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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Machiite, Al2Ti3O9, a New Oxide Mineral from the Murchison Carbonaceous Chondrite: A New Ultra-refractory Phase from the Solar Nebula

Machiite (IMA 2016-067), Al2Ti3O9, is a new mineral that occurs as a single euhedral crystal, 4.4 mm in size, in contact with an euhedral corundum grain, 12 mm in size, in a matrix of the Murchison CM2 carbonaceous chondrite. The mean chemical composition of holotype machiite by electron probe microanalysis is (wt%) TiO2 59.75, Al2O3 15.97, Sc2O3 10.29, ZrO2 9.18, Y2O3 2.86, FeO 1.09, CaO 0.44, SiO2 0.20, MgO 0.10, total 99.87, giving rise to an empirical formula (based on 9 oxygen atoms pfu) of (Al1.17Sc0.56Y0.10Ti4+0.08Fe0.06Ca0.03Mg0.01)(Ti4+2.71Zr0.28Si0.01)O9. The general formula is (Al,Sc)2(Ti4+,Zr)3O9. The end-member formula is Al2Ti3O9. Machiite has the C2/c schreyerite-type structure with a = 17.10 Å, b = 5.03 Å, c = 7.06 Å, b = 107°, V = 581 Å3, and Z = 4, as revealed by electron backscatter diffraction. The calculated density using the measured composition is 4.27 g/cm3. The machiite crystal is highly 16O-depleted relative to the coexisting corundum grain (D17O = –0.2 ±2.4‰ and –24.1 ± 2.6‰, respectively; where D17O = d17O – 0.52 ×d18O). Machiite is a new member of the schreyerite (V2Ti3O9) group and a new Sc,Zr-rich ultrarefractory phase formed in the solar nebula, either by gas-solid condensation or as a result of crystallization from a Ca, Al-rich melt having solar-like oxygen isotopic composition (D17O ~ –25‰) under high-temperature (~1400–1500 °C) and low-pressure (~10-4–10-5 bar) conditions in the CAI-forming region near the protosun. The currently observed disequilibrium oxygen isotopic composition between machiite and corundum may indicate that machiite subsequently experienced oxygen isotopic exchange with a planetary-like 16O-poor gaseous reservoir either in the solar nebula or on the CM chondrite parent body. The name machiite is in honor of Chi Ma, mineralogist at California Institute of Technology, for his contributions to meteorite mineralogy and discovery of many new minerals representing extreme conditions of formation.

Machiite↗
NASA NTRS2018

I-Xe Dating of Aqueous Alteration in the CI Chondrite Orgueil: I. Magnetite and Ferromagnetic Separates

The I-Xe system was studied in a ferromagnetic sample separated from the Orgueil CI carbonaceous chondrite with a hand-held magnet and in two magnetite samples, one chemically separated before and the other one after neutron irradiation. This work was done in order to investigate the effects of chemical separation by LiCl and NaOH on the I-Xe system in magnetite. Our test demonstrated that the chemical separation of magnetite before irradiation using either LiCl or NaOH, or both, does not contaminate the sample with iodine and thus cannot lead to erroneous I-Xe ages due to introduction of uncor-related128*Xe. The I-Xe ages of two Orgueil magnetite samples are mutually consistent within experimental uncertainties and, when normalized to an absolute time scale with the reevaluated Shallowater aubrite standard, place the onset of aqueous alteration on the CI parent body at 4564.3 ± 0.3 Ma, 2.9 ± 0.3 Ma after formation of the CV Ca-AI-rich inclusions (CAIs). The I-Xe age ofthe ferromagnetic Orgueil separate is 3.4 Ma younger, corresponding to a closure of the I-Xe system at 4560.9 ± 0.2 Ma. These and previously published I-Xe data for Orgueil (Hohenberg et al., 2000) indicate that aqueous alteration on the CI parent body lasted for at least 5 Ma. Although the two magnetite samples gave indistinguishable I-Xe ages, their temperature release profiles differed. One of the two Orgueil magnetites released less radiogenic Xe than the other, 80% of it corresponding to the low-temperature peak of the release profile, compared to only 6% in case of the second Orgueil magnetite sample. This could be due to the difference in iodine trapping efficiencies for magnetite grains of different morphologies. Alternatively, the magnetite grains with the lower radiogenic Xe concentrations may have formed at a later stage of alteration when iodine in an aqueous solution was depleted.

