Volume 33, Issue 4
October 1989, pages 449-540
pp 449-454 October 1989 Relativity
Spin precession of a charged particle in a uniform magnetic field on a static space-time
We investigate the ratio of spin precession frequency to orbital frequency for a spinning charged particle confined to circular orbit in the equatorial plane of a compact object, with a uniform magnetic field, as described by the Wald and the Ernst potentials. In order to see the difference in behaviours for particles with differentg values we consider the cases of electron and proton separately.
pp 455-465 October 1989 Statistical Mechanics
Method of most probable distribution: New solutions and results
The variational conditions implied by the most probable equilibrium distribution for a dilute gas are set up exactly in terms of the digamma function without necessarily invoking a Stirling approximation. Through a sequence of lemmas it is proved that, at any given kinetic temperature, there are three classes of self-consistent solutions characterized by the parameterβ$$\beta \bar \gtrless 0$$ 0 and by non-Maxwellian tails. These ambiguities persist even for a free ideal gas.
pp 467-479 October 1989 Particle Physics
Higgs bosons inE_{6} and intermediate mass scales
T Vasantha Rao Pratibha Nuthakki
Considering the importance ofE_{6} as the grand unification group in superstring theories, several breakdown patterns ofE_{6} through maximal subgroups are studied. The Higgs which break the low energy group and give masses to the fermions are determined in each case. At each scale we consider minimal Higgs and apply extended survival hypothesis to determine the limits on the mass scales. The combination of intermediate mass scales that give rise to acceptable electroweak mixing angle and unification mass is determined. Proton decay rate is found to be acceptable in all cases except one.
pp 481-492 October 1989 Nuclear Physics
A new representation of the heavy ion Coulomb potential
P Basu P Bhattacharya M L Chatterjee
The Coulomb potential between two heavy ions at their interpretation condition has been represented in terms of two point charges with reduced effective charge, dependent on overlap volume. This representation enables visualization of the dynamic development of the deformations of the colliding nuclei as a function of the degree of overlap. The potential has been compared with well known potentials for heavy-ion collisions. This Coulomb potential gave good agreement in reproducing excitation functions for fusion for a large number of heavy-ion systems.
pp 493-503 October 1989 Experimental Techniques And Instrumentation
Number albedo measurements from stratified layers of iron, concrete and aluminium
A layer of stratified combination composed of selected radiation shielding materials acquires better shielding property. Albedo is used in such measurements as an integral measure ofγ-ray scattering. The stratified slabs of alternating heterogeneous layers have been found to have a virtual homogeneous property with a definite effective atomic number. The angular distribution of back-scattered photons as well as the total number albedo values for iron, aluminium and concrete in stratified combination for 662 keV and 1250 keV photons are reported.
pp 505-511 October 1989 Spectroscopy
N Singh H S Aulakh K L Allawadhi B S Sood
The total attenuation cross-sections in elements 6⩽Z⩽82 forK_{α} andK_{β} groups of lines of elements Zr, Sn and Ba andL_{l},L_{α},L_{β} andL_{γ} groups of lines of the elements Au, Pb, Th and U have been measured. The experimentally measured attenuation cross-sections have been found in good agreement with the theoretical estimates.
pp 513-519 October 1989 Condensed Matter Physics
Magnetic properties of Zr doped Y_{9}Co_{7}
R Ranganathan J L Tholence B V B Sarkissian
Detailed measurements of magnetization and ac susceptibility at low temperatures of 1% Zr-substituted Y_{9}Co_{7} are presented. All results are indicative of itinerant weak ferromagnetism withT_{c} ∼ 9.5 K. The zero-field magnetizations followT^{2} orT^{4/3} behaviour as in the Ni-substituted system. The estimated critical exponents areβ=0.38±0.03,γ=1.16±0.05. It is argued that the main effect of the non-magnetic Zr-substitution in Y_{9}Co_{7} is to stabilize the ferromagnetic ordering by suppressing the ‘hopping’ of Co atoms along thec-axis sites of the hexagonal structure.
pp 521-540 October 1989 Condensed Matter Physics
Magnetization curves of hard superconductor samples with non-zero demagnetization factor
We present exact solutions of Bean’s critical state model for some sample shapes having non-zero demagnetization factorN. Virgin and hysteresis magnetization curves are obtained for samples in the shape of (i) a sphere (ii) a spheroid (iii) a cylinder of circular cross-section with its axis perpendicular to the field and (iv) a cylinder of elliptical cross section with its axis perpendicular to the field. Some interesting features seen in these first solutions forN ≠ 0 are discussed.
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