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393 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Be(B3H7)2 by Materials Project

BeB5H13BH is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four boranediylradical molecules and four BeB5H13 clusters. In each BeB5H13 cluster, Be2+ is bonded in a 4-coordinate geometry to four H+0.71+ atoms. There are a spread of Be–H bond distances ranging from 1.53–1.59 Å. There are five inequivalent B2- sites. In the first B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.34 Å. In the second B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. In the third B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. In the fourth B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.34 Å. In the fifth B2- site, B2- is bonded in a tetrahedral geometry to four H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.26 Å. There are thirteen inequivalent H+0.71+ sites. In the first H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the second H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the third H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the fourth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the fifth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the sixth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the seventh H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the eighth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the ninth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the tenth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the eleventh H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the twelfth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the thirteenth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom.

36 MATERIALS SCIENCE↗
NASA NTRS1994

Multifrequency studies of bright radio supernova remnants. 2: W49B

We report radio observations of the supernova remnant W49B using the Very Large Array (VLA) of the NRAO at 90, 20, and 6 cm. This work continues the study of the properties of young, bright supernova remnants (SNRs) begun with 3C 391 (Moffett & Reynolds 1994). Here we present high-resolution images of total intensity, polarization, and spectral index of W49B. In large-scale morphology it is basically a box-shaped remnant expanding into an apparently inhomogeneous medium, but we also find small-scale structures, arcs and filaments, which lie interior to the outer shell in projection. The actual spatial position of the filaments is unknown, though we suspect that they are in the remnant interior rather than on the front or back face of the blast wave. In addition, their distribution in two dimensions suggests the projection of a helical structure. The shell edge, sharply rising in brightness for at least 3/4 of its circumference, still remains unresolved at our highest resolution (4 sec). This for our assumed distance of 8 kpc, the width of the region in which the emission appears is less than 0.16 pc, indicating short mean free paths for shock-accelerated electrons and high levels of MHD turbulence presumably causing the scattering. We find no polarized flux at 90 or 20 cm, with 3 sigma upper limits in polarized intensity of 36 mJy at 90 cm (45 sec resolution) and 7.2 mJy at 20 cm (5 sec resolution), or 22 micro-Jy/sq arcsec and 370 micro-jy/sq arcsec, respectively, for any emission extended on those scales. Polarized flux is present at 6 cm, but at a very low mean polarized fraction (total polarized flux divided by total flux) of 0.44% +/- 0.06%, which, as for 3C 391, is much lower than typical for bright SNRs at this frequency. The morphology in polarized intensity is poorly correlated with that in total intensity. We see excursions in the polarized fraction up to at least 10% in a few locations, but even where polarization is seen, typical levels are a few percent. Tangled or disordered magnetic fields in the emitting region of the radio shell may be responsible for depolarizing the radio synchrotron radiation, but some form of internal Faraday depolarization may also occur. We estimate the foreground Faraday rotation measure to be about -450 rad/sq m, similar to that found for 3C 391, which is also the Galactic plane and just about as distant. Spectral index images created from the total intensity images show that the spectral index across W49B is constant to within about Delta alpha approximately 0.1 in bright regions. This result weakly supports a common origin of the radio-emitting electrons, as in the blast wave, rather than in inhomogeneous turbulent regions of differing properties due to the stochastic (second-order Fermi) acceleration process. Variations at the level of Delta alpha approximately 0.1 are seen, but their significance is doubtful. New observations at 90 cm, using experimental three-dimensional imaging technology, may improve on this limit.

Moffett, David A.↗
DOE OSTI2025

Reaction-in-flight neutrons as a diagnostic for hydrodynamical mixing in double shell inertial confinement fusion capsules

We examine reaction-in-flight (RIF) neutrons as diagnostics for hydrodynamical mixing of high-Z shell material into the hotspot of double shell capsules that are designed for the National Ignition Facility. In particular, we consider the effects of different levels of mixing of tungsten shell material into the DT gas on RIF spectra. Using a set of 1D simulations from the radiation hydrodynamic code xRAGE to determine the temperature and density profiles of the mixed W-DT gas, we find that increasing the mass of mix systematically reduces the ratio of RIF neutrons to primary 14 MeV neutrons. The shape of the RIF spectrum also changes with mix, with the predicted spectrum softening in energy with increasing mix.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

The Lyman- α forest from LBGs: First 3D correlation measurement with DESI and prospects for cosmology

