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@PHDTHESIS{Kaleja:236616,
      author       = {Kaleja, Oliver},
      title        = {{H}igh-precision mass spectrometry of nobelium, lawrencium
                      and rutherfordium isotopes and studies of long-lived isomers
                      with {SHIPTRAP}},
      school       = {Johannes-Gutenberg Universität Mainz},
      type         = {Dissertation},
      publisher    = {Johannes Gutenberg-Universität Mainz},
      reportid     = {GSI-2020-01337},
      pages        = {147 p.},
      year         = {2020},
      note         = {Dissertation, Johannes-Gutenberg Universität Mainz, 2020},
      abstract     = {In this work, the first successful application of the
                      recently developed Phase-Imaging Ion-Cyclotron Res-onance
                      (PI-ICR) technique in the region of the heaviest elements is
                      presented. For the first time, theatomic masses of several
                      nobelium (No,Z= 102), lawrencium (Lr,Z= 103) and
                      rutherfordium (Rf,Z= 104) isotopes and isomers have been
                      measured directly, reaching uncertainties on the order of
                      fewkeV/c2using the Penning-trap mass spectrometer SHIPTRAP.
                      These heavy radionuclides were producedin fusion-evaporation
                      reactions and separated from the primary beam by the
                      velocity filter SHIP locatedat the GSI Helmholtz Centre for
                      Heavy Ion Research in Darmstadt, Germany. The mass
                      measurementswere carried out at production rates of few ions
                      per second down to few ions per minute. To improvethe
                      overall efficiency on stopped and thermalized ions, the
                      recently developed cryogenic gas-stopping cellwas
                      implemented into the existing beam line. Its performance
                      with respect to purity and efficiency hasbeen characterized
                      and improved. The overall efficiency of SHIPTRAP is
                      increased by about one orderof magnitude with respect to
                      previous measurements on heavy ions. The atomic masses are
                      determinedby measuring the cyclotron frequency of the ion of
                      interest in the strong magnetic field of a 7 T
                      super-conducting magnet. The atomic masses of251No,254Lr
                      and257Rf were measured directly for the firsttime, reaching
                      high precision. The latter marks the very first direct
                      high-precision mass spectrometry of asuperheavy element with
                      a detection rate of one detected ion per day and only five
                      ions in total. In addi-tion, the uncertainties of the atomic
                      masses of254No and255,256Lr have been reduced by up to two
                      ordersof magnitude with respect to previous experiments at
                      SHIPTRAP. The precise determination of bindingenergies is
                      key in nuclear physics as it is a model-independent quantity
                      comprising all interactions that arepresent within the
                      atomic nucleus. This allows studying, e.g.,
                      quantum-mechanical shell effects, which areelementary for
                      the existence of (super-)heavy elements. The results of this
                      work are used to benchmarkatomic mass models in the vicinity
                      of the deformed neutron shell closure atN= 152. Furthermore,
                      thesemeasurements will provide additional anchor points of
                      very heavy odd-Nand odd-Zas well as odd-Anuclides, affecting
                      the masses up to darmstadtium (Z= 110). With the enhanced
                      mass resolving powerof up to 11 000 000, the isomeric
                      states251mNo,254mLr and255mLr were resolved from their
                      respectiveground states despite low excitation energies of
                      tens of keV. Their masses and the corresponding
                      excitationenergies were measured directly for the first
                      time. Up to now, only tentative level energies were
                      derivedfrom previousα-decay spectroscopy experiments. This
                      work proves the feasibility of PI-ICR in the regionof the
                      heaviest elements at lowest yields and particle integrals.
                      It paves the way to precisely study exoticsuperheavy species
                      with very long half-lives which becomes inevitable when
                      progressing towards the islandof stability.},
      cin          = {SHP / MSH},
      cid          = {I:(DE-Ds200)SHP-20080822OR107 /
                      I:(DE-Ds200)MSH-20150313OR333},
      pnm          = {612 - Cosmic Matter in the Laboratory (POF3-612) / FAIR
                      Phase-0 - FAIR Phase-0 Research Program (GSI-FAIR-Phase-0)},
      pid          = {G:(DE-HGF)POF3-612 / G:(Ds200)GSI-FAIR-Phase-0},
      experiment   = {EXP:(DE-Ds200)U238-20200803 / EXP:(DE-Ds200)U312-20200803},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.25358/OPENSCIENCE-5111},
      url          = {https://repository.gsi.de/record/236616},
}