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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Using GPUs to Enable Simulation with Computational Gravitational Dynamics in Astrophysics
Not provided.
Soft x-ray multilayers for astrophysics applications
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Identification of $\gamma$-decaying resonant states in 26 Mg and their importance for the astrophysical s process
The 22 Ne(α, n) reaction is expected to provide the dominant neutron source for the weak s process in massive stars and intermediate-mass (IM) Asymptotic Giant Branch (AGB) stars. However, the production of neutrons in such environments is hindered by the competing 22 Ne(α,γ) 26 Mg reaction. Here, the 11 B( 16 O,p) fusion-evaporation reaction was used to identify γ-decay transitions from 22 Ne + α resonant states in 26 Mg. Spin-parity restrictions have been placed on a number of α-unbound excited states in 26 Mg and their role in the 22 Ne(α,γ)26Mg reaction has been investigated. In particular, a suspected natural-parity resonance at E c.m. = 557(3) keV, that lies above the neutron threshold in 26 Mg, and is known to exhibit a strong α-cluster character, was observed to γ decay. Furthermore, a known resonance at E c.m. = 466(4) keV has been definitively assigned 2 + spin and parity. Consequently, uncertainties in the 22 Ne(α,γ) stellar reaction rate have been reduced by a factor of ~20 for temperatures ~0.2 GK.
Concept Development for Astrophysically Relevant Turbulence on NIF
We carried out the research proposed in the proposal and developed a specific concept for the generation of fully developed Rayleigh-Taylor turbulence on NIF
New Mexico Center for Particle Physics (NMCPP) -- Task A: Collider Physics; Task A2: Collider Physics; Task B: Particle Astrophysics
During the period 2010-2012, we conducted particle physics research with the ATLAS and CDF experiments and developed new instrumentation for tracking fundamental particles.
Development of a high-density gas-jet target for nuclear astrophysics and reaction studies with rare isotope beams. Final Report
The purpose of this project was to develop a high-density gas jet target that will enable a new program of transfer reaction studies with rare isotope beams and targets of hydrogen and helium that is not currently possible and will have an important impact on our understanding of stellar explosions and of the evolution of nuclear shell structure away from stability. This is the final closeout report for the project.
Breakup of loosely bound nuclei at intermediate energies for nuclear astrophysics and the development of a position sensitive microstrip detector system and its readout electronics using ASICs technologies
The work performed under this grant has led to the development of a detection system that will be used to measure reaction rates for proton or neutron capture reactions at stellar energies on radioactive ions far from stability. The reaction rates are needed to better understand the physics of nucleosynthesis in explosive stellar processes such as supernovae and x-ray burst events. The radioactive ions will be produced at the Radioactive Ion Beam Facility (RIBF) at RIKEN near Tokyo, Japan. During the course of this work, the group involved in this project has expanded by several institutions in Europe and Japan and now involves collaborators from the U.S., Japan, Hungary, Romania, Germany, Spain, Italy, China, and South Korea. As part of the project, a novel design based on large-area silicon detectors has been built and tested and the performance characterized in a series of tests using particle beams with a variety of atomic numbers at the Cyclotron Institute of Texas A&M University and the Heavy Ion Medical Accelerator in Chiba facility (HIMAC) in Chiba, Japan. The work has involved mechanical construction of a special purpose vacuum chamber, with a precision mounting system for the silicon detectors, development of a new ASICs readout system that has applications with a wide variety of silicon detector systems, and the development of a data acquisition system that is integrated into the computer system being used at RIBF. The parts noted above that are needed to carry out the research program are completed and ready for installation. Several approved experiments that will use this system will be carried out in the near future. The experimental work has been delayed due to a large increase in the cost and availability of electrical power for RIBF that occurred following the massive earthquake and tsunami that hit Japan in the spring of 2011. Another component of the research carried out with this grant involved developing the theoretical tools that are required to extract the information from the experiments that is needed to determine the stellar reaction rates. The tools developed through this part of the work will be made freely available for general use.