The Lyman-α (Lyα) forest is a key tracer of large-scale structure at redshifts z > 2, traditionally studied using the spectra of luminous but relatively rare quasars. In this work, we explore the viability of using the fainter yet significantly more abundant Lyman Break Galaxies (LBGs) as alternative background sources for Lyα forest studies. We analyze 4,151 Lyα forest skewers extracted from LBG spectra obtained in the DESI pilot surveys conducted in the COSMOS and XMM-LSS fields. From this dataset, we present the first measurement of the Lyα forest auto-correlation function derived exclusively from LBG spectra, probing comoving separations up to 48 h -1 Mpc at an effective redshift of z eff = 2.70. The measured LBG Lyα forest auto-correlation is consistent with that derived from DESI DR2 quasar Lyα forest spectra at a comparable redshift, validating the use of LBGs as reliable background sources for Lyα forest analyses. In addition, we measure the cross-correlation between the LBG Lyα forest and the positions of 13,362 galaxies, demonstrating that this observable serves as a sensitive diagnostic for assessing the precision and accuracy of galaxy redshift estimates, and for identifying and correcting systematic offsets. Finally, using both synthetic LBG spectra and Fisher matrix forecasts, we show that a future wide-area survey covering ∼5,000 deg 2 , targeting 1,000 LBGs per square degree at signal-to-noise levels comparable to our sample, could enable LBG-based Lyα forest baryon acoustic oscillation (BAO) measurements with expected uncertainties of σ α ISO = 0.4% (isotropic) and σ α AP = 1.3% (Alcock-Paczynski). This performance is further enhanced when combining the BAO analysis with a Lyα forest Full Shape (FS) approach, yielding a predicted uncertainty of σ α ISO FS = 0.6%. These results open a new avenue for precision cosmology at high redshift using the Lyα forest in dense LBG samples.

Lyman alpha forest↗
DOE OSTI2020

Simple, compact, high-resolution monochromatic x-ray source for characterization of x-ray calorimeter arrays

X-ray calorimeters routinely achieve very high spectral resolution, typically a few eV full width at half maximum (FWHM). Measurements of calorimeter line shapes are usually dominated by the natural linewidth of most laboratory calibration sources. This compounds the data acquisition time necessary to statistically sample the instrumental line broadening and can add systematic uncertainty if the intrinsic line shape of the source is not well known. To address these issues, we have built a simple, compact monochromatic x-ray source using channel cut crystals. A commercial x-ray tube illuminates a pair of channel cut crystals that are aligned in a dispersive configuration to select the Kα1 line of the x-ray tube anode material. The entire device, including the x-ray tube, can be easily hand-carried by one person and may be positioned manually or using a mechanical translation stage. The output monochromatic beam provides a collimated image of the anode spot with magnification of unity in the dispersion direction (typically 100 μm–200 μm for the x-ray tubes used here) and is unfocused in the cross-dispersion direction so that the source image in the detector plane appears as a line. We measured output count rates as high as 10 count/s/pixel for the Hitomi soft x-ray spectrometer, which had 819 μm square pixels. We implemented different monochromator designs for energies of 5.4 keV (one design) and 8.0 keV (two designs), which have effective theoretical FWHM energy resolution of 0.125 eV, 0.197 eV, and 0.086 eV, respectively; these are well-suited for optimal calibration measurements of state-of-the art x-ray calorimeters. We measured an upper limit for the energy resolution of our Cr Kα1 monochromator of 0.7 eV FWHM at 5.4 keV, consistent with the theoretical prediction of 0.125 eV.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Materials Data on B10H13 by Materials Project

