Articles written in Pramana – Journal of Physics
Volume 1 Issue 2 August 1973 pp 112-116 Instruments And Techniques
The development of a neutron moisture gauge, using Cf252 as a source of fast neutrons and muscovite as a detector of thermal-neutron-induced-fission in Pu239 target, is reported. The laboratory and the field calibrations of the instrument reveal a linear relation between track count rate and the moisture volume fraction.
Low cost, low weight, simplicity of operation, thermal stability and elimination of electronic gadgets and power supplies are the attractive features of this instrument. The main drawback is its poor detection efficiency for thermal neutrons and the consequent unsuitability as a routine logging instrument. Its special features make it particularly suited to deep bore hole logging such as in oil exploration.
Volume 13 Issue 6 December 1979 pp 645-651 Molecular Physics
Normal co-ordinates, force fields and isotopic frequencies have been calculated for some
Volume 19 Issue 1 July 1982 pp 1-12 Quantum Mechanics
A purely analytical method designed to compute the two-electron integrals that appear in an
Volume 24 Issue 5 May 1985 pp 715-726 Nuclear Physics
Single channel single level
Volume 30 Issue 2 February 1988 pp 115-127 Nuclear Physics
Two features of32S(
Volume 42 Issue 4 April 1994 pp 365-374
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.
Volume 64 Issue 3 March 2005 pp 323-332
Some recent developments in boundary layer instabilities and transition are reviewed. Background disturbance levels determine the instability mechanism that ultimately leads to turbulence. At low noise levels, the traditional Tollmien-Schlichting route is followed, while at high levels, a ‘by-pass’ route is more likely. Our recent work shows that spot birth is related to the pattern of secondary instability in either route.
Volume 82 Issue 2 February 2014 pp 353-358 Contributed Papers
In this article, we report size-dependent measurement of the shift in peak of upconversion photoluminescence spectra compared to that of normal photoluminescence using a 800 nm femtosecond laser and its second harmonic. It has been shown that the upconversion photoluminescence is always red-shifted compared to that of normal PL in all the samples. By measuring the power-dependent upconversion photoluminescence (UCPL), it has been shown that the origin of UCPL from MPA-capped CdTe nanoparticles is mainly of two-photon absorption
Volume 82 Issue 2 February 2014 pp 359-364 Contributed Papers
We show that in a GaAs0.86P0.14/Al0.7Ga0.3As near-surface quantum well, there is coherent oscillation of holes observed in time-resolved reflectivity signal when the top barrier of the quantum well is sufficiently thin. The quantum well states interact with the surface states under the influence of the surface electric field. The time period of the observed oscillation is 120±10 fs.
Volume 82 Issue 2 February 2014 pp 413-417 Contributed Papers
In this article, we report a method to achieve a precisely tunable highly stable probe beam generation for performing pump–probe experiment around a given wavelength by tilting a sum frequency generation (SFG) crystal angle. The width of the generated third-harmonic beam is of the order of 2 nm throughout the tunable range. This method of probe beam generation has its application in isolating contributions from closely separated excitation states.
Volume 84 Issue 3 March 2015 pp 409-421
Drops moving on a substrate under the action of gravity display both rolling and sliding motions. The two limits of a thin sheet-like drop in sliding motion on a surface, and a spherical drop in roll, have been extensively studied. We are interested in intermediate shapes. We quantify the contribution of rolling motion for any intermediate shape, and recently obtained a universal curve for the amount of roll as a function of a shape parameter using hybrid lattice Boltzmann simulations. In this paper, we discuss the linear relationship which is expected between the Capillary and Bond numbers, and provide detailed confirmation by simulations. We also show that the viscosity of the surrounding medium can qualitatively affect dynamics. Our results provide an answer to a natural question of whether drops roll or slide on a surface and carry implications for various applications where rolling motion may or may not be preferred.
Volume 93 | Issue 5
Click here for Editorial Note on CAP Mode