Magnetospheric free-boundary problem in axial symmetry.
Approximate solution of magnetospheric free boundary for steady state interaction between field-free streaming plasma and magnetic dipole
FREE BOUNDARY↗
SEARCH · Engineering Papers
Results for “ELECTROMAGNETIC INTERACTIONS”
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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Photoneutron cross sections for Au
Photoneutron cross sections were measured for Au in the entire energy range of the ({gamma},n) channel based on a direct neutron-counting technique with quasimonochromatic {gamma} rays produced in inverse Compton-scattering of laser photons with relativistic electrons. We present results of the measurement in comparison with the past data.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Proposal for GPD studies at COMPASS
The study of nucleon structure through Generalised Parton Distributions (GPD) is one major part of the future COMPASS-II physics program and can be performed using exclusive reactions like Deeply Virtual Compton Scattering (DVCS) and Meson Production. The high energy of the muon beam allows to measure the x{sub B}-dependence of the t-slope of the DVCS cross section. The use of positive and negative polarised muon beams allows to determine the Beam Charge and Spin Difference of the DVCS cross sections to access the real part of the Compton form factor related to the dominant GPD H. The sensitivity of both measurements is examined and confronted to existing models or global fits of the data. Preliminary beam test data were analyzed and demonstrated the feasibility of the identification of the DVCS reaction using the COMPASS experimental set-up.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
STUDY OF FOUR YOUNG TeV PULSAR WIND NEBULAE WITH A SPECTRAL EVOLUTION MODEL
We study four young pulsar wind nebulae (PWNe) detected in TeV {gamma}-rays, G21.5-0.9, G54.1+0.3, Kes 75, and G0.9+0.1, using the spectral evolution model developed and applied to the Crab Nebula in our previous work. We model the evolution of the magnetic field and the particle distribution function inside a uniformly expanding PWN considering a time-dependent injection from the pulsar and radiative and adiabatic losses. Considering uncertainties in the interstellar radiation field (ISRF) and their distance, we study two cases for each PWN. Because TeV PWNe have a large TeV {gamma}-ray to X-ray flux ratio, the magnetic energy of the PWNe accounts for only a small fraction of the total energy injected (typically a few Multiplication-Sign 10{sup -3}). The {gamma}-ray emission is dominated by inverse Compton scattering off the infrared photons of the ISRF. A broken power-law distribution function for the injected particles reproduces the observed spectrum well, except for G0.9+0.1. For G0.9+0.1, we do not need a low-energy counterpart because adiabatic losses alone are enough to reproduce the radio observations. High-energy power-law indices at injection are similar (2.5-2.6), while low-energy power-law indices range from 1.0 to 1.6. The lower limit of the particle injection rate indicates that the pair multiplicity is larger than 10{sup 4}. The corresponding upper limit of the bulk Lorentz factor of the pulsar winds is close to the break energy of the broken power-law injection, except for Kes 75. The initial rotational energy and the magnetic energy of the pulsars seem anticorrelated, although the statistics are poor.
79 ASTRONOMY AND ASTROPHYSICS↗
Gluon distributions in nuclei probed at energies available at the CERN Large Hadron Collider
Using updated gluon distributions from global fits to data, we investigate the sensitivity of direct photoproduction of heavy quarks and exclusive production of vector mesons to varying strength of gluon modifications. Implications of using these processes for constraining nuclear gluon distributions are discussed.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Experimental investigation of the interaction between the electron gas and the excited atoms in a plasma by means of a xenon laser
Xenon laser effect on interaction between electron gas and excited atoms in plasma
LASER↗
Extraction of the Compton Form Factor H from DVCS Measurements in the Quark Sector
Working at twist 2 accuracy and assuming the dominance of the Generalized Parton Distribution H we study the helicity-dependent and independent cross sections measured in Hall A, the beam spin asymmetries measured in Hall B at Jefferson Laboratory and beam charge, beam spin and target spin asymmetries measured by Hermes. We extract the real and imaginary parts of the Compton Form Factor H, the latter being obtained with a 20-50 % uncertainty. We pay extra attention to the estimation of systematic errors on the extraction of H. We discuss our results and compare to other extractions as well as to the popular VGG model.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Photoproduction of K{Sigma}(1385) from the nucleon
The reactions of K{Sigma}(1385) photoproduction, i.e., {gamma}p {yields} K{sup +}{Sigma}{sup 0}(1385) and {gamma} {yields} K{sup +}{Sigma}{sup -}(1385), are investigated in the resonance energy region for studying the role of the nucleon and {Delta} resonances of masses around 2 GeV. The Lagrangians for describing the decays of these resonances into the K{Sigma}(1385) channel are constructed and the decay amplitudes are obtained, which allows us to determine the coupling constants using the predictions of quark models or the data listed by the Particle Data Group. The resulting cross sections are compared to the data from the Thomas Jefferson National Accelerator Facility and the SPring-8, which indicates nontrivial contributions from the two-star-rated resonances in the Particle Data Group as well as from some missing resonances predicted by a quark model.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Incoherent {phi} photo-production from deuteron in SPring-8/LEPS
