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@INPROCEEDINGS{Maharaj:1043679,
      author       = {Maharaj, Dalini and Rücker, Ulrich and Li, Jingjing and
                      Zakalek, Paul and Gutberlet, Thomas},
      title        = {{H}arnessing the {C}omplementary {P}roperties of {M}ethane
                      and {P}arahydrogen for the {D}esign of an {I}ntense {V}ery
                      {C}old {N}eutron {S}ource for the {H}igh {B}rilliance
                      {S}ource},
      reportid     = {FZJ-2025-02977},
      year         = {2025},
      abstract     = {Very cold neutron (VCN) sources present an exciting
                      opportunity for scientists to access unprecedented length
                      and time scales, and achieve improved resolution in neutron
                      experiments. VCNs are defined over a wide spectral range,
                      from 1 meV (9 Å) down to a few hundred neV (> several 100
                      Å). Recent advancements in the development of thermal
                      scattering kernels for candidate very cold neutron (VCN)
                      moderator materials have opened opportunities for exploring
                      conceptual designs of VCN sources tailored to emerging
                      high-intensity compact accelerator-driven neutron sources
                      (HiCANS) like the High Brilliance Neutron Source (HBS). In
                      contrast to the expansive moderator designs typical of large
                      reactor and spallation sources, HiCANS, with a smaller
                      source, necessitate compact moderator solutions. At the HBS,
                      a hydrogen-rich moderator is required to effectively slow
                      neutrons to the VCN energy range within the limited volume
                      that aligns with the target footprint of the HBS. Methane is
                      a promising candidate to serve as a VCN moderator since it
                      possesses a desirable low-lying rotor mode at ~ 1 meV, which
                      serves as a pathway for neutron moderation to VCN energies.
                      However, thin geometries are required to limit neutron
                      absorption. Owing to the characteristic dip in the total
                      neutron scattering cross section of liquid parahydrogen
                      (l-pH₂), below the thermal energy scale, thermal neutrons
                      are efficiently converted to cold neutrons, and cold
                      neutrons are subsequently easily transmitted in l-pH₂.
                      Informed also by earlier studies, a moderator concept,
                      harnessing the properties of both methane l-pH₂ has been
                      conceived, wherein a thin, large-surface area plate of
                      methane is boosted by a parahydrogen backing. A geometrical
                      optimisation of the moderator concept was conducted in PHITS
                      and the results shall be presented and compared against the
                      low dimensional l-pH₂. Perspectives are also provided for
                      instruments which may be optimally fed with this moderator
                      at HiCANS facilities.},
      month         = {Jul},
      date          = {2025-07-06},
      organization  = {The International Conference on
                       Neutron Scattering, Bella Center in
                       Copenhagen, Denmark, with the last day
                       at the European Spallation Source (ESS)
                       in nearby Lund, Sweden (Denmark), 6 Jul
                       2025 - 10 Jul 2025},
      subtyp        = {Invited},
      cin          = {JCNS-2 / JCNS-HBS / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)JCNS-HBS-20180709
                      / $I:(DE-82)080009_20140620$},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/1043679},
}