Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “In(HO)3”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Statistical analysis of AFE GN&C aeropass performance

Performance of the guidance, navigation, and control (GN&C) system used on the Aeroassist Flight Experiment (AFE) spacecraft has been studied with Monte Carlo techniques. The performance of the AFE GN&C is investigated with a 6-DOF numerical dynamic model which includes a Global Reference Atmospheric Model (GRAM) and a gravitational model with oblateness corrections. The study considers all the uncertainties due to the environment and the system itself. In the AFE's aeropass phase, perturbations on the system performance are caused by an error space which has over 20 dimensions of the correlated/uncorrelated error sources. The goal of this study is to determine, in a statistical sense, how much flight path angle error can be tolerated at entry interface (EI) and still have acceptable delta-V capability at exit to position the AFE spacecraft for recovery. Assuming there is fuel available to produce 380 ft/sec of delta-V at atmospheric exit, a 3-sigma standard deviation in flight path angle error of 0.04 degrees at EI would result in a 98-percent probability of mission success.

Chang, Ho-Pen↗
NASA NTRS1997

Protostars and Disks

The research concentrated on high angular resolution (arc-second scale) studies of molecular cloud cores associated with very young star formation. New ways to study disks and protoplanetary systems were explored. Findings from the areas studied are briefly summarized: (1) molecular clouds; (2) gravitational contraction; (3) jets, winds, and outflows; (4) Circumstellar Disks (5) Extrasolar Planetary Systems. A bibliography of publications and submitted papers produced during the grant period is included.

Ho, Paul↗
DOE OSTI2020

Materials Data on LiHo(WO4)2 by Materials Project

LiHo(WO4)2 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (2.04 Å) and two longer (2.17 Å) Li–O bond lengths. Ho3+ is bonded to six O2- atoms to form distorted HoO6 octahedra that share corners with eight equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 47–61°. There are a spread of Ho–O bond distances ranging from 2.23–2.34 Å. W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four equivalent HoO6 octahedra and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 47–61°. There are a spread of W–O bond distances ranging from 1.82–2.21 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and one W6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ho3+, and one W6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two equivalent W6+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two equivalent W6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effects of isoalcohol blending with gasoline on autoignition behavior in a rapid compression machine: Isopropanol and isobutanol

Alcohols, and particularly isoalcohols, are potentially advantageous blendstocks towards achieving efficient, low-carbon intensity internal combustion engines. Their use in advanced configurations, such as boosted spark-ignition or spark-assisted compression ignition, requires a comprehensive understanding of their blending effects on the low- and intermediate-temperature autoignition behavior of petroleum-derived gasoline. This work reports an experimental and modeling study of such autoignition characteristics quantified in a twin-piston rapid compression machine. Isopropanol and isobutanol are blended into a research-grade gasoline (FACE-F) at oxygenate blend levels of 0 to 30% vol/vol, with tests conducted at pressures of 20 and 40 bar, temperatures from 700 to 1000 K, and dilute stoichiometric fuel loadings. Changes to overall reactivity, including first-stage and main ignition times, and preliminary exothermicity are established, with comparisons made to previous measurements with ethanol-blended FACE-F gasoline. Furthermore, it is found that at low-temperature/NTC conditions (700–860 K) the isoalcohols suppress first-stage reactivity and associated heat release while main ignition times are extended. At NTC/intermediate-temperature (860–1000 K) conditions changes to fuel reactivity are less significant with isopropanol slightly suppressing reactivity and isobutanol promoting ignition. Detailed chemical kinetic modeling is used to interpret the experimental measurements. Overall trends of suppression or promotion in the blending behavior are reasonably captured by the model. Sensitivity and rate of production analyses indicate that at lower temperatures H-atom abstraction reactions from the surrogate fuel molecules (e.g., cyclopentane, isooctane) and the isoalcohols via OH are important leading to TC 3 H 6 OH and IC 4 H 8 OH–C radicals, for isopropanol and isobutanol respectively, which act as scavengers in the system. At higher temperatures, similar chemistries are dominant, but there is an increasing importance of abstraction by HO 2 . The kinetic modeling also indicates that the promoting effect of isobutanol at higher temperatures is due to the increased abstractions at the γ-sites, while at lower temperatures abstraction at the α-site leads to greater reactivity suppression.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsHo(WO4)2 by Materials Project

