• R K Sheline

      Articles written in Pramana – Journal of Physics

    • Characterization of energy levels in the nucleus170Lu

      P C Sood R K Sheline R W Hoff

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      Configuration assignments are derived for the observed energy levels in the odd-odd deformed nucleus170Lu99 based on the calculations of the two-particle band head energies for a zero range residual interaction, the beta-feeding characteristics, and the observed features for similar bands in the neighbouring nuclei. In particular, specific assignments are given for theJπ=1+ levels at 198.4 keV, 349.0 keV and 785.5 keV. The ambiguities with respect to the assignments for theKπ=3 bands are discussed. A new isomer withJπ=7+ and half-life of several seconds is predicted around (225±25) keV and experiments are suggested to identify it.

    • Effective decoupling in some odd-A odd-Z rotational bands

      Kiran Jain A K Jain R K Sheline

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      A systematic analysis of the results of single quasiparticle-plus-rotor bandmixing calculations is presented wherein the empirically noticed characteristic effective decoupling patterns and their systematics in certain odd-A odd-Z rotational bands based onh9/2, d1/2, h11/2 andg7/2 orbitals are reproduced. The strategy adopted allows us to obtain an almost unique set of parameter values for a given decoupling pattern. The composition of wavefunctions in terms of core rotational angular momentum supports the idea of effective decoupling. These wavefunctions are then used to analyse the extent and nature of Coriolis coupling in these bands. It is found that either one or both parts of the Coriolis energies, diagonal and non-diagonal, are significant in most of the cases and the non-diagonal part is mainly responsible for the effective decoupling. These Coriolis effects prominently affect the intrabandB(M1) andB(E2) values and their variation with spin is discussed. An unusual feature in theB(M1) value of theh9/2 orbital based band is pointed out.

    • Variation of interband interaction strength in odd-A nuclei

      Kiran Jain A K Jain R K Sheline

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      Bandcrossing in 31 rotational bands of 25 different odd-A nuclei in the rare-earth region has been analysed by using a two-band mixing formalism with a constant band interaction within the framework of the effective decoupling picture. The interband interaction strengthV between the one-quasiparticle band and the three-quasiparticle band exhibits a variation with the neutron number which is not different from the oscillatory behaviour observed in even-even nuclei and does not show signs of any appreciable phase shifting as predicted by theory. However, the overall range of variation ofV is greater than that observed in even-even systems.

    • Characterization of isomers of the nucleus154Pm

      P C Sood R K Sheline

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      Consideration of the expected two-quasiparticle structures and their estimated band head energies, and the selection rules for beta transition rates for the154Nd →154Pm →154Sm decays are used to deduce the configurations for the isomers and the low-spin structures in the neutron rich doubly odd nucleus61154Pm93. The 2.68 m high spin isomer and the 1.73 m low spin isomer are respectively assigned the spin-parity 4+ and 1+ with the configuration {p:5/2 [532↑] +n:3/2 [521↑]} with the 2.68 m isomer lying lower in energy, and thus forming the154Pm ground state. Two-quasiparticle character of the beta-connected states in154Nd decay and154Pm decay is discussed.

    • Newby shift ofK=0 rotational bands in odd-odd rare-earths

      Alpana Goel A K Jain R W Hoff R K Sheline

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      A data set of 29 experimentally determined Newby shifts in rare-earth nuclei is examined for the reliability of each values. Using this data set, Newby shifts are obtained which are free from the Coriolis and the particle-particle coupling effects. These new empirical values help resolve the failure of a recently proposed rule for the sign of the Newby shift in the {5/2[413]p − 5/2[642]n} configuration of160Tb and the {5/2[402]p − 5/2[512]n} configuration of174Lu. Also the Newby shifts are significantly modified in two other cases namely the {1/2[411]p − 1/2[521]n} configuration in168Tm and the {1/2[541]p − 1/2[521]n} configuration in172Lu. Only marginal changes are seen in the rest of the cases in the rare-earth nuclei.

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