• R P Patel

      Articles written in Pramana – Journal of Physics

    • Characteristics of the fast electron emission produced during the cleavage of crystals

      B P Chandra N L Patel S S Rahangdale R P Patel V K Patle

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      The present paper reports the fast electron emission produced during the cleavage of alkali halide crystals and models the dynamics of the process. The mechano-emission arises as a result of the ionization of surface traps at the expense of the energy which is released in the annihilation of the defects which are formed during cleavage. The slow electrons which appear upon the ionization of surface traps are subsequently accelerated in the field of negatively charged segment of the freshly cleaved surface. Considering the basic mechanism of fast electron emission, expressions are derived which are able to explain satisfactorily the temporal, thermal, charge, surface, coloration, water adsorption and other characteristics of the fast electron emission produced during the cleavage of crystals. The decay time of the charges on the newly created surfaces, and the velocity of cracks can be determined from the measurements of fast electron emission produced during the cleavage of crystals. It is shown that two types of diffusing centres are responsible for the charge relaxation and thereby for the emission of fast electrons produced during the cleavage of alkali halide crystals.

    • Observation of very low frequency emissions at Indian Antarctic station, Maitri

      R P Patel R P Singh Ashok K Singh A K Gwal D Hamar

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      Recently, we have succeeded in recording VLF emissions at the Indian Antarctic station, Maitri (geom. lat. 62°S, geom. long. 57.23°E,L = 45) using a T-type antenna, pre/main amplifiers and digital audio tape recorder. VLF hiss in the frequency ranges 11–13 kHz and 13–14.5 kHz and some riser-type emissions in the frequency range 3–5 kHz and magnetospheric lines at about 6.2, 8.0 and 9.2 kHz are reported for the first time. The generation and propagation mechanism of these emissions are discussed briefly.

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