Eur. Phys. J. A (2000) 8: 41-58
https://doi.org/10.1007/s10050-000-4503-0

Level structure of ¹²³Cs observed from ¹²³Ba decay and described using the IBFM and CQPC models

¹ Institut des Sciences Nucléaires, IN2P3-CNRS/Université Joseph Fourier, 38026, Grenoble-Cedex, France
² CSNSM, IN2P3-CNRS, Bt. 104, 91405, Campus Orsay, France
³ Institut de Physique Nucléaire, IN2P3-CNRS, B.P. 1, 91406, Orsay-Cedex, France
⁴ I.A.A. Université Libre de Bruxelles, Boulevard du Triomphe, 1050, Brussels, Belgium
⁵ Institute of Nuclear Research, Pf. 51, 4001, Debrecen, Hungary
⁶ Departamento de Física Atómica Molecular y Nuclear, Universidad de Sevilla, Aptdo. 1065, 41080, Sevilla, Spain
⁷ Departamento de Física Aplicada, ESII, Universidad de Sevilla, Sevilla, Spain
⁸ Institute of Experimental Physics, Warsaw University, Hoża 69, 00681, Warsaw, Poland

^* e-mail: gizon@isn.in2p3.fr

Received: 3 January 2000
Revised: 25 February 2000
Published online: 11 September 2013

Abstract

The decay of ¹²³Ba to ¹²³Cs has been studied with mass-separated sources. Singles spectra of γ-rays, X-rays and conversion electrons as well as γ - γ - t, γ - e ⁻ - t, and X - e ⁻ - t coincidences were recorded. A level scheme of ¹²³Cs has been constructed including 26 new excited states and 82 transitions. The existence of a I ^π = 11/2⁻, T _1/2 = 1.7 s isomer, bandhead of the h _11/2 band, is confirmed. Its excitation energy equals 156.3 keV. A new T _1/2 = 114 ns isomer has been established at 232 keV using the in-beam recoil catcher technique. It is assigned to the I ^π = 9/2⁺ bandhead of the gpg _9/2 band. Collective bands based on the 1/2⁺ ground state and first 3/2⁺ excited state are proposed. The level structure is described in the frame of the interacting boson-fermion and core-quasiparticle coupling models.