Multi-phonon γ vibrational bands and chiral vibrations in the A∼100 neutron-rich region

¹ School of Energy and Power Engineering, Shandong University, Jinan 250061, China
² Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
³ Université de Lyon 1, CNRS/IN2P3, UMR5822, IP2I, F-69622 Villeurbanne Cedex, France
⁴ GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
⁵ Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064, India
⁶ Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai - 400094, India
⁷ Department of Physics, Government Degree College Shopian, Jammu and Kashmir 192303, India
⁸ Department of Physics, Islamic University of Science and Technology, Awantipora 192122, India
⁹ Department of Physics, University of Kashmir, Srinagar 190 006, India
¹⁰ School of Space Science and Technology, Institute of Space Sciences, Shandong University, Weihai 264209, China
¹¹ WeiHai Research Institute of Industrial Technology, Shandong University, Weihai 264209, China
¹² School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, China
¹³ Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
¹⁴ Department of Physics, Tsinghua University, Beijing 100084, China

^* e-mail: ehwang@sdu.edu.cn
^** e-mail: m.abushawish@ip2i.in2p3.fr

Published online: 11 April 2025

Abstract

We present experimental evidence for the one- and two-phonon γ vibrational bands in the isotopes ^103−108Mo by analyzing high-statistics γ-γ-γ and γ-γ-γ-γ coincidence data from the spontaneous fission of ²⁵²Cf. The consistency of the one- and two-phonon γ bands in both odd- and even-mass isotopes within this range provides a robust test for microscopic theories. Additionally, we have identified evidence for one-, two-, and possibly three-phonon γ bands in ^103,105Nb. Triaxial projected shell model calculations successfully reproduce the level structures and align well with the excitation energies of the observed one- and two-phonon γ bands. The potential existence of three-phonon γ bands in ^103,105Nb is further supported by recent particle-vibration coupling model calculations. Furthermore, chiral vibrational bands have been observed in ^104,106Mo.