B10H13 is alpha U-like structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of four B10H13 clusters. there are ten inequivalent B sites. In the first B site, B is bonded in a single-bond geometry to one B and one H atom. The B–B bond length is 1.79 Å. The B–H bond length is 1.20 Å. In the second B site, B is bonded in a distorted water-like geometry to two H atoms. There is one shorter (1.19 Å) and one longer (1.33 Å) B–H bond length. In the third B site, B is bonded in a distorted trigonal non-coplanar geometry to three H atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. In the fourth B site, B is bonded in a distorted hexagonal planar geometry to six B atoms. There are a spread of B–B bond distances ranging from 1.73–1.79 Å. In the fifth B site, B is bonded in a water-like geometry to one B and two H atoms. There is one shorter (1.20 Å) and one longer (1.33 Å) B–H bond length. In the sixth B site, B is bonded in a distorted single-bond geometry to one B and one H atom. The B–H bond length is 1.19 Å. In the seventh B site, B is bonded in a distorted single-bond geometry to one B and one H atom. The B–H bond length is 1.20 Å. In the eighth B site, B is bonded in a distorted water-like geometry to two H atoms. There is one shorter (1.20 Å) and one longer (1.33 Å) B–H bond length. In the ninth B site, B is bonded in a water-like geometry to one B and two H atoms. There is one shorter (1.19 Å) and one longer (1.33 Å) B–H bond length. In the tenth B site, B is bonded in a distorted trigonal non-coplanar geometry to three H atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. There are thirteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one B atom. In the second H site, H is bonded in a single-bond geometry to one B atom. In the third H site, H is bonded in a single-bond geometry to one B atom. In the fourth H site, H is bonded in a single-bond geometry to one B atom. In the fifth H site, H is bonded in an L-shaped geometry to two B atoms. In the sixth H site, H is bonded in an L-shaped geometry to two B atoms. In the seventh H site, H is bonded in a single-bond geometry to one B atom. In the eighth H site, H is bonded in a single-bond geometry to one B atom. In the ninth H site, H is bonded in a single-bond geometry to one B atom. In the tenth H site, H is bonded in a single-bond geometry to one B atom. In the eleventh H site, H is bonded in an L-shaped geometry to two B atoms. In the twelfth H site, H is bonded in an L-shaped geometry to two B atoms. In the thirteenth H site, H is bonded in a single-bond geometry to one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Impact of systematic redshift errors on the cross-correlation of the Lyman-α forest with quasars at small scales using DESI Early Data

The Dark Energy Spectroscopic Instrument (DESI) will measure millions of quasar spectra by the end of its 5 year survey. Quasar redshift errors impact the shape of the Lyman-α forest correlation functions, which can affect cosmological analyses and therefore cosmological interpretations. Here, using data from the DESI Early Data Release and the first two months of the main survey, we measure the systematic redshift error from an offset in the cross-correlation of the Lyman-α forest with quasars. We find evidence for a redshift dependent bias causing redshifts to be underestimated with increasing redshift, stemming from improper modeling of the Lyman-α optical depth in the templates used for redshift estimation. New templates were derived for the DESI Year 1 quasar sample at z > 1.6 and we found the redshift dependent bias, Δr ∥ , increased from -1.94 ± 0.15 h -1 Mpc to -0.08 ± 0.04 h -1 Mpc (-205 ± 15 km s -1 to -9.0 ± 4.0 km s -1 ). These new templates will be used to provide redshifts for the DESI Year 1 quasar sample.

Lyman alpha forest↗
DOE OSTI2026

Probing the limits of cosmological information from the Lyman- α forest 2-point correlation functions

The standard cosmological analysis with the Lyα forest relies on a continuum fitting procedure that suppresses information on large scales and distorts the three-dimensional correlation function on all scales. In this work, we present the first cosmological forecasts without continuum fitting distortion in the Lyα forest, focusing on the recovery of large-scale information. Using idealized synthetic data, we compare the constraining power of the full shape of the Lyα forest auto-correlation and its cross-correlation with quasars using the baseline continuum fitting analysis versus the true continuum. We find that knowledge of the true continuum enables a ∼ 10% reduction in uncertainties on the Alcock-Paczyński (AP) parameter and the matter density, Ω m . We also explore the impact of large-scale information by extending the analysis up to separations of 240 h -1 Mpc along and across the line of sight. The combination of these analysis choices can recover significant large-scale information, yielding up to a ∼ 15% improvement in AP constraints. This improvement is analogous to extending the Lyα forest survey area by ∼ 40%.