Final Report for DoE Grant DE-SC-0011689 - Studies of Particle Astrophysics at the Cosmic Frontier
Our research focuses on the “Cosmic Frontier”, one of the three principle thrusts of the DoE Office of Science High Energy Physics research program. The 2013 community summer study “Snowmass on the Mississippi” catalyzed joint work to describe the status and future prospects of this research thrust. Over its history, the field of cosmic ray studies has provided many discoveries of central importance to the the progress of high energy physics, including the identification of new elementary particles, measurements of particle interactions far above accelerator energies, and the confirmation of neutrino oscillations. In our research we continued this tradition, employing 2 instruments (the Auger Observatory and the HAWC Observatory) to study high energy physics questions using cosmic rays. One approach to addressing particle physics questions at the cosmic frontier is to study the very highest energy cosmic rays. This has been the major thrust of our research effort. The two largest currently operating ultra-high energy cosmic ray (UHECR) observatories are the Pierre Auger Observatory in the Southern hemisphere, covering an area of 3000 km 2 and the Telescope Array (TA) in the Northern hemisphere, covering about 700 km 2 . The observatories sample the cosmic ray air showers at ground level (with 1660 water Cerenkov stations in the Auger surface detector), and also measure the longitudinal development of air showers on clear moonless nights (approx. 10% of the events) using atmospheric fluorescence detectors. The observatories have recently installed low energy extensions, which provide an overlap with the LHC energy regime. The Auger and TA teams have established joint working groups to discuss experimental methods, compare data analyses and modeling, and perform cross calibrations. Another approach is to study high energy gamma rays. The High Altitude Water Cerenkov (HAWC) gamma-ray observatory is located at 4100 m above sea level near Pico de Orizaba in central Mexico. HAWC is the most sensitive, wide field of view, TeV gamma-ray observatory in operation. After 4 years of construction, operation of the full detector began in March 2015. The HAWC detector contains 300 tanks each 7.3 m in diameter and 4.5 m deep containing pure water. Each water tank is instrumented with 4 upward-viewing photomultiplier tubes mounted at their bottom. The water tanks record the energy deposited by and arrival times of the constituent components of impinging extensive air showers (EAS). The tanks are close-packed to optimize the spatial sampling of the shower front. The distribution of deposited energy across the shower is used for gamma-hadron rejection. Showers with large energy deposit away from the core are rejected as being hadron-initiated. The detector operates at full efficiency above 3 TeV. The angular resolution above that energy approaches 0.1 degree. As the detector operates both day and night, the wide field of view of ~2 sr, allows ~2/3 of the sky to be observed each day.
Phenomenology of astrophysical neutrinos
Research during this time period resulted in four publications, which covered three main areas, as detailed below. Pre-supernova neutrinos the diffuse supernova neutrino background high energy neutrinos at IceCube
The LLNL Program in Nuclear Structure and Nuclear Astrophysics (NSNA) (FY19 Annual Report)
Our major efforts in FY18-19 were devoted to carrying out the second GRETINA/CHICO2 campaign at ANL and the JANUS campaign at MSU/NSCL. Among a total of 13 fielded experiments, three were for Ph.D. thesis projects; two students at MSU and one at UNC at Chapel Hill. Two experiments in the JANUS campaign were led by LLNL; namely, the study of nuclear structure in 72 Se and 76 Se using the sub-barrier Coulomb excitation method. The data analysis was completed for both selenium isotopes and the results were published. The 72 Se results have been submitted to DOE/SC/NP as a science highlight and the article won a prestigious LLNL S&T Excellence in Publication Award in FY19. For experiments fielded in FY17 at TRIUMF/ISAC2 using TIGRESS/Bambino, the data analysis was completed recently and the 21 Mg results were published in FY19. For the results on the mirror nuclei 23 Mg and 23 Na, the manuscript was written and is in circulation among the coauthors. We intend to submit it for publication later this calendar year. These efforts address the isospin symmetry in the sd shell nuclei in terms of the electromagnetic properties measured with the sub-barrier Coulomb excitation method. The proposal to upgrade CHICO2 to CHICOX by resizing the detector chamber to be compatible to GRETA was approved in FY17 with a budget spread over three fiscal years starting FY18. The preliminary design was completed but cannot be finalized until the design for the GRETA holding frame is completed by the LBNL GRETA team in FY19. The fabrication will proceed once the physical compatibility of CHICOX to GRETA holding frame is confirmed. The narrative below focuses on the research efforts for which LLNL led or played a key role. This report includes two sections: 1) Evolution of shell structure and collectivity in neutron-rich nuclei, and 2) Investigating nucleosynthesis and the Standard Model with β decay.
