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At least 775 records · Page 43

Do Satellite Magnetic Anomaly Data Accurately Portray the Crustal Component?

Scalar aeromagnetic data obtained during the U.S. Naval Oceanographic Office (NOO)-Vector Magnetic Survey of the conterminous United States were upward continued by equivalent point source inversion and compared with POGO satellite magnetic anomaly and preliminary scalar MAGSAT data. Initial comparisons indicate that the upward continued NOO data is dominated by long wavelength (approximately equal to 1000 to 3000 km) anomalies which are not present in the satellite anomaly data. Thus, the comparison of the data sets is poor. Several possible sources for these differences are present in the data analysis chain. However, upon removal of these long wavelengths from the upward continued NOO data, a close comparison observed between the anomalies verifies that satellite magnetic anomaly data do portray the crustal component within a range of wavelengths from roughly 1000 km down to the resolution limit of the observations.

Vonfrese, R. R. B.↗

Electromagnetic fluctuation spectra of collective oscillations in magnetized Maxwellian equal mass plasmas for low-frequency waves

Recently, the general electromagnetic fluctuation theory for magnetized plasmas has been used to study the steady-state fluctuation spectra and the total intensity of low-frequency collective weakly damped modes for parallel wave vectors in Maxwellian plasmas. Now, we address the same question with respect to an arbitrary direction of the wave-vector. Here, we analyze this problem for equal mass plasmas. These plasmas are a very good tool to study various plasma phenomena, as they considerably facilitate the theoretical consideration and at the same time provide with their clear physical picture. Finally, we compare our results in the limiting case of parallel wave vectors with the previous study.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Scalar mesons in a linear sigma model with (axial-)vector mesons

The structure of the scalar mesons has been a subject of debate for many decades. In this work we look for qq states among the physical resonances using an extended Linear Sigma Model that contains scalar, pseudoscalar, vector, and axial-vector mesons both in the non-strange and strange sectors. We perform global fits of meson masses, decay widths and amplitudes in order to ascertain whether the scalar qq states are below or above 1 GeV. We find the scalar states above 1 GeV to be preferred as qq states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A guidance and navigation system for continuous low-thrust vehicles

A midcourse guidance and navigation system for continuous low thrust vehicles was developed. The equinoctial elements are the state variables. Uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time trajectory is defined; equations of motion and measurements are linearized about this trajectory. An exponential cost criterion is constructed and a linear feedback quidance law is derived. An extended Kalman filter is used for state estimation. A short mission using this system is simulated. It is indicated that this system is efficient for short missions, but longer missions require accurate trajectory and ground based measurements.

Jack-Chingtse, C.↗

Measurement of polarization observables in vector meson photoproduction using a transversely-polarized frozen-spin target and polarized photons at CLAS, Jefferson Lab

The study of baryon resonances provides a deeper understanding of the strong interaction because the dynamics and relevant degrees of freedom hidden within them are re ected by the properties of the excited states of baryons. Higher-lying excited states at and above 1.7 GeV/c 2 are generally predicted to have strong couplings to final states involving a heavier meson, e. g. one of the vector mesons, ρ, ω φ, as compared to a lighter pseudoscalar meson, e. g. π and η. Decays to the ππΝ final states via πΔ also become more important through the population of intermediate resonances. We observe that nature invests in mass rather than momentum. The excited states of the nucleon are usually found as broadly overlapping resonances which may decay into a multitude of final states involving mesons and baryons. Polarization observables make it possible to isolate single resonance contributions from other interference terms. The CLAS g9 (FROST) experiment, as part of the N* spectroscopy program at Jefferson Laboratory, accumulated photoproduction data using circularly- & linearly-polarized photons incident on a transversely-polarized butanol target (g9b experiment) in the photon energy range 0:3-2:4 GeV & 0:7-2:1 GeV, respectively. In this work, the analysis of reactions and polarization observables which involve two charged pions, either in the fully exclusive reaction γρ -> ρπ+π- or in the semi-exclusive reaction with a missing neutral pion, γρ -> ρπ + π - (π 0 ) will be presented. For the reaction ρπ + π - , eight polarization observables (I s , I c , P x , P y , $P^s_{x;y}$, $P^c_{x; y}$) have been extracted. The high statistics data rendered it possible to extract these observables in three dimensions. All of them are first-time measurements. The fairly good agreement of Is, Ic obtained from this analysis with the experimental results from a previous CLAS experiment provides support for the first-time measurements. For the reaction γρ -> ρω -> ρπ + π(π 0 , five polarization observables (T, Σ, F, H, P) have been extracted, four of which are first-time measurements at all energies. This analysis thus represents a comprehensive program on vector-meson photoproduction: The ω is observed and studied directly from the data and the polarization observables for the (broad) ω can be extracted from the double-pion reaction in a partial-wave analysis. The 13 polarization observables extracted in this analysis substantially augment the world database of polarization observables for these reactions and are expected to play a crucial role in identifying the contributing baryon resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Upwind relaxation algorithms for Euler/Navier-Stokes equations

