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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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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

The SDSS/APOGEE catalogue of HgMn stars

ABSTRACT We report on H-band spectra of chemically peculiar Mercury–Manganese (HgMn) stars obtained via the SDSS/APOGEE survey. As opposed to other varieties of chemically peculiar stars such as classical Ap/Bp stars, HgMn stars lack strong magnetic fields and are defined by extreme overabundances of Mn, Hg, and other heavy elements. A satisfactory explanation for the abundance patterns remains to be determined, but low rotational velocity is a requirement and involvement in binary/multiple systems may be as well. The APOGEE HgMn sample currently consists of 269 stars that were identified among the telluric standard stars as those whose metallic absorption content is limited to or dominated by the H-band Mn ii lines. Due to the fainter magnitudes probed by the APOGEE survey as compared to past studies, only 9/269 stars in the sample were previously known as HgMn types. The 260 newly identified HgMn stars represents a more than doubling of the known sample. At least 32 per cent of the APOGEE sample are found to be binary or multiple systems, and from multi-epoch spectroscopy, we were able to determine orbital solutions for at least one component in 32 binaries. Many of the multilined systems include chemically peculiar companions, with noteworthy examples being the HgMn+Ap/Bp binary HD 5429, the HgMn+HgMn binary HD 298641, and the HgMn+Bp Mn + Am triple system HD 231263. As a further peculiarity, roughly half of the sample produces narrow emission in the C i 16895 Å line, with widths and radial velocities that match those of the Mn ii lines.

Chojnowski, S. Drew↗
NASA NTRSDate not supplied

Preliminary Characterization of Spinel Troctolite Clast Identified in Apollo Next Generation Sample Analysis (ANGSA) Core 73002

The lunar magnesian (Mg-) suite is a diverse lithological group composed of Mg-rich mafic minerals. The Mg-suite consists primarily of troctolites, norites, gabbronorites, and spinel troctolites. These rocks exhibit contradictory geochemical traits, with mafic minerals bearing high Mg# (molar 100×Mg/[Mg+Fe]) indicating primitive parental magmas, but also plagioclase saturation and enrichments in incompatible trace elements (i.e., KREEP) indicate more evolved parental magmas. A variety of models have been invoked to explain the occurrence and petrogenesis of the Mg-suite. Here, we report on a new spinel troctolite clast found in Apollo Next Generation Sample Analysis (ANGSA) program core 73002. Sample 73002 was acquired at Station 3 during Apollo 17 as the upper part of a double-drive tube with sample 73001. During processing, the spinel troctolite clast (0.066 g) was found at the 4.0–4.5 cm depth interval.

A. C. Stadermann↗
DOE OSTI2018

Standardized protocols and procedures can precisely and accurately quantify non-structural carbohydrates

Non-structural carbohydrates (NSCs), the stored products of photosynthesis, building blocks for growth, and fuel for respiration, are central to plant metabolism, but their measurement is challenging. Differences in methods and procedures among laboratories can cause results to vary widely, limiting our ability to integrate and generalize patterns in plant C balance among studies. A recent assessment found that NSC concentrations measured for a common set of samples can vary by an order of magnitude, but sources for this variability were unclear. We measured a common set of nine plant material types, and two synthetic samples with known NSC concentrations, using a common protocol for sugar extraction and starch digestion, and three different sugar quantification methods (ion chromatography, enzyme, acid) in six laboratories. We also tested how sample handling, extraction solvent, and centralizing parts of the procedure in one laboratory affected results. NSC concentrations measured for synthetic samples were within about 11.5% of known values for all three methods. However, differences among quantification methods were the largest source of variation in NSC measurements for natural plant samples because the three methods quantify different NSCs. The enzyme method quantified only glucose, fructose, and sucrose, with ion chromatography we additionally quantified galactose, while the acid method quantified a large range of mono- and oligosaccharides. For some natural samples, acid method quantification doubled sugar relative to the other methods, demonstrating that trees allocate C to a range of sugar molecules. Sample handling had little effect on measurements, while ethanol sugar extraction improved accuracy over water extraction. Our results demonstrate that reasonable accuracy of NSC measurements can be achieved when different methods are used, as long as protocols are robust and standardized. Thus, we provide detailed protocols for the extraction, digestion and quantification of NSCs in plant samples, which should improve the comparability of NSC measurements among laboratories.

