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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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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Simulation of Particle-Material Interactions

This paper gives an overview of the particle transport theory essentials, the basics of particle-material interaction simulation, physical quantities needed to simulate particle transport and interactions in materials, Monte Carlo simulation flow, response of additive detectors, statistical weights and other techniques to minimize statistical errors. Effects in materials under irradiation, materials response related to component lifetime and performance are considered with a focus on high-energy and high-power accelerator applications. Implementation of simulation of particle-material interactions in the modern Monte Carlo codes along with the code s main features and results of recent benchmarking are described.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

A Search for Light Weakly-Interacting Massive Particles with SuperCDMS and Applications to Neutrino Physics

Cosmological and astrophysical evidence indicates that 85% of the matter content of the universe is in the form of non-baryonic dark matter. A large number of experiments are currently undertaking searches for weakly-interacting massive particles (WIMPs), the leading class of particle candidates for dark matter. This thesis describes the results of such a search with the SuperCDMS experiment, which uses Ge detectors cooled to 50 mK to detect ionization and phonons produced by particle interactions. We perform a blind analysis of 577 kg d of exposure on 7 detectors targeting WIMPs with masses < 30GeV/$c^{2}$, where anomalous results have been reported by previous experiments. No significant excess is observed and we set an upper limit on the spin-independent WIMP-nucleon cross section of 1.2 x 10$^{-42}$ cm2 at 8 GeV/$c^{2}$ We also set constraints on dark matter interactions independent of the dark matter halo physics, as well as on annual modulation of a dark matter signal. Cryogenic detectors similar to SuperCDMS also have potential applications in neutrino physics. We study several configurations in which dark matter detectors could be used with an intense neutrino source to detect an unmeasured Standard Model process called coherent neutrino scattering. This process may be useful, for example, as a calibration for next-generation dark matter detectors, and for constraining eV-scale sterile neutrinos. In addition, small cryogenic X-ray detectors on sounding rockets with large fields-of-view have the unique ability to constrain sterile neutrino dark matter. We set limits on sterile neutrino dark matter using an observation by the XQC instrument, and discuss prospects for a future observation of the galactic center using the Micro-X instrument.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Nonadditive Interactions Unlock Small-Particle Mobility in Binary Colloidal Monolayers

We examine the organization and dynamics of binary colloidal monolayers composed of micron-scale silica particles interspersed with smaller-diameter silica particles that serve as minority component impurities. These binary monolayers are prepared at the surface of ionic liquid droplets over a range of size ratios (σ = 0.16–0.66) and are studied with low-dose minimally perturbative scanning electron microscopy (SEM). The high resolution of SEM imaging provides direct tracking of all particle coordinates over time, enabling a complete description of the microscopic state. In these bidisperse size mixtures, particle interactions are nonadditive because interfacial pinning to the droplet surface causes the equators of differently sized particles to lie in separate planes. By varying the size ratio, we control the extent of nonadditivity in order to achieve phase behavior inaccessible to additive 2D systems. Across the range of size ratios, we tune the system from a mobile small-particle phase (σ < 0.24) to an interstitial solid (0.24 < σ < 0.33) and furthermore to a disordered glass (σ > 0.33). These distinct phase regimes are classified through measurements of hexagonal ordering of the large-particle host lattice and the lattice’s capacity for small-particle transport. Altogether, we explain these structural and dynamic trends by considering the combined influence of interparticle interactions and the colloidal packing geometry. Our measurements are reproduced in molecular dynamics simulations of 2D nonadditive disks, suggesting an efficient method for describing confined systems with reduced dimensionality representations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Shock and contact interaction with a simple cubic array of particles

Shock-particle interaction is a fundamental pillar of multiphase compressible flows that has been studied at length for many decades. However, little attention has been paid to the interaction of particles with a contact interface that follows a shock in shock tube experiments and applications relating to blast waves. Presently, the phenomenon is studied at the microscale via particle resolved simulations of shock contact systems interacting with a structured array of particles as well as isolated particles. Simulations are conducted at particle volume fractions of 0%, 5%, 10%, 20%, and 40% at three contact Mach numbers. Additionally, the diaphragm position is varied, which controls the timing of the shock arrival time in relation to the contact arrival time. The modification to the drag on these stationary particles by the contact is analyzed and compared to the compressible Maxey–Riley–Gatignol model, which is adequate for the single particle cases but does not account for fluid mediated particle–particle interactions.