Lyman alpha forest↗
NASA NTRS2010

Orion Entry Performance-Based Center-of-Gravity Box

The Orion capsule is designed both for Low Earth Orbit missions to the ISS and for missions to the moon. For ISS class missions, the capsule will use an Apollo-style direct entry. For lunar return missions, depending on the timing of the mission, the capsule could perform a direct entry or a skip entry of up to 4800 n.mi. in order to land in the coastal waters of California. The physics of atmospheric re-entry determine the capability of the Orion vehicle. For a given vehicle mass and shape, physics tells us that the driving parameters for an entry vehicle are the hypersonic lift-to-drag ratio (L/D) and the flight path angle at entry interface (gamma(sub EI)). The design of the Orion atmospheric re-entry must meet constraints during both nominal and dispersed flight conditions on landing accuracy, heating rate, total heat load, sensed acceleration, and proper disposal of the Service Module. These constraints define an entry corridor in the space of L/D-gamma(sub EI); if the vehicle falls within this corridor, then all constraints are met. The gamma(sub EI) dimension of the corridor can be further constrained by the gloads experienced during emergency entries. Thus, the entry performance for the Orion vehicle can be described completely by the L/D. Bounds on the hypersonic L/D necessary to achieve all the mission requirements can be defined for the given entry corridor. Landing accuracy performance drives the lower limit on L/D. In order to achieve the desired landing accuracy, a minimum L/D must be ensured. The design of the Thermal Protection System (TPS) drives the upper limit on L/D. A higher L/D can drive mass into the design of the TPS. Conversely, once the TPS is designed, the L/D must be ensured to stay below a certain limit in order for the TPS to stay within its design envelop. The L/D must stay within its upper and lower bounds during dispersed flight conditions. L/D is a function of both the aerodynamics and the center-of-gravity (CG) of the vehicle. The aerodynamics of the vehicle are determined by Computational Fluid Mechanics (CFD) and wind tunnel tests. However, the aerodynamics are not known precisely. Instead, an aerodynamic database has been developed where the aerodynamic coefficients are known to fall within a probabilistic band defined by upper and lower bounds. It is expected that the probabilistic band will shrink after the first missions are flown and real-world data is collected. Until that time, the Orion must be designed to the current aerodynamic database. Thus, for a given aerodynamic database with given uncertainties, the allowable range in L/D can be mapped to an allowable box for the CG location. The CG box is used to set requirements on the dispersions allowed for vehicle packaging and cargo storage. As the aerodynamic uncertainties decrease, the size of the CG box can increase. This paper discusses the technique used to map the minimum and maximum L/D bounds set by the entry performance requirements to the allowable dispersions in CG while accounting for aerodynamic uncertainties. The L/D is defined as the ratio of the lift force to the drag force. It is equivalent to the ratio of lift coefficient (C(sub L)) over drag coefficient (C(sub D)). C(sub L) and C(sub D) are functions of Mach number (M) and angle of attack (alpha). A Mach number of 25 is used as a measuring point of the hypersonic L/D. Variations in C(sub L), C(sub D) and alpha cause variations in L/D. Equation (1) shows the three contributions to the variation in L/D.

Rea, Jeremy R.↗
DOE OSTI2020

Materials Data on Bi20(PtBr12)3 by Materials Project

Bi20(PtBr12)3 is alpha Niobium phosphide-derived structured and crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of two Bi20(PtBr12)3 clusters. there are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in an octahedral geometry to six Bi+2.10+ atoms. There are three shorter (2.76 Å) and three longer (2.77 Å) Pt–Bi bond lengths. In the second Pt2- site, Pt2- is bonded in an octahedral geometry to six Bi+2.10+ atoms. There are two shorter (2.76 Å) and four longer (2.77 Å) Pt–Bi bond lengths. There are seven inequivalent Bi+2.10+ sites. In the first Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form BiPtBr4 square pyramids that share a cornercorner with one BiPtBr4 square pyramid, an edgeedge with one BiBr6 octahedra, and edges with four BiPtBr4 square pyramids. There are a spread of Bi–Br bond distances ranging from 2.81–3.24 Å. In the second Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form BiPtBr4 square pyramids that share a cornercorner with one BiPtBr4 square pyramid, an edgeedge with one BiBr6 octahedra, and edges with four BiPtBr4 square pyramids. There are a spread of Bi–Br bond distances ranging from 2.88–3.08 Å. In the third Bi+2.10+ site, Bi+2.10+ is bonded to six Br1- atoms to form edge-sharing BiBr6 octahedra. There are a spread of Bi–Br bond distances ranging from 2.83–3.02 Å. In the fourth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form a mixture of edge and corner-sharing BiPtBr4 square pyramids. There are two shorter (2.87 Å) and two longer (3.05 Å) Bi–Br bond lengths. In the fifth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form a mixture of edge and corner-sharing BiPtBr4 square pyramids. There are a spread of Bi–Br bond distances ranging from 2.88–3.03 Å. In the sixth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form BiPtBr4 square pyramids that share a cornercorner with one BiPtBr4 square pyramid, an edgeedge with one BiBr6 octahedra, and edges with four BiPtBr4 square pyramids. There are two shorter (2.81 Å) and two longer (3.24 Å) Bi–Br bond lengths. In the seventh Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four Br1- atoms to form BiPtBr4 square pyramids that share a cornercorner with one BiPtBr4 square pyramid, an edgeedge with one BiBr6 octahedra, and edges with four equivalent BiPtBr4 square pyramids. There are two shorter (2.88 Å) and two longer (3.08 Å) Bi–Br bond lengths. There are eleven inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the second Br1- site, Br1- is bonded in an L-shaped geometry to two equivalent Bi+2.10+ atoms. In the third Br1- site, Br1- is bonded in an L-shaped geometry to two equivalent Bi+2.10+ atoms. In the fourth Br1- site, Br1- is bonded in an L-shaped geometry to two Bi+2.10+ atoms. In the fifth Br1- site, Br1- is bonded in an L-shaped geometry to two Bi+2.10+ atoms. In the sixth Br1- site, Br1- is bonded in an L-shaped geometry to two Bi+2.10+ atoms. In the seventh Br1- site, Br1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the eighth Br1- site, Br1- is bonded in an L-shaped geometry to two Bi+2.10+ atoms. In the ninth Br1- site, Br1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the tenth Br1- site, Br1- is bonded in an L-shaped geometry to two Bi+2.10+ atoms. In the eleventh Br1- site, Br1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi20(PtI12)3 by Materials Project