Landhäusser, Simon M.↗
DOE OSTI2018

13 TeV pp collisions, SM type, PYTHIA8 generator: tev13pp_pythia8_minbias_a14

MinBias events used to mix with signal processes. 5k events per file. Pythia8 Minimum bias (ND+SD+DD) sample with Tune A14 with NNPDF23LO PDF, inspired by ATLAS run2. Events include non-diffractive, single diffractive and double diffractive events. The sample used by hs-toolkit for mixing with signal events.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1971

Sedimentology of Apollo 11 and 12 lunar soils.

Differences in the modal composition of samples from an Apollo 11 core tube (10005) suggest the presence of at least three depositional units. The double-drive-tube core sample from the Apollo 12 site shows evidence of at least 16 depositional episodes. The earliest recognizable event at the Apollo 12 site carried light-colored soil rich in feldspathic-rock fragments into the area and may be related to ejection of ray material from Copernicus. Prior to the formation of Surveyor Crater at least 11 depositional episodes took place. Unit 7-8, the thickest unit intersected by the core tube, is tentatively identified as the Surveyor Crater ejecta blanket. Most of the soil at the Apollo 11 and 12 sites was probably generated locally with a smaller contribution coming from a more distant source possibly in the lunar highlands.

Lindsay, J. F.↗
NASA NTRS2012

Radio-to-Gamma-Ray Monitoring of the Narrow-line Seyfert 1 Galaxy PMN J0948+0022 from 2008 to 2011

We present more than three years of observations at different frequencies, from radio to high-energy γ-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z = 0.585). This source is the first NLS1 detected at energies above 100 MeV and therefore can be considered the prototype of this emerging new class of γ-ray emitting active galactic nuclei (AGN). The observations performed from 2008 August 1 to 2011 December 31 confirmed that PMN J0948+0022 generates a powerful relativistic jet, which is able to develop an isotropic luminosity at gamma-rays of the order of 1048 erg per second, at the level of powerful quasars. The evolution of the radiation emission of this source in 2009 and 2010 followed the canonical expectations of relativistic jets with correlated multiwavelength variability (gamma-rays followed by radio emission after a few months), but it was difficult to retrieve a similar pattern in the light curves of 2011. The comparison of gamma-ray spectra before and including 2011 data suggested that there was a softening of the highenergy spectral slope. We selected five specific epochs to be studied by modelling the broad-band spectrum, which are characterised by an outburst at gamma-rays or very low/high flux at other wavelengths. The observed variability can largely be explained by changes in the injected power, the bulk Lorentz factor of the jet, or the electron spectrum. The characteristic time scale of doubling/halving flux ranges from a few days to a few months, depending on the frequency and the sampling rate. The shortest doubling time scale at gamma-rays is 2.3 +/- 0.5 days. These small values underline the need of highly sampled multiwavelength campaigns to better understand the physics of these sources.

monitoring↗
DOE OSTI2014

Structural, electronic and magnetic properties of the series of double perovskites (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6}

Polycrystalline samples of the series of double perovskites Sr{sub 2−x}La{sub x}FeIrO{sub 6} were synthesized. Their structural, electronic and magnetic properties were investigated by X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, heat capacity and electrical resistivity experiments. The compounds crystallize in a monoclinic structure and were fitted in space group P2{sub 1}/n, with a significant degree of Fe/Ir cationic disorder. As in Ca{sub 2−x}La{sub x}FeIrO{sub 6} the Sr-based system seems to evolve from an antiferromagnetic ground state for the end members (x=0.0 and x=2.0) to a ferrimagnetic order in the intermediate regions (x∼1). Since Mössbauer spectra indicate that Fe valence remains 3+ with doping, this tendency of change in the nature of the microscopic interaction could be attributed to Ir valence changes, induced by La{sup 3+} electrical doping. Upon comparing both Ca and Sr series, Sr{sub 2−x}La{sub x}FeIrO{sub 6} is more structurally homogenous and presents higher magnetization and transition temperatures. Magnetic susceptibility measurements at high temperatures on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6} indicate a very high ferrimagnetic Curie temperature T{sub C}∼700K. For the Sr{sub 2}FeIrO{sub 6} compound, electrical resistivity experiments under applied pressure suggest that this material might be a Mott insulator. - Graphical abstract: The Weiss constant as a function of La doping for the (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6} series, indicating changes in Fe–Ir magnetic coupling on both families. - Highlights: • The double perovskite series (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6} were synthesized. • Changes in the Fe-Ir magnetic coupling due to La doping on both series. • Evidence of high T{sub C} on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6}. • Indication of Mott insulator behavior on Sr{sub 2}FeIrO{sub 6}.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