A description of and results from a solution algorithm for the compressible Navier-Stokes equations are presented. The main features of the algorithm are second or third order accurate upwind discretization of the convection and pressure derivatives and a relaxation scheme for the unfactored implicit backward Euler time method, implemented in a finite-volume formulation. Upwind methods were successfully used to obtain solutions to the Euler equations for flows with strong shock waves. The particular upwind method being used is based on the flux vector splitting technique developed by Van Leer and both second and third order accurate discretizations were developed. Currently, the most widely used implicit solution technique for the Navier-Stokes equations use approximate factorization (AF) methods to treat multidimensional problems. The time integration scheme being used in the present algorithm corresponds to a line Gauss-Seidel relaxation method. This method produces good convergence rates for steady-state flows, and most of the algorithm was vectorized on the NASA Langley VPS 32 computer. The Navier-Stokes algorithm was tested for several two-dimensional flow problems. Solutions for the problems gave excellent results. The presented effort is directed toward the extension of the scheme to the full three-dimensional Navier-Stokes equations.

Thomas, J. L.↗

Scalar Atomic Defect-Based Solid-State Self-calibrating Magnetometer (3SM) for Space Plasma Analysis

The Earth’s magnetosphere is a system of multiple, co-located particle populations interacting via plasma waves. Things to understand are driving processes, radiation belt and ring current issues, auroral physics, internal plasma processes, and magnetosphere-ionosphere mapping issues. These plasma-physics processes enable the Earth’s magnetosphere to evolve in response to temporal changes in the solar wind and they underlie the phenomena of space weather, which impacts spacecraft systems, astronauts, radio communications, and ground based electric-power grids. The objective of 3SM is to measure magnetic field strength and to calibrate the Vector Magnetometer (VM) device to maintain absolute accuracy during a mission. The 3SM features make the instrument preferably suited not only for the traditional role of scalar magnetometers as absolute references for the calibration of the on-board vector instruments, but also for extended operational capacities, such as higher frequency scalar measurements (of potential interest for magnetosphere studies for the low frequency part of the spectrum) or autonomous scalar / vector operations. Diamond has been the solid-state platform of choice for quantum device technologies for some time, however, it suffers from difficulties such as scalability, integration, and cost. While the diamond platform is very useful for quantum technologies, further development is needed to make it viable. The material platform of choice for NASA Glenn’s Quantum Sensing And Spin Physics (Q-SASP) is silicon carbide (SiC). This is due to the much higher industry development of the SiC material platform for high-power and high-temperature electronics. It leverages both the decades-long SiC development expertise and infrastructure at NASA Glenn and its growing capabilities in quantum metrology. To make SiC devices usable for quantum technologies such as quantum sources, a much deeper understanding of defects is needed. Q-SASP is developing quantum metrology capabilities to evaluate the energy structure, defect formation energy, band structure augmentation, generation/recombination rates, and limits of dipole-dipole coupling in non-metal implanted SiC devices. This can be achieved by analysis of zero-field splitting, low-field resonance, and singlet-triplet mixing through various forms of Electrically Detectable Magnetic Resonance (EDMR) and Near-Zero Field Magnetic Resonance (NZFMR) spectroscopy. This work will discuss recent system developments, device developments, computational modeling, and spectroscopy results and analysis of defects created by non-metal implantations in SiC devices. The defect formation energies of V Si ,V C , V C V Si , N C V Si , N Si , N C in 4H-SiC are previously reported values in other research [2]-[3]. The defect formation energies of PSi and PC were calculated in GPAW [fig 1A]. The basic underlying mechanism of the zero-field phenomenon is the mixing of singlet and triplet states [4]-[5]. In most spin-dependent transport, two electron spins are involved, and thus one must consider each of their interactions with the field. We investigated the electronic and magnetic properties of 4H-SiC and 6H-SiC. The defect formation energy helps us determine what types of defects we are observing in the SiC EDMR experiment. They have very low formation energy (it is negative). The phosphorus substitution in 4H-SiC is a very stable defect. The band diagrams provide us with vital information about how the electronic properties of SiC (such as band gap) change as we add non-metal defects. The zero-field splitting parameters allow us to study the inflection point in the NZFMR [fig 1B]. We clearly observed zero-field splitting. We also noted that the zero-field splitting remained constant with changing bias. We aspect it zero-field splitting to remain constant while the hyperfine and exchange interaction perturbations shift under the influence of an external magnetic field. This is the essence of quantum magnetometry and self-calibration.

space plasma↗

Classification and regression models of audio and vibration signals for machine state monitoring in precision machining systems