Bi20(PtI12)3 is alpha Niobium phosphide-derived structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one Bi20(PtI12)3 cluster. there are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in an octahedral geometry to six Bi+2.10+ atoms. There are four shorter (2.76 Å) and two longer (2.77 Å) Pt–Bi bond lengths. In the second Pt2- site, Pt2- is bonded in an octahedral geometry to six Bi+2.10+ atoms. There are a spread of Pt–Bi bond distances ranging from 2.76–2.78 Å. There are ten inequivalent Bi+2.10+ sites. In the first Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.10–3.28 Å. In the second Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are two shorter (3.11 Å) and two longer (3.28 Å) Bi–I bond lengths. In the third Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.03–3.42 Å. In the fourth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.04–3.40 Å. In the fifth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form a mixture of corner and edge-sharing BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.08–3.27 Å. In the sixth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form a mixture of corner and edge-sharing BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.10–3.23 Å. In the seventh Bi+2.10+ site, Bi+2.10+ is bonded to six I1- atoms to form edge-sharing BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 3.05–3.21 Å. In the eighth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.10–3.28 Å. In the ninth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form BiPtI4 square pyramids that share a cornercorner with one BiPtI4 square pyramid, an edgeedge with one BiI6 octahedra, and edges with four BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.03–3.41 Å. In the tenth Bi+2.10+ site, Bi+2.10+ is bonded to one Pt2- and four I1- atoms to form a mixture of corner and edge-sharing BiPtI4 square pyramids. There are a spread of Bi–I bond distances ranging from 3.08–3.26 Å. There are eighteen inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the second I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the third I1- site, I1- is bonded in a distorted T-shaped geometry to three Bi+2.10+ atoms. In the fourth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the fifth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the seventh I1- site, I1- is bonded in a 2-coordinate geometry to two Bi+2.10+ atoms. In the eighth I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the ninth I1- site, I1- is bonded in a 2-coordinate geometry to two Bi+2.10+ atoms. In the tenth I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the eleventh I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the twelfth I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the thirteenth I1- site, I1- is bonded in a distorted T-shaped geometry to three Bi+2.10+ atoms. In the fourteenth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+2.10+ atoms. In the fifteenth I1- site, I1- is bonded in a 2-coordinate geometry to two Bi+2.10+ atoms. In the sixteenth I1- site, I1- is bonded in a 2-coordinate geometry to two Bi+2.10+ atoms. In the seventeenth I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms. In the eighteenth I1- site, I1- is bonded in a distorted L-shaped geometry to two Bi+2.10+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

DESI DR1 Ly α 1D power spectrum: the Fast Fourier Transform estimator measurement

