Disordered Vector Models: From Higher Spins to Incipient Strings
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
SEARCH · Engineering Papers
Results for “Particle phenomena”
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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Data-driven discovery of reduced plasma physics models from fully kinetic simulations
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70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Input to the European strategy for particle physics: strong-field quantum electrodynamics
This document sets out the intention of the strong-field QED community to carry out, both experimentally and numerically, high-statistics parametric studies of quantum electrodynamics in the non-perturbative regime, at fields approaching and exceeding the critical or ‘Schwinger’ field of QED (F qed ≈ m 2 c 3 / eh ≈ 1.3 x 10 18 V/m) in the rest frame of a charged particle. In this regime, several exotic and fascinating phenomena are predicted to occur that have never been directly observed in the laboratory. These include Breit–Wheeler pair production, vacuum birefringence, and quantum radiation reaction. This experimental programme will also serve as a stepping stone towards studies of elusive phenomena such as elastic scattering of real photons and the conjectured perturbative breakdown of QED at extreme fields. State-of-the-art high-power laser facilities in Europe and beyond are starting to offer unique opportunities to study this uncharted regime at the intensity frontier, which is highly relevant also for the design of future multi-TeV lepton colliders. A transition from qualitative observational experiments to quantitative and high-statistics measurements can only be performed with large-scale collaborations and with systematic experimental programmes devoted to the optimisation of several aspects of these complex experiments, including detector developments, stability and tolerances studies, and laser technology.
Sarri, G. [Queen’s University Belfast (United King↗
Io sheath-accelerated electrons and ions
Recent results available from more rigorously analyzed Pioneer 10 data and the preliminary results of Pioneer 11 are used to further revise the satellite Io sheath acceleration model. The revised model is then employed to suggest an explanation for a number of earth-based and Pioneer 10 and 11 observations and to discuss other phenomena which might be detectable with future experiments. Particle acceleration near Io is discussed for the cases of negative sheath (face toward Jupiter) and positive sheath (face away from Jupiter). Io sputtering may explain the presence of atomic hydrogen and sodium in the vicinity of Io, and the accelerated particles may be important to the formation of the Io ionosphere. Directed fluxes of 100-keV electrons in the flux tube may lead to the decametric radio emissions, Jovian atmospheric heating, and optical and X ray emissions. Satellite modulation of decametric radio emissions is discussed.
Shawhan, S. D.↗
Particle dynamics associated with the space environment
A major factor in dust dynamics in a microgravity environment is the absence of settling; hence, Spacelab air will contain larger particles than a comparable laboratory on earth. In addition, the presence of low level acceleration fluctuations (thruster firings, crew motions, etc.) could inhibit dust removal by surface scavenging. Because of the presence of larger particles, aerosol dynamics at larger Reynolds numbers must be considered. An accurate drag coefficient for spherical particles was developed for the higher Reynolds number phenomena. A general graphic correlation for the drag coefficient as a function of Reynolds and Knudsen numbers was developed based on currently available drag data for spheres. The general equations that govern dust dynamics were reviewed.
Sandborn, V. A.↗
Waves In Space Plasmas (WISP): A space plasma lab active experiment
The Waves in Space Plasmas (WISP) series of Spacelab Space Plasma Labs devoted to active experimentation, are introduced. Space Plasma Lab-1 is keyed to active probing of the ionosphere and magnetosphere using controlled wave injections by the WISP VLF and HF transmitters, supported by a free-flying plasma diagnostics package instrumented with wave receivers and particle probe diagnostics, designed to measure radiation and propagation of plasma waves, precipitated particle fluxes due to wave/particle interactions, and similar phenomena resulting from wave injectons. The VLF transmitter delivers up to 1 kW of RF power into the antenna terminals over the range from 0.3 to 30 kHz. The HF transmitter delivers up to 500 W to the antenna over the range from 1 to 30 MHz. A dipole antenna commandable to any extension up to 300 m tip-to-tip is available.
Fredricks, R. W.↗
High Latitude Ionospheric Structure
The Earth's ionosphere is an important element in solar-terrestrial energy transfer processes. As a major terrestrial sink for many solar and magnetospheric events, the ionosphere has characteristic features that are traced to such seemingly remote phenomena as solar flares, radiation belt wave-particle interactions and magnetospheric substorms. In considering the multiple of solar-terrestrial plasma interactions, it is important to recognize that the high-latitude ionosphere is not altogether a simple receptor of various energy deposition processes. The high-altitude ionosphere plays an active feedback role by controlling the conductivity at the base of far-reaching magnetic field lines and by providing a plasma source for the magnetosphere. Indeed, the role of the ionosphere during magnetospheric substorms is emerging as a topic for meaningful study in the overall picture of magnetospheric-ionospheric coupling.
