• D R Kulkarni

      Articles written in Pramana – Journal of Physics

    • Shape-excited states of28Si

      D R Kulkarni S P Pandya

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      The Hartree-Fock (HF) minima for the nucleus28Si were obtained for the prolate, oblate and spherical shapes using the interaction obtained by Preedom and Wildenthal. The interaction gives rise to large energy separation between the prolate and the oblate shapes. The spherical solution is just 2 MeV above the lowest HF (oblate) minimum. The spectrum projected from the oblate HF state is in good agreement with the experimental spectrum. The transition probabilities for the different energy levels also agree reasonably well. The configuration mixing calculations performed on the basis of states projected from the three shapes indicate that there is no significant mixing of different projected states. The second 02+ state, thus obtained, corresponds to the third 03+ state in the experimental spectrum and stems dominantly from the spherical HF state. It is seen that the structure of the energy levels of28Si, especially the second 02+ level is very sensitive to the two body interaction. The results are compared with those obtained using the renormalised interaction of Kuo.

    • Intrashell quartet excited states

      A K Dhar D R Kulkarni K H Bhatt

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      The intrashell quartet states are obtained by exciting two protons and two neutrons from the highest occupied orbital to the lowest unoccupied orbital of the lowest Hartree-Fock solutions for some even-even (N=Z) nuclei in the ds and fp shells. These intrinsic quartet states are found to be very high in energy. The states with good angular momenta are obtained by diagonalizing the Hamiltonian matrix constructed in the basis of the states projected from the lowest prolate and oblate HF states and the quartet excited intrinsic states with proper care of the non-orthogonality of these states. It was observed that for20Ne both the projection as well as the orthogonalization procedures significantly change the energy separations of the original intrinsic states and the low lying excited states do not have a well-defined quartet structure. The excited states of24Mg and28Si which seem to have dominant quartet structure lie very high up in energy. In contrast to these nuclei, quartet excited states are not likely to provide a reasonable description of the eigenstates of the fp shell nuclei44Ti,48Cr and52Fe.

    • Shape mixing as an approximation to shell model24Ne

      S B Khadkikar D R Kulkarni S P Pandya

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      Band mixing calculations have been done for24Ne including the two degenerate prolate and oblate Hartree-Fock states and also some particle-hole excited states in the projection formalism using an interaction obtained by Preedom and Wildenthal. The energy spectrum agrees very well with the experimental results as well as the exact shell model calculations. Thus the band mixing calculations provide a good approximation to the lengthy exact shell-model calcuations. In addition they offer a physical insight into the collective nature of the nucleus as nuclear states are described in terms of only a few ‘intrinsic’ states.

    • A band-mixing Hartree-Fock model for62Zn

      D R Kulkarni V L Narasimham S P Pandya

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      Energy levels and electromagnetic transitions in62Zn have been calculated using band-mixing formalism in the framework of deformed Hartree-Fock theory. Matrix elements of Adjusted-Surface Delta Interaction (ASDI) and of Tabakin interaction have been used. Detailed structure of various nuclear states in terms of bands has been discussed. Although the calculated spectra for both the interactions are somewhat compressed as compared to the observed spectra, the ASDI results are in substantially better agreement with experiments. Several additional states of high spin (J>4) have been predicted.B(E2) transitions between inter-band as well as some of the intraband states are calculated to stimulate further experiments.

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