I-Xe systematics↗
NASA NTRSDate not supplied

Less-Altered CI Lithology in the Kaidun Meteorite Breccia

One of the most interesting initial results of the characterization of the asteroid Ryugu regolith material returned by the Hayabusa2 spacecraft is the presence of a significant quantity of less-aqueously altered CI material, tentatively called “CI2”. This lithology is characterized by an approximately ten-fold increase in the amount of an hydrous ferromagnesian silicates over what is found n CI1 chondrites, with these being principally olivine, low- and high-calcium pyroxene. Remnant CAI phases are found as well as probable chondrule fragments. Magnetite, pyrrhotite and hydroxyapatite are abundant. The main carbonate is calcite. Matrix is mainly a mixture of saponite and serpentine phases. Assuming that this lithology should be a better representative of the more “primordial” mineralogy of early nebular solids than more processed CI1 material, we have been re-examining CI lithologies found as separate meteorites as well as clasts in other meteorites, seeking similar CI2 material. The Kaidun breccia is notorious for including almost every type of meteorite class except CR2 (which is ironic considering that Kaidun is still officially classified as CR2). We report here the discovery of a probable CI2 lithology in one carbonaceous chondrite-rich Kaidun sample.

Michael Zolensky↗
NASA NTRSDate not supplied

Hayabusa2#’s Exploration to Asteroids 2001 CC21 and 1998 KY26 Provides Key Insights Into Planetary Defense

The Hayabusa2 extended mission, nicknamed Hayabusa2# (SHARP: Small Hazardous Asteroid Reconnaissance Probe), started its mission after the Hayabusa2 spacecraft successfully returned in December 2020 to the Earth with Ryugu's samples and released the Sample Return Capsule containing it. Hayabusa2#’s key operations include flying by Near Earth Asteroid (98943) 2001 CC21 and rendezvousing with Near-Earth Asteroid 1998 KY26. The flyby is planned to be in 2026, and the rendezvous will be in 2031. Detailed investigations of these targets enable maturing key knowledge and technologies necessary for planetary defense. This paper reviews the characteristics of these targets and strategies to maximize outcomes from the mission. The spacecraft will fly by 2001 CC21 at a speed of ~5 km/s in 2026. Given constraints on the spacecraft condition, not designed to perform a flyby operation, operational plans require careful assessments to maximize the proximity observations of this asteroid. The ~700 m diameter asteroid's shape is currently unknown, though lightcurve observations suggest the asteroid is elongated. While the spin pole is not constrained well, the spin period is about 5.02 h with uncertainties of 0.01 h [1]. The taxonomic class may be L-type, which implies the presence of Calcium-aluminum-rich inclusions (CAI), one of the primitive materials in the solar system [2], although there are studies suggesting an S-type. Therefore, this must be carefully examined. Photometric and spectroscopic observations will strongly constrain this asteroid’s properties. Our rendezvous target, 1998 KY26, is a ~30 m diameter roundish object spinning at a spin period of 10.7 min, which may represent one of the common groups of Near Earth Asteroids in size and composition that give a higher likelihood of threatening the Earth. Radar and optical observations reconstructed this asteroid's shape with high uncertainties and inferred that its surface composition might be similar to that of carbonaceous asteroids [3]. No spacecraft has ever visited such small bodies. Hayabusa2# visiting 1998 KY26 will be the first mission to document its geophysical properties, offering strong insights into what most frequent invaders look like [4].