Source record↗
Collisionless shocks in the heliosphere: Reviews of current research
The present conference on heliospheric collisionless shocks considers such macrostructure-, microstructure-, and particle acceleration-related topics as interplanetary shock phenomena near and within 1 AU, as well as beyond, planetary bow shocks, shock formation and evolution in the solar atmosphere, MHD and gasdynamic theories for planetary bow waves, and subcritical collisionless shock waves. Also discussed are ion reflection, gyration, and dissipation at supercritical shocks, the numerical simulation of quasi-perpendicular collisionless shocks, electron distributions near collisionless shocks, the microtheory of collisionless shock current layers, plasma waves and instabilities, the electron foreshock, upstream suprathermal ions, and both diffusive and shock drift acceleration.
Tsurutani, Bruce T.↗
Simulation of the electron acoustic instability for a finite-size electron beam system
Simulations of the electron acoustic instability for a finite-size electron beam system are performed with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The results show that the beam radiates electrostatic electron acoustic waves whose decay time outside the beam agrees with the spatial decay length derived from the linear dispersion equation. The ambient cold electrons in a diffusion region surrounding the beam are heated to a higher temperature by absorbing the radiated electron acoustic waves, with the heating occurring mainly in the parallel direction. In the heat diffusion region, the temperature of the cold electrons decreases with distance from the beam with a temperature gradient length smaller than the decay length of the wave energy. The results are discussed with respect to the DE 1 plasma and wave observations in the polar cusp region.
Lin, C. S.↗
Multipoint observations of the magnetopause - Results from ISEE and AMPTE
Multiple spacecraft observations of the magnetopause have made it possible to infer boundary motion and structure, and to compare these with theoretical expectations. the results of the ISEE mission indicate the magnetopause is thicker than expected, often ten magnetosheath ion gyroradii or more, and that its characteristic radial motion is usually sub-Alfvenic. With small spacecraft separations it is possible to infer considerable small-scale magnetic structure within the current layer, suggesting filamentary currents much smaller than an ion gyroradius. Such a microstructure may be important in particle diffusion and, hence, reconnection. There are also phenomena on much larger scales, the highly variable boundary layer, flux transfer events and surface waves due to dynamic pressure variations, the structure of which can be best determined when spacecraft separations are large.
Elphic, R. C.↗
The Radiative Effect on Cloud Microphysics from the Arctic to the Tropics
Cloud representation is one of the largest uncertainties in the current weather and climate models. In this article, the observations and modeling of the radiative effect on (cloud) microphysics (REM) from the Arctic to the Tropics are overviewed, providing a new direction to meet the challenge of cloud representation. REM deals with the radiation-induced temperature difference between cloud particles and air. It leads to two common phenomena observed at the surface—dew and frost—and impacts clouds aloft significantly, which is noticed via the wide occurrence of horizontally oriented ice crystals (HOICs). However, REM has been overlooked by all of the operational weather and climate models. Based on the bin model of REM and the global distribution of radiative cooling/warming, the observations of REM from several platforms (e.g., aircrafts, field campaigns, and satellites) are coordinated in this article, yielding a global picture on REM. As a result, the picture is compatible with the global distribution of HOICs and other ice crystal characteristics obtained from various clouds on the globe, such as diamond dust (or clear-sky precipitation) in the Arctic, sub-visual cirrus clouds in the tropical tropopause layer, and other cirrus clouds from the low to high latitudes. In addition, ice crystals possess relatively strong REM compared to liquid drops because their aspect ratio is usually not one. The global picture on REM can be used by the weather and climate modelers to diagnose their cloud representation biases. It can also be used to improve the atmospheric ice retrieval algorithm from satellite observations.
cloud microphysics↗
The influence of grain growth in circumstellar dust envelopes on observed colors and polarization of some eruptive stars
R CrB stars are classical examples of stars where dust envelope formation takes place. Dust envelope formation was detected around the Kuwano-Honda object (PU Vul) in 1980 to 1981 when the star's brightness fell to 8(sup m). Such envelopes are also formed at nova outbursts. The process of dust envelope formation leads to appreciable variations in optical characteristics, which are seen in specific color and polarization variations in the course of light fading and the appearance of IR radiation. It is shown that the model of a circumstellar dust envelope with aligned particles of changing size can be successfully applied to explain most phenomena observed at the time of light minima for a number of eruptive stars. The polarization may arise in a nonspherical dust envelope or be produced by alignment of nonspherical particles.
Efimov, Yu. S.↗
Containerless Experimentation in Fluid Dynamics and Crystal Growth on Earth and in Microgravity
The experimental techniques used for the investigation of the shape dynamics and flows within single isolated fluid particles have been refined to the point where detailed differences between phenomena observed in 1 G and in microgravity can be accurately measured.
