Non-parametric Reconstruction of Cluster Mass Distribution from Strong Lensing: Modelling Abell 370

We describe a new non-parametric technique for reconstructing the mass distribution in galaxy clusters with strong lensing, i.e., from multiple images of background galaxies. The observed positions and redshifts of the images are considered as rigid constraints and through the lens (ray-trace) equation they provide us with linear constraint equations. These constraints confine the mass distribution to some allowed region, which is then found by linear programming. Within this allowed region we study in detail the mass distribution with minimum mass-to-light variation; also some others, such as the smoothest mass distribution. The method is applied to the extensively studied cluster Abell 370, which hosts a giant luminous arc and several other multiply imaged background galaxies. Our mass maps are constrained by the observed positions and redshifts (spectroscopic or model-inferred by previous authors) of the giant arc and multiple image systems. The reconstructed maps obtained for \a370 reveal a detailed mass distribution, with substructure quite different from the light distribution. The method predicts the bimodal nature of the cluster and that the projected mass distribution is indeed elongated along the axis defined by the two dominant cD galaxies. But the peaks in the mass distribution appear to be offset from the centres of the cDs. We also present an estimate for the total mass of the central region of the cluster. This is in good agreement with previous mass determinations. The total mass of the central region is M=(2.0-2.7) 10^14 Msun/h50, depending on the solution chosen.Comment: 14 pages(19 postscript figures), minor corrections, MNRAS in pres

Low-Energy Elastic-Scattering Of Electrons From Neon Atoms

The multiconfiguration Hartree-Fock method of Saha, Pindzola, and Compton [Phys. Rev. A 38, 128 (1988)] applied to photoionization of atoms has been extended in order to consider elastic scattering of electrons from neon atoms. The dynamical polarization and the electron-correlation effects, which are very important in this case, have been taken into account more accurately in the ab initio method through the configuration-interaction procedure. Phase shifts, and differential, integral, and momentum-transfer cross sections for electrons elastically scattered from neon atoms are reported for the impact-energy range from 0.136 to 70 eV. The calculated results are compared with experimental and other theoretical results. It is found that the present multiconfigurational self-consistent-field method yields high-quality results which show excellent agreement with experiment and compare well with other theoretical results

Accurate Abinitio Calculation On The Low-Energy Elastic-Scattering Of Electrons From Helium

The multiconfiguration Hartree-Fock method developed by Saha [Phys. Rev. A 39, 5048 (1989)] to study scattering of electrons from atoms has been applied to the low-energy elastic scattering of electrons from helium atoms. The short-range electron correlation and the long-range dynamical polarization of the target by the scattering electron, which are very important in these calculations, have been taken into account in an accurate ab initio manner through the configuration-interaction procedure. Detailed results for phase shifts, elastic differential, integral-elastic, and momentum-transfer cross sections for electrons elastically scattered from helium are reported for the low and intermediate energies ranging from 0.58 to 50 eV. The present results are compared with accurate experimental measurements and theoretical calculations. It is found that the present multiconfiguration self-consistent-field method produces high-quality results that show excellent agreement with experimental measurements and compare well with other accurate theoretical calculations

Ab Initio Calculation For Low-Energy Elastic Scattering Of Electrons From Chlorine Atoms

We have performed ab initio calculations of scattering length, differential, total, and momentum-transfer cross sections for elastic scattering of electrons from open-shell atoms; in particular, the chlorine atom. The polarization of chlorine atoms due to the scattered electrons and the electron correlation effects that are very important in the calculation are taken into account through the configuration-interaction procedure using the multiconfiguration Hartree-Fock method for continuum wave functions. Phase shifts for various partial waves calculated in this approximation have been used to calculate elastic differential, total elastic, and momentum-transfer cross sections for low energies ranging from 0-27.2 eV. The scattering length is calculated with wave functions computed exactly at zero energy. The results are compared with other available theoretical data

Multiconfiguration Hartree-Fock Calculation Of The Photoionization Of The Cs 7D Excited-State

The numerical multiconfiguration Hartree-Fock method is used to calculate the photoionization cross section for the Cs 7d excited state. The electron correlation and the dynamical core-polarization effects, which are very important for photoionization-cross-section calculations of the cesium atom, have been taken into account in an ab initio manner through the configuration-interaction procedure. A minimum has been found in the total photoionization cross section. The calculation of the photoionization angular-distribution asymmetry parameter is proved to be an excellent test to determine the existence and location of the minimum in the cross section. The length and velocity forms of the cross section and the asymmetry parameter are found to be in excellent agreement over the entire incident photon energy range considered, suggesting that converged results may be obtained in this interval with the present approach. The results obtained are compared with the recent experimental measurements of the absolute photoionization cross section and are found to be in good agreement

Suspension Design, Modeling, and Testing of a Thermo-Acoustic-Driven Linear Alternator

The Score-Stove™ generates electricity from a wood-burning cooking stove using a thermo-acoustic engine (TAE) that converts heat to sound through a linear alternator (LA). This paper introduces a prototype hemitoroidal suspension that was refined into a segmented trapezoidal shape that gave a higher cyclic life for the LA and includes a critical evaluation that compares a theoretical analysis with experimental results. The results show an improvement from the 40% efficiency of a standard loudspeaker used in reverse as an LA to 70–80% efficiency with the new suspension and a double Halbach array magnetic topology

Partial photoionization cross section and resonance structure of Br

The partial photoionization cross sections for the outer p subshell of the ground state of bromine are calculated in all available open channels as determined by LS coupling for photon energies from the P-3 to S-1 thresholds. The electron correlations which an important in this case have been taken into account using the multiconfiguration Hartree-Fock approximation for the hound and the continuum wave functions. The resonance structures between the P-3 and D-1 threshold and between the D-1 and S-1 threshold have been identified. In order to compare with experiment a frame transformation is applied to transform the LS dipole matrix elements to jj coupling. The calculated energy positions for the autoionizing resonances 4p(4)(D-1)md, 4p(4)(D-1)ns and 4p(4)(S-1)md and 4p(4)(S-1)ns are compared with recent experimental measurements, and are found to be in excellent agreement

Ab initio calculation for low-energy elastic scattering of electrons from sulfur atoms

The multiconfiguration Hartree-Fock method for continuum wave functions has been used to perform calculations of elastic scattering of electrons from the open-shell sulfur atom at low energies. The electron correlation and polarization of the sulfur atom by the scattered electron, which are very important in this calculation, have been taken into account very accurately ab initio through the configuration-interaction procedure by optimizing both bound and continuum orbitals simultaneously at each kinetic energy of the scattered electron. The scattering lengths, phase shifts, and differential, total and momentum-transfer cross sections for electrons elastically scattered from sulfur atoms are calculated for the impact-energy range from 0 to 27.2 eV. The wave functions computed exactly at zero energy are used to compute the scattering length. The present results are compared with other available theoretical results

Interacting spinor and scalar fields in Bianchi type-I Universe filled with viscous fluid: exact and numerical solutions

We consider a self-consistent system of spinor and scalar fields within the framework of a Bianchi type I gravitational field filled with viscous fluid in presence of a $\Lambda$ term. Exact self-consistent solutions to the corresponding spinor, scalar and BI gravitational field equations are obtained in terms of $\tau$, where $\tau$ is the volume scale of BI universe. System of equations for $\tau$ and \ve, where \ve is the energy of the viscous fluid, is deduced. Some special cases allowing exact solutions are thoroughly studied.Comment: 18 pages, 6 figure