreme pressure can sometimes change its structure from one form, or phase, to another. Determining exactly how crystals change phase under compression is an important area of materials physics research. The availability of x-ray diffraction at synchrotron facilities has allowed scientists to observe compression-driven phase changes in unprecedented detail. Most of the research in this field has focused on pressure-induced phase changes using slow (static) compression on the minute timescale. Now, utilizing x-ray diffraction at the APS, a multi-institution research team led by scientists at Sandia National Laboratories has observed, over nanosecond timescales, microstructural phase changes within a two-element (calcium fluoride) crystal subjected to extreme pressures. The high pressures were achieved both through high-velocity instantaneous shock compression and by statically squeezing the samples. The researchers expect that their real-time observations of phase transitions within calcium fluoride will provide a template for the phase transitions of similarly-structured compounds. More generally, it is anticipated that the experimental methods and results of this study will lead to improved modeling of phase transitions over nanosecond timescales, within a wide range of complex materials.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The International Science and Technology Center: Product of the Past or Prototype for the Future?

The International Science and Technology Center (ISTC) – originally formed in the early 1990s to address the potential issue of “brain drain” from underemployed and underpaid nuclear weapons scientists, engineers, and technicians in the former Soviet Union – still exists to this day. Through more than two decades of changing circumstances and worldviews, the ISTC has had to reorganize, move countries, streamline its internal processes, and broaden its scope of work in an attempt to remain a relevant and useful tool for international science cooperation in the 21st century. Critics see it as a product of the past in a modern world that no longer requires the redirection of former Soviet scientists, while proponents argue that the established networks and trust from the international community that the ISTC has developed throughout its history make it a critical and useful tool for current and future science cooperation and threat reduction. Through historical and budget analysis, this paper hopes to answer the following questions: (1) how has the ISTC evolved throughout its history to become what it considers to be a useful tool for the future of science cooperation and threat reduction, and (2) if the ISTC still serves a purpose, what is that purpose, and how can they continue to adapt and evolve to better serve that purpose?

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2014

Large Scale Computing and Storage Requirements for Basic Energy Sciences: Target 2017. Report of the NERSC Requirements Review Conducted October 8–9, 2013, Gathersburg, MD

The National Energy Research Scientific Computing Center (NERSC) is the primary computing center for the DOE Office of Science, serving approximately 5,000 users working on some 700 projects that involve nearly 600 codes in a wide variety of scientific disciplines. In addition to large-scale computing and storage resources NERSC provides support and expertise that help scientists make efficient use of its systems. The latest review revealed several key requirements, in addition to achieving its goal of characterizing BES computing and storage needs. high-level findings are: 1) Scientists will need access to significantly more computational and storage resources to achieve their goalds and reach BES research objectives; 2) Users will need assistance from NERSC to prepare for Cori (NERSC-8) and follow-on manycore systems; 3) Research teams need to run complex jobs of many different types and scales; 4) BES is a leader in innovative use of HPC and requires a diverse set of resources and services from NERSC; and 5) BES facilities need computational analysis and data storage resources beyond what they can provide. This report expands upon these key points and add others. The results are based upon representative samples, called "case studies," of the needs of science teams within BES. The case study topics were selected by the NERSC meeting coordinators and BES program managers to represent the BES production computing workload. Prepared by BES workshop participants, the case studies contain a summary of science goals, methods of solution, current and future computing requirements, and special software and support needs. Also included are strategies for computing in the highly parallel "many-core" environment that is expected to dominate HPC architectures over the next few years.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Design Considerations for the Field Use of Safeguards Technology

The process of safeguards technology development, deployment, and use should be carried out in such a way that it supports the International Atomic Energy Agency’s (IAEA’s) international safeguards verification mission, while also being efficient in terms of both cost and time. This process, however, may be hindered by a lack of communication between the scientists or engineers developing the technology and the safeguards inspectors who would be using the equipment, as well as by a general lack of facility experience among the scientists or engineers designing safeguards technology. The latter point is particularly true for new graduates and junior staff working at design laboratories, who typically have not had significant experience in an industrial facility setting or in working with or for the IAEA directly. As a result, junior safeguards staff may have difficulty understanding inspector needs and the limitations of using safeguards technology in the field, often leading to inefficiencies (in the form of increased cost and time spent) in the safeguards technology design process. To mitigate this knowledge gap, the Y-12 National Security Complex in Oak Ridge, Tennessee, has developed a list of design considerations that should be incorporated when developing safeguards technology. Project findings with respect to nondestructive assay technology are detailed in this paper.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Accelerator Physics Center at Fermilab : History and Accomplishments (2007-2018)

Fermilab’s Accelerator Physics Center (APC) was created in June 2007 with mission to carry out research and development to keep the US leading high-energy physics laboratory at the forefront of accelerator science, technology and facility operation. In support of the FNAL high-energy physics research mission, APC scientists and enginners conducted accelerator R&D aimed at next-generation and beyond accelerator facilities; provided accelerator physics support for existing operational programs and the evolution thereof; trained accelerator scientists and engineer and established experimental programs for a broad range of accelerator R&D that can be accessed by both Fermilab staff and the US and world HEP community. APC was a center-place for in-depth design, research and development efforts which allowed the Laboratory to make intelligent decisions on the ILC in the US, on the Muon Collider, as well as originate projects like PIP-II (through the Proton Driver/Project-X work), LHC-AUP (via LARP) and the IOTA/FAST R&D facility. APC was also the birthplace and host of many national and international collaborations and several educational/training programs in beam physics resulted in 27 PhD theses. In the Fall 2018, following an important milestone of the first beam circulating in the IOTA ring, the APC was re-organized into several departments in Accelerator Division, charged to carry out the accelerator physics research with IOTA/FAST beams and making it relevant for future upgrades of the Fermilab accelerator complex.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Final Report: Student Support for the "Frontiers in Attosecond & Ultrafast X-ray Science" School

