Article

Observation of Superheavy Nuclei Produced in the Reaction of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>86</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow><mml:mi>r</mml:mi></mml:math>with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>P</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>208</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow><mml:mi>b</mml:mi></mml:math>

V. NinovNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720Κ. Ε. GregorichNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720W. LovelandDepartment of Chemistry, Oregon State University, Corvallis, Oregon 97331A. GhiorsoNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720D. C. HoffmanDepartment of Chemistry, University of California, Berkeley, California 94720D. M. LeeNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720H. NitscheNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720W.J. Świa̧teckiNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720U. KirbachNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720C. A. LaueNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720J. L. AdamsNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720J. B. PatinNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720D. A. ShaughnessyDepartment of Chemistry, University of California, Berkeley, California 94720D. A. StrellisNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720P. A. WilkDepartment of Chemistry, University of California, Berkeley, California 94720

1999lv

ABI

Abstract

Following a prediction by Smola\ifmmode \acute{n}\else \'{n}\fi{}czuk [Phys. Rev. C 59, 2634 (1999)], we searched for superheavy element formation in the bombardment of ${}^{208}\mathrm{Pb}$ with 449-MeV ${}^{86}\mathrm{Kr}$ ions. We have observed three decay chains, each consisting of an implanted heavy atom and six subsequent $\ensuremath{\alpha}$ decays, correlated in time and position. In these decay chains, a rapid (ms) sequence of high energy $\ensuremath{\alpha}$ particles ( ${E}_{\ensuremath{\alpha}}\ensuremath{\ge}10\mathrm{MeV}$) indicates the decay of a new high- $Z$ element. The observed chains are consistent with the formation of $^{293}118$ and its decay by sequential $\ensuremath{\alpha}$-particle emission to $^{289}116$, $^{285}114$, $^{281}112$, $^{277}110$, ${}^{273}\mathrm{Hs}$ ( $Z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}108$) and ${}^{269}\mathrm{Sg}$ ( $Z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}106$). The production cross section is ${2.2}_{\ensuremath{-}0.8}^{+2.6}\mathrm{pb}$.

Identifiers

DOI: 10.1103/physrevlett.83.1104

Citations and references

Cited by 50 references

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