Evolution of collectivity in ^126,128Xe studied in Coulomb excitation measurements

¹ Lawrence Livermore National Laboratory, Livermore, California 94550, USA
² Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
³ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
⁴ Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
⁵ Department of Physics, Kyushu Sangyo University, Fukuoka 813-8503, Japan
⁶ School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
⁷ Center for Computational Sciences, University of Tsukuba, 1-1-1, Tennodai Tsukuba, Ibaraki 305-8577, Japan
⁸ Institute of Natural Sciences, Senshu University, Tokyo 101-8425, Japan
⁹ Los Alamos National Laboratory, Los Alamos, NM 87545, USA

^* e-mail: kisyov1@llnl.gov
^** Present address: TRIUMF, Vancouver, British Columbia V6T 2A3, Canada

Published online: 26 May 2023

Abstract

The characteristics of ^126,128Xe were investigated in Coulomb excitation measurements performed at the National Superconducting Cyclotron Laboratory (NSCL) Re-accelerator facility, ReA3, Michigan State University (MSU). The Xe nuclei were accelerated to sub-barrier energies and were impinged on ¹⁹⁶Pt and ²⁰⁸Pb targets in separate experimental runs. The scattered nuclei and the de-excitation γ-rays were detected using the JANUS setup. Electromagnetic matrix elements were extracted from the experimental data with the help of the GOSIA/GOSIA2 codes. The results were compared to schematic Davydov-Filippov γ-rigid rotor theoretical calculations and large-scale calculations within a newly-established microscopic shell model (called PMMU model). The experimental results agree well with the theoretical predictions, except for the quadrupole moments of the second 2⁺ states in both nuclei, therefore challenging the interpretation of the γ-bands structure.