Here we present a data-driven method for monitoring machine status in manufacturing processes. Audio and vibration data from precision machining are used for inference in two operating scenarios: (a) variable machine health states (anomaly detection); and (b) settings of machine operation (state estimation). Audio and vibration signals are first processed through Fast Fourier Transform and Principal Component Analysis to extract transformed and informative features. These features are then used in the training of classification and regression models for machine state monitoring. Specifically, three classifiers (K-nearest neighbors, convolutional neural networks and support vector machines) and two regressors (support vector regression and neural network regression) were explored, in terms of their accuracy in machine state prediction. It is shown that the audio and vibration signals are sufficiently rich in information about the machine that 100% state classification accuracy could be accomplished. Data fusion was also explored, showing overall superior accuracy of data-driven regression models.

42 ENGINEERING↗

Magnetic Phases and Inhomogeneous Micromagnetic Structures in a Ferrite Garnet Film with Orientation (210)

Possible magnetic states of a cubic ferromagnet with a uniaxial anisotropy induced along the [210] direction are theoretically investigated. It is demonstrated that the orientation phase diagram of a magnet is nontrivial and admits the existence of three types of magnetic phases that differ in transformational properties and the presence of quintuple points, isostructural phase transitions, etc. It is found that magnetic inhomogeneities, regardless of the values of parameters of the matter, have a common structure: they correspond to 180-degree domain boundaries with a noncircular trajectory of the magnetization vector. The features of homogeneous and inhomogeneous magnetic states, found in these materials, make it possible to explain the manifestation of a flexomagnetoelectric effect in them.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Deciphering the mechanism of near-threshold $$J/\psi $$ photoproduction

Abstract The photoproduction of the $$J/\psi $$ J / ψ off the proton is believed to deepen our understanding of various physics issues. On the one hand, it is proposed to provide access to the origin of the proton mass, based on the QCD multipole expansion. On the other hand, it can be employed in a study of pentaquark states. The process is usually assumed to proceed through vector-meson dominance, that is the photon couples to a $$J/\psi $$ J / ψ which rescatters with the proton to give the $$J/\psi p$$ J / ψ p final state. In this paper, we provide a compelling hint for and propose measurements necessary to confirm a novel production mechanism via the $$\varLambda _c \bar{D}^{(*)}$$ Λ c D ¯ ( ∗ ) intermediate states. In particular, there must be cusp structures at the $$\varLambda _c \bar{D}^{(*)}$$ Λ c D ¯ ( ∗ ) thresholds in the energy dependence of the $$J/\psi $$ J / ψ photoproduction cross section. The same mechanism also implies the $$J/\psi $$ J / ψ -nucleon scattering lengths of order 1 mfm. Given this, one expects only a minor contribution of charm quarks to the nucleon mass.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

New formalism for two-photon quantum optics. I - Quadrature phases and squeezed states. II - Mathematical foundation and compact notation

A new formalism for analyzing two-photon devices, such as parametric amplifiers and phase-conjugate mirrors, is proposed in part I, focusing on the properties and the significance of the quadrature-phase amplitudes and two-mode squeezed states. Time-stationary quasi-probability noise is also detailed for the case of Gaussian noise, and uncertainty principles for the quadrature-phase amplitudes are outlined, as well as some important properties of the two-mode states. Part II establishes a mathematical foundation for the formalism, with introduction of a vector notation for compact representation of two-mode properties. Fundamental unitary operators and special quantum states are also examined with an emphasis on the two-mode squeezed states. The results are applied to a previously studied degenerate limit (epsilon = 0).

Caves, C. M.↗

Entanglement enabled intensity interferometry in ultrarelativistic ultraperipheral nuclear collisions

An important tool in studying the subfemtoscale spacetime structure of matter in ultrarelativistic heavy-ion collisions is Hanbury Brown–Twiss (HBT) intensity interferometry of identical particles in the final state of the collisions. We propose that a variant of the entanglement enabled intensity interferometry (𝐸 2 ⁢𝐼 2 ) framework introduced by Cotler and Wilczek can provide a powerful alternative to HBT interferometry in extracting fundamental nonperturbative features of quantum chromodynamics at high energies. We apply this framework to demonstrate that the spatial distributions of color singlet (pomeron) configurations in nuclei are sensitive to measurements of exclusive resonant decays of 𝜌 mesons into 𝜋 ± pairs in ultrarelativistic ultraperipheral nuclear collisions (UPCs) at the Relativistic Heavy Ion Collider and the Large Hadron Collider. A preliminary analysis suggests that the model-independent extraction of pomeron distributions will require careful treatment of the interplay of 𝐸 2 ⁢𝐼 2 in the vector meson exclusive decay with the incoherent cross section for exclusive vector meson production. The 𝐸 2 ⁢𝐼 2 framework developed here is quite general. It can also be employed as a tool to extract information on the spin structure of pomeron couplings as well as enhance the discovery potential for rare odderon configurations from exclusive vector meson decays into few-particle final states both in UPCs and at the Electron-Ion Collider.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Effects of PFOS on the behavior, growth, emergence, and predation susceptibility of larval mosquitoes ( Culex quinquefasciatus )

