Eur. Phys. J. A (2018) 54: 217
https://doi.org/10.1140/epja/i2018-12651-x

Regular Article - Theoretical Physics

Superdeformed band in the N = Z + 4 nucleus ⁴⁰Ar : A projected shell model analysis

¹ School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China
² School of Science, Huzhou University, 313000, Huzhou, China
³ Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, 200240, Shanghai, China
⁴ Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
⁵ Department of Physics and Astronomy, University of Tennessee, 37996, Knoxville, TN, USA

^* e-mail: sunyang@sjtu.edu.cn

Received: 7 August 2018
Accepted: 8 November 2018
Published online: 17 December 2018

Abstract

⁴⁰Ar is among the few sd -shell nuclei known to exhibit superdeformation. An interesting question is whether the experimentally identified superdeformed rotational band in ⁴⁰Ar has an axially or triaxially deformed shape. Projected shell model calculations assuming an axially deformed basis are performed up to high spins for this nucleus. Our detailed analysis of the wave functions reveals that the high-spin states are dominated by mixed 0-, 2-, and 4-quasiparticle configurations with different K-components. The calculated electric quadrupole transition probabilities reproduce well the known experimental data and suggest a reduced but still significant collectivity in the high spin region. Due to the mixing of various multi-quasiparticle K-configurations, axial asymmetry emerges in the calculation. Throughout the entire rotational band, the extracted triaxial deformation parameters are small but non-zero. Relations of triaxiality and unnatural spin-parity states of the superdeformed side-band are discussed.