• B J Roy

      Articles written in Pramana – Journal of Physics

    • Investigation of two- and three-nucleon transfer reactions in12C +56Fe

      Hari S Patel B Srinivasan B J Roy M G Betigeri

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      Multi-nucleon transfer reactions56Fe(12C, X) have been studied at an incident12C energy of 60 MeV. Angular distributions of10Be and9Be corresponding to 2p and 2p 1n transfer reactions in transition to low-lying states in the residual nuclei have been measured. The angular distribution data for 2p transfer have been analysed in terms of finite range DWBA calculations assuming a one-step transfer of two protons. The spectroscopic factors for three low-lying transitions observed in56Fe(12C,10Be)58Ni have been extracted. Transfer probabilities for the ground state transition in two- and three-nucleon stripping channels have been obtained and compared with the corresponding sequential transfer probabilities in order to emphasise the role of direct transfer of nucleons vis-a-vis sequential transfer.

    • ENSTAR detector forη- mesic studies

      A Chatterjee B J Roy V Jha P Shukla H Machner

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      We have initiated a search for a new type of nuclear matter, theη-mesic nucleus, using beams from the multi-GeV hadron facility, COSY at Juelich, Germany. A large acceptance scintillator detector, ENSTAR has been designed and built at BARC, Mumbai and fully assembled and tested at COSY. A test run for calibration and evaluation has been completed. In this contribution we present the design and technical details of the ENSTAR detector and how it will be used to detect protons and pions (the decay products ofη-mesic bound state). The detector is made of plastic scintillators arranged in three concentric cylindrical layers. The readout of the detectors is by means of optical fibres. The layers are used to generate ΔEE spectra for particle identification and total energy information of stopped particles. The granularity of the detector allows for position (θ and ϕø determination making the event reconstruction kinematically complete

    • Isospin symmetry violation, meson production and η-nucleus interaction studies

      B J Roy V Jha A Chatterjee H Machner

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      We have studied isospin symmetry violation in nuclear reactions by measuring simultaneously the cross-section of the following two reactionsp +d3H π+ andp +d3He π0. The experiment was perfomed at the cooler synchrotron accelerator COSY, Jülich at several beam energies close to the correspondingη production threshold. We also have ongoing programmes onη-nucleus final-state interaction studies viap+6 Li →7 Be +η reactions, high resolution search for dibaryonic resonances and lambda-proton final state interaction studies. The experimental details and results obtained so far are presented here

    • Study ofη-nucleus interaction through the formation ofη-nucleus bound state

      V Jha B J Roy A Chatterjee H Machner

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      The question of possible existence ofη-mesic nuclei is quite intriguing. Answer to this question will deeply enrich our understanding ofη-nucleus interaction which is not so well-understood. We review the experimental efforts for the search ofη-mesic nuclei and describe the physics motivation behind it. We present the description of an experiment for the search ofη-nucleus bound state using the GeV proton beam, currently being performed at COSY

    • Reaction mechanism study of 7Li(7Li, 6He) reaction at above Coulomb barrier energies

      V V Parkar V Jha S Santra B J Roy K Ramachandran A Shrivastava K Mahata A Chatterjee S Kailas

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      The elastic scattering and the 6He angular distributions were measured in 7Li + 7Li reaction at two energies, $E_{lab} = 20$ and 25 MeV. FRDWBA calculations have been performed to explain the measured 6He data. The calculations were very sensitive to the choice of the optical model potentials in entrance and exit channels. The one-step proton transfer was found to be the dominant reaction mechanism in 6He production.

    • Measurement of multinucleon transfer cross-sections in 58Ni,56Fe(12C, 𝑥); 𝑥: 13,11C, 11,10B, 10,9,7Be, 8Be𝑔.s. and 7,6Li at 𝐸(12C) = 60 MeV

      B J Roy A Parmar T Nandi Biraja Mohanty M Oswal Sunil Kumar A Jhingan V Jha D C Biswas

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      Cross-sections for one- and multinucleon transfer reactions, namely, 58Ni(12C, 13C), 58Ni(12C, 11C), 58Ni(12C, 11B), 58Ni(12C, 10B), 58Ni(12C, 10Be), 58Ni(12C, 9Be), 58Ni(12C, 8Be𝑔.s.), 58Ni(12C, 7Be), 58Ni(12C, 7Li) and 58Ni(12C, 6Li) have been measured at an incident energy of 60 MeV. The reaction cross-section for the corresponding transfer channels in the system 12C+56Fe have also been measured under the same kinematical conditions. Angular distribution of the elastic scattering cross-section is measured at 60 MeV. The measured elastic scattering angular distributions for these two systems have been analysed using the optical model search code SFRESCO and the potential parameters are extracted. The multinucleon transfer data are analysed to obtain cross-section dependence on the number of nucleons transferred and on the ground state 𝑄-values. The transfer probabilities for multinucleon stripping are extracted. A detailed comparison in the multiparticle stripping and elastic scattering cross-sections between these two systems are made to understand the mechanism of multinucleon transfer and possible role of two extra protons in 58Ni target nucleus as compared to the 56Fe core.

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