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@INPROCEEDINGS{Schwab:884203,
      author       = {Schwab, Alexander},
      title        = {{C}old moderator systems at {HBS}},
      reportid     = {FZJ-2020-03116},
      year         = {2020},
      abstract     = {The Jülich High Brilliance Neutron Source (J-HBS) will
                      provide neutrons to differentinstruments by utilizing
                      optimized Target-Moderator-Reflector (TMR) assemblies inthe
                      form of multiple target stations with different pulse
                      structures. These TMR unitsproduce neutrons of the required
                      wavelengths by using different combinations ofmoderators and
                      reflectors. For instruments that require long wavelength
                      neutrons,cryogenic materials are used to slow thermal
                      neutrons down to the cold energyrange. These so-called
                      “cold moderators” are optimized with regard to
                      neutronbrilliance by choosing the appropriate material and
                      dimensions.Two commonly used cold moderators, liquid
                      hydrogen and solid mesitylene, weretested in optimized
                      compact geometries at the Big Karl facility of the
                      synchrotronCOSY at the Forschungszentrum Jülich by
                      conducting neutron time-of-flight (TOF)measurements. The
                      effects of temperature (mesitylene) and ortho-para
                      ratio(hydrogen) on the moderators’ performance were
                      investigated in systematicexperimental parameter studies.
                      The efficiencies of the used cold moderators werecompared
                      and neutron transport simulation models have been
                      validated.With the aim to shift the neutron energy spectrum
                      to even lower values, a coldmoderator system is currently
                      being developed, which allows the use of
                      solidifiedmoderators at operating temperatures below 10 K.
                      For this system, methane will beused in phase II, as it is
                      one of the most promising candidates at such lowtemperatures
                      due to its low-lying energy levels, which allow the transfer
                      of smallamounts of energy. However, the use of solid methane
                      is challenging from anengineering perspective due to its low
                      thermal conductivity and poor radiationresistance.In this
                      presentation, the previously used cryogenic systems will be
                      described and theresults of the measurements at Big Karl
                      will be presented. Furthermore, preliminarydesign aspects of
                      the planned “10 K” cryostat will be discussed.},
      month         = {Sep},
      date          = {2020-09-17},
      organization  = {6th International HBS Meeting -
                       Virtual Meeting, Forschungszentrum
                       Jülich GmbH (Germany), 17 Sep 2020 -
                       18 Sep 2020},
      subtyp        = {Invited},
      cin          = {JCNS-2 / PGI-4 / JARA-FIT / JCNS-HBS},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
                      $I:(DE-82)080009_20140620$ / I:(DE-Juel1)JCNS-HBS-20180709},
      pnm          = {144 - Controlling Collective States (POF3-144) / 524 -
                      Controlling Collective States (POF3-524) / 6212 - Quantum
                      Condensed Matter: Magnetism, Superconductivity (POF3-621) /
                      6213 - Materials and Processes for Energy and Transport
                      Technologies (POF3-621) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (POF3-623)},
      pid          = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-524 /
                      G:(DE-HGF)POF3-6212 / G:(DE-HGF)POF3-6213 /
                      G:(DE-HGF)POF3-6G4},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/884203},
}