fluid↗
Self-consistent PIC simulations of ultimate space charge compensation with electron lenses
Further progress of fundamental particle physics requires high intensity and high brightness of accelerated proton and ion beams. This goal is essential for the FAIR hadron beams at GSI, for the neutrino production at the facilities such as Fermilab and JPARC, and for the Large Hadron Collider luminosity at CERN. One of the most formidable obstacles toward that goal is the beam's own space charge, whose forces cause beam emittance growth, losses and lifetime degradation. Typically, such effects become intolerable when the space charge tune-shift parameter Δ QSC exceeds ~ - (0.25–0.5). To reduce these detrimental effects, it was suggested to use electron lenses to compensate the space charge forces. Furthermore, this paper reports on detailed particle-in-cell space charge and electron lens compensation simulations for extremely intense proton bunches whose space charge tune-shift parameter exceeds -1.0. Different scenarios were evaluated based on reduction in the emittance growth and particle loss at a 4σ aperture. Further, we investigate phenomena and issues related to the focusing lattice errors, importance of the transverse and longitudinal matching of the electron beam profiles to the proton ones, and vary the strength and the number of the electron lenses distributed around a circular machine to optimize the reduction of harmful space charge effects.
43 PARTICLE ACCELERATORS↗
Particle Theory and Cosmology
This project covered theoretical studies in particle physics, particle astrophysics and cosmology, aiming to bridge theoretical models with observable phenomena. The central focus was on exploring innovative mechanisms that could simultaneously address several outstanding puzzles in these areas, including the nature of dark matter, the muon g-2 anomaly, the existence of topologically stable monopoles, the generation of observable gravitational waves from early universe phenomena and high energy cosmic rays. One of the major achievements of this project was the development of models that predict new physics accessible through current and forthcoming experimental setups, both in particle colliders and astrophysical observations. These models have been instrumental in proposing verifiable predictions concerning supersymmetric extensions, the dynamics of cosmic strings and monopoles, and the intricate processes underpinning baryogenesis and reheating post-inflation. In tackling the dark matter conundrum, the project proposed several candidates within extended frameworks, such as light Z' models, pseudo-Goldstone dark matter, and scenarios integrating dark matter with inflationary cosmology. Each model outlined pathways for detection through direct, indirect, and collider search strategies, marking significant strides in the hunt for dark matter. Another cornerstone of the project was the in-depth analysis of inflationary models compliant with the Trans-Planckian Censorship Conjecture, highlighting the compatibility of axion dark matter within such frameworks. This not only provided a coherent picture of early universe cosmology but also delineated clear experimental signatures. The exploration of grand unified theories yielded insights into the potential discovery of monopoles and novel particle configurations at energy scales accessible to current and future colliders. This endeavor expanded the predictive power of these theories, particularly in the context of proton decay and the properties of Higgs-portal dark matter. Throughout the project, significant emphasis was placed on ensuring the theoretical developments were grounded in experimental testability. This led to a series of publications across prestigious journals, each contributing to the vibrant discourse at the intersection of particle physics and cosmology. In summary, this project has elucidated pathways beyond the Standard Model that are ripe for exploration through both ongoing and upcoming experimental efforts. The comprehensive approach adopted herein not only enhances our understanding of the fundamental forces and constituents of the universe but also propels the field towards new frontiers in high-energy physics and cosmology.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Initial observations of low energy charged particles near the earth's bow shock on ISEE-1
Initial measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE 1 are reported. ULECA is an electrostatic deflection - total energy sensor consisting of a collimator, a deflection analyzer, and an array of solid-state detectors. The position of a given detector, which determines the energy per charge of an incident particle, together with the measured energy, determines the particle's charge state. It is found that a rich variety of phenomena are operative in the transthermal energy regime (about 10 keV/Q to 100 keV/Q) covered by ULECA. Specifically, observations are presented of locally accelerated protons, alpha particles, and heavier ions in the magnetosheath and upstream of earth's bow shock. Preliminary analysis indicates that the behavior of these locally accelerated particles is most similar at the same energy per charge.
Ipavich, F. M.↗
Beyond the Standard Model New Physics Searches with SBND
SBND (Short-Baseline Near Detector) is a 112-ton liquid argon time projection chamber located on the Booster Neutrino Beam at Fermi National Accelerator Laboratory, and is the near detector of the Short-Baseline Neutrino program. The primary goals of SBND are to provide flux constraints for sterile neutrino searches, conduct world-leading neutrino cross-section measurements on argon, and perform Beyond the Standard Model (BSM) new physics searches with its high-precision particle identification capabilities. SBND’s prospects and tools for detecting a variety of BSM phenomena produced in a neutrino beam, such as sub-GeV dark matter, dark neutrinos, heavy neutral leptons and millicharged particles, are discussed.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Transient phenomena originating at the sun - An interplanetary view
Analyses of several transient phenomena which occurred in 1978 and 1979 are presented using data from the Pioneer Venus, ISEE, and Pioneer 10 and 11 spacecraft. The interplanetary phenomena studied are associated with solar flares and coronal holes. The observations show that phenomena originating at the sun affect the structure of the particle and field regimes throughout the explored solar system, extending out to at least 17-20 AU in the vicinity of the elliptic plane over a range of azimuthal angles greater than 90 deg. High frequency fluctuations in the interplanetary medium appear beyond 1 AU, indicating that transient phenomena are significantly modified by their passage through this medium.
Intriligator, D. S.↗