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@INPROCEEDINGS{Westphal:1018169,
      author       = {Westphal, Moritz and Engels, Ralf W. and Faatz, Nicolas and
                      Kannis, Chrysovalantis and Klimczok, Berthold and Mandiwal,
                      Aditya and Maubach, Maike and Soltner, Helmut},
      title        = {{M}easurement of the occupation number of metastable atoms
                      in the hyperfine-substate β$_3$ in an atomic hydrogen beam},
      volume       = {433},
      publisher    = {Sissa Medialab Trieste, Italy},
      reportid     = {FZJ-2023-04609},
      pages        = {007},
      year         = {2023},
      abstract     = {After its discovery in 1947 by Willis Eugene Lamb and
                      Robert C. Retherford the Lamb shift was used to create Lamb
                      shift polarimeter to separate the 2S${_{1/2}}$ α1 and α2
                      hyperfinesubstates of hydrogen as well as the α3 substate
                      of deuterium. But for a new project at theTechnical
                      University of Munich, investigation of the bound-beta decay
                      of a neutron into a hydrogen atom anda neutrino, a Lamb
                      shift polarimeter is needed that is also capable of
                      separating the β3substate of hydrogen. Unfortunately, our
                      first attempt to use a Sona transition unit toexchange the
                      occupation numbers between α1 and β3 failed, because of
                      the unexpectedcomplexity of the transitions in this unit
                      [1]. The second idea of using a new kind of spinfilterwhich
                      uses two radio frequencies to separate all four hyperfine
                      substates of hydrogen alsofailed.Our third attempt is now to
                      build a transition unit that can induce magnetic dipole
                      transitionsbetween α2 and β3 as well as between α2 and
                      β4 (π transitions, i.e. an exchange of the occupation
                      numbers of these states). This is a similartransition to
                      what is used in atomic beam sources, in this case not for
                      ground state atoms but for metastableatoms, which requires a
                      much lower radio frequency. Another difference of this new
                      idea isthe smaller interaction time of the atoms with the
                      photons inside the transition unit due totheir much higher
                      velocity of roughly 2⋅10$^5$ m/s compared to velocities of
                      about 10$^3$ m/s in an atomic beam source.},
      month         = {Sep},
      date          = {2022-09-26},
      organization  = {19th Workshop on Polarized Sources,
                       Targets and Polarimetry, Mainz
                       (Germany), 26 Sep 2022 - 30 Sep 2022},
      cin          = {IKP-2 / IKP-TA / ZEA-1},
      cid          = {I:(DE-Juel1)IKP-2-20111104 / I:(DE-Juel1)IKP-TA-20111104 /
                      I:(DE-Juel1)ZEA-1-20090406},
      pnm          = {612 - Cosmic Matter in the Laboratory (POF4-612)},
      pid          = {G:(DE-HGF)POF4-612},
      typ          = {PUB:(DE-HGF)8},
      doi          = {10.22323/1.433.0007},
      url          = {https://juser.fz-juelich.de/record/1018169},
}