From Apollo to Artemis: Opening and Processing Lunar Core 73002 for the ANGSA Program

The Apollo mission returned 382 kg of lunar material comprising rock, soil and core samples. Some of these samples were intentionally set aside after their return from the Moon for future study, including samples sealed on the lunar surface, frozen samples and samples stored under Helium. The Apollo Next Generation Sample Analysis (ANGSA) program was established to study thesesamples, in part to help bridge the gap between Apollo and the next generation of lunar science and exploration.Apollo 17 double drive tube core sample 73001/73002 was collected about 50 meters east of Lara Crater from a landslide deposit originating from South Massif. After separating the two halves, the lower drive tube 73001 was immediately sealed in a special vacuum container. Both drive tubes were then placed in an Apollo Lunar Sample Return Container (ALSRC) and returned to Earth under vacuum. Total sample weight and length of 73001/73002 is 1263.0 g and up to 60 cm, with the upper drive 73002 containing 429.7 g and 23 cm of material ( which was then compressed to 18.5 cm during extrusion in the lab). We will present the meticulous methods involved in preparing for, opening and processing lunar core 73002, the upper half of the double drive tube. This includes searching and locating procedures and tools, practicing assembly and extrusion in a mock-up, and finally opening and dissecting the core sample 73002. Challenges (both expected and unexpected) encountered along the way and lessons learned during this project will help pave the way towards improving future lunar sample return missions and advancing insight into the Moon’s history

C. H. Krysher↗
NASA NTRS1987

Relativistic beaming and the nuclei of double-lobed quasars

If the simple relativistic beaming model for extragalactic radio sources is at all correct, Doppler boosting may bias us toward choosing those objects pointing nearly at us in flux-density limited samples. In order to minimize any such effects in statistical tests of physical theories of these objects, an attempt is made to define a complete sample of sources with random orientations. For a sample of 26 double-lobed quasars, the dependence of a number of observable features on the angle to the line of sight and on the superluminal velocity is examined, and the distribution of superluminal velocities for the sources is measured. Two new superluminals are reported, and their apparent velocities and nuclear strengths are discussed.

Hough, David H.↗
NASA NTRSDate not supplied

Exploring A Lunar Landslide Deposit In The Taurus-Littrow Valley (TLV). Variations In Mineralogy And Mineral Volatile Traps.

The double drive tube core sample (73001/73002), collected at Station 3 during the Apollo 17 mission, penetrated a lunar landslide deposit that was transported from the slope of the South Massif into the TLV (Figure 1). Orbital data suggest that this deposit represents multiple events that were triggered by movement along the Lee-Lincoln scarp [e.g., 1] or impact events [e.g., 2,3]. Although numerous core and trench samples were collected during the Apollo pro-gram and numerous landslide deposits have been identified on the lunar surface by orbital missions [e.g., 3], the Station 3 double drive tube is the only core that penetrated a landslide deposit. The intentions of our study are: to establish the stratigraphy of the deposit; to better understand the processes at work during the event(s), including the role of volatiles in the event(e.g., fluidization-enabled flow, escape of fluidizing volatiles) [1] and the capability of deposits for trapping indigenous volatiles; the number of landslide events; and the trigger(s) of such events. Here, we report some initial petrologic observations of the < 1mm fraction of the regolith. A companion abstract [4] emphasizes <1 mm lithic fragments, compares them to surface lithologies, and to > 4 mm lithic fragments.

