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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Extension of state-vector splitting to the Navier-Stokes equations

A multi-dimensional upwind scheme for solving the Euler equations has been extended to solve the Navier-Stokes equations. These methods share the property of not requiring body-fitted computational grids. A time advance scheme which is second-order accurate in time and space has been developed for use in conjunction with state-vector splitting to accurately resolve regions with significant gradients in flow quantities. The scheme has been tested on several simple viscous flow problems for which analytic solutions are known; the agreement of computation with theory is excellent.

Gooch, Carl F.↗
NASA NTRS1995

Convergent spray process for environmentally friendly coatings

Conventional spray application processes have poor transfer efficiencies, resulting in an exorbitant loss in materials, solvents, and time. Also, with ever tightening Environmental Protection Agency (EPA) regulations and Occupational Safety and Health Administration requirements, the low transfer efficiencies have a significant impact on the quantities of materials and solvents that are released into the environment. High solids spray processes are also limited by material viscosities, thus requiring many passes over the surface to achieve a thickness in the 0.125 -inch range. This results in high application costs and a negative impact on the environment. Until recently, requirements for a 100 percent solid sprayable, environmentally friendly, lightweight thermal protection system that can be applied in a thick (greater than 0.125 inch) single-pass operation exceeded the capability of existing systems. Such coatings must be applied by hand lay-up techniques, especially for thermal and/or fire protection systems. The current formulation of these coatings has presented many problems such as worker safety, environmental hazards, waste, high cost, and application constraints. A system which can apply coatings without using hazardous materials would alleviate many of these problems. Potential applications include the aerospace thermal protective specialty coatings, chemical and petroleum industries that require fire-protection coatings that resist impact, chemicals, and weather. These markets can be penetrated by offering customized coatings applied by automated processes that are environmentally friendly.

Scarpa, Jack↗
NASA NTRS2001

Our Sun IV: The Standard Model and Helioseismology: Consequences of Uncertainties in Input Physics and in Observed Solar Parameters

Helioseismic frequency observations provide an extremely accurate window into the solar interior; frequencies from the Michaelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO) spacecraft, enable the adiabatic sound speed and adiabatic index to be inferred with an accuracy of a few parts in 10(exp 4) and the density with an accuracy of a few parts in 10(exp 3). This has become a Serious challenge to theoretical models of the Sun. Therefore, we have undertaken a self-consistent, systematic study of the sources of uncertainties in the standard solar models. We found that the largest effect on the interior structure arises from the observational uncertainties in the photospheric abundances of the elements, which affect the sound speed profile at the level of 3 parts in 10(exp 3). The estimated 4% uncertainty in the OPAL opacities could lead to effects of 1 part in 10(exp 3); the approximately 5%, uncertainty in the basic pp nuclear reaction rate would have a similar effect, as would uncertainties of approximately 15% in the diffusion constants for the gravitational settling of helium. The approximately 50% uncertainties in diffusion constants for the heavier elements would have nearly as large an effect. Different observational methods for determining the solar radius yield results differing by as much as 7 parts in 10(exp 4); we found that this leads to uncertainties of a few parts in 10(exp 3) in the sound speed int the solar convective envelope, but has negligible effect on the interior. Our reference standard solar model yielded a convective envelope position of 0.7135 solar radius, in excellent agreement with the observed value of 0.713 +/- 0.001 solar radius and was significantly affected only by Z/X, the pp rate, and the uncertainties in helium diffusion constants. Our reference model also yielded envelope helium abundance of 0.2424, in good agreement with the approximate range of 0.24 to 0.25 inferred from helioseismic observations; only extreme Z/X values yielded envelope helium abundance outside this range. We found that other current uncertainties, namely, in the solar age and luminosity, in nuclear rates other than the pp reaction, in the low-temperature molecular opacities, and in the low-density equation of state, have no significant effect on the quantities that can be inferred from helioseismic observations. The predicted pre-main-sequence lithium depletion is uncertain by a factor of 2. The predicted neutrino capture rate is uncertain by approximately 30% for the Cl-27 experiment and by approximately 3% for Ga-71 experiments, while the B-8 neutrino flux is uncertain by approximately 30%.