Mechanics↗
DOE OSTI2017

A Search For Weakly Interacting Massive Particles Utilizing A Profile Likelihood Ratio Technique With The Super CDMS Soudan Experiment

Dark matter accounts for ~26.8% of the universe’s mass and ~85% of the matter of the universe. The majority of dark matter is in the form of non-baryonic dark matter. Among all the dark matter particle candidates, the Weakly Interacting Massive Particle (WIMP) is considered the most promising. Tens of experiments around the world are under the searches of WIMPs. The Super Cryogenic Dark Matter Search (SuperCDMS) is one of the leading direct dark matter search experiments. Its latest experiment was located in the Soudan Underground Laboratory in northern Minnesota. By placing its germanium (Ge) detectors deep underground, it aimed at performing a rare-event search in the case that a WIMP would collide with a Ge nucleus and leave a Ge nuclear recoil signal in the detectors. These Ge detectors were operated at a temperature of ~50 mK to reduce the noise from disturbing the ionization and phonon signal collections. A high mass WIMP search analysis is performed on the recent collected data sets at Soudan. It aims at exploring WIMPs with masses from the order of 10 GeV/c 2 and above. With a raw exposure of 1657.54 kg-days, an exclusion limit is set on the spin-independent WIMP-nucleon cross section at 1.32 ×10 -44 cm 2 for a 75 GeV/c2 WIMP at a 90% confidence level by the profile likelihood ratio technique. Neutrons are the most dangerous background in a direct dark matter search experiment. The nuclear recoil signal that a neutron produces in a Ge detector is indistinguishable from vii that a WIMP produces. Protection against them is one of the key aspects for the next generation of SuperCDMS experiment at SNOLAB. An active neutron veto system was proposed to be implemented in this future experiment to make it more robust from neutrons. The feasibility of both the plastic and liquid neutron veto systems was studied.

Qiu, Hang↗
DOE OSTI2015

Nanophotonic force microscopy: Characterizing particle–surface interactions using near-field photonics

Direct measurements of particle–surface interactions are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions. Current techniques are limited in their ability to measure pico-Newton scale interaction forces on submicrometer particles due to signal detection limits and thermal noise. In this paper, we present a new technique for making measurements in this regime, which we refer to as nanophotonic force microscopy. Using a photonic crystal resonator, we generate a strongly localized region of exponentially decaying, near-field light that allows us to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle we are able to map out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. Finally, as shown in this Letter, our technique is not limited by thermal noise, and therefore, we are able to resolve interaction forces smaller than 1 pN on dielectric particles as small as 100 nm in diameter.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Origin of a sensitive dependence of calculated {beta}{beta}-decay amplitudes on the particle-particle residual interaction

In the present work the sensitivity of calculated {beta}{beta}-decay amplitudes to a realistic residual interaction is analyzed in the framework of the approach of O. A. Rumyantsev and M. H. Urin, Phys. Lett. B 443, 51 (1998). and V. A. Rodin, M. H. Urin, and A. Faessler, Nucl. Phys. A 747, 297 (2005). Both the Gamow-Teller (GT) and Fermi (F) matrix elements M{sup 2}{nu} for two-neutrino {beta}{beta} decay (2{nu}{beta}{beta} decay), along with the monopole transition contributions to the total matrix elements M{sup 0{nu}} of neutrinoless {beta}{beta} decay (0{nu}{beta}{beta} decay), are calculated within the quasiparticle random-phase approximation (QRPA). In the aforementioned approach decompositions of M{sup 2{nu}} and M{sup 0{nu}} can be obtained in terms of the corresponding energy-weighted sum rules S. It is shown that in most of the cases almost the whole dependence of M{sup 2{nu}} and M{sup 0{nu}} on the particle-particle (p-p) renormalization parameter g{sub pp} is accounted for by the g{sub pp} dependence of the corresponding sum rules S. General expressions relating S to a realistic residual particle-particle interaction are derived, which show a pronounced sensitivity of S to the singlet-channel interaction in the case of F transitions and to the triplet-channel interaction in the case of GT transitions. Thus, the sensitivity of M{sup 2{nu}} and M{sup 0{nu}} to the SU(4)-symmetry-breaking part of the p-p residual interaction is dictated by the generic structure of the {beta}{beta}-decay amplitudes. Therefore, a choice of this part in a particular calculation needs a special caution. Finally, a better isospin-consistent way of renormalization of a realistic residual p-p interaction to use in QRPA calculations is suggested.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

