Eur. Phys. J. A (2005) 23: 201-215
https://doi.org/10.1140/epja/i2004-10079-7

Isomers in neutron-rich A ≈ 190 nuclides from ²⁰⁸Pb fragmentation

¹ Department of Physics, University of Surrey, GU2 7XH, Guildford, UK
² TRIUMF, 4004 Wesbrook Mall, V6T 2A3, Vancouver, Canada
³ Wright Nuclear Structure Laboratory, Yale University, CT 06520, New Haven, USA
⁴ Institute of Experimental Physics, Warsaw University, PL-00681, Warsaw, Poland
⁵ GSI, Planckstrasse 1, D-64291, Darmstadt, Germany
⁶ Division of Nuclear Physics, Lund University, SE-22100, Sweden
⁷ IKS, KU Leuven, Celestijnenlaan 200 D, B-3000, Leuven, Belgium
⁸ Department of Physics, University of Notre Dame, IN 46556, South Bend, USA
⁹ Departamento de Fısica de Partıculas, University of Santiago de Compostela, 15706, Santiago de Compostela, Spain
¹⁰ School of Engineering, University of Brighton, BN2 4GJ, Brighton, UK
¹¹ Oliver Lodge Laboratory, University of Liverpool, L69 7ZE, Liverpool, UK
¹² Schuster Laboratory, University of Manchester, M13 9PL, Manchester, UK
¹³ Department of Physics, University of Jyväskylä, 40351, Jyväskylä, Finland
¹⁴ TUNL, Duke University, NC 27708-0308, Durham, USA
¹⁵ CEN Bordeaux-Gradignan/CNRS, F-33175, Gradignan Cedex, France
¹⁶ Department of Physics and Astronomy, University of Tennessee, TN 37996-1200, Knoxville, USA
¹⁷ CEA Saclay, DSM/DAPNIA/SPhN, F-91191, Gif-sur-Yvette Cedex, France
¹⁸ GANIL, BP 5027, F-14021, Caen Cedex, France
¹⁹ Department of Radiation Sciences, Uppsala University, S-61182, Nyköping, Sweden
²⁰ IPN, 91406, Orsay Cedex, France
²¹ CLRC Daresbury Laboratory, WA4 4AD, Warrington, UK
²² Department of Technical Physics, Peking University, 100871, Beijing, PRC

^* e-mail: p.walker@surrey.ac.uk

Received: 21 July 2004
Accepted: 23 September 2004
Published online: 7 December 2004

Abstract

Relativistic projectile fragmentation of ²⁰⁸Pb has been used to produce isomers in neutron-rich, A ≈ 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of γ-rays emitted by stopped ions has led to the assignment of isomers in ¹⁸⁸Ta, ¹⁹⁰W, ¹⁹²Re, ¹⁹³Re, ¹⁹⁵Os, ¹⁹⁷Ir, ¹⁹⁸Ir, ²⁰⁰Pt, ²⁰¹Pt, ²⁰²Pt and ²⁰³Au, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for ¹⁷⁴Er, ¹⁷⁵Er, ¹⁸⁵Hf, ¹⁹¹Re, ¹⁹⁴Re and ¹⁹⁹Ir. In most cases, time-correlated, singles γ-ray events provided the first spectroscopic data on excited states for each nuclide. In ²⁰⁰Pt and ²⁰¹Pt, the assignments are supported by γ-γ coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics.