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Andreyev AN, Huyse M, Van Duppen P, Qi C, Liotta RJ, Antalic S, Ackermann D, Franchoo S, Heßberger FP, Hofmann S, Kojouharov I, Kindler B, Kuusiniemi P, Lesher SR, Lommel B, Mann R, Nishio K, Page RD, Streicher B, Šáro Š, Sulignano B, Wiseman D, Wyss RA. Signatures of the Z = 82 shell closure in α-decay process. PHYSICAL REVIEW LETTERS 2013; 110:242502. [PMID: 25165917 DOI: 10.1103/physrevlett.110.242502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Indexed: 06/03/2023]
Abstract
In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the (186)Po decay is reported here, allowed us for the first time to clearly show that crossing the Z = 82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N = 126 and Z = 82 shell closures strongly influence the α-formation probability.
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Affiliation(s)
- A N Andreyev
- Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium and Department of Physics, University of York, York YO10 5DD, United Kingdom and Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai-mura, Ibaraki 319-1195, Japan
| | - M Huyse
- Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium
| | - P Van Duppen
- Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium
| | - C Qi
- Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden
| | - R J Liotta
- Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden
| | - S Antalic
- Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia
| | - D Ackermann
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | | | - F P Heßberger
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - S Hofmann
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Institut für Physik, Goethe-Universität Frankfurt, 60438 Frankfurt, Germany
| | - I Kojouharov
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - B Kindler
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - P Kuusiniemi
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - S R Lesher
- Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium
| | - B Lommel
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - R Mann
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - K Nishio
- Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai-mura, Ibaraki 319-1195, Japan
| | - R D Page
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - B Streicher
- Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia
| | - Š Šáro
- Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia
| | - B Sulignano
- GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
| | - D Wiseman
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - R A Wyss
- Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden
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Abstract
Understanding the fundamental excitations of many-fermion systems is of significant current interest. In atomic nuclei with even numbers of neutrons and protons, the low-lying excitation spectrum is generally formed by nucleon pair breaking and nuclear vibrations or rotations. However, for certain numbers of protons and neutrons, a subtle rearrangement of only a few nucleons among the orbitals at the Fermi surface can result in a different elementary mode: a macroscopic shape change. The first experimental evidence for this phenomenon came from the observation of shape coexistence in 16O (ref. 4). Other unexpected examples came with the discovery of fission isomers and super-deformed nuclei. Here we find experimentally that the lowest three states in the energy spectrum of the neutron deficient nucleus 186Pb are spherical, oblate and prolate. The states are populated by the alpha-decay of a parent nucleus; to identify them, we combine knowledge of the particular features of this decay with sensitive measurement techniques (a highly efficient velocity filters with strong background reduction, and an extremely selective recoil-alpha-electron coincidence tagging methods). The existence of this apparently unique shape triplet is permitted only by the specific conditions that are met around this particular nucleus.
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Helariutta K, Enqvist T, Jones P, Julin R, Juutinen S, Jämsen P, Kankaanpää H, Kuusiniemi P, Leino M, Muikku M, Piiparinen M, Savelius A, Trzaska WH, Törmänen S, Uusitalo J, Allatt RG, Butler PA, Greenlees PT, Page RD. First observation of excited states in 192Po. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 54:R2799-R2801. [PMID: 9971716 DOI: 10.1103/physrevc.54.r2799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Delion DS, Florescu A, Huyse M, Wauters J, Insolia A, Liotta RJ. alpha decay as a probe for phase transitions in nuclei. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 54:1169-1176. [PMID: 9971451 DOI: 10.1103/physrevc.54.1169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Wauters J, Bijnens N, Huyse M. Comment on "Prolate-oblate band mixing and new bands in 182Hg". PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 53:3163-3164. [PMID: 9971307 DOI: 10.1103/physrevc.53.3163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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7
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Bindra KS, Hua PF, Babu BR, Baktash C, Barreto J, Cullen DM, Davids CN, Deng JK, Garrett JD, Halbert ML, Hamilton JH, Johnson NR, Kirov A, Kormicki J, Lee IY, Ma WC, McGowan FK, Ramayya AV, Sarantites DG, Soramel F, Winchell D. Reply to "Comment on 'Prolate-oblate band mixing and new bands in 182Hg' ". PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 53:3165. [PMID: 9971308 DOI: 10.1103/physrevc.53.3165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Takigawa N, Yoshida S, Hagino K, Patra SK, Praharaj CR. Reply to "Comment on 'Shape and superdeformed structure in Hg isotopes in relativistic mean field model' and 'Structure of neutron-deficient Pt, Hg, and Pb isotopes' ". PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 53:1038-1040. [PMID: 9971032 DOI: 10.1103/physrevc.53.1038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Bijnens N, Decrock P, Franchoo S, Gaelens M, Huyse M, Hwang H, Reusen I, Szerypo J, Wauters J, Correia JG, Jokinen A. Intruder states and the onset of deformation in the neutron-deficient even-even polonium isotopes. PHYSICAL REVIEW LETTERS 1995; 75:4571-4574. [PMID: 10059943 DOI: 10.1103/physrevlett.75.4571] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Wauters J, Bijnens N, Folger H, Huyse M, Hwang HY, Kirchner R. Alpha decay of 186Pb and 184Hg: The influence of mixing of 0(+) states on alpha -decay transition probabilities. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1994; 50:2768-2773. [PMID: 9969974 DOI: 10.1103/physrevc.50.2768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Yoshida S, Patra SK, Takigawa N, Praharaj CR. Structure of neutron-deficient Pt, Hg, and Pb isotopes. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1994; 50:1398-1403. [PMID: 9969801 DOI: 10.1103/physrevc.50.1398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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