M J Cato↗
NASA NTRS1990

A homogeneous sample of binary galaxies: Basic observational properties

A survey of optical characteristics for 585 binary systems, satisfying a condition of apparent isolation on the sky, is presented. Influences of various selection effects distorting the average parameters of the sample are noted. The pair components display mutual similarity over all the global properties: luminosity, diameter, morphological type, mass-to-luminosity ratio, angular momentum etc., which is not due only to selection effects. The observed correlations must be caused by common origin of pair members. Some features (nuclear activity, color index) could acquire similarity during synchronous evolution of double galaxies. Despite the observed isolation, the sample of double systems is seriously contaminated by accidental pairs, and also by members of groups and clusters. After removing false pairs estimates of orbital mass-to-luminosity ratio range from 0 to 30 f(solar), with the mean value (7.8 plus or minus 0.7) f(solar). Binary galaxies possess nearly circular orbits with a typical eccentrity e = 0.25, probably resulting from evolutionary selection driven by component mergers under dynamical friction. The double-galaxy population with space abundance 0.12 plus or minus 0.02 and characteristic merger timescale 0.2 H(exp -1) may significantly influence the rate of dynamical evolution of galaxies.

Karachentsev, I. D.↗
DOE OSTI2023

Broadband, 920-nm mirror thin film damage competition

This year’s competition proposed to survey the state-of-the-art broadband, near-IR multilayer dielectric (MLD) mirrors designed for ultra-short, pulsed laser applications. The requirements for the coatings were a minimum reflection of 99.5% at 45-degree incidence angle for S-polarization from 830 nm to 1010 nm and group delay dispersion (GDD) < ± 50 fs 2 . The participants in this effort selected the coating materials, coating design, and deposition method. Samples were damage tested at a single testing facility to enable direct comparison among the participants using a 25 ± 5 fs OPCPA laser system operating at 5 Hz. A double blind test assured sample and submitter anonymity. The damage performance results, sample rankings, details of the deposition processes, coating materials and substrate cleaning methods are shared here. We found that multilayer coatings using tantala and/or hafnia as high index materials were top performers within several coating deposition groups. Specifically, dense coatings by ion-beam sputtering (IBS), magnetron sputtering (MS), and electron-beam ion assisted deposition (e-beam IAD) exhibited highest damage initiation onset (LIDT) while e-beam coatings were low performers. In addition, damage growth onset (LDGT) was also examined and the results are reported here for all samples as this performance metric plays an important role in establishing the safe operational conditions for larger aperture, ultrashort pulsed lasers. As a result, not all coating samples in the survey met the GDD requirements stated above and associated measurements are discussed in the context of the present and past competitions focused on similar broadband, near-IR MLD coatings.

42 ENGINEERING↗
NASA NTRS1977

Grain size, petrographic, and FMR studies of the double core 60009/10 - A study of soil evolution

Six samples from the upper core 60010 of the double drive core 60009/60010 were analyzed for grain size distribution, petrographic particle types and abundances, magnetic fraction, and ferromagnetic resonance. It was found that the magnetic fraction of these soils is not equivalent to the agglutinate fraction, and magnetic separation partitions high-FeO agglutinate from low-FeO agglutinates. Various maturity indices are in essential agreement. The deposition of most or all of the core could have occurred in a single event. If that is the case, the core units have no time-stratigraphic significance and do not reflect individual cratering events.

Mckay, D. S.↗
NASA NTRS2005

Tomographic Location of Potential Melt-Bearing Phenocrysts in Lunar Glass Spherules

In 1971, Apollo 17 astronauts collected a 10 cm soil sample (74220) comprised almost entirely of orange glass spherules. Below this, a double drive-tube core sampled a 68 cm thick horizon comprised of orange glass and black beads (crystallized equivalents of orange glass). Primitive lunar glass spherules (e.g.-A17 orange glasses) are thought to represent ejecta from lunar mare fire fountains [1, 2]. The fire-fountains were apparently driven by a combination of C-O gas ex-solution from orange glass melt and the oxidation of graphite [3, 4]. Upon eruption, magmas lost their volatiles (e.g., S, CO, CO2) to space. Evidence for volatile escape remains as volatile-rich coatings on the exteriors of many spherules [e.g., 5,6]. Moreover, [7] showed that Type I and II Fe-Ni-rich metal particles found within orange glass olivine phenocrysts, or free-floating in the glass itself, are powerful evidence for the volatile driving force for lunar fire fountains.

