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@ARTICLE{Houben:21221,
      author       = {Houben, A. and Schweika, W. and Brückel, T. and
                      Dronskowski, R.},
      title        = {{N}ew neutron-guide concepts and simulation results for teh
                      {POWTEX} instrument},
      journal      = {Nuclear instruments $\&$ methods in physics research / A},
      volume       = {680},
      issn         = {0168-9002},
      address      = {Amsterdam},
      publisher    = {North-Holland Publ. Co.},
      reportid     = {PreJuSER-21221},
      pages        = {124 - 133},
      year         = {2012},
      note         = {Jorg Voigt is acknowledged for taking part in discussions
                      about elliptic neutron guides. Klaus Lieutenant and Michael
                      Fromme are acknowledged for their effort on the VITESS
                      software. We acknowledge funding from the German Federal
                      Ministry of Education and Research (BMBF) in the frame of a
                      "Verbundforschungsprojekt".},
      abstract     = {The POWTEX instrument will be a high-intensity
                      time-of-flight diffractometer at a continuous reactor
                      source. Its design utilizes several new concepts and is
                      suited for small samples. Herein, the optimization of the
                      guide system is presented. It is based on two coupled
                      elliptic neutron guides intersected by the pulse-chopper as
                      an eye of a needle to increase the time resolution and to
                      reduce the background transported from the source. The
                      optical properties of two coupled ellipses are investigated
                      with respect to their design constraints in terms of
                      geometry and regarding the choice of the super-mirror
                      coating. It is shown that low-divergent neutrons are
                      preferentially transported near the pulse-chopper.
                      Accordingly, a numerical optimization is utilized to tailor
                      the coating to the instrument requirements using the
                      back-tracing method that has been developed for the VITESS
                      Monte-Carlo simulation package for virtual instrumentation.
                      The procedure allows for a cost and background optimization
                      because the me-value can be kept as low as needed. For a
                      diffractometer, the homogeneity of the divergence profile is
                      crucial. Herein, the new development of neutron guides with
                      octagonal cross sections is investigated. Appendix A shows a
                      step-by-step description of the newly developed optimization
                      features within VITESS as it was used for POVVTEX. (C) 2012
                      Elsevier B.V. All rights reserved.},
      keywords     = {J (WoSType)},
      cin          = {PGI-4 / JCNS-2 / JARA-FIT},
      ddc          = {530},
      cid          = {I:(DE-Juel1)PGI-4-20110106 / I:(DE-Juel1)JCNS-2-20110106 /
                      $I:(DE-82)080009_20140620$},
      pnm          = {Grundlagen für zukünftige Informationstechnologien
                      (FUEK412) / 544 - In-house Research with PNI (POF2-544)},
      pid          = {G:(DE-Juel1)FUEK412 / G:(DE-HGF)POF2-544},
      experiment   = {EXP:(DE-MLZ)POWTEX-20140101},
      shelfmark    = {Instruments $\&$ Instrumentation / Nuclear Science $\&$
                      Technology / Physics, Particles $\&$ Fields / Spectroscopy},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000304894600021},
      doi          = {10.1016/j.nima.2012.03.015},
      url          = {https://juser.fz-juelich.de/record/21221},
}