Here, we present the one-dimensional Lyman-α forest power spectrum measurement derived from the data release 1 (DR1) of the Dark Energy Spectroscopic Instrument (DESI). The measurement of the Lyman-α forest power spectrum along the line of sight from high-redshift quasar spectra provides information on the shape of the linear matter power spectrum, neutrino masses, and the properties of dark matter. In this work, we use a Fast Fourier Transform (FFT)-based estimator, which is validated on synthetic data in a companion paper. Compared to the FFT measurement performed on the DESI early data release, we improve the noise characterization with a cross-exposure estimator and test the robustness of our measurement using various data splits. We also refine the estimation of the uncertainties and now present an estimator for the covariance matrix of the measurement. Furthermore, we compare our results to previous high-resolution and eBOSS measurements. In another companion paper, we present the same DR1 measurement using the Quadratic Maximum Likelihood Estimator (QMLE). These two measurements are consistent with each other and constitute the most precise one-dimensional power spectrum measurement to date, while being in good agreement with results from the DESI early data release.

Lyman alpha forest↗
DOE OSTI2020

Materials Data on H9BrO4 by Materials Project

H9O4Br is alpha U structured and crystallizes in the monoclinic P2_1 space group. The structure is zero-dimensional and consists of two H9O4Br clusters. there are eighteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 1.01 Å. The H–Br bond length is 2.20 Å. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.52 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.48 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 1.00 Å. The H–Br bond length is 2.21 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.60 Å) H–O bond length. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.02 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourteenth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.14 Å) and one longer (1.30 Å) H–O bond length. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 1.01 Å. The H–Br bond length is 2.23 Å. In the sixteenth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.59 Å) H–O bond length. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 0.99 Å. The H–Br bond length is 2.26 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to three H1+ atoms. In the sixth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the seventh O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the eighth O2- site, O2- is bonded in a water-like geometry to two H1+ atoms. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted L-shaped geometry to two H1+ atoms. In the second Br1- site, Br1- is bonded in a 2-coordinate geometry to two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on W25O73 by Materials Project

W25O73 is alpha Rhenium trioxide-like structured and crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. there are thirteen inequivalent W sites. In the first W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of W–O bond distances ranging from 1.86–2.04 Å. In the second W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of W–O bond distances ranging from 1.89–2.01 Å. In the third W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 2–10°. There are a spread of W–O bond distances ranging from 1.84–2.09 Å. In the fourth W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 1–10°. There are a spread of W–O bond distances ranging from 1.84–2.09 Å. In the fifth W site, W is bonded to six O atoms to form a mixture of distorted edge and corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 2–32°. There are a spread of W–O bond distances ranging from 1.83–2.19 Å. In the sixth W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of W–O bond distances ranging from 1.89–2.01 Å. In the seventh W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of W–O bond distances ranging from 1.89–1.97 Å. In the eighth W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 1–10°. There are a spread of W–O bond distances ranging from 1.86–2.08 Å. In the ninth W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of W–O bond distances ranging from 1.89–1.97 Å. In the tenth W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 2–9°. There are a spread of W–O bond distances ranging from 1.86–2.06 Å. In the eleventh W site, W is bonded to six O atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of W–O bond distances ranging from 1.88–2.00 Å. In the twelfth W site, W is bonded to six O atoms to form a mixture of edge and corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 1–32°. There are a spread of W–O bond distances ranging from 1.82–2.18 Å. In the thirteenth W site, W is bonded to six O atoms to form a mixture of edge and corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 7–27°. There are a spread of W–O bond distances ranging from 1.84–2.10 Å. There are thirty-seven inequivalent O sites. In the first O site, O is bonded in a linear geometry to two W atoms. In the second O site, O is bonded in a linear geometry to two W atoms. In the third O site, O is bonded in a linear geometry to two equivalent W atoms. In the fourth O site, O is bonded in a linear geometry to two W atoms. In the fifth O site, O is bonded in a linear geometry to two W atoms. In the sixth O site, O is bonded in a linear geometry to two W atoms. In the seventh O site, O is bonded in a linear geometry to two W atoms. In the eighth O site, O is bonded in a linear geometry to two equivalent W atoms. In the ninth O site, O is bonded in a linear geometry to two W atoms. In the tenth O site, O is bonded in a bent 120 degrees geometry to two W atoms. In the eleventh O site, O is bonded in a linear geometry to two equivalent W atoms. In the twelfth O site, O is bonded in a linear geometry to two W atoms. In the thirteenth O site, O is bonded in a linear geometry to two equivalent W atoms. In the fourteenth O site, O is bonded in a linear geometry to two equivalent W atoms. In the fifteenth O site, O is bonded in a linear geometry to two W atoms. In the sixteenth O site, O is bonded in a linear geometry to two W atoms. In the seventeenth O site, O is bonded in a linear geometry to two W atoms. In the eighteenth O site, O is bonded in a linear geometry to two W atoms. In the nineteenth O site, O is bonded in a linear geometry to two equivalent W atoms. In the twentieth O site, O is bonded in a linear geometry to two W atoms. In the twenty-first O site, O is bonded in a linear geometry to two W atoms. In the twenty-second O site, O is bonded in a linear geometry to two equivalent W atoms. In the twenty-third O site, O is bonded in a linear geometry to two W atoms. In the twenty-fourth O site, O is bonded in a linear geometry to two W atoms. In the twenty-fifth O site, O is bonded in a distorted trigonal non-coplanar geometry to three W atoms. In the twenty-sixth O site, O is bonded in a linear geometry to two equivalent W atoms. In the twenty-seventh O site, O is bonded in a linear geometry to two W atoms. In the twenty-eighth O site, O is bonded in a distorted T-shaped geometry to three W atoms. In the twenty-ninth O site, O is bonded in a linear geometry to two W atoms. In the thirtieth O site, O is bonded in a linear geometry to two equivalent W atoms. In the thirty-first O site, O is bonded in a linear geometry to two equivalent W atoms. In the thirty-second O site, O is bonded in a linear geometry to two equivalent W atoms. In the thirty-third O site, O is bonded in a linear geometry to two W atoms. In the thirty-fourth O site, O is bonded in a linear geometry to two W atoms. In the thirty-fifth O site, O is bonded in a linear geometry to two W atoms. In the thirty-sixth O site, O is bonded in a linear geometry to two equivalent W atoms. In the thirty-seventh O site, O is bonded in a linear geometry to two equivalent W atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on POs6C18ClO18 by Materials Project