Per-/polyfluoroalkyl substances (PFAS) have been commonly used over several decades for a variety of products and are very persistent in the environment. However, not much is known about their direct effects on aquatic invertebrates and their ecosystems. We examined the survival, behavior, development, and predation susceptibility of mosquito larvae Culex quinquefasciatus exposed to concentrations of perfluorooctanesulfonic acid (PFOS) ranging from 0.02 to 453.7 µg/L. PFOS exposure resulted in reduced larval survival, with a 48 hour LC50 (concentration with 50 % mortality) of 255.99 µg/L. PFOS exposure also resulted in reduced developmental success and slower maturation to adulthood (and thus slower emergence from the water) compared to control larvae. PFOS also resulted in delays in reaction to prodding stimuli, which were meant to simulate a predator attack, and longer reactions to prodding. Larvae exposed to PFOS also spent more time at the bottom of the water column, rather than at the surface where respiration takes place. Effects of larval mosquito PFOS exposure on predation by unexposed damselfly naiads (genus Ischnura) were not detected. Overall, this research suggests that PFOS impacts mosquito larvae survival, behavior, development, and adult emergence, which could have important implications for food webs or public health given the role of mosquitos as disease vectors.

Food web dynamics↗

Counting topological interface modes using simplicial characteristic classes

A computational approach for predicting the number of topological interface modes (TIMs) in hermitian systems using the spectral flow—monopole correspondence is presented. The number of TIMs is determined by calculating the Chern number of a complex line bundle of local polarisation vectors over a phase space sphere surrounding a Weyl point. The Chern number is computed by constructing the simplicial first Chern class of a discrete vector bundle on a simplicial mesh. This approach is gauge invariant, derivative free, structure preserving, and robust to noise. The algorithm is shown to reproduce the expected number of TIMs for the case of equatorial fluid waves and the topological Langmuir cyclotron wave. The possibility of using this algorithm to analyse experimental measurements of bulk wave polarisations and predict the associated number of TIMs is explored in a synthetic example.

discrete vector bundles↗

Search for Massive Resonances Decaying into Pairs of Boosted Bosons in Semi-Leptonic Final States at $\sqrt{s} =$ 8 TeV

A search for new resonances decaying to WW, ZZ, or WZ is presented. Final states are considered in which one of the vector bosons decays leptonically and the other hadronically. Results are based on data corresponding to an integrated luminosity of 19.7 inverse femtobarns recorded in proton-proton collisions at $\sqrt{s}$ = 8 TeV with the CMS detector at the CERN LHC. Techniques aiming at identifying jet substructures are used to analyze signal events in which the hadronization products from the decay of highly boosted W or Z bosons are contained within a single reconstructed jet. Upper limits on the production of generic WW, ZZ, or WZ resonances are set as a function of the resonance mass and width. We increase the sensitivity of the analysis by statistically combining the results of this search with a complementary study of the all-hadronic final state. Upper limits at 95% confidence level are set on the bulk graviton production cross section in the range from 700 to 10 femtobarns for resonance masses between 600 and 2500 GeV, respectively. These limits on the bulk graviton model are the most stringent to date in the diboson final state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Coherent states for the relativistic harmonic oscillator

Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.

Aldaya, Victor↗

A Nanosized {Ni II 18 } Cluster with a ‘Flying Saucer’ Topology Exhibiting Slow Relaxation of Magnetisation Phenomena at Both 15 K and 1.3 K

A high-nuclearity {Ni 18 } complex (1) with a unique ‘flying saucer’ motif has been prepared from the organic chelate, α-methyl-2-pyridine-methanol (mpmH), in conjunction with bridging azido (N 3 - ) and peroxido (O 2 2- ) ligands. Magnetic susceptibility measurements revealed the presence of both ferro- and antiferromagnetic exchange interactions between the metal centres in 1, and the stabilization of spin states with appreciable S values at two different temperature regimes. The end-on bridging azido and alkoxido groups are in all likelihood the ferromagnetic mediators, while the η 3 :η 3 :μ 6 -bridging peroxides most likely promote the antiparallel alignment of the metals’ spin vectors, yielding an overall non-zero spin ground state for the centrosymmetric compound 1. Furthermore, the {Ni 18 } nanosized cluster behaves as a single-molecule magnet, exhibiting magnetic hysteresis at low temperatures and two relaxation processes at 15 K and 1.3 K, a very rare phenomenon in polynuclear magnetic 3d-metal clusters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