48Ca+249Bk fusion reaction leading to element Z = 117: long-lived α-decaying 270Db and discovery of 266Lr.
The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."
Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Khuyagbaatar
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Yakushev
Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Düllmann
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Ackermann
Helmholtz Institute Mainz, 55099 Mainz, Germany.
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Andersson
Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
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Asai
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Block
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Boll
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Brand
University of Liverpool, Liverpool L69 7ZE, United Kingdom.
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Cox
The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Dasgupta
Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Derkx
Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Di Nitto
Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Eberhardt
Helmholtz Institute Mainz, 55099 Mainz, Germany.
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Even
The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Evers
Lund University, 22100 Lund, Sweden.
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Fahlander
Lund University, 22100 Lund, Sweden.
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Forsberg
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Gates
Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Gharibyan
Lund University, 22100 Lund, Sweden.
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Golubev
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Gregorich
Vanderbilt University, Nashville, Tennessee 37235, USA.
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Hamilton
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Hartmann
University of Liverpool, Liverpool L69 7ZE, United Kingdom.
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Herzberg
Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Heßberger
The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Hinde
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Hoffmann
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Hollinger
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Hübner
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Jäger
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Kindler
Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Kratz
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Krier
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Kurz
Helmholtz Institute Mainz, 55099 Mainz, Germany.
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Laatiaoui
Saha Institute of Nuclear Physics, Kolkata 700064, India.
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Lahiri
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Lang
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Lommel
Saha Institute of Nuclear Physics, Kolkata 700064, India.
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Maiti
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Miernik
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Minami
University of Liverpool, Liverpool L69 7ZE, United Kingdom.
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Mistry
Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Mokry
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Nitsche
University of Oslo, 0315 Oslo, Norway.
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Omtvedt
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Pang
University of Liverpool, Liverpool L69 7ZE, United Kingdom and University of Jyväskylä, 40351 Jyväskylä, Finland.
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Papadakis
Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Renisch
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Roberto
Lund University, 22100 Lund, Sweden.
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Rudolph
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Runke
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Rykaczewski
Lund University, 22100 Lund, Sweden.
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Sarmiento
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
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Schädel
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Schausten
University of Oslo, 0315 Oslo, Norway.
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Semchenkov
Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Shaughnessy
Paul Scherrer Institute, 5232 Villigen, Switzerland and University of Bern, 3012 Bern, Switzerland.
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Steinegger
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Steiner
Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Tereshatov
Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Thörle-Pospiech
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Tinschert
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Torres De Heidenreich
Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Trautmann
Paul Scherrer Institute, 5232 Villigen, Switzerland and University of Bern, 3012 Bern, Switzerland.
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Türler
University of Jyväskylä, 40351 Jyväskylä, Finland.
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Uusitalo
Lund University, 22100 Lund, Sweden.
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Ward
Institute of Electron Technology, 02-668 Warsaw, Poland.
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Wegrzecki
Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Wiehl
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Van Cleve
Helmholtz Institute Mainz, 55099 Mainz, Germany.
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Yakusheva