title: Signatures of the Z = 82 shell closure in α-decay process.
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.
authors.affiliation: 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.
authors.forename: A N
authors.initials: AN
authors.lastname: Andreyev
authors.affiliation: Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Huyse
authors.affiliation: Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Van Duppen
authors.affiliation: Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Qi
authors.affiliation: Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden.
authors.forename: R J
authors.initials: RJ
authors.lastname: Liotta
authors.affiliation: Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia.
authors.forename: S
authors.initials: S
authors.lastname: Antalic
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Ackermann
authors.affiliation: IPN Orsay, F-91406 Orsay Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Franchoo
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: F P
authors.initials: FP
authors.lastname: Heßberger
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Institut für Physik, Goethe-Universität Frankfurt, 60438 Frankfurt, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Hofmann
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Kojouharov
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Kindler
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Kuusiniemi
authors.affiliation: Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium.
authors.forename: S R
authors.initials: SR
authors.lastname: Lesher
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Lommel
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Mann
authors.affiliation: Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai-mura, Ibaraki 319-1195, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nishio
authors.affiliation: Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom.
authors.forename: R D
authors.initials: RD
authors.lastname: Page
authors.affiliation: Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia.
authors.forename: B
authors.initials: B
authors.lastname: Streicher
authors.affiliation: Department of Nuclear Physics and Biophysics, Comenius University, 84248 Bratislava, Slovakia.
authors.forename: Š
authors.initials: Š
authors.lastname: Šáro
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Sulignano
authors.affiliation: Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Wiseman
authors.affiliation: Department of Physics, Royal Institute of Technology, 10405 Stockholm, Sweden.
authors.forename: R A
authors.initials: RA
authors.lastname: Wyss
mesh_terms: D000512:Alpha Particles; D009502:Neutrons; D009686:Nuclear Physics; D011059:Polonium / Q000737:chemistry*
chemical_list: D011059:Polonium