CsHo(WO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 2.97–3.49 Å. Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.35 Å. W6+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing WO6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of W–O bond distances ranging from 1.85–2.18 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Cs1+ and two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Ho3+, and one W6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Cs1+, one Ho3+, and two equivalent W6+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Cs1+, one Ho3+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of f -element complexation on the radiolysis of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP])

A systematic study of the impact on the chemical reactivity of the oxidising n-dodecane radical cation (RH˙ + ) with f-element complexed 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) has been undertaken utilizing time-resolved electron pulse radiolysis/transient absorption spectroscopy and high-level quantum mechanical calculations. Lanthanide ion complexed species, [Ln((HEH[EHP]) 2 ) 3 ], exhibited vastly increased reactivity (over 10× faster) in comparison to the non-complexed ligand in n-dodecane solvent, whose rate coefficient was k = (4.66 ± 0.22) × 10 9 M -1 s -1 . Similar reactivity enhancement was also observed for the corresponding americium ion complex, k = (5.58 ± 0.30) × 10 10 M -1 s -1 . The vastly increased reactivity of these f-element complexes was not due to simple increased diffusion-control of these reactions; rather, enhanced hole transfer mechanisms for the complexes were calculated to become energetically more favourable. Interestingly, the observed reactivity trend with lanthanide ion size was not linear; instead, the rate coefficients showed an initial increase (Lu to Yb) followed by a decrease (Tm to Ho), followed by another increase (Dy to La). This behaviour was excellently predicted by the calculated reaction volumes of these complexes. In conclusion, complementary cobalt-60 gamma irradiations for select lanthanide complexes demonstrated that the measured kinetic differences translated to increased ligand degradation at steady-state timescales, affording ~38% increase in ligand loss of a 1:1 [La((HEH[EHP]) 2 ) 3 ]: HEH[EHP] ratio system.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Materials Data on Ho2CoTe2(SO7)2 by Materials Project

Ho2CoTe2(SO7)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.26–2.57 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent SO4 tetrahedra. There are a spread of Co–O bond distances ranging from 2.05–2.13 Å. Te4+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Te–O bond distances ranging from 1.90–1.92 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Ho3+ and one S6+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Co2+ and one S6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ho3+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ho3+ and one Te4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+, one Co2+, and one Te4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+, one Co2+, and one Te4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho6Pb2Se11 by Materials Project

Ho6Pb2Se11 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are six inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with three HoSe6 octahedra, corners with two equivalent PbSe7 pentagonal bipyramids, and edges with five HoSe6 octahedra. The corner-sharing octahedra tilt angles range from 9–43°. There are a spread of Ho–Se bond distances ranging from 2.81–2.89 Å. In the second Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with three HoSe6 octahedra, corners with two equivalent HoSe7 pentagonal bipyramids, and edges with five HoSe6 octahedra. The corner-sharing octahedra tilt angles range from 7–43°. There are a spread of Ho–Se bond distances ranging from 2.80–2.97 Å. In the third Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with three HoSe6 octahedra, corners with four equivalent PbSe7 pentagonal bipyramids, edges with five HoSe6 octahedra, and an edgeedge with one PbSe7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 9–48°. There are a spread of Ho–Se bond distances ranging from 2.81–2.92 Å. In the fourth Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with three HoSe6 octahedra, corners with four equivalent HoSe7 pentagonal bipyramids, edges with five HoSe6 octahedra, and an edgeedge with one HoSe7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 7–57°. There are a spread of Ho–Se bond distances ranging from 2.82–2.89 Å. In the fifth Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with two HoSe6 octahedra, corners with two equivalent HoSe7 pentagonal bipyramids, corners with two equivalent PbSe7 pentagonal bipyramids, edges with two equivalent HoSe6 octahedra, edges with three equivalent HoSe7 pentagonal bipyramids, and edges with three equivalent PbSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 48–57°. There are a spread of Ho–Se bond distances ranging from 2.80–2.92 Å. In the sixth Ho3+ site, Ho3+ is bonded to seven Se2- atoms to form distorted HoSe7 pentagonal bipyramids that share corners with eight HoSe6 octahedra, edges with four HoSe6 octahedra, edges with two equivalent PbSe7 pentagonal bipyramids, and faces with two equivalent HoSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 17–67°. There are a spread of Ho–Se bond distances ranging from 2.86–3.23 Å. There are two inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pb–Se bond distances ranging from 2.91–3.65 Å. In the second Pb2+ site, Pb2+ is bonded to seven Se2- atoms to form distorted PbSe7 pentagonal bipyramids that share corners with eight HoSe6 octahedra, edges with four HoSe6 octahedra, edges with two equivalent HoSe7 pentagonal bipyramids, and faces with two equivalent PbSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 24–68°. There are a spread of Pb–Se bond distances ranging from 2.95–3.36 Å. There are eleven inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Pb2+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ho3+ and two equivalent Pb2+ atoms. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to two Ho3+ and two equivalent Pb2+ atoms. In the fourth Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Ho3+ atoms. In the fifth Se2- site, Se2- is bonded in a 4-coordinate geometry to two Ho3+ and two equivalent Pb2+ atoms. In the sixth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to four Ho3+ and one Pb2+ atom. In the seventh Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Ho3+ and one Pb2+ atom. In the eighth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Pb2+ atoms. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Ho3+ and one Pb2+ atom. In the tenth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ho3+ and two equivalent Pb2+ atoms. In the eleventh Se2- site, Se2- is bonded to five Ho3+ atoms to form distorted edge-sharing SeHo5 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoAl3(BO3)4 by Materials Project

