Article

New Superheavy Element Isotopes:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Pu</mml:mi><mml:mprescripts/><mml:none/><mml:mn>242</mml:mn></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mmultiscripts><mml:mi>Ca</mml:mi><mml:mprescripts/><mml:none/><mml:mn>48</mml:mn></mml:mmultiscripts><mml:mo>,</mml:mo><mml:mn>5</mml:mn><mml:mi>n</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mn>1</mml:mn><mml:mprescripts/><mml:none/><mml:mn>285</mml:mn></mml:mmultiscripts><mml:mn>14</mml:mn></mml:math>

Paul A. EllisonDepartment of Chemistry, University of California, Berkeley, CA 94720, USAΚ. Ε. GregorichLawrence Berkeley National Laboratory, Berkeley, California 94720, USAJ. S. BerrymanLawrence Berkeley National Laboratory, Berkeley, California 94720, USAD. L. BleuelLawrence Livermore National Laboratory, Livermore, California 94550, USAR. M. ClarkLawrence Berkeley National Laboratory, Berkeley, California 94720, USAI. DragojevićLawrence Berkeley National Laboratory, Berkeley, California 94720, USAJ. DvořákGSI Helmholtzzentrum für Schwerionenforschung, GmbH, 64550 Darmstadt, GermanyP. FallonLawrence Berkeley National Laboratory, Berkeley, California 94720, USAC. Fineman-SotomayorDepartment of Chemistry, University of California, Berkeley, California 94720, USAJ. M. GatesLawrence Berkeley National Laboratory, Berkeley, California 94720, USAOliver GotheDepartment of Chemistry, University of California, Berkeley, California 94720, USAI. Y. LeeLawrence Berkeley National Laboratory, Berkeley, California 94720, USAW. LovelandDepartment of Chemistry, Oregon State University, Corvallis, Oregon 97331, USAJohn P. McLaughlinDepartment of Chemistry, University of California, Berkeley, California 94720, USAS. PaschalisLawrence Berkeley National Laboratory, Berkeley, California 94720, USAM. PetriLawrence Berkeley National Laboratory, Berkeley, California 94720, USAJ. QianLawrence Berkeley National Laboratory, Berkeley, California 94720, USAL. StavsetraInstitute for Energy Technology, N-2007 Kjeller, NorwayM. WiedekingLawrence Livermore National Laboratory, Livermore, California 94550, USAH. NitscheDepartment of Chemistry, University of California, Berkeley, California 94720, USA

2010lv

ABI

Abstract

The new, neutron-deficient, superheavy element isotope $^{285}114$ was produced in $^{48}\mathrm{Ca}$ irradiations of $^{242}\mathrm{Pu}$ targets at a center-of-target beam energy of 256 MeV (${E}^{*}=50\text{ }\text{ }\mathrm{MeV}$). The $\ensuremath{\alpha}$ decay of $^{285}114$ was followed by the sequential $\ensuremath{\alpha}$ decay of four daughter nuclides, $^{281}\mathrm{Cn}$, $^{277}\mathrm{Ds}$, $^{273}\mathrm{Hs}$, and $^{269}\mathrm{Sg}$. $^{265}\mathrm{Rf}$ was observed to decay by spontaneous fission. The measured $\ensuremath{\alpha}$-decay $Q$ values were compared with those from a macroscopic-microscopic nuclear mass model to give insight into superheavy element shell effects. The $^{242}\mathrm{Pu}(^{48}\mathrm{Ca},5n)^{285}114$ cross section was ${0.6}_{\ensuremath{-}0.5}^{+0.9}\text{ }\text{ }\mathrm{pb}$.

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Identifiers

DOI: 10.1103/physrevlett.105.182701

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