1.5D Quasilinear Model for Alpha Particle-TAE Interaction in ARIES ACT-I

We study the TAE interaction with alpha particle fusion products in ARIES ACT-I using the 1.5D quasilinear model. 1.5D uses linear analytic expressions for growth and damping rates of TAE modes evaluated using TRANSP profiles to calculates the relaxation of pressure profiles. NOVA-K simulations are conducted to validate the analytic dependencies of the rates, and to normalize their absolute value. The low dimensionality of the model permits calculating loss diagrams in large parameter spaces.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils

LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a ∼7-tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for 𝑝⁢𝑝-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the <100 keV energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Chaotic Dynamics Driven by Particle-Core Interactions

High-intensity beams in modern linacs are frequently encircled by diffuse halos, which drive sustained particle losses and result in gradual degradation of accelerating structures. In large part, the growth of halos is facilitated by internal space-charge forces within the beams, and detailed characterization of this process constitutes an active area of ongoing research. A partial understanding of dynamics that ensue within space-charge dominated beams is presented by the particle-core interaction paradigm – a mathematical model wherein single particle dynamics, subject to the collective potential of the core, are treated as a proxy for the broader behavior of the beam. In this work, we investigate the conditions for the onset of large-scale chaos within the framework of this model, and demonstrate that the propensity towards stochastic evolution is strongly dependent upon the charge distribution of the beam. In particular, we show that while particle motion within a uniformly charged beam is dominantly regular, rapid deterministic chaos readily arises within space-charge dominated Gaussian beams. Importantly, we find that for sufficiently high values of the beam’s space charge and beam pulsation amplitude, enhanced chaotic mixing between the core and the halo can lead to an enhanced radial diffusion of charged particles. We explain our results from analytic grounds by demonstrating that chaotic motion is driven by the intersection of two principal resonances of the system, and derive the relevant overlap conditions. Additionally, our analysis illuminates a close connection between the mathematical formulation of the particle-core interaction model and the Andoyer family of integrable Hamiltonians

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Early Career: The search for weakly interacting dark matter with liquid xenon

We report results from a search for weakly interacting dark matter particles obtained with the LUX experiment. LUX was located at a depth of 4850 feet at the Sanford Underground Research Facility in Lead, South Dakota from 2013 through 2016. It found no evidence for dark matter particle interactions and set new constraints on the properties of such particles for masses between 6 GeV and 100 TeV. The work reported here also characterized the performance of such experiments by developing a new calibration technique based upon a tritium beta decay source.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Improved rubber nanofillers

During this task, Silane functionalized TiO2 and HK3Ti4O4(SiO4)3 were sent to Goodyear (GY) for testing. These materials were characterized based on their interaction with the model elastomer, squalene. The Van der Waals interactions and Hamaker Constants for ZnO particles in squalene and rubber materials were characterized and it was determined that a 10-20 nm spacing was necessary between primary filler particles to maintain a stable nanocomposite. Contact angle measurements on the ZnO and ZnO-silane materials indicated that the solvent should wet the particles, and solvophobic attractions should not be present. These studies showed that the surface modification with sulfosilane coupling agents was successful, and high levels of dispersion of the particles remained possible. Further, a novel surface charging phenomenon where negative surface charging is developed in the squalene environment was observed and corroborated by measurements of particle size and of the surface modified materials in squalene. This impacts the dispersion of the particles according to the traditional colloidal interpretation of electrostatic repulsive forces between particles. Additionally, thin nanocomposite fibers were developed using electrospinning. The size and shape of the oxides did not change during the electrospinning process, although the shape of the fiber and the distribution of the particles, particularly for ZnO, was not ideal. There was an obvious increase in elastic modulus and hardness from the addition of the oxides, but differentiating the oxides, and particularly the surfactants, was difficult. The A-1289 lead to the greatest dispersion of the filler particles, while the A-1589 and the NXT produced clustered particle aggregates. This agrees with previous study of these materials in low molecular weight squalene solvent studies reported earlier. The behavior of the nanoparticle ZnO and the microparticle silica is different as well, with the ZnO being contained within the elastomer, and the SiO2 forming monolayers at the surface of the elastomer. The dynamic mechanical analysis did not show clear trends between the surface modification and the aggregate structure. In the silica particles, the NXT led to the least particle interaction, followed by the A-1289 and highest particle interaction found for the A-1589. For the nanosized ZnO, the best dispersion was found for the A-1589, with both the A-1289 and NXT exhibiting frequency dependent responses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Nonlinear dynamics of beta-induced Alfvén eigenmode in tokamak

