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@PHDTHESIS{Xu:201580,
      author       = {Xu, Xiaodong},
      othercontributors = {Scheidenberger, Christoph},
      title        = {{O}bservation and investigation of the new proton-unbound
                      nuclei $^{30}${A}r and $^{29}${C}l with in-flight decay
                      spectroscopy},
      school       = {Justus-Liebig-Universität Gießen},
      type         = {Dr.},
      reportid     = {GSI-2017-00682},
      pages        = {134 p.},
      year         = {2016},
      note         = {Justus-Liebig-Universität Gießen, Diss., 2016},
      abstract     = {Two-proton (2p) radioactivity is an exotic nuclear decay
                      mode resulting in the simultaneous emission of two protons.
                      The ground-state 2p radioactivity was discovered in the
                      decay of 45Fe in 2002. Later, this novel decay mode was also
                      found in the decays of 48Ni, 54Zn, and 19Mg. <br>In order to
                      study a promising 2p radioactivity candidate 30Ar, an
                      experiment was performed at the Fragment Separator of GSI in
                      Darmstadt (Germany). The in-flight decay technique, which is
                      based on the tracking of the in-flight decay products by
                      using the silicon strip detectors, was employed. Several
                      calibration and alignment procedures were performed to
                      achieve the best-possible accuracy of position and angle
                      measurements. In order to determine the angular and
                      half-life resolutions as well as the detection efficiency,
                      the decays of the previously-known 2p emitter 19Mg were
                      remeasured. The 2p radioactivity of 19Mg ground state and
                      sequential emission of protons from several known excited
                      states in 19Mg were confirmed. The deduced 2p decay energies
                      are consistent with previous data. The evidence on a new
                      excited state in 19Mg at $8.9^(+0.8)_(-0.7)$ MeV above the
                      2p threshold was found. It was tentatively suggested that
                      this new 19Mg state decays by sequential emission of protons
                      via two unknown 18Na resonances at $2.5^(+0.7)_(-0.3)$ MeV
                      and $4.0^(+1.5)_(-0.6)$ MeV above the 1p threshold,
                      respectively.Two previously-unknown proton-unbound nuclei
                      30Ar and 29Cl were identified by measuring the trajectories
                      of their in-flight decay products 28S+p+p and 28S+p,
                      respectively. The analysis of 28S-proton angular
                      correlations provided information on the decay energies and
                      structure of the observed states in 30Ar and 29Cl. The
                      assigned ground state and first excited state of 29Cl were
                      found at $1.8^(+0.1)_(-0.1)$ MeV and $2.3^(+0.1)_(-0.1)$ MeV
                      above the one-proton threshold, respectively. The ground
                      state of 30Ar was found to be $2.45^(+0.05)_(-0.10)$ MeV
                      above the 2p emission threshold. Due to a strong
                      Thomas-Ehrman shift, the lowest states in 30Ar and 29Cl
                      point to a violation of isobaric mirror symmetry in the
                      structure of these unbound nuclei. Detailed theoretical
                      calculations of the correlations between 2p decay products
                      followed by the Monte Carlo simulations of the detector
                      response to the 2p decay were performed in order to
                      investigate the decay mechanism of the 30Ar ground state.
                      Its decay is located in a transition region between
                      simultaneous 2p decay and sequential emission of protons.
                      Such an interplay between the true three-body and the
                      sequential two-body decay mechanisms is the first-time
                      observation in a nuclear ground state. The theoretical
                      investigations of the transition dynamics demonstrated a
                      surprisingly strong sensitivity of the decay correlation
                      patterns to the 2p decay energy of the 30Ar ground state and
                      the one-proton decay energy as well as the one-proton decay
                      width of the 29Cl ground state. The first hint on so-called
                      fine structure in the decay of 30Ar*(2+) was obtained by
                      detecting two decay branches into both ground state and
                      first excited state of 28S. The comparison of the
                      experimental 28S-proton angular correlations with those
                      resulting from the Monte Carlo simulations of the detector
                      response illustrates that other observed 30Ar excited states
                      decay by sequential emission of protons via intermediate
                      resonances in 29Cl. The decay schemes of the observed states
                      in 30Ar and 29Cl were constructed.},
      cin          = {FRS / SuperFRS-EC@FAIR},
      cid          = {I:(DE-Ds200)FRS-20110310OR124 /
                      I:(DE-Ds200)Coll-FAIR-SuperFRS-EC},
      pnm          = {612 - Cosmic Matter in the Laboratory (POF3-612) /
                      SUC-GSI-Giessen - Strategic university cooperation GSI-U
                      Gießen (SUC-GSI-GI) / HGF-IVF-VH-GS-201 - HGS-HIRe :
                      (HGF-IVF-VH-GS-201)},
      pid          = {G:(DE-HGF)POF3-612 / G:(DE-Ds200)SUC-GSI-GI /
                      G:(DE-Ds200)HGF-IVF-VH-GS-201},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:hebis:26-opus-122036},
      url          = {https://repository.gsi.de/record/201580},
}