Search NASA⌕ Search

SEARCH · Search NASA

Results for “Spin operator”

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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Earth-catalyzed detection of magnetic inelastic dark matter with photons in large underground detectors

Inelastic dark matter with moderate splittings, $\mathcal{O}$ (few to 150) keV, can upscatter to an excited state in the Earth, with the excited state subsequently decaying, leaving a distinctive monoenergetic photon signal in large underground detectors. The photon signal can exhibit sidereal-daily modulation, providing excellent separation from backgrounds. Using a detailed numerical simulation, we examine this process as a search strategy for magnetic inelastic dark matter with the dark matter mass near the weak scale, where the upscatter to the excited state and decay proceed through the same magnetic dipole transition operator. At lower inelastic splittings, the scattering is dominated by moderate mass elements in the Earth with high spin, especially 27 Al, while at larger splittings, 56 Fe becomes the dominant target. We show that the proposed large volume gaseous detector CYGNUS will have excellent sensitivity to this signal. Xenon detectors also provide excellent sensitivity through the inelastic nuclear recoil signal, and if a future signal is seen, we show that the synergy among both types of detection can provide strong evidence for magnetic inelastic dark matter. In the course we have calculated nuclear response functions for elements relevant for scattering in the Earth, which are publicly available on GitHub.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Quasilinear theory for inhomogeneous plasma

Here, this paper presents quasilinear theory (QLT) for a classical plasma interacting with inhomogeneous turbulence. The particle Hamiltonian is kept general; for example, relativistic, electromagnetic and gravitational effects are subsumed. A Fokker–Planck equation for the dressed ‘oscillation-centre’ distribution is derived from the Klimontovich equation and captures quasilinear diffusion, interaction with the background fields and ponderomotive effects simultaneously. The local diffusion coefficient is manifestly positive-semidefinite. Waves are allowed to be off-shell (i.e. not constrained by a dispersion relation), and a collision integral of the Balescu–Lenard type emerges in a form that is not restricted to any particular Hamiltonian. This operator conserves particles, momentum and energy, and it also satisfies the H -theorem, as usual. As a spin-off, a general expression for the spectrum of microscopic fluctuations is derived. For on-shell waves, which satisfy a quasilinear wave-kinetic equation, the theory conserves the momentum and energy of the wave–plasma system. The action of non-resonant waves is also conserved, unlike in the standard version of QLT. Dewar's oscillation-centre QLT of electrostatic turbulence is proven formally as a particular case and given a concise formulation. Also discussed as examples are relativistic electromagnetic and gravitational interactions, and QLT for gravitational waves is proposed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Excitation spectra of quantum matter without quasiparticles. I. Sachdev-Ye-Kitaev models

Here, we study the low-frequency spectra of complex Sachdev-Ye-Kitaev models at general densities. The analysis applies also to SU(M) magnets with random exchange at large M. The spectral densities are computed by numerical analysis of the saddle-point equations on the real frequency ω axis at zero temperature T. The asymptotic low-ω behaviors are found to be in excellent agreement with the scaling dimensions of irrelevant operators which perturb the conformally invariant critical states. Of possible experimental interest is our computation of the universal spin spectral weight of the SU(M) magnets at low ω and T; this includes a contribution from the time reparametrization mode, which is the boundary graviton of the holographic dual. This analysis is extended to a random t-J model in the following paper [M. Tikhanovskaya et al., following paper, Phys. Rev. B 103, 075142 (2021)].

36 MATERIALS SCIENCE↗
DOE OSTI2024

Relevance of anisotropy in the Kondo effect: Lessons from the symplectic case

A Kondo model with symplectic symmetry was recently put forward as the effective low-energy theory of a superconducting-island device coupled to multiple leads. This model, which possesses non-Fermi liquid physics and effective anyons, was argued to belong to the class of topological Kondo effects. Here, we clarify the extent of stability of its exotic fixed point using perturbative and numerical renormalization group in conjunction with bosonization and conformal field theory. In contrast to previous claims, we show that asymmetry in the coupling to the leads destabilizes the non-Fermi liquid. Other destabilizing perturbations include asymmetry in the superconducting pairing or internal energy of the individual quantum dots in the island. Nevertheless, these perturbations all generate the same relevant operators. Thus, only a small number of couplings need to be tuned individually, and these can be selected according to experimental convenience. Our results highlight a common misconception that anisotropy in single-channel Kondo couplings is always irrelevant. As demonstrated, relevant terms will emerge whenever the group generators do not span the full space of impurity operators. This calls for a more detailed inspection of models that exhibit this property, such as large-spin impurities and SO⁡( M ) Kondo models.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Deep Reinforcement Learning Based Control of Wind Turbines for Fast Frequency Response

