• R P Sharma

      Articles written in Pramana – Journal of Physics

    • Excited atomic state of Li

      CV K Baba M G Betigeri V M Datar M B Kurup R P Sharma P Singh

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      An optical transition of 3489 A has been shown to arise from Li using beam foil spectroscopic technique. The mean life of the state emitting this radiation has been measured to be 2.23 ä 0.08 n sec.

    • Fabrication of lithium-drifted silicon detectors by constant temperature method

      R P Sharma A S Divatia

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      A new approach for lithium drifting in silicon is described where the silicon devices under drift are held at constant temperature and bias at normal air ambient, and the drift process is terminated at the end of an estimated time depending upon the thickness of wafers. A 4-channel lithium drifting unit with electronically controlled oven has been constructed for this purpose. Full details of the fabrication procedure are given. A sizable number of Si(Li) detectors have been fabricated using this approach. The quality of the detectors is tested with241Am alphas and conversion electrons from209Bi and137Cs sources. The detectors are regularly used for nuclear physics experiments at this Centre.

    • Development of high resolution silicon surface barrier detectors

      R P Sharma

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      Fabrication methods for silicon surface barrier detectors and their correlated properties which result in the production of high resolution (< 20 keV) devices have been studied. The techniques for fabrication and testing of the detectors currently employed at our Centre are presented. An FWHM of 14keV for 5·486 MeV241Am α has been achieved. Our results are therefore comparable with the best in the world.

    • Effect of annealing on the opto-electronic properties of Cu0.9In1.0Se2.0 films

      R P Sharma Pankaj Garg J C Garg

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      The influence of annealing on the structure and opto-electronic properties of Cu0.9In1.0Se2.0 films prepared by solution growth technique has been studied. The films annealed at 500–520°C in air, vacuum (10−4 torr), In-vapour and Se-vapour show polycrystalline chalcopyrite structure with orientation perpendicular to the (220) plane. Films annealed in Se-vapour at 500°C for 30 min have maximum grain size (560 Å), minimum optical energy gap, maximum absorption coefficient, lowest resistivity, maximum photosensitivity and thus are suitable for photovoltaic applications. Annealing in In-vapour or in vacuum changesp-type CuInSe2 inton-type which possibly arises due to the increase in Se vacancies.

    • Measurement of excitation functions and mean projected recoil ranges of nuclei in12C-induced reactions on vanadium

      M Ismail R P Sharma M H Rashid

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      Excitation function and mean projected recoil ranges of nuclei produced in the12C-induced reactions on51V target were measured by conventional stacked foil and thick-target thick-recoil-catcher technique for bombarding energiesE ≤ 84 MeV for12C ion beam. The measured recoil ranges are converted to momentum transfer. Information on momentum transfer was used to get clues about some aspects of the interaction such as complete fusion which corresponds to full momentum transfer and incomplete fusion reaction mechanism. The measured excitation functions are compared with the calculation based on the statistical model which describes only equilibrium decay of the compound nucleus using the Cascade code and the geometry dependent hybrid model which describes equilibrium as well as pre-equilibrium decay of the compound nucleus using the Alice/91 code. The measured excitation functions and average ranges of the radioisotope products of the reactions12C on51V indicate that the three separate reaction mechanisms could be attributable to complete fusion of12C, incomplete fusion of8Be and incomplete fusion of4He respectively with the target. The8Be and4He are the break-up component of12C into8Be +4He. The predictions of the codes, especially the Cascade, generally agree with the measured cross-sections which could be attributed to complete fusion of12C with the target51V.

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