The following is the final report for DOE grant (DE-SC0017269) which supported the establishment of a new School for training young scientist in the area of attosecond and x-ray sciences. The topic of the School was well aligned with the roadmap defined by the DOE BESAC. The first-of-a-kind school entitled the “Frontiers of Attosecond and Ultrafast X-ray Science” (http://www.erice-attosecond.it/) (FAXS) was held during March 19-28, 2017 at the Ettore Majorana Foundation and Centre for Scientific Culture (http://www.ccsem.infn.it/) in Erice, Sicily. The FAXS Directors were Louis DiMauro (The Ohio State University, USA), Alicja Domaracka (CIMAP-CNRS, France) and Mauro Nisoli (Politecnico di Milano, Italy). The DOE funds were used to support the registration fee for young scientist (graduate students and postdocs) from US institutions (see attached list). The registration fee included participation, lodging and meals over the duration of the School.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Five rad things you can do with an “atom smasher”

Early in the 20th century, scientists began to unravel the atom’s inner workings, discovering tiny particles like protons, neutrons and electrons. To better understand how these particles work, pioneer scientists developed and built “atom smashers,” huge machines that accelerate particles to near the speed of light and crash them into each other at extremely high energies.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2012

Revised Guidelines for the NSLS-II Beamline Shielding Design

The annual dose to NSLS-II1 beamline scientists will be kept well below federal limits and within BNL administrative levels through shielding, operational procedures, and administrative controls. Shielding guidelines to the beamline design have been provided to reduce radiation levels external to the beamline enclosures during normal operation to <0.05 mrem/h and as low as reasonably achievable. Assuming occupancy of 2000 hours per year, this will reduce annual dose limit to the beamline scientists to 100 mrem or less.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Study of Regional Climate Change Final Technical Report

Anthropogenic activity of fossil fuel and biomass burning emissions increase tropospheric aerosol concentrations causing a direct cooling effect by scattering solar radiation and thus increasing the Earth’s albedo. In addition, the aerosols can act as cloud condensation nuclei to regulate cloud droplet number and size, thereby changing both the cloud albedo, and the cloud lifetime and precipitation. Thus, the aerosol climate effect concerns intricate aerosol-cloud-radiation-precipitation interactions which are recognized to introduce the largest uncertainties in using GCMs to project future regional climate changes. The climate effects of aerosols are significant in the land regions of the Northern Hemisphere, in particular the sulfate aerosols over East Asia where significant anthropogenic SO 2 emissions have been observed and concentrations of other aerosol species are also high. The objective of the present project is to advance “modeling aerosol-cloud-climate interactions” in two areas: the aerosol-cloud microphysics interactions and model simulations of aerosol effects on regional climate with focus on East Asia. To achieve the objective, in addition to analyzing relevant observations, the project conducts and diagnoses regional and global climate model simulations. Specifically, two collaborative tasks were carried out: Task-1: Incorporating a physics-based, two-moments cloud scheme developed by J. P. Chen/National Taiwan University (NTU) into regional models (WRF and WRF-Chem) to study “aerosol-cloud microphysics interactions over eastern China and the southeast Pacific” ; for latter region, CMIP5 models exhibit distinct biases in (weaker) cloud radiative effects and (warmer) sea surface temperature. The task is conducted in collaboration with J.-P. Chen, H.-W. Xue/Peking University, and H. Liao/Institute of Atmospheric Physics; and Task-2: Diagnosis of NCAR-CESM and WRF model simulations of “aerosol climate effects” focusing on changes of circulation, precipitation and clouds over East Asia. The task is conducted in collaboration with J.-P. Chen, and I-Chun Tsai & H.-H. Hsu/Academia Sinica. For each task, several topical studies were carried out and documented in eleven (11) articles (five for Task-1 and six for Task-2), published in: J. Atmospheric Sciences (2); J. Climate (1); Climate Dynamics (3); J. Geophysical Research (2); Geophysical Research Letter (1); Int. J. Climatology (1); and Advances in Atmospheric Sciences (1). In addition, Wei-Chyung Wang (the PI) continues serving as the U. S. Chief Scientist for the joint agreement, “Climate Sciences”, between the U. S. DOE and China Ministry of Sciences and Technology (Riches et al., 2010). In this capacity, he works closely with Michael Riches/DOE (the U. S. Manager) to coordinate the scientific exchanges (visiting scientists) between the two countries. Educations (graduate students) and trainings (postdoctoral research associates) are key elements of the research project.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

New X-Ray Spectrometer Developed

X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) are useful tools for characterizing numerous properties of a given material. They can give elemental composition, metal oxidation states, spin state, orbital occupancy, and more. A drawback is that these types of measurements have historically needed synchrotron light sources to generate high flux X-ray beams and high-resolution monochromators to provide a monoenergetic excitation source. Synchrotrons are building-sized facilities (often operated in the U.S. by the DOE) and have the scheduling complexities and logistical issues that accompany any large-scale research facility. There are added challenges for scientists wishing to analyze radioactive samples such as plutonium or other actinides. These limitations are now mitigated by a small, “portable” X-ray emission and absorption spectrometers developed by Los Alamos scientists and the University of Washington.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