Os6C18PO18Cl is alpha U structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two Os6C18PO18Cl clusters. there are six inequivalent Os+1.33- sites. In the first Os+1.33- site, Os+1.33- is bonded in a 4-coordinate geometry to three C+2.22+ and one P5+ atom. All Os–C bond lengths are 1.91 Å. The Os–P bond length is 2.33 Å. In the second Os+1.33- site, Os+1.33- is bonded in a 3-coordinate geometry to three C+2.22+ and one P5+ atom. All Os–C bond lengths are 1.91 Å. The Os–P bond length is 2.37 Å. In the third Os+1.33- site, Os+1.33- is bonded in a 3-coordinate geometry to three C+2.22+ and one P5+ atom. There is one shorter (1.90 Å) and two longer (1.91 Å) Os–C bond length. The Os–P bond length is 2.32 Å. In the fourth Os+1.33- site, Os+1.33- is bonded in a 4-coordinate geometry to three C+2.22+, one P5+, and one Cl1- atom. There are a spread of Os–C bond distances ranging from 1.89–1.94 Å. The Os–P bond length is 2.48 Å. The Os–Cl bond length is 2.53 Å. In the fifth Os+1.33- site, Os+1.33- is bonded in a 3-coordinate geometry to three C+2.22+ and one P5+ atom. All Os–C bond lengths are 1.91 Å. The Os–P bond length is 2.35 Å. In the sixth Os+1.33- site, Os+1.33- is bonded in a 4-coordinate geometry to three C+2.22+, one P5+, and one Cl1- atom. There is one shorter (1.89 Å) and two longer (1.92 Å) Os–C bond length. The Os–P bond length is 2.48 Å. The Os–Cl bond length is 2.52 Å. There are eighteen inequivalent C+2.22+ sites. In the first C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.17 Å. In the fifth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the sixth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the seventh C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the eighth C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the ninth C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the tenth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the eleventh C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the twelfth C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the thirteenth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the fourteenth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the fifteenth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the sixteenth C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.17 Å. In the seventeenth C+2.22+ site, C+2.22+ is bonded in a distorted linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. In the eighteenth C+2.22+ site, C+2.22+ is bonded in a linear geometry to one Os+1.33- and one O2- atom. The C–O bond length is 1.16 Å. P5+ is bonded in a 6-coordinate geometry to six Os+1.33- atoms. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the fourteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the fifteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the sixteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the seventeenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. In the eighteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.22+ atom. Cl1- is bonded in an L-shaped geometry to two Os+1.33- atoms.

36 MATERIALS SCIENCE↗