Eur. Phys. J. A (2005) 24: 13-22
https://doi.org/10.1140/epja/i2004-10116-7

Collective structures of the ¹³¹Cs nucleus

¹ Department of Physics, Panjab University, 160 014, Chandigarh, India
² Department of Physics, Guru Nanak Dev University, 143 005, Amritsar, India
³ Oliver Lodge Laboratory, University of Liverpool, L69 7ZE, UK
⁴ Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nußallee 14-16, D-53115, Bonn, Germany
⁵ Nuclear Science Centre, Aruna Asaf Ali Marg, 110 067, New Delhi, India

Received: 6 September 2004
Accepted: 8 December 2004
Published online: 17 January 2005

Abstract

The collective structures of ¹³¹Cs have been investigated by in-beam γ-ray spectroscopic techniques following the ¹²⁴Sn (^11B , 4n) reaction at a beam energy E _lab = 57MeV. The previously established rotational bands, built on πg _7/2, πd _5/2 and the unique-parity πh _11/2 orbitals, have been extended and evolve into new bands involving rotationally aligned ν(h _11/2)² and π(h _11/2)² quasiparticles. In addition, a new multiquasiparticle band based on the πg _7/2 ⊗ νg _7/2 ⊗ νh _11/2 configuration has also been observed. Theoretical interpretations for the assigned configurations are discussed in the framework of Total Routhian Surface (TRS) and Tilted Axis Cranking (TAC) model calculations. TAC model calculations predict a decrease in the B(M1) values with increasing rotational frequency for the πg _7/2/πd _5/2 ⊗ ν(h _11/2)² and πh _11/2 ⊗ ν(h _11/2)² bands, thus indicating a magnetic rotation character for these bands.