• Alpana Goel

      Articles written in Pramana – Journal of Physics

    • 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.

    • Signature inversion in theK=4 band in doubly-odd152Eu and156Tb nuclei: Role of theh9/2 proton orbital

      Alpana Goel Ashok K Jain

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      The phenomenon of signature inversion in the doubly-odd nuclei152Eu and156Tb is understood within the framework of a two-quasiparticle plus rotor model. It is shown that theh9/2:1/2[541] proton orbital plays a crucial role in reproducing this phenomenon.

    • Signature splitting in magnetic rotational bands

      A Mita Ashok K Jain Alpana Goel Balraj Singh

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      Nearly-spherical nuclei in three mass regions have recently been observed to exhibit rotational-like features. We have identified almost 80 such bands; largest number (43) lie in the lead region. Most of these bands are assigned oblate multi-quasiparticle configurations. Their interpretation in terms of ‘magnetic rotation’ does not allow for signature splitting in these bands. We have however found signature splitting as well as signature inversion in many bands. We apply the two-quasiparticle plus rotor model to understand the occurrence of signature splitting vis-a-vis the role of ‘shears mechanism’ in these bands.

    • Systematic of signature inversion in $(h_{11/2})_{\text{p}}\otimes (i_{13/2})_{\text{n}}$ for odd–odd nuclei in rare-earth nuclei

      Kawalpreet Kalra Alpana Goel Sukhjeet Singh Sushil Kumar A K Jain

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      Systematic features of the signature inversion phenomenon in $(h_{11/2})_{\text{p}}\otimes (i_{13/2})_{\text{n}}$ in doubly-odd rare-earth nuclei are presented. These features are generally observed in high-$j$ orbitals, mainly, in $(h_{9/2})$, $(h_{11/2})$ and $(i_{13/2})$. Calculations are carried out within the framework of the two quasiparticle plus rotor model (TQPRM) to explain strong odd–even staggering and signature inversion observed in these high-$j$ orbitals. The shifting of point of inversion to lower/higher spin with the increase in neutron/proton numbers is well explained by the calculations. It is found that 1/2[541] proton orbital of $h_{9/2}$ is necessary in the lower mass region to obtain the point of inversion.

    • Predicting superdeformed rotational band-head spin in A ∼ 190 mass region using variable moment of inertia model

      V S Uma Alpana Goel Archana Yadav A K Jain

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      The band-head spin (𝐼0) of superdeformed (SD) rotational bands in 𝐴 ∼ 190 mass region is predicted using the variable moment of inertia (VMI) model for 66 SD rotational bands. The superdeformed rotational bands exhibited considerably good rotational property and rigid behaviour. The transition energies were dependent on the prescribed band-head spins. The ratio of transition energies over spin 𝐸𝛾/2𝐼 (RTEOS) vs. angular momentum (𝐼 ) have confirmed the rigid behaviour, provided the band-head spin value is assigned correctly. There is a good agreement between the calculated and the observed transition energies. This method gives a very comprehensive interpretation for spin assignment of SD rotational bands which could help in designing future experiments for SD bands.

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