arXiv subjects

R. Bingham

Publications and source records attributed to R. Bingham.

64 records · Page 4Linked to original sources

arXiv2006

Statistical properties of the continuum Salerno model

The statistical properties of the Salerno model is investigated. In particular, a comparison between the coherent and partially coherent wave modes is made for the case of a random phased wave packet. It is found that the random phased induced spectral broadening gives rise to damping of instabilities, but also a broadening of the instability region in quasi-particle momentum space. The results can be of significance for condensation of magnetic moment bosons in deep optical lattices.

nlin.CD↗

arXiv2006

Using high-power lasers for detection of elastic photon-photon scattering

The properties of four-wave interaction via the nonlinear quantum vacuum is investigated. The effect of the quantum vacuum is to generate photons with new frequencies and wave vectors, due to elastic photon-photon scattering. An expression for the number of generated photons is derived and using state-of-the-art laser data it is found that the number of photons can reach detectable levels. In particular, the prospect of using the high repetition Astra Gemini system at the Rutherford Appleton Laboratory is discussed. The problem of noise sources is reviewed, and it is found that the noise level can be reduced well below the signal level. Thus, detection of elastic photon-photon scattering may for the first time be achieved.

hep-ph↗

arXiv2005

Fundamental Physics with the Laser Astrometric Test Of Relativity

The Laser Astrometric Test Of Relativity (LATOR) is a joint European-U.S. Michelson-Morley-type experiment designed to test the pure tensor metric nature of gravitation - a fundamental postulate of Einstein's theory of general relativity. By using a combination of independent time-series of highly accurate gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the Shapiro time delay on interplanetary scales (to a precision respectively better than 0.1 picoradians and 1 cm), LATOR will significantly improve our knowledge of relativistic gravity. The primary mission objective is to i) measure the key post-Newtonian Eddington parameter γwith accuracy of a part in 10^9. (1-γ) is a direct measure for presence of a new interaction in gravitational theory, and, in its search, LATOR goes a factor 30,000 beyond the present best result, Cassini's 2003 test. The mission will also provide: ii) first measurement of gravity's non-linear effects on light to ~0.01% accuracy; including both the Eddington βparameter and also the spatial metric's 2nd order potential contribution (never measured before); iii) direct measurement of the solar quadrupole moment J2 (currently unavailable) to accuracy of a part in 200 of its expected size; iv) direct measurement of the "frame-dragging" effect on light by the Sun's gravitomagnetic field, to 1% accuracy. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor theories of gravity by looking for a remnant scalar field in today's solar system. We discuss the mission design of this proposed experiment.

gr-qc↗

arXiv2005

Dipolar radiation from spinning dust grains coupled to an electromagnetic wave

In this letter we investigate how the complex rotation and quivering motion of an elongated polarized dust grain in the presence of a monochromatic electromagnetic wave can originate dipolar emission with two distinct spectral components. We present a model for the emission of radiation by elongated polarized dust grains under the influence of both an external electromagnetic wave and a constant background magnetic field. The dust, exhibiting rotational motion at the external electromagnetic field frequency w0 as well as quivering motion at frequency W0, proportional to the em field amplitude, will radiate with frequencies that will depend on the external field wavelength and amplitude. The radiated spectra exibits a frequency around w0, and sidebands at w0+-W0 and w0+-2W0. Since the amplitude and the frequency of the background electromagnetic field are independent parameters, this model establishes a correlation between different spectral components of galactic dipolar emission, which may help to explain the correlation between a component of the Galactic microwave emission and the 100micons thermal emission from interstellar dust, that has been recently measured.

physics.plasm-ph↗

arXiv2005

A Mission to Explore the Pioneer Anomaly

The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. These spacecraft had exceptional acceleration sensitivity. However, analysis of their radio-metric tracking data has consistently indicated that at heliocentric distances of $\sim 20-70$ astronomical units, the orbit determinations indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of $\sim(5.99 \pm 0.01)\times 10^{-9}$ Hz/s, which can be interpreted as a constant sunward acceleration of each particular spacecraft of $a_P = (8.74 \pm 1.33)\times 10^{-10} {\rm m/s^2}$. This signal has become known as the Pioneer anomaly. The inability to explain the anomalous behavior of the Pioneers with conventional physics has contributed to growing discussion about its origin. There is now an increasing number of proposals that attempt to explain the anomaly outside conventional physics. This progress emphasizes the need for a new experiment to explore the detected signal. Furthermore, the recent extensive efforts led to the conclusion that only a dedicated experiment could ultimately determine the nature of the found signal. We discuss the Pioneer anomaly and present the next steps towards an understanding of its origin. We specifically focus on the development of a mission to explore the Pioneer Anomaly in a dedicated experiment conducted in deep space.

gr-qc↗

arXiv2005

A kinetic approach to Bose-Einstein condensates: self-phase modulation and Bogoliubov oscillations

A kinetic approach to the Bose-Einstein condensates (BECs) is proposed, based on the Wigner-Moyal equation (WME). In the quasi-classical limit, the WME reduces to the particle number conservation equation. Two examples of application are: i) a self-phase modulation of a BE condensate beam where we show that part of the beam is decelerated and eventually stops as a result of the gradient of the effective self-potential; ii) the derivation of a kinetic dispersion relation for sound waves in the BECs, including a collisionless Landau damping.

nlin.PS↗

arXiv2004

Nonlinear model for magnetosonic shocklets in plasmas

Exact nonlinear equations for magnetosonic shocklets in a uniform hot magnetoplasma are derived by using the nonlinear magnetohydrodynamic equations. Analytic as well as numerical solutions of the nonlinear equations are presented. Shock-like structures of the ion fluid velocity and magnetic field (or the plasma density) perturbations are obtained. The results may have relevance to the understanding of fast magnetosonic shocklets that have been recently observed by onboard instruments of the Cluster spacecraft at the Earth's bow shock.

physics.plasm-ph↗

arXiv2003

A Concept for an STJ-based Spectrograph

We describe a multi-order spectrograph concept suitable for 8m-class telescopes, using the intrinsic spectral resolution of Superconducting Tunneling Junction detectors to sort the spectral orders. The spectrograph works at low orders, 1-5 or 1-6, and provides spectral coverage with a resolving power of R~8000 from the atmospheric cutoff at 320 nm to the long wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept - the cryogenics, thermal baffling and magnetic field biasing - are identified as being feasible.

astro-ph↗

arXiv1998

Comment on "Ponderomotive force due to neutrinos"

The derivation of the ponderomotive force due to neutrinos by Hardy and Melrose, Phys.Rev.D v.54, p.6491 (1996) is based on a flawed analysis of the ponderomotive force concept. Their conclusions also contain an erroneous physical assumption related to the neutrino emission in supernovae. A correct analysis shows the importance of the ponderomotive force due to neutrinos in type II supernovae explosions.

physics.plasm-ph↗

arXiv1998

Ponderomotive force of quasi-particles in a plasma

We derive the force exerted in the background plasma by an arbitrary distribution of non interacting quasi-particles, corresponding to either collective excitations of the plasma (plasmons, phonons) or em dressed particles (photons, neutrinos). Our approach is based on the effective Hamiltonian describing the quasi-classical dynamics of the individual particles in the presence of a background medium. We recover the usual results for the relativistic ponderomotive force of a photon gas, and we derive the force, due to weak interactions, exerted by the electron-neutrinos in a background medium containing electrons, positrons and neutrons with arbitrary distribution functions. Generalization to other background species and other neutrino flavors is also discussed.

physics.plasm-ph↗