HoAl3(BO3)4 is Calcite-derived structured and crystallizes in the trigonal R32 space group. The structure is three-dimensional. Ho3+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Ho–O bond lengths are 2.33 Å. Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.95 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.38 Å) and one longer (1.39 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All B–O bond lengths are 1.39 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one B3+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Al3+, and one B3+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one B3+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1993

A new observational and numerical study of tidal interactions in M81-M82-NGC3077 system

A nearby system of interacting galaxies M81-M82-NGC3077 triplet (D = 3.3 Mpc; Freeman & Madore 1988) has been studied using multi-wavelength observations and numerical simulations to obtain a comprehensive understanding on the dynamics and the consequences of tidal interactions in a group environment. The VLA 12-field Mosaic H I observations of 2 x 1.5 deg. region have revealed a vast array of H I filaments which suggests that the severity and extent of tidal disruptions far exceed the previous estimates. A tidal remnant of the former H I disk of M82 extending up to 30 kpc (in projection) is identified for the first time, and the pervasive effects of the tidal disruption are traced into the inner disk by optical and CO observations, including a kinematic trace of a large scale bar potential (Yun, Ho, & Lo 1992). The H I disk of M81 is traced out to 40 kpc in radius, and a large scale (l approx. 20 kpc) velocity anomaly ('High Velocity Trough'), which may be a remnant of a gaseous collision, is found within the disk of M81. The large H I bridge between M81 and NGC 3077 (van der Hulst 1979) is also found to extend approx. greater than 50 kpc further, bending around NGC 3077, toward M82. The total H I detected in this experiment, 5.6 x 10(exp 9) solar mass, represents the majority of the single-dish flux (Appleton, Davies, & Stephenson 1981) and suggests that the bulk of H I found in the region belongs to the three galaxies and the tidal filaments. The impact and details of the tidal interactions have been further examined through the use of numerical techniques. The 'restricted 3-body' approach was used to simulate the observed distribution of tidal H I streamers connecting the three galaxies, and the success of the simulation is further strengthened by the accurate predictions on the gas kinematics.

Yun, M. S.↗
DOE OSTI2020

Materials Data on Ho2Si2O7 by Materials Project

Ho2Si2O7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with three equivalent HoO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, edges with two equivalent HoO7 pentagonal bipyramids, and edges with two SiO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.22–2.49 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent HoO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and edges with two equivalent HoO7 pentagonal bipyramids. There is three shorter (1.63 Å) and one longer (1.70 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent HoO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and edges with two equivalent HoO7 pentagonal bipyramids. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ho3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Ho3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ho3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ho3+ and two Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoCuPbS3 by Materials Project

HoCuPbS3 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Ho3+ is bonded to six S2- atoms to form HoS6 octahedra that share corners with two equivalent HoS6 octahedra, edges with two equivalent HoS6 octahedra, and edges with four equivalent CuS4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are four shorter (2.73 Å) and two longer (2.78 Å) Ho–S bond lengths. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent CuS4 tetrahedra and edges with four equivalent HoS6 octahedra. There are a spread of Cu–S bond distances ranging from 2.32–2.42 Å. Pb2+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Pb–S bond distances ranging from 2.99–3.32 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Ho3+, two equivalent Cu1+, and two equivalent Pb2+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Ho3+, one Cu1+, and three equivalent Pb2+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Ho3+, one Cu1+, and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Yb Substitution and Ultralow Thermal Conductivity of the Ca 3– x Yb x AlSb 3 (0 ≤ x ≤ 0.81(1)) System