Boothroyd, Arnold I.↗
NASA NTRS2004

A Selected Operational History of the Internal Thermal Control System (ITCS) for International Space Station (ISS)

The Internal Thermal Control System (ITCS) has been developed jointly by Boeing Corporation, Huntsville, Alabama and Honeywell Engines & Systems, Torrance, California to meet the internal thermal control needs for the International Space Station (ISS). The ITCS provides heat removal for the critical life support systems and thermal conditioning for numerous experiment racks. The ITCS will be fitted on a number of modules on the ISS. The first US Element containing the ITCS, Node 1, was launched in December 1998. Since Node 1 does not contain a pump to circulate the fluid it was not filled with ITCS fluid until after the US Laboratory Module was installed. The second US Element module, US Laboratory Module, which contains the pumps and all the major ITCS control hardware, was launched in February 2001. The third US Element containing the ITCS, the US Airlock, was launched in July 2001. The dual loop system of the ITCS is comprised of a lowtemperature loop (LTL) and a moderate-temperature loop (MTL). Each loop has a pump package assembly (PPA), a system flow control assembly (SFCA), a threeway mixing valve (TWMV), several rack flow control assemblies (RFCA), cold plates, pressure sensors, temperature sensors, pump bypass assembly (PBA) and a heat exchanger. In addition, the MTL has an additional TWMV, a payload regeneration heat exchanger (P/RHE) and a manual flow control valve (MFCV). The LTL has a service performance and checkout unit (SPCU) heat exchanger. The two loops are linked via one loop crossover assembly (LCA) providing cross loop capabilities and a single PPA, two-loop functionality. One important parameter monitored by the ground stations and on-orbit is the amount of fluid leakage from the ITCS. ISS fluid leakage is of importance since ITCS fluid is costly to re-supply, may be difficult to clean up in zero-g, and if uncontained could lead to equipment failures and potential hazards. This paper examines the nominal leakage observed over period of a year of on-orbit operation and compares this with analysis predictions. This paper also addresses the off-nominal leakage and a fluid transfer event causing significant changes in accumulator quantity.

Patel, Vipul P.↗
NASA NTRS2014

Tri-Gas Pressurization System Testing and Modeling for Cryogenic Applications

The use of Tri‐gas in rocket propulsion systems is somewhat of a new technology. This paper defines Tri‐gas as a mixture of gases composed largely of helium with a small percentage of a stoichiometric mixture of hydrogen and oxygen. When exposed to a catalyst the hydrogen and oxygen in the mixture combusts, significantly raising the temperature of the mixture. The increase in enthalpy resulting from the combustion process significantly decreases the required quantity of gas needed to pressurize the ullage of the vehicle propellant tanks. The objective of this effort was to better understand the operating characteristics of Tri‐gas in a pressurization system with low temperature applications. In conjunction with ongoing programs at NASA Marshall Space Flight Center, an effort has been undertaken to evaluate the operating characteristics of Tri‐gas through modeling and bench testing. Through improved understanding of the operating characteristics, the risk of using this new technology in a launch vehicle propulsion system was reduced. Bench testing of Tri‐gas was a multistep process that targeted gas characteristics and performance aspects that pose a risk to application in a pressurization system. Pressurization systems are vital to propulsion system performance. Keeping a target ullage pressure in propulsions tanks is necessary to supply propellant at the conditions and flow rates required to maintain desired engine functionality. The first component of testing consisted of sampling Tri‐gas sources that had been stagnant for various lengths of time in order to determine the rate at which stratification takes place. Second, a bench test was set up in which Tri‐gas was sent through a catalyst bed. This test was designed to evaluate the performance characteristics of Tri‐gas, under low temperature inlet temperatures, in a flight‐like catalyst bed reactor. The third, most complex, test examined the performance characteristics of Tri‐gas at low temperature temperatures in a test configuration built to more closely resemble a vehicle pressurization system. The results of these bench tests address various risks that all relate to underperformance of Tri‐gas pressurization systems.

