The effect of exchange in autoionization processes

The effect of including distortion (with and without exchange) in the wavefunction for the continuum electron while calculating the probability of autoionization of 2s ^{2 1} S. 2s2p ^1,3 P, 2p ^{2 1} D and 2p ^{2 1} S states of He and Li⁺ has been studied.     

Equilibrium theory of two-dimensional simple liquids

Using the Wigner-Kirkwood expansion and bare Lennard-Jones (LJ) (12-6) potential, an effectiveLJ potential is derived, which includes the quantum effects through the expressions of the effective diameter∂(T, λ) and well-depth (T, λ). We use theWCA perturbation theory to calculate the free energy and pressure for theLJ and effectiveLJ potentials. Simple analytic expressions are given for the reference system and the first order correction calculated. The results are quite good at high density. The quantum effects on the free energy and pressure are also discussed.     

Characterization and photoluminescence properties of some MLn2(1−x)O4:2xEu or 2xTb systems (M=Ba or Sr, Ln=Gd or La)

BaGd₂O₄, BaLa₂O₄ and SrLa₂O₄ powders doped with different concentrations of Eu³⁺ or Tb³⁺ are prepared by combustion synthesis method and the samples were further heated to 500, 700 and 900 °C to improve the crystallinity of the materials. The structure and morphology of materials have been examined by X-ray diffraction and scanning electron microscopy. It is remarkable that all the samples of BaGd₂O₄, BaLa₂O₄ and SrLa₂O₄ have similar morphology. The SEM images show homogeneous aggregates of varying shapes and sizes, which are composed of a large number of small elliptical shaped crystallites with an average diameter of about 0.5-3.0 μm. Photoluminescence for all materials increases with increase of temperature and shows a maximum for the samples heated to 900 °C with 4 mole% doping of Eu³⁺ or Tb³⁺ ions. The luminescence is almost same for all powders when doped with same concentration of Eu³⁺.     

Relation Between CPT Violation in Neutrino Masses and Mixings

The neutrino parameters determined from the solar neutrino data and the anti-neutrino parameters determined from KamLAND reactor experiment are in good agreement with each other. However, the best fit points of the two sets differ from each other by about 10⁻⁵ eV² in mass-square difference and by about 2° in the mixing angle. Future solar neutrino and reactor anti-neutrino experiments are likely to reduce the uncertainties in these measurements. This, in turn, can lead to a signal for CPT violation in terms a non-zero difference between neutrino and anti-neutrino parameters. In this paper, we propose a CPT violating mass matrix which can give rise to the above differences in both mass-squared difference and mixing angle and study the constraints imposed by the data on the parameters of the mass matrix.     

Paracharge phenomenology: systematics of the new hadrons

A systematic semiquantitative account of all aspects of the strong and electromagnetic interactions of all the newly discovered hadronic states (theψ’s, theχ’s, etc.) is presented within the framework of the paracharge scheme. Extensions of ideas familiar from the SU₃ classification scheme to SU₄ are shown to provide an understanding of the new states seen in the decays ofψ (3.1) andψ′ (3.7), including their masses and gross decay characteristics. The decays ofψ (3.1) andψ′ (3.7) themselves are studied in some detail. Since these are of electromagnetic origin in the scheme, their electromagnetic mixing with the resonance at 4.15 GeV (theP-state of the scheme) is important. Once this is taken into account, the resulting picture is in excellent agreement with available data.     

An efficient method of measuring impedances of fluid machinery manifolds

Knowledge of the acoustical impedances is required to understand the fluid oscillations in the manifolds of positive displacement machinery. This paper presents an impedance measurement method which puts emphasis on the lower frequencies. The technique is based on providing a known volume velocity excitation to the manifold through an electrodynamic, shaker driven, oscillating piston. Harmonic, random and transient excitations have been utilized. Digital data acquisition and processing techniques are used to acquire piston displacement and acoustic pressure signals for input and transfer impedances. The proposed method is direct and efficient. It is applied to the measurement of the acoustical impedances of a two-cylinder refrigeration compressor discharge system. Various aspects of the measurement procedures are discussed along with the recommendations.     

Tetragonal distortion for AIBIIICVI2 chalcopyrite compounds

Pauli-force constants and Simons-Bloch radii for the atoms of groups IB, III and VI are reported. The latter have been used to define a dimensionless quantity ΔX_ch which is found to be correlated in an analytical way with the observed tetragonal distortion δ of A^IB^IIIC^VI₂ type chalcopyrite compounds.     

Propagation of longitudinal ultrasonic waves in RbH2PO4 near its ferroelectric phase transition temperature

Ferroelectric phase transition in RbH₂PO₄ has been investigated using propagation of longitudinal acoustic waves along the polar axis near the transition temperature. The velocity of this mode is continuous across the transition temperature. Velocity data in the ferroelectric phase are analyzed in terms of coupled soft modeacoustic mode model of Pytte to obtain the temperature dependence of the soft mode frequency. The attenuation data in the ferroelectric phase show power law dependence. It follows scaling behaviour of the type predicted by Kawasaki from the mode-mode coupling theory and the dynamical scaling.     

Stationary axially symmetric Brans-Dicke-Maxwell fields

A method is presented which enables one to obtain solutions to the stationary axially symmetric Brans-Dicke fields coupled to source-free Maxwell fields from the solutions of the Einstein-Maxwell equations in Einstein's theory. The Brans-Dicke analog of the Kerr-Newman solution has been obtained as an example.     

Multiple scattering of gamma rays in water,concrete and sand

The transmitted photon spectra of¹³³Ba,²²Na,¹³⁷Cs,⁵⁴Mn and⁶⁰Co point sources are measured through different thicknesses of water, concrete and sand. The multiple-scatter peaks observed in these materials at 60, 90 and 100 keV energies respectively are found to be independent of incident photon energy and thickness of the medium.