Here, a series of Yb-substituted Zintl phases in the Ca 3–x Yb x AlSb 3 (0 ≤ x ≤ 0.81(1)) system has been synthesized by initial arc melting and post-heat treatment, and their isotypic crystal structures were characterized by both powder and single crystal X-ray diffraction analysis. All four title compounds adopted the Ca 3 AlAs 3 -type structure (space group Pnma, Pearson code oP28, Z = 4). The overall structure can be described as a combination of the 1-dimensional (1D) infinite chain of ∞ 1 [Al(Sb 2 Sb 2/2 )] formed by two vertices sharing [AlSb 4 ] tetrahedral moieties and three Ca 2+ /Yb 2+ mixed sites located in between these 1D chains. The charge balance and the resultant independency of the 1D chains in the title system were explained by the Zintl-Klemm formalism [Ca 2+ /Yb 2+ ] 3 [(4b-Al 1– )(1b-Sb 2– ) 2 (2b-Sb 1– ) 2/2 ]. A series of DFT calculations proved that (1) the band overlap between the d-orbital states from two types of cations and the p-orbital states from Sb at the high symmetry Γ point implied a heavily doped degenerate semiconducting behavior of the quaternary Ca 2 YbAlSb 3 model and (2) the site preference of Yb for the M1 site was due to the electronic-factor criterion based on the Q values of each atomic site. The electron localization function calculations also proved that the two different shapes of lone pairs of the Sb atoms—the “umbrella-shape” and the “C-shape”—are determined by local geometry and the coordination environment on the anionic frameworks. Thermoelectric measurements of the quaternary title compound Ca 2.19(1) Yb 0.81 AlSb 3 showed an approximately two times larger ZT value than that of ternary Ca 3 AlSb 3 at 623 K due to increased electrical conductivity and ultralow thermal conductivity originated from Yb substitution for Ca.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1989

Progress in computing nozzle/plume flow fields

The long-term goal is to develop the capability to predict chemically-reacting, multi-stream nozzle and plume flow fields. Two basic Navier-Stokes solvers, including the widely used F-3D code, are upgraded to include several upwind difference schemes and portable chemistry packages. Current computational capabilities for solving equilibrium single-stream and multi-stream, frozen gas, and finite rate chemistry problems are described. A variety of complex nozzle and plume flows were computed. Solutions presented include axisymmetric plume flow for ideal and equilibrium air, 3-D NASP nozzle/afterbody flow, and an internal nozzle calculation comparing various finite-rate chemistry packages.

Ruffin, Stephen M.↗
NASA NTRS2013

Einstein@Home All-Sky Search for Periodic Gravitational Waves in LIGO S5 Data

This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50, 1 190] Hzand and with frequency derivative range of approx. [-20,1.1] x 10(exp-10) H(sub 0)z s(exp-1) for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we report upper limits on the intrinsic gravitational wave strain amplitude ho. For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h(exp 0) greater than 7.6 x 10(exp-25) at a 90% confidence level. This search is about a factor 3 more sensitive than the previous Einstein@Home search of early S5 LIGO data.

J Aasi↗
NASA NTRS2022

The First Gradual Solar Energetic Particle Event With an Enhanced He-3 Abundance on Solar Orbiter

The origin of 3 He abundance enhancements in gradual solar energetic particle (SEP) events remains largely unexplained. Two mechanisms have been suggested: the reacceleration of remnant flare material by coronal mass ejection (CME)-driven shocks in interplanetary space, and concomitant activity in the corona. We explore the first gradual SEP event with enhanced 3 He abundance that was observed by Solar Orbiter. The event started on 2020 November 24 and was associated with a relatively fast halo CME. During the event, the spacecraft was at 0.9 au from the Sun. The event-averaged 3 He/ 4 He abundance ratio is 24 times higher than the coronal or solar wind value, and the timing of the 3He intensity was similar to that of other species. We inspected available imaging, radio observations, and the spacecraft magnetic connection to the CME source. The most probable cause of the enhanced 3He abundance apparently are residual 3He ions remaining from a preceding long period of 3 He-rich SEPs on 2020 November 17–23.

Solar particle emission↗