Hayabusa2#↗
NASA NTRS2022

A Unifying View of Estimation and Control Using Belief Propagation With Application to Path Planning

The use of estimation techniques on stochastic models to solve control problems is an emerging paradigm that falls under the rubric of Active Inference (AI) and Control as Inference (CAI). In this work, we use probability propagation on factor graphs to show that various algorithms proposed in the literature can be seen as specific composition rules in a factor graph. We show how this unified approach, presented both in probability space and in log of the probability space, provides a very general framework that includes the Sum-product, the Max-product, Dynamic programming and mixed Reward/Entropy criteria-based algorithms. The framework also expands algorithmic design options that lead to new smoother or sharper policy distributions. We propose original recursions such as: a generalized Sum/Max-product algorithm, a Smooth Dynamic programming algorithm and a modified versions of the Reward/Entropy algorithm. The discussion is carried over with reference to a path planning problem where the recursions that arise from various cost functions, although they may appear similar in scope, bear noticeable differences. We provide a comprehensive table of composition rules and a comparison through simulations, first on a synthetic small grid with a single goal with obstacles, and then on a grid extrapolated from a real-world scene with multiple goals and a semantic map.

Francesco A. N. Palmieri↗
NASA NTRS2024

The Effects of Peel Ply on the Damage Tolerance Characteristics of the Space Launch System (SLS) Payload Adapter Fitting (PAF)

A payload adaptor fitting (PAF) has been manufactured at NASA’s Marshall Space Flight Center (MSFC) in support of the Space Launch System (SLS) program. This structure is essentially a large cone made up of eight curved “lobes” that are joined together to form the cone. The lobes were manufactured via automated fiber placement (AFP). The PAF will carry predominantly compressive loads thus compression strength will be the focus of this study. The lobes are sandwich structure made with aluminum honeycomb core and carbon/epoxy face sheets. The lobes will be inserted into metallic rings at the top and bottom of the cone to form the full cone. Both front and back exterior surfaces of each lobe have a plain weave fabric placed at ±45⁰ to the vertical direction to help prevent fiber “breakout” during drilling. The face sheet of each lobe is thickest at the top and plies are dropped as the cone reaches the main acreage in the bottom section of the cone. The entire structure used resin impregnated peel ply that, once removed, supplies a good bonding surface for secondary bonding steps. The peel ply can be removed either directly after cure, or just before any bonding operation. Since foreign object impact can occur to the structure at any time during its life, damage tolerance of the PAF structure both with and without peel ply needed to be addressed because a previous study, albeit with limited data, showed some significant differences in damage tolerance whether the peel ply was present or not [1]. A literature search showed no results for comparing impact damage on composite laminates with and without peel ply. Load versus deflection of impact curves, visual damage, dent depth, damage as ascertained by thermography and cross-sectional microscopy were evaluated as part of the damage resistance of the structure. Compression After Impact (CAI) was performed to assess damage tolerance. The impact tests were conducted on representative specimens both with and without the peel ply present.

Sandwich Structure↗
DOE OSTI2021

Conductive Metallophthalocyanine Framework Films with High Carrier Mobility as Efficient Chemiresistors

Abstract The poor electrical conductivity of two‐dimensional (2D) crystalline frameworks greatly limits their utilization in optoelectronics and sensor technology. Herein, we describe a conductive metallophthalocyanine‐based NiPc‐CoTAA framework with cobalt(II) tetraaza[14]annulene linkages. The high conjugation across the whole network combined with densely stacked metallophthalocyanine units endows this material with high electrical conductivity, which can be greatly enhanced by doping with iodine. The NiPc‐CoTAA framework was also fabricated as thin films with different thicknesses from 100 to 1000 nm by the steam‐assisted conversion method. These films enabled the detection of low‐concentration gases and exhibited remarkable sensitivity and stability. This study indicates the enormous potential of metallophthalocyanine‐based conductive frameworks in advanced stand‐off chemical sensors and provides a general strategy through tailor‐make molecular design to develop sensitive and stable chemical sensors for the detection of low‐concentration gases.

