Set Of Phase Shifts Research Articles

Hadron structure functions within a chiral quark model

We calculate the polarization observables in nucleon-nucleon scattering using a non-relativistic constituent quark model with chiral symmetry. The coupling of the 1S0(NN) partial wave to the 5D0(NΔ) partial wave is included. The results are compared to the polarization observables obtained from the different phase shift analyses. The sensitivity to the different experimental sets of phase shifts is discussed. We find that some of the polarization observables are extremely sensitive to small modifications of the phase shifts. However, the agreement with the experimental data is generally satisfactory. The largest deviations are seen in those observables which mainly depend on the spin-orbit interaction.

Fixed-energy inversion of 5-eVe–Xe−atomscattering

Fixed-energy inverse scattering theory has been used to define central and spin-orbit Schr\"odinger potentials for the scattering of 5-eV polarized electrons from Xe atoms. The results are typical for a range of such data; including energies above threshold when the potentials become complex. The phase shifts obtained from an analysis of the measured differential cross section and analyzing power were used as input data. Both semiclassical (WKB) and fully quantal inversion methods were used to extract central and spin-orbit interactions. The analysis shows that information additional to the set of input phase shifts extracted from these (and similar) data may be needed to ascertain physical potentials.

Limited entropic uncertainty as new principle of quantum physics

In this paper the Principle of Limited Entropic Uncertainty (LEU-Principle) for the canonic conjugate variables in quantum physics is proved in a more general form by using Tsallis-like entropies for positive nonextensivities ( q>0). Results on experimental tests of this new principle for the angle-angular momentum variables in the quantum scattering are illustrated by using 49 sets of pion-nucleus phase shifts.

Improved sensitivities in MW dispatch for control of voltage

This paper describes the derivation of linear sensitivities used in the dispatch of MW controls for alleviation of voltage violations. Such a set of sensitivities is important for the selection and co-ordination of necessary changes to MW generation, phase shifter settings and, as a last resort, load shedding where reactive power controls are insufficient. The sensitivity analysis has been embedded in a qualitative reasoning based decision support tool in which operators' considerations such as cost, control effectiveness, preservation of control margin and ease of implementation are modeled in such a way that priorities can be adjusted and results achieved quickly. Results are presented demonstrating the accuracy and effectiveness of the proposed approach both for a standard test system and a system representing a real network.

Entropic uncertainty relations for nonextensive quantum scattering

In this paper the angle-angular momentum entropic uncertainty relations are obtained for Tsallis-like entropies for nonextensive quantum scattering of spinless particles. The number-phase entropic uncertainty relations are also proved for nonextensive quantum scattering. Numerical results on the experimental tests of these entropic uncertainty relations, for the nonextensive ( q≠1) statistics case are obtained by calculations of Tsallis-like scattering entropies from the 48 experimental sets of the pion-nucleus phase shifts.

Optimal location of phase shifters in the French network by genetic algorithm

Series FACTS such as series capacitors or phase shifters, by controlling the power flows in a network, can help reduce the flows in heavily loaded lines, resulting in an increased loadability of the network and a reduced cost of production. The influence of multiple phase shifters on the network flows is complex, because they interact on one another, and the problem of the optimal location is essential. This paper proposes an index for measuring the benefit of a given set of phase shifters. The best location for a set of phase shifters is found by a genetic algorithm for a 36 line test case and for the French network.

Active, broadband detection and localization of target in an uncertain multipath environment with a horizontal array: An optimum physics-based signal processing approach

Active detection and localization of a target using a horizontal array is implemented via optimum physics-based signal processing. This approach provides a robust method of detection and localization by incorporating anya priori knowledge of the physical environment, however uncertain or incomplete. The active return from a target in a dense multipath environment is assumed to be well modeled as the sum of weighted, delayed, and phase-shifted replicas of the active source transmission. These signal model parameters (i.e., the set of weights, delays, and phase shifts) vary as a function of the physical environment. An acoustic propagation model drives the optimum detector by mapping prior descriptions of the physical environment to a stochastic description of the signal model parameters. The optimum processor additionally provides localization estimates in bearing, range, and depth for a horizontal array. Illustrative simulation results will be presented in the form of receiver operator characteristics (ROC). Experimental results are anticipated. [Work supported by Digital System Resources.]