Taylor, B.↗
NASA NTRS2019

Turbulence Model Implementation and Verification in the SENSEI CFD Code

This paper outlines the implementation and verification of the negative Spalart-Allmaras turbulence model into the SENSEI CFD code. The SA-neg turbulence model is implemented in a flexible, object-oriented framework where additional turbulence models can be easily added. In addition to outlining the new turbulence modeling framework in SENSEI, an overview of the other general improvements to SENSEI is provided. The results for four 2D test cases are compared to results from CFL3D and FUN3D to verify that the turbulence models are implemented properly. Several differences in the results from SENSEI, CFL3D, and FUN3D are identified and are attributed to differences in the implementation and discretization order of the boundary conditions as well as the order of discretization of the turbulence model. When a solid surface is located near or intersects an inflow or outflow boundary, higher order boundary conditions should be used to limit their effect on the forces on the surface. When the turbulence equations are discretized using second order spatial accuracy, the edge of the eddy viscosity profile seems to be sharper than when a first order discretization is used. However, the discretization order of the turbulence equation does not have a significant impact on output quantities of interest, such as pressure and viscous drag, for the cases studied.

Jackson, Charles W.↗
NASA NTRSDate not supplied

Entry, Descent, and Landing Analysis of Low Mass Martian Probe for Surface Climate Network

Aeolus is a mission to provide the first direct measurements of Martian atmospheric wind speeds and correlate them with thermal and compositional data to bring together a complete systematic description for the global energy balance and climate cycles of Mars. Objective A of the Mars Exploration Program Analysis Group (MEPAG) Goal II cites a Science Investigation Area to develop a network of surface landers to provide global, diurnal and synoptic coverage of the near-surface environment to characterize present Mars climate [1]. Aeolus will characterize the present Martian global climate system via an orbiter element and a novel surface network element. A series of low mass, low power probes will be distributed across the Martian surface and measure pressure, sky opacity, temperature, wind speed, water vapor and other trace gases. Low mass and power electrical systems designed to operate in extreme cold and daily thermal cycling for one Martian year could facilitate lower cost, Class-D science probes. Aeolus is targeting a total per-probe mass of <5 kg. Recent advances in nanofabrication of chip-scale sensors that are highly robust to temperature and shock, combined with a novel packaging concept (the deployable sensor probe [2]) originally developed by the Aerospace Corp., for the first time enables a Mars surface climate sensor network. These probes are folded flat during transit to Mars and automatically deploy into the final reentry configuration once released from the orbiter. The capability to fold for stowage significantly increases the probe quantity carried by the orbiter.

EDL↗
NASA NTRS2005

Field Evaluations Test Plan for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel

Headquarters National Aeronautics and Space Administration (NASA) chartered the Acquisition Pollution Prevention (AP2) Office to coordinate agency activities affecting pollution prevention issues identified during system and component acquisition and sustainment processes. The primary objectives of the AP2 Office are to: (1) Reduce or eliminate the use of hazardous materials (HazMats) or hazardous processes at manufacturing, remanufacturing, and sustainment locations. (2) Avoid duplication of effort in actions required to reduce or eliminate HazMats through joint center cooperation and technology sharing. To achieve a substrate condition suitable for the application of a coating system, both new and old (in-situ) substrates must undergo some type of surface preparation and/or depainting operation to ensure adhesion of the new coating system. The level of cleanliness or anchor profile desired is typically a function of the type of coating to be applied and the specification being adhered to. In high performance environments, cleanliness and surface profile requirements for carbon steel (the dominant substrate for facilities, structures and equipment) dictates the use of abrasive media. Many of the abrasive media currently used across NASA and Air Force Space Command (AFSPC) installations generate large quantities of fugitive particulate emissions and waste. The high quantities of airborne dust and waste generated from these operations pose significant environmental concern. Efforts to contain emissions and the reduce quantity of waste generated have significant implications on project cost; this is often a deterrent to engaging in maintenance activities. In response to recent technological developments and NASA's and AFSPC's need to undertake environmentally conscious corrosion prevention projects, a review of the industry needs to be undertaken to evaluate surface preparation technologies (materials and processes) for embrace. This project will identify, evaluate and approve alternative surface preparation technologies for use at NASA and AFSPC installations. Materials and processes will be evaluated with the goal of selecting those processes that will improve corrosion protection at critical systems, facilitate easier maintenance activity, extend maintenance cycles, eliminate flight hardware contamination and reduce the amount of hazardous waste generated. This Field Evaluations Test Plan defines the field evaluation and testing requirements for validating alternative surface preparation/depainting technologies and supplements the JTP. The field evaluations will be performed at Stennis Space Center, Mississippi, under the oversight of the Project Engineer. Additional field evaluations may be performed at other NASA centers or AFSPC facilities.

