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
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.
PACS: 21.10.Tg Lifetimes – / 23.20.Lv γ transitions and level energies – / 25.70.Mn Projectile and target fragmentation –
© Società Italiana di Fisica and Springer-Verlag, 2005