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@PHDTHESIS{Lehr:246069,
      author       = {Lehr, Christopher},
      title        = {{L}ow-energy dipole response of the halo nuclei 6,8{H}e},
      school       = {Technische Universität Darmstadt},
      type         = {Dissertation},
      publisher    = {TU Darmstadt},
      reportid     = {GSI-2022-00322},
      pages        = {139 S.},
      year         = {2022},
      note         = {Dissertation, Technische Universität Darmstadt, 2021},
      abstract     = {In this thesis the low-energy dipole response of 6He and
                      8He is investigated using relativistic Coulomb excitation in
                      inverse kinematics. The dipole strength distributions of 6He
                      and 8He are extracted and presented up to 15 MeV excitation
                      energy. This is the first complete measurement of the
                      low-energy dipole response of 8He. An experiment is
                      presented that has been performed to measure the decay of
                      6He and 8He after electromagnetic excitation with high
                      precision and statistics. For the first time a four neutron
                      decay channel is successfully measured and analyzed using
                      the invariant-mass method. The combination of the neutron
                      detectors new Large Area Neutron Detector (NeuLAND) and
                      Neutron Detection System for Breakup of Unstable Nuclei with
                      Large Acceptance (NEBULA) at the Superconducting Analyzer
                      for multi-particle from Radio Isotope Beams (SAMURAI) setup
                      at the RIKEN Nishina Center in Japan made this possible. The
                      full setup is presented and the measurement principles are
                      explained. The calibration procedures and analysis
                      techniques applied in this work are described in detail.
                      This includes an improved procedure to identify and subtract
                      the contribution by nuclear excitation reactions from the
                      measured cross section. For the momentum reconstruction of
                      the high energy neutrons, a new reconstruction algorithm is
                      developed. The setups acceptance, efficiency and relative
                      energy resolution is characterized using GEANT4 simulations.
                      The cross talk rejection performance of the developed
                      reconstruction algorithm is determined and correction
                      procedures are developed. The results obtained on the dipole
                      response of 6He and 8He are compared to previous results
                      from experiment and theory. Furthermore, correlations in the
                      ground state are investigated in a cluster approach. The
                      final-state correlations are investigated in Jacobi
                      coordinates and by comparing to a phase-space decay. New
                      results on the 5He and 7He ground-state resonances are
                      presented and discussed as a side topic.},
      cin          = {KRA / R3B@FAIR},
      cid          = {I:(DE-Ds200)KRA-20150901OR349 / I:(DE-Ds200)Coll-FAIR-R3B},
      pnm          = {612 - Cosmic Matter in the Laboratory (POF4-612)},
      pid          = {G:(DE-HGF)POF4-612},
      experiment   = {$EXP:(DE-Ds200)Experiment_without_proposal_number-20200803$},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:tuda-tuprints-202676},
      doi          = {10.26083/TUPRINTS-00020267},
      url          = {https://repository.gsi.de/record/246069},
}