Lewis, Pattie↗
NASA NTRS1987

Evaluation of the ERBE scene identification algo-rithm

The sensitivity of the radiation budget parameters and the scene selection process to different factors is evaluated. The use of ERB-7 CLE models provides instantaneous albedo and longwave flux values which are in essential agreement in the 70 deg cutoff case with those from the SAB method. The increase in albedo with increasing satellite zenith angle cutoff is not apparent at the target area level for different surface types. GOES models seem to show an increase in instantaneous albedo at the global level with satellite zenith angle of the same nature as the ERB-7 models investigated in a previous report and are, therefore, probably not an improvement. The use of recently derived NCLE models did not make a noticeable change in the budget parameters; but the cloud classification did show hemispherical differences and caused a day-night readjustment of cloudiness amounts. Preliminary results for an additional month (December 1979) indicate good agreement between the SAB and MLE methods. Additional work is required to establish the agreement for all seasons. Comparison of derived cloud amounts with other data sets such as THIR/TOMS indicates good zonal agreement. Sampling adequacy investigations at different temporal averaging intervals with the SAB method, indicate large uncertainties in small time average cases. For a 6-day averaging period, sampling is very poor with only 23% of the globe contributing toward the global mean albedo. Effect of modifications to the MLE procedure seem to have little effect on the derived budget quantities in an averaged sense. Significant differences in the flux values due to differences in scene selection are apparent in individual target areas studies. A modification of the MLE procedure to mimic the perpendicular bisector algorithm indicated no effect on the gross radiation budget quantities.

Vemury, S. K.↗
DOE OSTI2025

Harnessing Nanobodies for Precision Targeting of Proteoforms: Opportunities and Challenges in Therapeutics and Diagnostics

Proteoforms are biologically distinct yet structurally similar proteins that play key roles in driving disease progression but are rarely accounted for in the development of therapeutics and diagnostics. Nanobodies (Nbs) have emerged as a therapeutic and diagnostic “silver bullet” as they possess unique structural and functional attributes that offer advantages over traditional antibodies. One of the most profound advantages of Nbs is the heightened sensitivity and ability to distinguish subtle changes in the conformation of a given protein. Thus, Nbs have significant potential as therapeutic and diagnostic agents that can identify and distinguish specific pathological proteoforms that underlie a given disease. However, there remain significant challenges in obtaining sufficient quantities and purities of specific proteoform antigens that are required for engineering proteoform-specific Nbs. Recent advancements in chemical biology tools for precision proteoform synthesis have made this task feasible for the first time. In this perspective, we discuss the advantages and challenges associated with developing proteoform-specific Nbs and how success in this endeavor will significantly advance the fields of therapeutics and diagnostics.

Antigens↗
DOE OSTI2023

Renewable Energy Materials Properties Database: Summary

Renewable energy is providing a growing share of electricity generation in the United States, with generation from utility scale wind and solar increasing by 12% and 29%, respectively, in 2020 (EIA 2021). Installation of new renewable energy facilities requires material inputs that range from common construction materials to specialized, high-performance materials that may have limited availability. This report summarizes the Department of Energy (DOE) Wind Energy Technologies Office (WETO) and DOE Solar Energy Technologies Office (SETO) database of materials used in domestic wind and solar installations. The Energy Act of 2020 directs WETO and SETO to deliver a "comprehensive physical property database of materials for use in [wind and solar] energy technologies, which shall identify the type, quantity, country of origin, source, significant uses, projected availability, and physical properties of materials used in [wind and solar] energy technologies" by no later than September 1, 2022. This report is the summary and directions for use of the Renewable Energy Materials Property Database (REMPD), in response to that direction. The related full text of the Energy Act of 2020 is provided in Appendix A. The focus of the REMPD and this accompanying report is on quantifying the raw and processed materials used in renewable energy technologies. The database contains information on the amount of each material that goes into wind and solar power plants, descriptions of the relevant material properties, and the primary countries of origin for each material. Some materials go through several stages of processing and/or are incorporated into subcomponents that make up the completed energy generation facilities. This report does not analyze supply chains for the production of renewable energy plant components. The Department of Energy has carried out related analysis in response to Executive Order 14017, which directed production of "America's Supply Chains" reports for Wind and Solar. The supply chain reports can be found at https://www.energy.gov/sites/default/files/2022-02/Wind%20Supply%20Chain%20Report%20-%20Final%202.25.22.pdf (Wind) and https://www.energy.gov/sites/default/files/2022-02/Solar%20Energy%20Supply%20Chain%20Report%20-%20Final.pdf (Solar). Additional reports in this series that are relevant to wind, solar and hybrid plants include: Energy Storage at https://www.energy.gov/sites/default/files/2022-02/Energy%20Storage%20Supply%20Chain%20Report%20-%20final.pdf and Neodymium Magnets at https://www.energy.gov/sites/default/files/2022-02/Neodymium%20Magnets%20Supply%20Chain%20Report%20-%20Final.pdf.

