• S Saha

      Articles written in Pramana – Journal of Physics

    • Growth of CdS nanoparticles by chemical method and its characterization

      R Bhattacharya S Saha

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      In the present work a simple chemical reduction method is followed to grow CdS nanoparticles at room temperature. The grown sample is ultrasonicated in acetone. The dispersed sample is characterized using electron diffraction technique. Simultaneously optical absorption of this sample is studied in the range of 400–700 nm. The photoluminescence spectrum of the sample is also studied. Results show the formation of nanoparticles. Hence an increase in band gap compared to bulk CdS and the as-prepared CdS nanoparticles have surface sulphur vacancies.

    • Electric field distribution and simulation of avalanche formation due to the passage of heavy ions in a parallel grid avalanche counter

      D Kanjilal S Saha

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      Electric field distributions and their role in the formation of avalanche due to the passage of heavy ions in parallel grid avalanche type wire chamber detectors are evaluated using a Monte Carlo simulation. The relative merits and demerits of parallel and crossed wire grid configurations are studied. It is found that the crossed grid geometry has marginally higher gain at larger electric fields close to the avalanche region. The spatial uniformity of response in the two wire grid configurations is also compared.

    • Coupling between drainage and coarsening in wet foam

      S Saha S Bhaumik A Roy

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      Drainage and coarsening are two coupled phenomena during the evolution of wet foam. We show the variation in the growth rate of bubble size, along the height in a column of Gillette shaving foam, by microscope imaging. Simultaneously, the drainage of liquid at the same heights has been investigated by Raman spectroscopic measurements. The observations made in these two sets of experiments indicate the coupling between drainage and coarsening in wet foam. We could explain the correlation between our observed data on drainage and coarsening by the empirical relation, proposed by others, in the literature.

    • Nucleation efficiency of R134a as a sensitive liquid for superheated drop emulsion detector

      Mala Das R Sarkar P K Mondal S Saha B K Chatterjee S C Roy

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      Superheated emulsion detector is known to detect neutrons, γ-rays and other charged particles. The present work includes the study of nucleation efficiency of super-heated drops of one of the CFC-free liquids, R134a (C2H2F4), to fast neutrons, its response to 𝛾-rays from 241Am and 137Cs and compare its nucleation efficiency with that of R12. The observation indicates that because of the presence of hydrogen, the nucleation efficiency is less in R134a than in R12 in the present neutron energy range of considera-tion. R134a is one of the most environment-friendly, commercially available liquid that is suitable for superheated drop detector, specially in neutron dosimetry and one needs to investigate it in detail.

    • Investigation of exotic modes of spinning nuclei near 90Zr

      R Palit S Saha

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      Recently, a digital data acquisition system with 96 channels has been set up for the Indian National Gamma Array (INGA) consisting of 24 Compton-suppressed clover detectors. The digital system provides higher throughput, better energy resolution and better stability for the multidetector Compton-suppressed clover array compared to the previous conventional system with analog shaping. A number of nuclear spectroscopic experiments have been carried out using the array. Selected results from this array will be presented which highlight different excitations of nuclei near-shell gaps.

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