48Ca+249Bk fusion reaction leading to element Z = 117: long-lived α-decaying 270Db and discovery of 266Lr

J Khuyagbaatar; A Yakushev; Ch E Düllmann; D Ackermann; L-L Andersson; M Asai; M Block; R A Boll; H Brand; D M Cox; M Dasgupta; X Derkx; A Di Nitto; K Eberhardt; J Even; M Evers; C Fahlander; U Forsberg; J M Gates; N Gharibyan; P Golubev; K E Gregorich; J H Hamilton; W Hartmann; R-D Herzberg; F P Heßberger; D J Hinde; J Hoffmann; R Hollinger; A Hübner; E Jäger; B Kindler; J V Kratz; J Krier; N Kurz; M Laatiaoui; S Lahiri; R Lang; B Lommel; M Maiti; K Miernik; S Minami; A Mistry; C Mokry; H Nitsche; J P Omtvedt; G K Pang; P Papadakis; D Renisch; J Roberto; D Rudolph; J Runke; K P Rykaczewski; L G Sarmiento; M Schädel; B Schausten; A Semchenkov; D A Shaughnessy; P Steinegger; J Steiner; E E Tereshatov; P Thörle-Pospiech; K Tinschert; T Torres De Heidenreich; N Trautmann; A Türler; J Uusitalo; D E Ward; M Wegrzecki; N Wiehl; S M Van Cleve; V Yakusheva

doi:10.1103/PhysRevLett.112.172501

48Ca+249Bk fusion reaction leading to element Z = 117: long-lived α-decaying 270Db and discovery of 266Lr

Phys Rev Lett. 2014 May 2;112(17):172501. doi: 10.1103/PhysRevLett.112.172501. Epub 2014 May 1.

Authors

J Khuyagbaatar¹, A Yakushev², Ch E Düllmann³, D Ackermann², L-L Andersson⁴, M Asai⁵, M Block², R A Boll⁶, H Brand², D M Cox⁷, M Dasgupta⁸, X Derkx⁹, A Di Nitto¹⁰, K Eberhardt⁹, J Even⁴, M Evers⁸, C Fahlander¹¹, U Forsberg¹¹, J M Gates¹², N Gharibyan¹³, P Golubev¹¹, K E Gregorich¹², J H Hamilton¹⁴, W Hartmann², R-D Herzberg⁷, F P Heßberger¹, D J Hinde⁸, J Hoffmann², R Hollinger², A Hübner², E Jäger², B Kindler², J V Kratz¹⁰, J Krier², N Kurz², M Laatiaoui⁴, S Lahiri¹⁵, R Lang², B Lommel², M Maiti¹⁵, K Miernik⁶, S Minami², A Mistry⁷, C Mokry⁹, H Nitsche¹², J P Omtvedt¹⁶, G K Pang¹², P Papadakis¹⁷, D Renisch¹⁰, J Roberto⁶, D Rudolph¹¹, J Runke², K P Rykaczewski⁶, L G Sarmiento¹¹, M Schädel¹⁸, B Schausten², A Semchenkov¹⁶, D A Shaughnessy¹³, P Steinegger¹⁹, J Steiner², E E Tereshatov¹³, P Thörle-Pospiech⁹, K Tinschert², T Torres De Heidenreich², N Trautmann¹⁰, A Türler¹⁹, J Uusitalo²⁰, D E Ward¹¹, M Wegrzecki²¹, N Wiehl⁹, S M Van Cleve⁶, V Yakusheva⁴

Affiliations

¹ Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
² GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
³ Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
⁴ Helmholtz Institute Mainz, 55099 Mainz, Germany.
⁵ Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
⁶ Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
⁷ University of Liverpool, Liverpool L69 7ZE, United Kingdom.
⁸ The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
⁹ Helmholtz Institute Mainz, 55099 Mainz, Germany and Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
¹⁰ Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
¹¹ Lund University, 22100 Lund, Sweden.
¹² Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
¹³ Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
¹⁴ Vanderbilt University, Nashville, Tennessee 37235, USA.
¹⁵ Saha Institute of Nuclear Physics, Kolkata 700064, India.
¹⁶ University of Oslo, 0315 Oslo, Norway.
¹⁷ University of Liverpool, Liverpool L69 7ZE, United Kingdom and University of Jyväskylä, 40351 Jyväskylä, Finland.
¹⁸ GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
¹⁹ Paul Scherrer Institute, 5232 Villigen, Switzerland and University of Bern, 3012 Bern, Switzerland.
²⁰ University of Jyväskylä, 40351 Jyväskylä, Finland.
²¹ Institute of Electron Technology, 02-668 Warsaw, Poland.

PMID: 24836239
DOI: 10.1103/PhysRevLett.112.172501

Abstract

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."