Microscopic study of band structures of neutron-rich 153,155,157 Sm isotopes
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Microscopic study of band structures of neutron-rich 153,155,157 Sm isotopes Rakesh K. Pandit1, Shivali Sharma2 , Rani Devi2,a
, S. K. Khosa2
1 Department of Physics, Govt. College for Women Parade, Jammu, J&K 180001, India 2 Department of Physics, University of Jammu, Jammu, J&K 180006, India
Received: 28 May 2020 / Accepted: 6 October 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A systematic study of band structures of some odd mass Samarium isotopes with neutron numbers 91 ≤ N ≤ 95 is carried out by employing projected shell model. The theoretical results have been obtained for band head energies, energy spectra, transition energies and moment of inertia. The calculations on comparison with the experimental data show a reasonably good agreement. The band spectra and transition energies for higher spin states are also predicted in these isotopes. The calculations successfully provide good understanding of the change in structure of the yrast bands and excited bands in terms of single and multi-quasiparticle configurations. The future experimental work will test the predictions made in this paper.
1 Introduction In rare earth nuclei, a shape transition from spherical shape to deformed shape has been observed at the neutron number (N) 90 [1]. In this mass region around A ~ 150, nuclear deformation changes quickly with only small change in mass number of isotopes. For example, in the case of samarium (Sm) isotopes, nuclear deformation changes rapidly with neutron number and particularly, in odd-A Sm isotopes, deformation sets in at 151 Sm which is distinctly pronounced in 153 Sm isotope. For the first time, Kenefick and Sheline [2] studied the level structure of odd-A isotopes of Sm. They identified some rotational bands in 153,155 Sm, but it was a limited study based on (d,p) results and uncertain assignments of rotational bands were proposed. Later, Rekstad et al. [3] studied high spin states of 153 Sm using 150 Nd (γ,nγ)153 Sm reaction and two rotational bands were identified and built on νi13/2 and νh11/2 configurations up to the spins 21/2+ and 19/2− , respectively. Besides this, authors of Ref. [3] have also studied low spin positive and negative parity rotational bands. Hayakawa et al. [4] extended the level scheme of bands built on νi13/2 and νh11/2 configurations of 153 Sm up to spins 33/2+ and 21/2− , respectively, by using in-beam spectroscopy. The nucleus 155 Sm was previously investigated by Schreckenbach et al. [5]. They investigated the rotational band structure of 155 Sm via primary and secondary γ-rays and by internal conversion electrons following thermal neutron capture. The authors of Ref. [5] established model independent levels and their spin parity (Iπ ) assignments for 155 Sm. They proposed the negative parity ground state band built on K 3/2 having Nilsson configuration 3/2− [521]. Since then,
a e-mail: [email protected] (corresponding author)
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