Volume 42, Issue 2
February 1994, pages 85-165
pp 85-88 February 1994
An identity forR_{n}embedded intoE_{n+1}
Guillermo González José L López-Bonilla Marco A Rosales
An identity is obtained for a Riemanniann-space (R_{n}) locally and isometrically embedded into a pseudo-Euclidean (n+1)-space (E_{n+1}), relating the corresponding second fundamental form with the intrinsic geometry ofR_{n}. Forn=4 such an identity reduces to a previous result by Goenner.
pp 89-95 February 1994
The Maxwell tensor for the Liénard-Wiechert field as an exact divergence
José L López-Bonilla Jesús Morales Marco A Rosales
A potential for the bounded part of the Maxwell tensor associated to the Liénard-Wiechert field has been obtained by van Weert. In this paper we explicitly derive the non-local potential for the radiative part of such a tensor.
pp 97-105 February 1994
Photon polarisation asymmetries in (p,p′γ) experiments
A R Usha Devi A Sudha Rao G Ramachandran
The Stokes parameters characterising the polarization of the photon in theγ-decay of^{12}C*(1^{+}) are examined in correlation with the scattered proton in^{12}C(p,p′)^{12}C*(1^{+}). This opens up the possibility of efficiently determining empirically the six inelastic scattering amplitudes utilizing only 13 measurements. We identify several alternative sets of such measurements to encourage experimental efforts in this direction.
pp 107-122 February 1994
S K Kataria Aruna Nijasure V S Ramamurthy A K Dutta
The leptodermous expansion of the total ground state energy of a nucleus into volume, surface, curvature and gauss curvature contributions has been studied starting from a semi-classical energy density formalism of extended Thomas Fermi type. A numerical procedure was used to obtain the surface energy and curvature energy contributions from surface moments of energy density profilesH(r) for a sequence of nuclei withN=Z and neglecting the coulomb interaction for the three Skyrme forces. A transition to the liquid drop model type expansion in increasing powers ofA^{−1/3} is then made, taking into account the dependence of the central density and the surface structure on the mass of the nucleus. It is found that there is no inconsistency between the curvature contribution to the total energy in the leptodermous expansion and theA^{−1/3} term contribution in the liquid drop model expansion. It has been shown that the earlier apparent anomaly between the above two methods arises due to the use of semi-infinite approximation and the mass dependence of the central density and the surface structure of finite nuclei.
pp 123-133 February 1994
Kiran Kumar R K Choudhury A Saxena
Dynamical trajectory calculations were carried out for the reactions of^{11}B+^{237}Np and^{12}C,^{16}O and^{19}F+^{232}Th, having mass asymmetries on either side of the Businaro-Gallone critical mass asymmetry α_{BG}, in order to examine the mass asymmetry dependence of fusion reactions in these systems. The compound nucleus formation times were calculated as a function of the partial wave of the reaction for all the systems. This study brings out that for systems with α<α_{BG}, the formation times are significantly larger than for α>α_{BG}, which is caused by the dynamical effects involved in the large scale shape changes taking place in the fusion process as well as due to the interplay between the thermal and the collective motion during the collision process. The calculated time scales are comparable to the experimental values derived from the pre-fission neutron multiplicity measurements.
pp 135-139 February 1994
Pre-equilibrium effects in the formation of meta stable states
R Upadhyay Ch V Sastry R K Jain J Rama Rao
Isomeric yield ratios have been measured for^{93}Nb(α, 2n)^{95m,g}Tc reaction in the energy range 25–60 MeV. The ratios were compared with theoretical values obtained by means of two models one based on compound nucleus mechanism only and the other including pre-equilibrium effects. The trend of experimental ratios is better reproduced by the latter model, although there remains some discrepancy as to the magnitude at higher energies.
pp 141-148 February 1994
Generation of ultrasonic waves in water by an elliptical Gaussian laser beam
M S Sodha S Konar M P Verma V Rai
The paper presents an analysis of ultrasonic wave generation in water by intensity modulated elliptical Gaussian laser beams. It is found that generated acoustic radiation is highly directional both in polar and azimuthal directions. An increase in the assymmetry of the transverse intensity distribution from the Gaussian dependence enhances the source directivity considerably. An obvious conclusion is that elliptical Gaussian beams are better choice in applications where it is desired to communicate in an approximately prescribed small solid angle.
pp 149-157 February 1994
Local scaling transformation function and atomic shell structure in density functional theory
The method of local scaling transformation in density functional theory calculates a transformation function (TRF) in order to generate an optimized atomic N-electron wave function from a trial density and a reference density/wave function. The TRFsf(r) for several atomic systems are studied and it is observed that the number of minima in df(r)/dr equals the number of atomic shells, except whenρ=ρ_{0} andf=r.
pp 159-165 February 1994
Hypervirial perturbation theory for eigenenergies for two types of atomic potentials
Eigenenergies are calculated for the potentialsV_{1}(r)=−(a/r)[1+(1+br)e^{−2br}] andV_{2}(r)=−(v/r)[1 −λr(1−Z^{−1})(1+λr)^{−1}], using renormalized series technique. Accurate results produced here for various eigenstates agree with those available in the literature.
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