14 SOLAR ENERGY↗
NASA NTRS1971

Stratification calculations in a heated cryogenic oxygen storage tank at zero gravity

A cylindrical one-dimensional model of the Apollo cyrogenic oxygen storage tank has been developed to study the effect of stratification in the tank. Zero gravity was assumed, and only the thermally induced motions were considered. The governing equations were derived from conservation laws and solved on a digital computer. Realistic thermodynamic and transport properties were used. Calculations were made for a wide range of conditions. The results show the fluid behavior to be dependent on the quantity in the tank or equivalently the bulk fluid temperature. For high quantities (low temperatures) the tank pressure rose rapidly with heat addition, the heater temperature remained low, and significant pressure drop potentials accrued. For low quantities the tank pressure rose more slowly with heat addition and the heater temperature became high. A high degree of stratification resulted for all conditions; however, the stratified region extended appreciably into the tank only for the lowest tank quantity.

Shuttles, J. T.↗
NASA NTRS2011

The Radio/Gamma-Ray Connection in Active Galactic Nuclei in the Era of the Fermi Large Area Telescope

We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose.We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the OwensValley RadioObservatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10(exp -7) for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 10(exp -6) to 9.0 10(exp -8). Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10(exp -7)) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

Ackermann, M.↗
DOE OSTI2024

Helium-electrospray improves sample delivery in X-ray single-particle imaging experiments

Abstract Imaging the structure and observing the dynamics of isolated proteins using single-particle X-ray diffractive imaging (SPI) is one of the potential applications of X-ray free-electron lasers (XFELs). Currently, SPI experiments on isolated proteins are limited by three factors: low signal strength, limited data and high background from gas scattering. The last two factors are largely due to the shortcomings of the aerosol sample delivery methods in use. Here we present our modified electrospray ionization (ESI) source, which we dubbed helium-ESI (He-ESI). With it, we increased particle delivery into the interaction region by a factor of 10, for 26 nm-sized biological particles, and decreased the gas load in the interaction chamber corresponding to an 80% reduction in gas scattering when compared to the original ESI. These improvements have the potential to significantly increase the quality and quantity of SPI diffraction patterns in future experiments using He-ESI, resulting in higher-resolution structures.

Science & Technology - Other Topics↗
DOE OSTI2025

Excess Density as a Descriptor for Electrolyte Solvent Design

Electrolytes mediate interactions between the cathode and anode and determine performance characteristics of batteries. Mixtures of multiple solvents are often used in electrolytes to achieve desired properties, such as viscosity, dielectric constant, boiling point, and melting point. Conventionally, multi-component electrolyte properties are approximated with linear mixing, but in practice, significant deviations are observed. Excess quantities can provide insights into the molecular behavior of the mixture and could form the basis for designing high-performance electrolytes. Here we investigate the excess density of commonly used Li-ion battery solvents such as cyclic carbonates, linear carbonates, ethers, and nitriles with molecular dynamics simulations. We additionally investigate electrolytes consisting of these solvents and a salt. The results smoothly vary with mole percent and are fit to permutation-invariant Redlich-Kister polynomials. Mixtures of similar solvents, such as cyclic-cyclic carbonate mixtures, tend to have excess properties that are lower in magnitude compared to mixtures of dissimilar substances, such as carbonate-nitrile mixtures. We perform experimental testing using our automated test stand, Clio, to provide validation to the observed simulation trends. We quantify the structure similarity using SOAP fingerprints to create a descriptor for excess density, enabling the design of electrolyte properties. To a first approximation, this will allow us to estimate the deviation of a mixture from ideal behavior based solely upon the structural dissimilarity of the components.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Cluster Structures with Machine Learning Support in Neutron Star M-R relations