The beta-induced Alfvén eigenmode (BAE) excited by energetic particles in toroidal plasmas is studied in the global gyrokinetic simulations. It is found that the nonlinear BAE dynamics depends on the deviation from the marginality. In the strongly driven case, the mode exhibits a bursting state with fast and repetitive chirping. The nonlinear saturation is determined by the thermal ion nonlinearity and has no clear dependence on the linear growth rate. In the weakly driven case, the mode reaches a nearly steady state with small frequency chirping. The nonlinear dynamics is dominated by the energetic particle nonlinearity. In both cases, the nonlinear intensity oscillation and frequency chirping are correlated with the evolution of the coherent structures in the energetic particle phase space. Due to the radial variation of the mode amplitude and the radially asymmetric guiding center dynamics, the wave-particle interaction in the toroidal geometry is much more complex than the conventional one-dimensional wave-particle interaction paradigm.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Search for the standard model Higgs boson in $l\nu+b\bar{b}$ final states in 9.7 fb$^{-1}$ of $p\bar{p}$ collisions with the DØ detector

Humans have always attempted to understand the mystery of Nature, and more recently physicists have established theories to describe the observed phenomena. The most recent theory is a gauge quantum field theory framework, called Standard Model (SM), which proposes a model comprised of elementary matter particles and interaction particles which are fundamental force carriers in the most unified way. The Standard Model contains the internal symmetries of the unitary product group SU(3) c ⓍSU(2) L Ⓧ U(1) Y , describes the electromagnetic, weak and strong interactions; the model also describes how quarks interact with each other through all of these three interactions, how leptons interact with each other through electromagnetic and weak forces, and how force carriers mediate the fundamental interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Effect of Mach number and volume fraction in air-shock interacting with a bed of randomly distributed spherical particles

Shock-particle interaction is a fundamental problem in many engineering applications, with the dynamics being heavily influenced by the incident-shock Mach number and the particle volume fraction. In this paper we present fully resolved inviscid simulations of an incident-shock wave traveling through a bed of randomly distributed spherical particles. We vary the strength of the incident shock along with the particle volume fraction in order to study the complex wave interaction during shock-particle interaction. In this study we are interested in the early-time behavior during which the particles do not move and hence in our simulations all the particles are fixed in space. We compute the streamwise average of flow field quantities to generate the x - t contour plots to study the unsteady oscillations inside the particle bed. We observe that the transmitted shock slows down under certain conditions and it is partly due to tortuosity and partly due to weakening caused by energy dissipation. We also present the force histories of the streamwise drag and lift forces for all the particles. The random distribution of particles leads to high variability in the drag force experienced by the particles. We compute the mean peak drag force as a function of the streamwise location to study the mean behavior of the transmitted shock. Based on our findings, we propose simple modifications to improve the current point-particle models used in Euler-Lagrange simulations of shock interacting with a bed of particles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Two-way coupled particle-turbulence interaction: Effect of numerics and resolution on fluid and particle statistics