In order to fulfill vital auxiliary grid services, such as load regulation, spin and non-spin reserve provision, and frequency support during emergencies, there is often a requirement for certain wind farms to operate in de-loaded modes. Leveraging the swift response capabilities of wind farms, this study demonstrates that reserving power in de-loaded modes can significantly enhance power grid stability and reliability during system contingencies. Controlling wind farms optimally for frequency support is intricate due to the nonlinearity of models and controllers and the complexity of wind farm interactions with power systems. Here, to address this challenge, this paper introduces a novel approach that integrates wind turbines into reinforcement learning-based solutions for frequency response. This innovative methodology utilizes the state-of-the-art reinforcement learning algorithm known as the surrogate-gradient-based evolutionary strategy. The proposed learning-based algorithm provides continuous control of wind farm output to rapidly stabilize system frequency and prevent unnecessary trips of under-frequency load shedding relays. To facilitate efficient training, parallel computing techniques are employed. The proposed methodology is evaluated on a modified IEEE-39 bus system, and simulation results reveal its efficacy in reliably supporting power system frequency and preventing the need for unnecessary load shedding.

Gao, Wei [Argonne National Laboratory (ANL), Argon↗
DOE OSTI2022

Investigating Gluonic Operators in Coordinate Space

In this dissertation, a method of extracting gluon momentum distributions inside hadrons, and particularly nucleons, is developed. In general, the utility and application of performing calculations in coordinate space at the operator level is discussed, and its application to the method of pseudodistributions in the lattice extraction of parton distributions. An introduction to the background field method and other techniques used in the calculation of corrections to gluon operators are provided. Then, an outline of the calculation of the uncontracted gluon bilocal operator at one-loop is given, and the result thereof. Using the result for the gluon bilocal operator restricted to spacelike separations, z = (0, 0, 0, z3), various projections and contractions are discussed for the spin averaged case, and for the polarization dependent case in a forward nucleon matrix element. Finally, matching relations between pseudodistributions and lightcone distributions are given for the unpolarized gluon distribution and for the polarized gluon distribution. Application of the results in recent actual lattice extractions of gluon PDFs is discussed, and future applications are outlined.

Morris, Wayne↗
NASA NTRS1975

Synchronous Meteorological Satellite spin testing

The end-to-end spin tests conducted on the Synchronous Meteorological Satellite are described in detail. It is noted that the objective of these tests was to demonstrate that the satellite performed its intended functions under spinning conditions and that all satellite functions were tested except for solar-panel illumination, pyrotechnic-device operation, VISSR infrared operation, and auxiliary propulsion-system operation. Tests discussed include antenna pointing, S-band and UHF equivalent isotropic radiated power, output-power ripple, bit error rate, synchronous electromagnetic interference, earth width measurement, and satellite magnetic-field measurement. The purpose, technique, salient results, and problems of each test are outlined.

Mcbrady, D. J.↗
NASA NTRS1977

Toroidal tank evaluation

The reported study had been conducted to determine the feasibility of developing toroidal tanks for an auxiliary propulsion system that could be integrated into a Pioneer spin-stabilized spacecraft. The system evaluated consisted of two toroidal tanks equipped with surface tension devices. One tank is intended for nitrogen tetroxide, the other for monomethylhydrazine. The study included the definition of a propellant acquisition system concept that could satisfy the requirements of a spinning tank. It was found that an oxidizer tank spin rate of 76 rpm and a fuel tank spin rate of 110 rpm would be required to produce liquid loss from the acquisition system during spacecraft operation. An investigation showed that toroidal tanks can be fabricated with present technology using either titanium or aluminum alloys. The preferred material would be titanium because of its significantly higher strength.

Fester, D. A.↗
NASA NTRS1990

Magnetic detector for projectiles in tubes

A new wall-mounted, magnetic detector is presented for measuring projectile passage times in tubes. The detector has the advantages of simplicity over laser and microwave techniques and has other advantages over the electrical contact wire technique. Representative data are presented. The detector is shown to be very insensitive to strong pressure waves and combustion, but able to detect the passage of the projectile (carrying one or two magnets) clearly. Two modes of operation of the detector are described and the use of these detectors to measure projectile velocities, accelerations, and spin rates is discussed.

