P K Iyengar
Articles written in Pramana – Journal of Physics
Volume 1 Issue 1 July 1973 pp 53-60 Solids
Mössbauer effect of Fe57 embedded as very dilute substitutional impurities in Pd2MnSn was studied. The impurities are seen to replace the three elements in the alloy. Although the Curie temperature of the alloy is 189K, well below the room temperature, the Mössbauer spectrum recorded at room temperature consisted of two distinct 6-finger magnetic hyperfine spectra and a single unsplit line. One of the 6-finger patterns which corresponds to an internal magnetic field of
Volume 2 Issue 3 March 1974 pp 126-137 Solids
The recoilless absorption spectra of iron in the ternary alloys CoFeGe, CoFeSb and FeMnGe, which possess B82 type structure, reveal the existence of different ordering temperatures of moments at 2(
Volume 2 Issue 4 April 1974 pp 179-188 Solids
Phonon frequencies in beryllium along the principal symmetry directions have been determined by means of the slow neutron inelastic scattering technique. The data are analysed in terms of a six-neighbour force constant model and the force constants are evaluated. It is concluded that strong tensor forces are present in beryllium and the importance of this finding to basic theories of lattice dynamics is pointed out.
Volume 11 Issue 3 September 1978 pp 251-288 Solids
Coherent inelastic neutron scattering techniques are employed to measure several branches of the phoon dispersion relation in KNO3 in its orthorhombic (α-phase or phase II) form at room temperature. Group theoretical selection rules for external modes of the crystal have been used in the measurements along the three symmetry directions Σ(ξ00), Δ(0ξ0) and Λ(00ξ).
Theoretical investigation of the lattice dynamics of the crystal is carried out on the basis of a rigid molecular-ion model using the external mode formalism. A two-body potential consisting of the Coulombic interaction and the Born-Mayer type short range interaction is assumed. The effective charges and radii of different atoms are determined by applying the stability criterion for the crystal. Dispersion curves are calculated, representation by representation, making use of group theoretical information. Comparison of theoretical results with experimental information on elastic constants, optical data and neutron results are made. Agreement between theoretical and the various experimental results may be considered very satisfactory.
Volume 19 Issue 4 October 1982 pp 323-336 Experimental Techniques And Instrumentation
Design and construction details of a horizontal 2 MV Tandem Van de Graaff accelerator built at Bhabha Atomic Research Centre are given. A terminal voltage of 2.15 MV has been achieved. Energy analysed Corona stabilized beams of protons and oxygen ions have been obtained. Experiments have been carried out to test the performance of the accelerator.
Volume 24 Issue 1-2 January 1985 pp 259-278 Atomic And Molecular Physics
Discovery of the neutron in 1932 by Chadwick ushered in a new era of scientific research and technology. The neutron is endowed with unique properties in its mass, life time, spin and magnetic moment etc and every important property has been used in the study of condensed matter, biological molecules, nuclear forces, stellar objects and other fields. Neutron has a wide range of applications in power production, breeding of fissile fuel, radiography, medicine and others.
Volume 93 | Issue 6
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