Euler-Lagrange point-particle simulation has emerged as a premier methodology for studying dispersed particle-laden flows. This method's popularity stems from its ability to resolve fine-scale fluid structures while also tracking individual particles at reduced cost using an appropriate particle acceleration model. However, the point-particle model has known convergence issues in that refinement of the fluid grid can lead to changes in the predicted statistics. The reasons for non-convergence are twofold: the point-particle two-way coupling force in the Navier-Stokes equations requires a numerical regularization and, without careful implementation, yields a singular force on the fluid with grid refinement. The second factor that yields grid-dependent statistics is that the point-particle force model in general depends on the undisturbed fluid velocity. When the undisturbed fluid velocity is not robustly modeled in a grid-insensitive way, the calculated force for both particles and fluid will be grid-dependent, contaminating their respective statistics. While the first issue regarding regularizing the point-particle source term has received attention in the literature, the consequences of robustly modeling the undisturbed velocity in the context of grid refinement of turbulence has received little attention. Here, we consider decaying homogeneous isotropic turbulence laden with particles at different Stokes numbers. For a given Stokes number, we systematically refine the grid and demonstrate that explicitly modeling the undisturbed fluid velocity yields relative grid insensitivity for the energy of the particle and fluid phases, as well as acceleration of the particles. We also demonstrate that an appropriately defined dissipation rate is also grid-insensitive when an undisturbed fluid velocity correction is used. In contrast, when the undisturbed fluid velocity is modeled using the conventional approach of interpolating the local fluid velocity to the particle location, we show this procedure yields divergent statistics with grid refinement. In particular, we show that higher-order interpolation of the fluid velocity in two-way coupled problems is worse than lower-order interpolation, in the absence of a correction procedure to estimate the undisturbed fluid velocity. We also examine velocity derivative statistics of the fluid phase and demonstrate that these statistics are not in general convergent even when the undisturbed fluid velocity is explicitly modeled. Collectively, the observations in this paper are used to present a philosophy on the types of questions which are answerable with point-particle methods.

42 ENGINEERING↗
DOE OSTI2015

EVIDENCE OF LANDAU AND CYCLOTRON RESONANCE BETWEEN PROTONS AND KINETIC WAVES IN SOLAR WIND TURBULENCE

The wave–particle interaction processes occurring in the solar wind provide crucial information to understand the wave dissipation and simultaneous particle heating in plasma turbulence. One requires observations of both wave fluctuations and particle kinetics near the dissipation range, which have, however, not yet been analyzed simultaneously. Here we show new evidence of wave–particle interactions by combining the diagnosis of wave modes with the analysis of particle kinetics on the basis of measurements from the WIND spacecraft with a high cadence of about 3 s. Solar wind protons appear to be highly dynamic in their velocity distribution consisting of varying anisotropic core and beam components. The basic scenario of solar wind proton heating through wave–particle interaction is suggested to be the following. Left-handed cyclotron resonance occurs continuously, and is evident from the observed proton core velocity distribution and the concurrent quasi-parallel left-handed Alfvén cyclotron waves. Landau and right-handed cyclotron resonances are persistent and indicated by the observed drifting anisotropic beam and the simultaneous quasi-perpendicular right-handed kinetic Alfvén waves in a general sense. The persistence of non-gyrotropic proton distributions may cast new light on the nature of the interaction between particles and waves near and beyond the proton gyro-frequency.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Gravitational scattering and beyond from extreme mass ratio effective field theory

We explore a recently proposed effective field theory describing electromagnetically or gravitationally interacting massive particles in an expansion about their mass ratio, also known as the self-force (SF) expansion. By integrating out the deviation of the heavy particle about its inertial trajectory, we obtain an effective action whose only degrees of freedom are the lighter particle together with the photon or graviton, all propagating in a Coulomb or Schwarzschild background. The 0SF dynamics are described by the usual background field method, which at 1SF is supplemented by a “recoil operator” that encodes the wobble of the heavy particle, and similarly computable corrections appearing at 2SF and higher. Our formalism exploits the fact that the analytic expressions for classical backgrounds and particle trajectories encode dynamical information to all orders in the couplings, and from them we extract multiloop integrands for perturbative scattering. As a check, we study the two-loop classical scattering of scalar particles in electromagnetism and gravity, verifying known results. We then present new calculations for the two-loop classical scattering of dyons, and of particles interacting with an additional scalar or vector field coupling directly to the lighter particle but only gravitationally to the heavier particle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