R Shanker
Articles written in Pramana – Journal of Physics
Volume 14 Issue 6 June 1980 pp 449-454 Solid State Physics
Electrical transport properties of CuWO4
The temperature dependence of the electrical conductivity, thermoelectric power and dielectric constant of the antiferromagnetic CuWO4 have been studied in the temperature range 300–1000 K. The conductivity results can be summarised by the equations σI=6.31 × 10−3 exp (−0.29 eV/kT) ohm−1 cm−1 in the temperature range 300–600 K and σII=3.16 × 105 exp (−1.48 eV/kT) ohm−1 cm−1 between 600 K and 1000 K. The thermoelectric power can be expressed by
Volume 24 Issue 5 May 1985 pp 749-755 Atomic And Molecular Physics
Polarised raman and infrared spectra and vibrational analysis for
R Shanker R A Yadav I S Singh O N Singh
The Raman spectrum of polycrystalline α-naphthylamine was recorded in the region 100–4000 cm−1. Polarisation measurements were made in CS2 and CHCl3 solutions. The infrared spectrum was recorded in nujol mull in the region 200–4000 cm−1. The resolution was better than 2 cm−1 and the accuracy of the measurements was within ± 2 cm−1 for all the spectra. Vibrational assignments have been proposed for the observed frequencies. Out of the 54 normal modes of vibrations, 51 modes could be observed experimentally.
Volume 45 Issue 3 September 1995 pp 291-304
A dedicated working setup for studying the process of atomic-field bremsstrahlung and its dependence on various parameters for keV electrons incident on a solid or a gaseous target has been indigenously developed. The setup consists of a high vacuum scattering chamber attached with a rotatable X-ray photon detector, a home-built high voltage electron gun with a replaceable tungsten-filament cathode, an isolated floating high voltage system, high vacuum pumping units, various signal processing electronic modules and an IBM PC/XT based 4K-multichannel analyzer. A brief description of the facility is presented. The performance of the facility has been tested by recording the bremsstrahlung spectra from 7.0 keV electrons on thin Ag, Au and 7.5 keV electrons on Hf targets; the corresponding spectra are presented and discussed. The gun can operate in the range of 0–8.0 kV accelerating voltage in the present configuration. Other feasible experiments that can be performed on the setup are also briefly mentioned.
Volume 49 Issue 5 November 1997 pp 521-533
SCORPION: A system for coincidences between recoil and projectile ions at NSC, New Delhi
M J Singh S K Goel R Shanker D O Kataria N Madhavan P Sugathan J J Das D K Avasthi A K Sinha
An on-line facility to measure coincidences between the recoil ions and the scattered projectiles (SCORPION) has been designed, fabricated and commissioned at Nuclear Science Centre (NSC), New Delhi. The facility consists of a four jaw slit assembly, a time of flight (TOF) spectrometer, a parallel plate electrostatic charge analyser and a one dimensional position sensitive parallel plate avalanche counter (PPAC). Details of the design and working principles of various components and the test results obtained for the Si
Volume 53 Issue 4 October 1999 pp 743-764 Research Articles
Multiple ionization of argon in coincidence with projectile ions in 60–120 MeV Si
MJ Singh DO Kataria N Madhavan P Sugathan JJ Das DK Awasthi AK Sinha R Shanker
A projectile ion-recoil ion coincidence technique has been employed to study the multiple ionization and the charge transfer processes in collisions of 60–120 MeV Si
Volume 58 Issue 3 March 2002 pp 499-519 Research Articles
RK Singh RK Mohanta R Hippler R Shanker
Development of a new
Volume 58 Issue 4 April 2002 pp 623-638 Research Articles
RK Singh RK Mohanta MJ Singh R Hippler SK Goel R Shanker
A time-of-flight spectrometer has been designed and fabricated for measuring the charge state distributions of target ions produced in collisions of keV-electrons with gaseous target atoms/molecules. The design details of the spectrometer and the description of experimental procedures for optimizing various parameters are presented and discussed. The working principle of the spectrometer, its time- and mass-focussing conditions, transmissions and detection efficiency etc. are given. A few typical test runs on multiple ionization of Ne and Ar gas atoms are illustrated. These spectra are found to yield the time resolution of about 10 ns for Ar4+ ion peak in 24.0 keV e− — Ar collisions while the mass resolution of the spectrometer is obtained about 10% at mass
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