J N Das
Articles written in Pramana – Journal of Physics
Volume 8 Issue 5 May 1977 pp 395-401 Solids
The present paper reports that triboluminescence (TBL) does not appear at the instant of impact of the load but a certain time lag is required for its appearance which depends on the value of the stress applied to the crystal. Since TBL appears in sugar crystals during the creation of new surfaces, the fracture-initiation time of the crystal has been taken to be the delay time in observing TBL pulse after the application of stress. The dependence of fracture-initiation time,
Volume 18 Issue 5 May 1982 pp 397-403 Atomic Physics
The method of Das developed recently to analyse elastic scattering of electrons by atoms has been extended in the present paper to inelastic scatterings. The method has been applied for the computation of 2
Volume 40 Issue 3 March 1993 pp 253-258
Triple differential cross-sections for ionization of hydrogen atoms by electrons and positrons have been calculated for symmetric coplanar geometry following a multiple scattering method suggested and used earlier by the authors. Results show single binary peaks exactly at 45° and double binary peaks exactly at 135° for higher energies as are expected from an analysis of Briggs . At lower energies there are certain deviations from these values. An analysis of scattering mechanism at peaks are also given. This supports Briggs’ explanation.
Volume 45 Issue 1 July 1995 pp 41-46
Schwinger variational principle has been used to calculate triple differential cross-sections for ionization of hydrogen atoms by positrons at intermediate and high energies for Ehrhardt type asymmetric geometry. The results agree in general with the calculations of Brauner
Volume 47 Issue 3 September 1996 pp 249-253
A hyperspherical partial wave method of Das to calculate cross sections for ionization of hydrogen atoms by electrons has been applied for low energies. Here effect of coupling among different partial waves is neglected.
Volume 47 Issue 4 October 1996 pp 263-269
Triple differential cross sections for ionization of hydrogen atoms in the metastable 2
Volume 50 Issue 1 January 1998 pp 53-61
The hyperspherical partial wave method (Das ) has been presented here in a symmetric form so that effects of coupling among different partial waves may be included in a systematic way. It is also outlined here how to solve the relevant coupled set of radial wave equations numerically. Some preliminary results are presented for
Volume 53 Issue 5 November 1999 pp 869-875 Research Articles
Energy spectrum of ejected electrons in ionization of hydrogen atoms has been calculated following a multiple scattering theory of Das and Seal . The results show peaks around two to three Rydbergs of energies of the ejected electrons, for incident electron energy of 250 eV and 500 eV, considered here, and for different combinations of the angular variables of the scattered and the ejected electrons, for scattering in a plane. The peaks are very similar to those observed in relativistic K-shell ionization of Ag atoms by electrons at 500 KeV energy . The physical origin of these peaks may be traced to the second order scatterings, scattering first by the atomic nucleus (or the atomic electron) and then a second time by the atomic electron. These peaks are, however, absent in the first Born results. Experimental verification of the present results and theoretical calculation by some other well-known methods will be interesting.
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