Bogdanoff, D. W.↗
NASA NTRS2001

Development of a fully integrated analysis system for ions based on ion-selective optodes and centrifugal microfluidics

A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

NASA Discipline Life Sciences Technologies↗
NASA NTRS2006

Intelligent Vision Systems Independent Research and Development (IR&D) 2006

This report summarizes results in conduct of research sponsored by the 2006 Independent Research and Development (IR&D) program at Marshall Space Flight Center (MSFC) at Redstone Arsenal, Alabama. The focus of this IR&D is neural network (NN) technology provided by Imagination Engines, Incorporated (IEI) of St. Louis, Missouri. The technology already has many commercial, military, and governmental applications, and a rapidly growing list of other potential spin-offs. The goal for this IR&D is implementation and demonstration of the technology for autonomous robotic operations, first in software and ultimately in one or more hardware realizations. Testing is targeted specifically to the MSFC Flat Floor, but may also include other robotic platforms at MSFC, as time and funds permit. For the purpose of this report, the NN technology will be referred to by IEI's designation for a subset configuration of its patented technology suite: Self-Training Autonomous Neural Network Object (STANNO).

Patrick, Clinton↗
DOE OSTI2023

Orientational Order in Spin-Cast Lead-Iodide Perovskite Nanocrystal Solids

Combined synthetic control over size and composition renders colloidal lead-halide perovskite nanocrystals a tunable platform for high-efficiency optoelectronic applications. However, the properties and operational stability of devices based on nanocrystal solids are often dictated by the method of the evaporation-induced assembly. Ubiquitous slow evaporation techniques can produce highly ordered nanocrystal domains but limit the prospects for scalable fabrication of continuous device layers, calling for investigation of approaches to more rapidly form ordered perovskite nanocrystal solids. Here, we study orientationally ordered lead-iodide perovskite nanocrystal solids prepared by conventional spin coating with molecular additives (excess ligand) to enhance ordering within the arrays. In situ X-ray scattering measurements reveal that orientational ordering occurs rapidly upon solvent removal during spin coating and can be further enhanced by manipulating the spin speed. We vary the additive ligand length and explore trade-offs between ordering and layered perovskite impurity formation. Arrays treated with the intermediate-length octylamine ligand exhibit increased in-plane electronic conductivity, suggesting orientational ordering and internanocrystal electronic coupling can be enhanced by the treatment. In conclusion, these results highlight the prospects of establishing long-range order in lead-halide perovskite nanocrystal solids by using simple and fast coating methods.

14 SOLAR ENERGY↗
DOE OSTI2023

Scrambling and operator entanglement in local non-Hermitian quantum systems

The breakdown of Lieb-Robinson bounds in local, non-Hermitian quantum systems opens up the possibility for a rich landscape of quantum many-body phenomenology. We elucidate this by studying information scrambling and quantum chaos in non-Hermitian variants of paradigmatic local quantum spin-chain models. We utilize a mixture of exact diagonalization and tensor network techniques for our numerical results and focus on three dynamical quantities: (i) out-of-time-ordered correlators (OTOCs), (ii) operator entanglement of the dynamics, and (iii) entanglement growth following a quench from product initial states. We show that while OTOCs fail to capture information scrambling in a simple, local, non-Hermitian transverse-field Ising model, the closely related operator entanglement is a robust measure of dynamical properties of interest. Moreover, we show that the short-time growth of operator entanglement can generically detect entanglement phase transitions in these systems while its long-time average is shown to be a reliable indicator of quantum chaos and entanglement phases. This allows us to extend operator entanglement-based diagnostics from previous works on closed and open quantum systems, to the new arena of monitored quantum dynamics. Finally, we remark on the efficacy of these dynamical quantities in detecting integrability/chaos in the presence of continuous monitoring.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRSDate not supplied

Surface Radiation Budget (SRB) Release 2.5 Longwave Daily Data in Native Format (SRB_REL2.5_LW_DAILY)

This SRB data set contains average Clear-sky upward and downward flux, surface upward and downward flux, and top of the atmosphere (TOA) upward flux measured at three hourly intervals for each day for the entire globe between 07/01/1983 and 06/30/2005. These LW surface and Top of Atmosphere (TOA) radiative parameters were derived with the Longwave algorithm of the NASA World Climate Research Programme/Global Energy and Water-Cycle Experiment (WCRP/GEWEX) Surface Radiation Budget (SRB) Project. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-06-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=Ranges from 1 degree (tropics and subtropics) to 120 degrees (the poles).; Temporal_Resolution=daily; Temporal_Resolution_Range=daily].

TOA UPWARD LONGWAVE FLUX↗
DOE OSTI2021

Manipulation of Hole Spin Transport in Germanium

Downscaling of the silicon metal-oxide-semiconductor field-effect transistor technology is expected to reach a fundamental limit soon. A paradigm shift in computing is occurring. Spin field-effect transistors are considered a candidate architecture for next-generation microelectronics. Being able to leverage the existing infrastructure for silicon, a spin field-effect transistor technology based on group IV heterostructures will have unparalleled technical and economical advantages. For the same material platform reason, germanium hole quantum dots are also considered a competitive architecture for semiconductor-based quantum technology. In this project, we investigated several approaches to creating hole devices in germanium-based materials as well as injecting hole spins in such structures. We also explored the roles of hole injection in wet chemical etching of germanium. Our main results include the demonstration of germanium metal-oxide-semiconductor field-effect transistors operated at cryogenic temperatures, ohmic current-voltage characteristics in germanium/silicon-germanium heterostructures with ferromagnetic contacts at deep cryogenic temperatures and high magnetic fields, evaluation of the effects of surface preparation on carrier mobility in germanium/silicon- germanium heterostructures, and hole spin polarization through integrated permanent magnets. These results serve as essential components for fabricating next-generation germanium-based devices for microelectronics and quantum systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Eikonal spin-dependent odderon and gluon Sivers function of a proton and its small-𝑥 evolution

