Physics Letters B (Jun 2022)
First observation of a shape isomer and a low-lying strongly-coupled prolate band in neutron-deficient semi-magic 187Pb
- W.Q. Zhang,
- A.N. Andreyev,
- Z. Liu,
- D. Seweryniak,
- H. Huang,
- Z.H. Li,
- J.G. Li,
- C.Y. Guo,
- D.T. Doherty,
- A.E. Barzakh,
- P. Van Duppen,
- J.G. Cubiss,
- B. Andel,
- S. Antalic,
- M. Block,
- A. Bronis,
- M.P. Carpenter,
- P. Copp,
- B. Ding,
- Z. Favier,
- F. Giacoppo,
- T.H. Huang,
- X.H. Yu,
- B. Kindler,
- F.G. Kondev,
- T. Lauritsen,
- G.S. Li,
- B. Lommel,
- H.Y. Lu,
- M. Al Monthery,
- P. Mošať,
- Y.F. Niu,
- C. Raison,
- W. Reviol,
- G. Savard,
- S. Stolze,
- G.L. Wilson,
- H.Y. Wu,
- Z.H. Wang,
- F.R. Xu,
- Q.B. Zeng,
- X.H. Zhou
Affiliations
- W.Q. Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- A.N. Andreyev
- Department of Physics, University of York, York, YO10 5DD, United Kingdom; Advanced Science Research Center (ASRC), Japan Atomic Energy Agency, Tokai-mura, Japan; Corresponding author at: Department of Physics, University of York, York, YO10 5DD, United Kingdom.
- Z. Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; Corresponding author at: Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.
- D. Seweryniak
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- H. Huang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- Z.H. Li
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- J.G. Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- C.Y. Guo
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- D.T. Doherty
- Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
- A.E. Barzakh
- Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, 188300 Gatchina, Russia
- P. Van Duppen
- KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001 Leuven, Belgium
- J.G. Cubiss
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
- B. Andel
- Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248 Bratislava, Slovakia
- S. Antalic
- Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248 Bratislava, Slovakia
- M. Block
- Helmholtz-Institut Mainz, Mainz, 55128, Germany; GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Darmstadt, 64291, Germany; Johannes-Gutenberg Universität, Mainz, 55099, Germany
- A. Bronis
- Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248 Bratislava, Slovakia
- M.P. Carpenter
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- P. Copp
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- B. Ding
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- Z. Favier
- Physics Department, CERN, 1211 Geneva 23, Switzerland
- F. Giacoppo
- Helmholtz-Institut Mainz, Mainz, 55128, Germany; GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Darmstadt, 64291, Germany
- T.H. Huang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- X.H. Yu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- B. Kindler
- GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Darmstadt, 64291, Germany
- F.G. Kondev
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- T. Lauritsen
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- G.S. Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- B. Lommel
- GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, Darmstadt, 64291, Germany
- H.Y. Lu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- M. Al Monthery
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
- P. Mošať
- Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248 Bratislava, Slovakia
- Y.F. Niu
- Lanzhou University, Lanzhou 730000, China
- C. Raison
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
- W. Reviol
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- G. Savard
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- S. Stolze
- Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA
- G.L. Wilson
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
- H.Y. Wu
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- Z.H. Wang
- Lanzhou University, Lanzhou 730000, China
- F.R. Xu
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- Q.B. Zeng
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- X.H. Zhou
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
- Journal volume & issue
-
Vol. 829
p. 137129
Abstract
Prompt and delayed γ-ray spectroscopy of the neutron-deficient, semi-magic isotope 187Pb has been performed using the recoil-decay and isomer-decay tagging techniques at the Argonne Gas-Filled Analyzer. A new 5.15(15)-μs isomeric state at only 308 keV above the spherical 3/2− ground state is identified and classified as a shape isomer. A strongly-coupled band is observed on top of the isomer, which is nearly identical to the one built on the prolate 7/2−[514] Nilsson state in the isotone 185Hg. Based on this similarity and on the result of the potential-energy surface calculations, the new isomer in 187Pb is proposed to originate from the same configuration. The retarded character of the 308-keV (7/2−)→3/2gs− transition with a deduced B(E2)=5.6(2)×10−4 W.u. can be well explained by the significant difference between the prolate parent and spherical daughter configurations, leading to the shape isomerism. The excitation energy of the isomer is surprisingly low, being roughly half of the excitation energies of the known 0+ intruder bandheads in the neighboring 186,188Pb isotopes. The combined results of the present work and the previous α-decay and laser spectroscopy studies present evidence for triple shape coexistence at low energy in the negative-parity configurations of 187Pb, which is well reproduced by the potential-energy surface calculations.
