Structural investigation of neutron-deficient Pt isotopes: the case of ¹⁷⁸Pt

¹ Institut für Kernphysik, Universität zu Köln, Zülpicher Strasse 77, 50937 Cologne, Germany
² iThemba LABS, National Research Foundation, P.O.Box 722, Somerset West, 7129, South Africa
³ Department of Physics, Stellenbosch University, Matieland, Stellenbosch 7602, South Africa
⁴ Department of Physics, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa

^* e-mail: fransen@ikp.uni-koeln.de

Published online: 4 December 2019

Abstract

Lifetime measurements with the recoil distance Doppler-shift technique have been performed to determine yrast E2 transition strengths in ¹⁷⁸Pt. The experimental data are related to those on neighboring Pt isotopes, especially recent data on ¹⁸⁰Pt, and compared to calculations within the interacting boson model and a Hartree-Fock Bogoliubov approach. These models predict prolate deformed ground states in Pt isotopes close to neutron midshell consistent with the experimental findings. Further, evidence was found that the prolate intruder structure observed in neutron-deficient Hg isotopes that is minimum in energy in ¹⁸²Hg becomes the ground state configuration in ¹⁷⁸Pt and neighboring ¹⁸⁰Pt with nearly identical transition quadrupole moments. The new data on ¹⁷⁸Pt are further discussed in the context of the systematics along the Pt isotopic chain with respect to a possible sharp shape transition towards a weakly deformed or a quasi-vibrational ground state whereas the prolate structure increases in energy in ^174,176Pt and becomes an intruder configuration similar to, for example, ^180,182Hg.