Interrelationship between Lab, Space, Astrophysical, Magnetic Fusion, and Inertial Fusion Plasma Experiments (Graduate support for DIII-D Frontier Science Experiments)
The project, to explore the use of the DIII-D facility to investigate questions of value to discovery plasma science and provide a deepened scientific understanding behind basic plasma processes that are outside of the fusion-energy-science research line, began in September 2016 when five discovery-plasma physicists were contacted by General Atomics to form a Frontier Science Experiments (FSE) panel for brainstorming and for implementing the FSE campaign at the DIII-D National Fusion Facility. After advertising the FSE opportunity at the annual plasma physics conference, the panel grew to include six others. By January 2017, the panel for reviewing and ranking proposals was established. Evaluation of FY2017 proposals took place in February 2017. Evaluation of FY2018 proposals took place in January 2018. This proposal began 15 August 2017 and funded two research assistantships for three students who interacted, gained expertise in experimental and computational physics, and shared responsibilities on the following projects within the DIII-D (non-fusion) Frontier Science Experiments (FSE) campaign: (1) "Impact of Magnetic Perturbations on Turbulence - Zonal Flow Interactions and Saturation", (2) "Nonlinear Processes during Toroidal Alfvén Mode-Mode Interaction", (3) "Self-Consistent Chaos in Magnetic Field Dynamics", (4) “Nonmodal Decomposition of Turbulence”, and (5) “Multi-harmonic EMIC Emission -- Species mix and distribution function dependence of instabilities near the ion-cyclotron frequency”. The outcome was a fraction of one doctoral dissertation and the entirety of one master of science thesis. The work took advantage of the unique capabilities of the DIII-D National Fusion Facility to serve as the first phase of the Frontier Science Experiment (FSE) campaign, an innovative concept aiming to advance fundamental understanding in 3 key general plasma science areas - particle acceleration and energetic particles in plasmas, turbulence and transport in plasmas, and nonlinear waves and processes – all at discovery’s cutting edge.
The LLNL Program in Nuclear Structure and Nuclear Astrophysics (NSNA) FY21 Annual Report
Two papers are included in this FY21 Annual Report: ''Evolution of shell structure and collectivity in neutron-rich nuclei'' and ''Investigating nucleosynthesis and the standard model with β decay.
MEASURING THE RADIATIVE PROPERTIES OF ASTROPHYSICAL MATTER USING THE Z MACHINE.
Abstract not provided.
Study of quasi-collisional effects in laboratory and astrophysical plasmas
High-amplitude turbulence excited in plasmas at small-scales can leave imprint on the radiation produced by (accelerated) plasma particles -- mostly electrons in electron-ion plasmas and both electrons and positrons in lepton pair plasmas. Furthermore, turbulence is known to introduce "effective collisional" effects -- anomalous resistivity, dissipation, diffusion, etc. -- in the otherwise collisionless plasmas. These effective collisions affect radiation transfer and modify optical and magneto-optic effects -- the transmittance and reflectivity coefficients, Faraday rotation, etc. Note that the effective collisions considered in this project are not resonant wave-particle interactions, but much less conventional randomization of particles’ paths. Therefore, we colloquially refer them to as "quasi-collisions". The study of quasi-collisions on transport, radiative and optical properties of plasmas is the main focus of this project.