Bulletin #10                                            May 16, 2000

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                 ATOMIC        MASS        DATA       CENTER

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    I - NEWS FROM EXPERIMENTS ON MASSES

    The ISOLTRAP Experiment        /          Dietrich Beck     Apr 2000

    More  than  40  masses  of short lived rare earth isotopes have been
    measured  with  the  ISOLTRAP spectrometer at ISOLDE/CERN during the
    years  1995  and  1996.  The  paper, which includes the experimental
    results,  a description of the atomic mass evaluation using the data
    and  the  discussion  of  the  results has now been submitted to the
    European  Physical  Journal. The preprint of this paper is available
    from the AMDC as a PDF file: "experimental/rare-earth.pdf" (620 kb).


    The Superheavy Nuclide 288 114  /  Yu.Ts.Oganessian et al.  Apr 2000

    In the bombardment of a 244Pu target with 48Ca ions, we observed two
    identical   decay  sequences  of  genetically  linked  events,  each
    consisting  of an implanted heavy atom, two subsequent alpha-decays,
    and terminated by a spontaneous fission.
      The decay properties of the synthesized nuclei are consistent with
    the  consecutive  alpha-decays originating from the parent even-even
    nucleus 288 114, produced in the 4n-evaporation channel with a cross
    section of about 1 pb.
      288-114   and   284-112  are  the  heaviest  known  alpha-decaying
    Even-Even  nuclides.
      Comparison of the  measured  decay  properties  of  these  two new
    even-even   nuclei   with   recent   theoretical   calculations   in
    macro-microscopic  model  indicates  that  nuclei in the vicinity of
    spherical  shell  closures  with  Z=114 and N=184 could be even more
    stable than predicted by theory.

    The preprint of this paper is available from the AMDC as a PDF file:
    "experimental/s-heavy288.pdf" (147 kb).


    II - GENERAL INFORMATION

    Please  send  contributions  to  the  next  bulletin of the AMDC to:
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    General information on the AMDC are given in bulletin #01.
       ftp access: ftp csnftp.in2p3.fr/pub/AMDC/document.list
       AMDC Web:   http://csnwww.in2p3.fr/amdc/  click:"access to files"
    "document.list"  is  the  comprehensive  list of documents and files
    available from AMDC.

    The  AMDC  bulletin is sent electronically 3 to 5 times per year. To
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    Address:   Atomic  Mass  Data  Center
               C.S.N.S.M. (IN2P3-CNRS)
               Batiment 108
               F-91405 Orsay campus (France)
    Telephone: +33 1 6915 5223   E-mail: audi@csnsm.in2p3.fr
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