Eur. Phys. J. A (2023) 59: 300
https://doi.org/10.1140/epja/s10050-023-01212-3

Regular Article - Experimental Physics

Lifetime measurement of the yrast 2${}^{+}$ state in ${}^{118}$Te

¹ Department of Physics, KTH Royal Institute of Technology, Roslagstullsbacken 21, 106 91, Stockholm, SE, Sweden
² Department of Physics and Astronomy, Uppsala University, Box 516, 751 20, Uppsala, Sweden
³ Department of Physics, University of Jyvaskylä, 40014, Jyväskylä, FI, Finland
⁴ Institut für Kernphysik, Universität zu Köln, 50937, Köln, Germany
⁵ Laboratorio de Radiaciones Ionizantes, Departamento de Física Fundamental, University of Salamanca, 37008, Salamanca, Spain
⁶ Oliver Lodge Laboratory, Department of Physics, University of Liverpool, L69 7ZE, Liverpool, UK
⁷ GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076, Caen Cedex 5, France
⁸ Department of Physics, University of Oslo, 0316, Oslo, NO, Norway
⁹ School of Physics and Astronomy, The University of Manchester, Oxford Road, M13 9PL, Manchester, UK
¹⁰ Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy
¹¹ Department of Physics, Stockholm University, 10691, Stockholm, SE, Sweden
¹² School of Computing Engineering and Physical Sciences, University of the West of Scotland, PA1 2BE, Paisley, UK
¹³ STFC Daresbury Laboratory, Daresbury, WA4 4AD, Warrington, UK
¹⁴ Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) GmbH, 590667, Köln, Germany

^a ebbace@kth.se

Received: 1 May 2023
Accepted: 3 December 2023
Published online: 20 December 2023

Abstract

The electromagnetic transition probabilities of the yrast $2^{+}$ states in the midshell Te isotopes, two protons above the closed shell at Sn, are of great importance for the understanding of nuclear collectivity in these isotopes and the role played by the neutron-proton interactions and cross-shell excitations. However, the large uncertainty of the experimental data for the midshell nucleus ¹¹⁸Te and the missing data for ¹¹⁶Te make it difficult to pin down the general trend of the evolution of transition probabilities as a function of the neutron number. In this work, the lifetime of the yrast $2^{+}$ state in ¹¹⁸Te was measured, with the aim of reducing the uncertainty of the previous measurement. The result is ${\tau }_{2+}=7.46(19)$ ps. In addition, the lifetime of the $4^{+}$ state was measured to be ${\tau }_{4+}=4.25(23)$ ps. The experimental transition rates are extracted from the measured lifetimes and compared with systematic large-scale shell-model calculations. The trend of the $B(\text{E2};0^{+}\to 2^{+})$ values in the midshell area is in good agreement with the calculations and the calculated $B_{4/2}$ ratio provide evidence for ¹¹⁸Te as a near perfect harmonic vibrator.