Ebel, D. S.↗
DOE OSTI2018

Structural and Magnetic Properties of the Series of Double-Perovskite Sr{sub 2−x}Bi{sub x}MnMoO{sub 6}

Polycrystalline samples of a series of double-perovskite Sr{sub 2−x}Bi{sub x}MnMoO{sub 6} (x = 0, 0.05, 0.10, 0.15, 0.20, and 0.25) were synthesized by solid-state reaction, and their structural and magnetic properties were investigated by means of X-ray power diffraction and magnetic measures. Rietveld analysis of room-temperature XRD data shows that all the samples are single phases and belong to the I4/m space group. The degree of Mn/Mo order (η) and the unit-cell volume decrease monotonically with the increase of Bi concentration. The field dependence of the magnetization suggests that all the samples are anti-ferromagnetism. With Bi doping, the magnetization increases at low Bi concentration (x ≤ 0.15), which indicates the formation of ferrimagnetic interaction between the Mo{sup 5+} and Mn{sup 2+} caused by the effect of the electron doping in the compounds; however, due to the decline of the Mn/Mo order (η), the magnetization tends to decrease upon the Bi concentration in the high doping levels (0.15 ≤ x ≤ 0.25). The non-monotonic variation of the Neel temperature (T{sub N}) is consistent with the variation tendency of magnetization upon Bi doping.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Double sided measurements and associated error bars for planar samples or subassemblies

Many of the high energy density (HED) experiments use targets with planar components usually in a multilayer stack as the physics package which is at the heart of the experiment. The physics package contains the sample part under study as well as other components as shown in Fig. 1, that when exposed to the laser drive applies pressure onto or shock the main component to take it to the desired state in the phase diagram. These other components may include the ablator, pusher, x-ray pre-heat shield, window or other special components. The components are usually glued together. Currently, experiments on NIF and Omega in the Dynamic Materials campaign use several platforms such as Diffraction, EOS and Strength (Ref 1-3) which all use such planar stack physics packages.

42 ENGINEERING↗
DOE OSTI2014

Enhanced magnetoresistance induced by oxygen deficiency in La{sub 0.4}Ca{sub 0.6}MnO{sub 3-δ} oxides

We report electrical features and magnetoresistance behavior of the oxygen deficient La{sub 0.4}Ca{sub 0.6}MnO{sub 3-δ} perovskites (δ = 0, 0.15, and 0.2). These samples will be referred to as S0, S15, and S20, respectively. The dependence of electrical transport on temperature and magnetic field is systematically investigated between 2 K and 400 K in magnetic field ranging up to 5 T. The parent compound shows a stable charge ordering/antiferromagnetic state with a semiconductor-like behavior in all considered temperature range. The variable range hopping and thermally activated hopping models are found to fit well with the electrical resistivity data at low and high temperatures, respectively. Oxygen deficiency tends to weaken the charge ordering and induce ferromagnetism and metallicity at low temperature. Metal insulator transition appears at higher fields for lower oxygen deficit (S15 sample) and without field for the S20 sample. The resistivity data for S15 sample are discussed in the framework of the variable-range hopping model. Abnormal transport properties were observed in the S20 sample, characterized by the double metal-insulator transitions and low minimum behavior. These results are discussed in terms of phenomenological percolation model, based on the phase segregation of ferromagnetic metallic clusters and paramagnetic insulating regions. While the parent compound shows no magnetoresistance, a large magnetoresistance is observed in the deficient samples at low temperature reaching 90% and 75% at 2 T for S15 and S20 samples, respectively. Noticeably, these values reached 98% and 91% at 5 T. The appearance of colossal magnetoresistance is attributed to the spin dependent hopping between spin clusters and/or ferromagnetic domains.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