Neutron stars (NS) are compact objects with strong gravitational fields, and a matter composition subject to extreme physical conditions. The properties of strongly interacting matter at ultra-high densities and temperatures impose a big challenge to our understanding and modelling tools. Some difficulties are critical, since one cannot reproduce such conditions in our laboratories or assess them purely from astronomical observations. The information we have about neutron star interiors are often extracted indirectly, e.g., from the star mass-radius relation. The mass and radius are global quantities and still have a significant uncertainty, which leads to great variability in studying the micro-physics of the neutron star interior. This leaves open many questions in nuclear astrophysics and the suitable equation of state (EoS) of NS. Recently, new observations appear to constrain the mass-radius and consequently has helped to close some open questions. In this work, utilizing modern machine learning techniques, we analyze the NS mass-radius (M-R) relationship for a set of EoS containing a variety of physical models. Our objective is to determine patterns through the M-R data analysis and develop tools to understand the EoS of neutron stars in forthcoming works.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Gravitational-wave signal of a core-collapse supernova explosion of a 15M ⊙ star

In this paper we report on the gravitational-wave signal computed in the context of a three-dimensional simulation of a core-collapse supernova explosion of a 15 M ⊙ star. The simulation was performed with our neutrino hydrodynamics code chimera . We detail the gravitational wave strains as a function of time, for both polarizations, and discuss their physical origins. We also present the corresponding spectral signatures. Gravitational wave emission in our model has two key features: low-frequency emission (less than 200 Hz) emanates from the gain layer as a result of neutrino-driven convection and the standing accretion shock instability (SASI), and high-frequency emission (greater than 600 Hz) emanates from the proto–neutron star due to Ledoux convection within it. The high-frequency emission dominates the gravitational wave emission in our model and emanates largely from the convective layer itself, not from the convectively stable layer above it, due to convective overshoot. Moreover, the low-frequency emission emanates from the gain layer itself, not from the proto–neutron star, due to accretion onto it. We provide evidence of the SASI in our model and demonstrate that the peak of our low-frequency gravitational wave emission spectrum corresponds to it. Given its origin in the gain layer, we classify the SASI emission in our model as p-mode emission and assign a purely acoustic origin, not a vortical–acoustic origin, to it. We compare the results of our three-dimensional model analysis with those obtained from the model’s two-dimensional counterpart and find a significant reduction in the strain amplitudes in the former case, as well as significant reductions in all related quantities. Our dominant proto–neutron star gravitational wave emission is not well characterized by emission from surface g modes, complicating the relationship between peak frequencies observed and the mass and radius of the proto–neutron star expressed by analytic estimates under the assumption of surface g-mode emission. We present our frequency normalized characteristic strain along with the sensitivity curves of current- and next-generation gravitational wave detectors. This simple analysis indicates that the spectrum of gravitational wave emission between approximately 20 Hz and approximately 1 kHz, stemming from neutrino-driven convection, the SASI, accretion onto the proto–neutron star, and proto–neutron star convection, will be accessible for a Galactic event.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Transverse spin asymmetries and the electron Yukawa coupling at an FCC-ee

We show that measurements of single transverse-spin asymmetries at an 𝑒 + ⁢𝑒 − collider can enhance the sensitivity to the electron Yukawa coupling, possibly enabling observation of the Standard Model value for this quantity. We demonstrate that the significance in both the 𝑏⁢$\overline{𝑏}$ and semileptonic 𝑊⁢𝑊 final states can be enhanced by factors of up to 3 compared to inclusive cross-section determinations of this coupling for transversely polarized electrons. If the positrons can be simultaneously longitudinally polarized, even at the level of 30%, the significance can be enhanced by a factor of 5 or more. The method utilizes quantum interference between the Higgs signal and the continuum background and is also applicable in other 𝑊⁢𝑊 and 𝑍⁢𝑍 final states.

Phenomenology↗