Yue, Yan↗
DOE OSTI2020

Optimization of the JUNO liquid scintillator composition using a Daya Bay antineutrino detector

To maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and 0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. In order to bridge the one order of magnitude in the detector size difference between Daya Bay and JUNO, the Daya Bay data were used to tune the parameters of a newly developed optical model. Then, the model and tuned parameters were used in the JUNO simulation. Overall, this enabled to determine the optimal composition for the JUNO LS: purified solvent LAB with 2.5 g/L PPO, and 1 to 4 mg/L bis-MSB.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

A Medium-/Low-Voltage Joint State Estimator Through Linear Uncertainty Propagation

Traditionally, distribution system state estimations (DSSE) are challenged by the lack of measurements at both primary and secondary sides of the system. The widely available cable television (CATV) voltage sensors installed in low-voltage (LV) networks bring opportunities to achieve higher quality DSSE covering a broader area of the distribution network. This study proposes a medium-/low-voltage (MV/LV) joint distribution system state estimation approach using the untapped CATV measurements. It aims at addressing the need for system situational awareness at the grid edge while improving the estimation accuracy at both the primary and secondary sides compared to its disjointed counterpart. Linearized measurement functions and boundary condition uncertainty propagation rules are derived to ensure the computational efficiency and accuracy of the joint state estimator. Numerical experiments are conducted on an IEEE test feeder to demonstrate the efficacy of the proposed method and the value of CATV measurements.

joint state estimation↗
DOE OSTI2025

Amplitude analysis of ψ3686→γKS0KS0

Using (2712 ± 14) × 106ψ(3686) events collected with the BESIII detector, we perform the first amplitude analysis of the radiative decay ψ3686→γKS0KS0$$ \psi (3686)\to \gamma {K}_S^0{K}_S^0 $$ within the mass region MKS0KS0<2.8$$ {M}_{K_S^0{K}_S^0}<2.8 $$ GeV/c2. Employing a one-channel K-matrix approach for the description of the dynamics of the KS0KS0$$ {K}_S^0{K}_S^0 $$ system, the data sample is well described with four poles for the f0-wave and three poles for the f2-wave. The determined pole positions are consistent with those of well-established resonance states. The observed f0 and f2 states are found to be in agreement with those produced in radiative J/ψ decays. The production behaviors of f0 and f2 poles in ψ3686→γKS0KS0$$ \psi (3686)\to \gamma {K}_S^0{K}_S^0 $$ are qualified with their residues and the converted branching fractions. By comparing with J/ψ→γKS0KS0$$ J/\psi \to \gamma {K}_S^0{K}_S^0 $$ decay, the ratios Bψ3686→γf0,2BJ/ψ→γf0,2$$ \frac{\mathcal{B}\left(\psi (3686)\to \gamma {f}_{0,2}\right)}{\mathcal{B}\left(J/\psi \to \gamma {f}_{0,2}\right)} $$ are determined, which provides crucial experimental inputs on the internal structure of the f0,2 states, especially their potential mixing with glueball components.

Ablikim, M↗
DOE OSTI2026

Search for the isospin-violating decays 𝜒 𝑐⁢𝐽 → $Λ\bar{⁢Σ}^0$ + c.c. and 𝜂 𝑐 → $Λ\bar{⁢Σ}^0$ + c.c.

Using a sample of (2712.4 ± 14.3) × 10 6 𝜓⁡(3686) events collected with the BESIII detector, we perform a search for the isospin-violating decays 𝜒 𝑐⁢𝐽 → $Λ\bar{⁢Σ}^0$ + c.c.(𝐽 = 0,1,2) and 𝜂 𝑐 → $Λ\bar{⁢Σ}^0$ + c.c. No significant signal for 𝜒 𝑐⁢𝐽 or 𝜂 𝑐 is observed in the $Λ\bar{⁢Σ}^0$ invariant mass distribution. The upper limits on the branching fractions at the 90% confidence level are set to be ℬ⁡(𝜒 𝑐⁢0 → $Λ\bar{⁢Σ}^0$ + c.c.) < 1.5 × 10 −6 , ℬ⁡(𝜒 𝑐⁢1 → $Λ\bar{⁢Σ}^0$ + c.c.) < 1.6 × 10 −6 , ℬ⁡(𝜒 𝑐⁢2 → $Λ\bar{⁢Σ}^0$ + c.c.) < 1.7 × 10 −6 , and ℬ⁡(𝜂 𝑐 → $Λ\bar{⁢Σ}^0$ + c.c.) < 6.2 × 10 −5 for the first time.

