Ca + Bk fusion reaction leading to element Z = 117; Long-lived -decaying Db and discovery of Lr

Ca+Bk核融合反応による117番元素の合成; 崩壊する長寿命核種Db及びLrの発見

Khuyagbaatar, J.*; Yakushev, A.*; Dllmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; 浅井 雅人  ; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; Dasgupta, M.*; Derkx, X.*; Di Nitto, A.*; Eberhardt, K.*; Even, J.*; Evers, M.*; Fahlander, C.*; Forsberg, U.*; Gates, J. M.*; Gharibyan, N.*; Golubev, P.*; Gregorich, K. E.*; Hamilton, J. H.*; Hartmann, W.*; Herzberg, R.-D.*; Heberger, F. P.*; Hinde, D. J.*; Hoffmann, J.*; Hollinger, R.*; Hbner, A.*; Jger, E.*; Kindler, B.*; Kratz, J. V.*; Krier, J.*; Kurz, N.*; Laatiaoui, M.*; Lahiri, S.*; Lang, R.*; Lommel, B.*; Maiti, M.*; Miernik, K.*; 南 志都*; Mistry, A.*; Mokry, C.*; Nitsche, H.*; Omtvedt, J. P.*; Pang, G. K.*; Papadakis, P.*; Renisch, D.*; Roberto, J.*; Rudolph, D.*; Runke, J.*; Rykaczewski, K. P.*; Sarmiento, L. G.*; Schdel, M.; Schausten, B.*; Semchenkov, A.*; Schaughnessy, D. A.*; Steinegger, P.*; Steiner, J.*; Tereshatov, E. E.*; Thrle-Pospiech, P.*; Tinschert, K.*; Torres De Heidenreich, T.*; Trautmann, N.*; Trler, A.*; Uusitalo, J.*; Ward, D. E.*; Wegrzecki, M.*; Wiehl, N.*; Van Cleve, S. M.*; Yakusheva, V.*

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

ドイツ重イオン研究所のガス充填型反跳核分離装置TASCAを用いてCa + Bk核融合反応で生成する原子番号117の超重元素の観測に成功した。この結果は、過去にロシアのフレーロフ研究所が報告した117番新元素の結果を再確認するもので、117番元素の合成及び発見を確かなものとする成果である。一方、117番元素からの崩壊連鎖の最後の原子核は、過去に報告されたDbではなく、未知核種Lrであり、Dbは非常に長い寿命を持つ崩壊核種であることを明らかにした。

The superheavy element with atomic number 117 was produced in the Ca + Bk fusion reaction using the gas-filled recoil separator TASCA at GSI in Germany. This result verified the previous result of the discovery of new element 117 reported by Flerov Laboratory of Nuclear Reactions in Russia, which makes certain the synthesis and discovery of element 117 in human history. On the other hand, the last nucleus in the decay chain from the element 117 was assigned to be the unknown nucleus Lr instead of the previously reported Db, and Db was found to be the -decaying nucleus with very long half-life.