The matrix element in the proton of the eikonal Odderon operator, with a helicity flip, has been shown to correspond to the dipole gluon Sivers function. We employ a three quark light-front model of the proton to determine the Sivers function at moderately small 𝑥 0 ∼ 0.1 and transverse momentum 𝑘 ⊥ ≲ 1 GeV. The model light-cone (LC) wave function predicts the properties of 𝑥⁢𝑓$^{⊥⁢𝑔}_{1⁢𝑇⁡}$(𝑥,𝑘 ⊥ ) such as its overall magnitude, the position of its peak in 𝑘 ⊥ , and its behavior at small 𝑘 ⊥ . We then compute numerically the Balitsky-Fadin-Kuraev-Lipatov anomalous dimension characterizing the power-law tail at 𝑘 ⊥ ≳ 1.5 GeV of the gluon Sivers function at small (but preasymptotic) LC momentum fractions 𝑥 ∼ 𝑥 0 ⁢𝑒 −1/𝛼 𝑠 : 𝑥⁢𝑓$^{⊥⁢𝑔}_{1⁢𝑇⁡}$⁡(𝑥,𝑘 ⊥ ) ∼ 𝑘$^{−3.3}_{⊥}$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution

We apply the formalism developed earlier for studying transverse momentum dependent parton distribution functions (TMDs) at small Bjorken x to construct the small- x asymptotics of the quark Sivers function. First, we explicitly construct the complete fundamental “polarized Wilson line” operator to sub-sub-eikonal order: this object can be used to study a variety of quark TMDs at small x . We then express the quark Sivers function in terms of dipole scattering amplitudes containing various components of the “polarized Wilson line” and show that the dominant (eikonal) term which contributes to the quark Sivers function at small x is the spin-dependent odderon, confirming the re- cent results of Dong, Zheng and Zhou. Our conclusion is also similar to the case of the gluon Sivers function derived by Boer, Echevarria, Mulders and Zhou. We also analyze the sub-eikonal corrections to the quark Sivers function using the constructed “polarized Wilson line” operator. We derive new small- x evolution equations re-summing double-logarithmic powers of α s ln 2 (1 /x ) with α s the strong coupling constant. We solve the corresponding novel evolution equations in the large- N c limit, obtaining a sub-eikonal correction to the spin-dependent odderon contribution. We conclude that the quark Sivers function at small x receives contributions from two terms and is given by ${f}_{1T}^{\perp q}\left(x,{k}_T^2\right)={C}_O\left(x,{k}_T^2\right)\frac{1}{x}+{C}_1\left({k}_T^2\right){\left(\frac{1}{x}\right)}^0+\cdots$ with the function C O ( x, ${k}_T^2$) varying slowly with x and the ellipsis denoting the subasymptotic and sub-sub-eikonal (order- x ) corrections.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1983

System description

The VAS, carried onboard the GOES 4 and 5 satellites, is a radiometer with 8 visible channel detectors and 6 thermal detectors that detect infrared radiation in 12 spectral bands. A filter wheel in front of the detector is used to achieve the spectral selection. The spatial resolution is 0.9 kilometer in the visible and 7 or 14 kilometers in the infrared depending on the detector used. Full Earth disk coverage is accomplished by spinning in the west to east direction at 100 rpm and by stepping a scan mirror from north to south. Additional VAS instrument characteristics are summarized. The VAS has three operating modes: the operational VISSR mode, the multispectral imaging (MSI) mode, and the dwell sounding (DS) mode. The operational VISSR mode is used by NOAA/NESS for its operational products, which include a visible picture and an 11 micrometer infrared (channel 8) picture at half hour intervals. The other modes are VAS unique. The MSI mode combines the operational VISSR capability (visible plus infrared window) with two additional spectral channels to provide half hourly full Earth disk imagery of atmospheric water vapor, temperature, and cloud distribution. The DS mode is used primarily for sounding to obtain the temperature and moisture profiles. In this mode, multiple spins on the same scan line in a given band are averaged to obtain the required signal to noise ratio for sounding.

Montgomery, H.↗