Ablikim, M. [Institute of High Energy Physics] (OR↗
DOE OSTI2025

Measurement of the branching fractions of D + → K + K − π + π + π − , ϕ π + π + π − , K S 0 K + π + π − π 0 , K S 0 K + η , and K S 0 K + ω decays

Using 20.3 fb − 1 of e + e − collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector operating at the BEPCII collider, the branching fractions of three hadronic charm meson decays, D + → ϕ π + π + π − , D + → K S 0 K + π + π − π 0 , and D + → K S 0 K + ω , are measured for the first time to be ( 0.54 ± 0.19 ± 0.02 ) × 10 − 4 , ( 2.51 ± 0.34 ± 0.14 ) × 10 − 4 , and ( 2.02 ± 0.35 ± 0.10 ) × 10 − 4 , respectively. Futhermore, the branching fractions of D + → K + K − π + π + π − and D + → K S 0 K + η are measured with improved precision, yielding values of ( 0.66 ± 0.11 ± 0.03 ) × 10 − 4 and ( 2.27 ± 0.22 ± 0.05 ) × 10 − 4 , respectively. Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2025

Observation of the decay ψ ( 3686 ) → Σ 0 Σ ¯ 0 ω

Using a dataset of ( 27.12 ± 0.14 ) × 10 8 ψ ( 3686 ) events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of the decay ψ ( 3686 ) → Σ 0 Σ ¯ 0 ω with a statistical significance of 8.9 σ . The measured branching fraction is ( 1.24 ± 0.1 6 stat ± 0.1 1 sys ) × 10 − 5 , where the first uncertainty is statistical and the second is systematic. Additionally, we investigate potential intermediate states in the invariant mass distributions of Σ 0 ω , Σ ¯ 0 ω and Σ 0 Σ ¯ 0 . A hint of a resonance is observed in the invariant mass distribution of M Σ 0 ( Σ ¯ 0 ) ω , located around 2.06 GeV / c 2 , with a significance of 2.5 σ . Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2025

Observation of the Charmonium Decay η c → γ γ in J / ψ → γ η c

Using ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector at the BEPCII collider, the decay η c → γ γ in J / ψ → γ η c is observed. We determine the product branching fraction B ( J / ψ → γ η c ) × B ( η c → γ γ ) = ( 5.23 ± 0.2 6 stat ± 0.3 0 syst ) × 10 − 6 . This result is consistent with the lattice QCD calculation ( 5.34 ± 0.16 ) × 10 − 6 from HPQCD in 2023. By using the world-average values of B ( J / ψ → γ η c ) and the total decay width of η c , the partial decay width Γ ( η c → γ γ ) is determined to be ( 11.30 ± 0.5 6 stat ± 0.6 6 syst ± 1.1 4 ref ) keV , which deviates from the corresponding world-average value by 3.4 σ . Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2021

Conductive Metallophthalocyanine Framework Films with High Carrier Mobility as Efficient Chemiresistors

Abstract The poor electrical conductivity of two‐dimensional (2D) crystalline frameworks greatly limits their utilization in optoelectronics and sensor technology. Herein, we describe a conductive metallophthalocyanine‐based NiPc‐CoTAA framework with cobalt(II) tetraaza[14]annulene linkages. The high conjugation across the whole network combined with densely stacked metallophthalocyanine units endows this material with high electrical conductivity, which can be greatly enhanced by doping with iodine. The NiPc‐CoTAA framework was also fabricated as thin films with different thicknesses from 100 to 1000 nm by the steam‐assisted conversion method. These films enabled the detection of low‐concentration gases and exhibited remarkable sensitivity and stability. This study indicates the enormous potential of metallophthalocyanine‐based conductive frameworks in advanced stand‐off chemical sensors and provides a general strategy through tailor‐make molecular design to develop sensitive and stable chemical sensors for the detection of low‐concentration gases.

Yue, Yan↗