A chiral quark model and the spin observables in nucleon-nucleon scattering

Abstract We calculate the polarization observables in nucleon-nucleon scattering using a non-relativistic constituent quark model with chiral symmetry. The coupling of the 1S0(NN) partial wave to the 5D0(NΔ) partial wave is included. The results are compared to the polarization observables obtained from the different phase shift analyses. The sensitivity to the different experimental sets of phase shifts is discussed. We find that some of the polarization observables are extremely sensitive to small modifications of the phase shifts. However, the agreement with the experimental data is generally satisfactory. The largest deviations are seen in those observables which mainly depend on the spin-orbit interaction.

System for conducting video communications over satellite communication link with aircraft having physically compact, effectively conformal, phased array antenna

A system architecture and communication methodology for significantly reducing the size of an aircraft antenna required to provide full broadcast quality video communications with an aircraft via a satellite communications link includes a combination of video bandwidth compression, spread spectrum waveform processing and an electronically steered, circular aperture phased array antenna, that is conformal with an airframe surface of the aircraft. The combination provides sufficient signal power to the aircraft, enables interference from other satellites to be rejected and maintains the power spectral density of the satellite's video transmission within FCC requirements. The polarization of the receive array is aligned with that of the incoming beam from the relay satellite by means of an error signal feed back path to control the steering weights of the array. Because the phased arrays are conformal, it is necessary to modify the phase shift settings produced by the antenna steering mechanism executed by the degree of departure of the conformal geometry of the array from a planar configuration. A coordinate transformation look-up table is coupled in the control feedback path from the antenna steering mechanism and the phase shift elements of the phased array.

FRIEDEL OSCILLATIONS ON A SQUARE LATTICE

An impurity in a conductor will cause oscillations in the charge density near the impurity. We calculate these Friedel Oscillations for impurities on a square lattice while using the tight-binding model. Far from the impurity the oscillations are described by a set of phase shifts. These are the same phase shifts which enter the Friedel Sum Rule.

Further analysis of 16O + 12C elastic scattering at [formula omitted]: How unambiguous are the potentials and phase shifts?

Elastic-scattering measurements on 16O + 12C at E A = 38 MeV were subjected to extensive optical-model analysis using local, L-independent potentials with either generalized Woods-Saxon or spline radial forms. Despite the good quality of the data and the probable presence of relatively weak absorption, many quite different potentials and their associated sets of phase shifts were found to give good fits with chi-squared close to unity. One ambiguity, concerning whether the remnant of a primary or a secondary rainbow has been observed, probably could be resolved by extending the measurements to larger angles.

Evaluation of the viscosity cross sections for elastic electron-atom collisions in krypton and xenon at low electron energies

The results of viscosity cross sections evaluations for elastic electron-atom scattering from rare gases krypton and xenon, carried out in the energy interval from 0.1 to 54.4 eV are presented and discussed. The evaluations are based on four independent sets of partialwave phaseshifts, one theoretical and three experimental, taken from literature. An analytical estimate for the contribution of all the terms not included in the summation, for truncation at any chosen value of the electron angular momentum, is derived. The validity of assumption of isotropic angular scattering is investigated in the energy range considered. The present results invariably show significant deviations from the values calculated with this assumption.

Deuteron structure from (p,2p) and (d,p) breakup data at medium energies.

The results of a nonrelativistic calculation of the exclusive {sup 2}H({ital p},2{ital p}){ital n} cross section and inclusive {sup 1}H({ital {rvec d}},{ital p}){ital X} cross section and tensor analyzing power {ital T}{sub 20}, based on an expansion of the scattering {tau} matrix up to double scattering, are presented. Five different wave functions, including Reid with soft core, Paris, Bonn, Amsterdam, and Moscow, as well as two {ital NN} phase-shift amplitude sets, VPI and Saclay-Geneva, are used. Detailed comparison with the data available indicates that double scattering is indeed important for both reaction channels. For ({ital p},2{ital p}) the complete calculation removes a discrepancy of a factor of 2 to 8 present if comparison is made with the impulse approximation only; the Paris wave function gives the best results. For ({ital {rvec d}},{ital p}) the complete calculation results agree fairly well with both cross section and {ital T}{sub 20} data up to {ital q}=200 MeV/{ital c}. However, neither an enhancement in {ital d}{sup 2}{sigma}, nor an abrupt turn toward less negative {ital T}{sub 20} values, both occurring for {ital q}{gt}250 MeV/{ital c}, can be explained by the present calculation. Neither the wave functions nor the {ital NN} amplitudes used are Lorentzmore » invariant, but the kinematics is treated relativistically. Possible causes for the discrepancy are briefly discussed.« less