We present measurements of differential cross sections and decay asymmetries of incoherent {phi}-meson photo-production from the deuteron at forward angles using linearly polarized photons beam in energy range from the production threshold to E = 2.4 GeV. The experiment was performed at the SPring-8/LEPS facility. The differential cross section of incoherent production shows a large suppression compared with the free proton case. The reduction for the deuteron cannot be clearly explained in terms of simple isospin asymmetry. The decay asymmetry of incoherent {phi} photo-production shows that the eta exchange process is small. Since the exclusive K{sup +}K{sup -}p cross section shows the same reduction with incoherent, both the proton and neutron cross section reduce similarly. Consequently, the {pi}-{eta} interference effect is small too. The present results suggest that our understanding of {phi} photo-production within a nucleus should be rearranged.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Charged pion photoproduction with the {Delta}(1232) baryon beyond the resonance region
We investigate the charged pion photoproduction off the proton target with the {Delta}(1232) baryon, i.e., {gamma}p{yields}{pi}{sup -{Delta}++}(1232) and {gamma}p{yields}{pi}{sup +{Delta}0}(1232), based on the effective Lagrangian method, beyond the resonance region, {radical}(s) > or approx. 2 GeV. We employ the {pi}- and {rho}-meson Regge trajectories in the t channel, in addition to the proton and {Delta} pole, in the s and u channels, respectively, and the contact-interaction contributions. A specific scheme for the form factor which satisfies the Ward-Takahashi identity, crossing symmetry, and on-shell condition is taken into account. We also consider a smooth interpolation between the Regge and Feynman propagators for the t-channel meson exchanges as a function of the Mandelstam variable s. We present the numerical results for the energy and angular dependences of the cross sections and the double- and single-polarization observables. It turns out that the present framework reproduces the experimental data qualitatively very well. In particular, the interpolation between the two propagators plays a crucial role in reproducing the high-energy experimental data correctly. The {pi}{sup +} decay-angle distribution is also studied using the {Delta}{sup ++}-decay frame, i.e., the Gottfried-Jackson frame. The present results will be a useful guide for future high-energy photon-beam experiments.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
WIMPless dark matter in anomaly-mediated supersymmetry breaking with hidden QED
Not Available
Feng, Jonathan L.↗
Repulsive and attractive Casimir interactions in liquids
The Casimir interactions in solid-liquid-solid systems as a function of separation distance have been studied by the Lifshitz theory. The dielectric permittivity functions for a wide range of materials are described by Drude, Drude-Lorentz, and oscillator models. We find that the Casimir forces between gold and silica or MgO materials are both repulsive and attractive. We also find the stable forms for the systems. Our studies would provide good guidance for future experimental studies on dispersion interactions.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Advances in ionospheric physics in the rocket and satellite era.
Cosmic radio wave, whistler and transmitted radio wave interactions with ionospheric magnetoplasma in collision-dominated, photoequilibrium and photoionization-dominated regions
PLASMA-ELECTROMAGNETIC INTERACTION↗
Effective theory for the nonrigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei
In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 0 2 + band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Application of the {gamma}SF method to palladium
Photoneutron cross sections were measured for {sup 108}Pd, {sup 106}Pd, and {sup 105}Pd with laser-Compton scattering {gamma}-ray beams in an application of the {gamma}SF method to a radioactive nucleus {sup 107}Pd. We present radiative neutron cross sections for {sup 107}Pd[6.5x10{sup 6} y] obtained with the {gamma}SF method.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Timelike Compton Scattering
Generalized Parton Distributions (GPDs) have become a key concept in our studies of hadron structure in QCD. The measurement of suitable experimental observables and the extraction of GPDs from these data is one of the high priority 12 GeV programs at Jefferson Lab. Deeply Virtual Compton Scattering (DVCS) is generally thought of as the most promising channel for probing GPDs in the valence quark region. However, the inverse process, Timelike Compton Scattering (TCS) can provide an important complementary measurement, in particular of the real part of the Compton amplitude and power corrections at intermediate values of Q{sup 2}. The first studies of TCS using real tagged and quasi-real untagged photons were performed in Hall B at Jefferson Lab.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
LEPS2: the second Laser-Electron Photon facility at SPring-8
A new project to construct the second beamline for the laser-electron photon beam at SPring-8 (LEPS2) has started. Based on the LEPS experience, the project aims to improve the intensity of the photon beam and to expand the detector acceptance by adopting the BNL-E949 detector, which is a hermetic detector in a large 1 T solenoid magnet. The central region of tracking chambers will be upgraded for the LEPS2. A new LEPS2 experimental building has just been constructed outside the experimental hall of the storage ring. The present status of the development of a frozen-spin polarized HD target is also reported.
43 PARTICLE ACCELERATORS↗
Effective field theories for superconducting systems with multiple Fermi surfaces
In this work we investigate the description of superconducting systems with multiple Fermi surfaces. For the case of one Fermi surface we re-obtain the result that the superconductor is more precisely described as a topological state of matter. Studying the case of more than one Fermi surface, we obtain the effective theory describing a time reversal symmetric topological superconductor. These results are obtained by employing a general procedure to construct effective low energy actions describing states of electromagnetic systems interacting with charges and defects. The procedure consists in taking into account the proliferation or dilution of these charges and defects and its consequences for the low energy description of the electromagnetic response of the system. We find that the main ingredient entering the low energy characterization of the system with more than one Fermi surface is a non-conservation of the canonical supercurrent triggered by particular vortex configurations.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