Evaluation of the viscosity cross sections for elastic electron-atom collisions in argon and neon at low electron energies above 0.13 eV

The importance of the viscosity cross section for elastic electron-atom collisions in various domains of electron kinetic and transport theories is pointed out. Results of numerical evaluations of the velocity-dependent viscosity cross sections for elastic electron-atom collisions in argon and neon are presented and discussed. Two series of results are given. They are based on theoretical and experimental sets of partial-wave phaseshifts for the two atomic species, taken from the literature. Special consideration is given to deviations, sometimes very significant, of the results obtained in the present calculations from those which would have followed if the scattering were assumed isotropic.

Lax conjecture about the eigenspeed of the KdV equation

The Lax conjecture for the KdV equation ut+6uux+uxxx=0 is proved. Let u be the solution of the KdV equation, which is defined for all x and t and vanishes at x=±∞. Then there exist a discrete set of positive numbers c1,...,cN —called the eigenspeeds of u—and sets of phase shifts θ±j such that limt→±∞ u(x+ct,t) ={S(x−θ±j,cj),0, if c=cj,if c≠cj, where S is a solitary wave [P. D. Lax, Commun. Pure Appl. Math. 21, 467 (1968)].

A measurement of the spin correlation parameter CNN (θ) in n-p scattering at 181 MeV

The spin correlation parameter C NN has been measured for n-p elastic scattering at 181 MeV. A comparison with predictions from various phase shift sets and potential models reveals sizeable deviations from the for the data Paris potential and Saclay phase shifts. For the Paris potential the deviations are directly related to an overprediction of the 3D 2 phase shift parameter.

Construction of a Schrödinger operator for nucleon-nucleon scattering at medium energy

The Marchenko method is used to construct a Schrödinger operator which generates a given set of nucleon-nucleon experimental phase shifts. Three examples concerning np scattering are considered ( 1S 0, 3P 1, 1D 2). In each case the Marchenko method is employed with some modification, the most important being the choice of a non-zero reference potential. The phase shifts which are obtained agree quite well with the input ones. A striking result is brought to light: If one considers a case where only real phase shifts are used as the input and a case where the full complex phase shifts are used, the two resulting Schrödinger operators are intrinsically different in nature.

Nucleon-nucleon phase shift analysis

An energy dependent phase-shift analysis is reported for pp, np and pn elastic scattering between 10 and 800 MeV. For the pp case a unique solution smoothly varying with energy is found. A resonant behaviour is observed only in the 1D2 phase shift near the mass 2.14 GeV. For np and pn scattering only a few complex polarization parameters are available ; therefore the solution is less precise, especially above 500 MeV. A fixed-energy analysis at 1 GeV is also reported providing a unique phase-shift set. The formalism, data base and compatibility with other analyses are discussed.

The interaction of pions with deuterons

There has been remarkable experimental and theoretical progress in the field ofπd interactions in the last few years. Within the uncertainties of the theory the experimental data in theπd breakup and theπd elastic scattering reaction can be fairly well reproduced. Theoretical problems remain in the absorption channel, but there is a hope that with a few additional measurements of tensor polarization and spin transfer observables in this reaction a partial wave amplitude analysis may localize the theoretical difficulties. In addition it is very important to provide data on the deuteron tensor polarizations and the spin transfer parameters for theπd elastic scattering reaction in order to obtain a reliable set of phase shifts, which may reveal resonance structures in this reaction channel.

Determination of the radial variations of the density and the shear modulus of a flaw from the angular dependence of the scattering amplitude

The inverse scattering theory is applied to determine the continuous variation of the elastic parameters of spherically symmetric flaw which is located within an isotropic and homogeneous host medium. From the angular dependence of the scattering amplitude, the phase shift for the transverse wave with polarization perpendicular to the scattering plane can be deduced for different partial waves. The knowledge of this set of phase shifts for two frequencies enables one to obtain the radial variation of the density and the shear modulus parameters of the flaw from the solution of a special difference equation which approximates the differential equation for the displacement of the transverse mode. The method has been applied successfully to obtain several different profiles for the density and the shear modulus parameters.