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@INPROCEEDINGS{Maharaj:1040554,
      author       = {Maharaj, Dalini and Rücker, Ulrich and Li, Jingjing and
                      Zakalek, Paul and Gutberlet, Thomas},
      title        = {{T}owards the {D}evelopment of a {C}ompact {V}ery {C}old
                      {N}eutron {S}ource for the {H}igh {B}rilliance {N}eutron
                      {S}ource ({HBS})},
      reportid     = {FZJ-2025-01921},
      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 [1]. VCNs are defined over a wide spectral
                      range, from 1 meV (9 Å) down to a few hundred neV (>
                      several100 Å). Recent advancements in the development of
                      thermal scattering kernels for candidate verycold neutron
                      (VCN) moderator and reflector materials under the HighNESS
                      project [2] have openedopportunities for exploring
                      conceptual designs of VCN sources tailored to emerging
                      high-intensitycompact accelerator-driven neutron sources
                      (HiCANS) like the High Brilliance Neutron Source (HBS)[3].
                      In contrast to the expansive moderator designs typical of
                      large reactor and spallation sources,HiCANS, with a smaller
                      source, necessitate highly efficient and compact moderator
                      solutions. Forthe ESS, moderator concepts have been
                      developed based on solid deuterium; however, at the HBS,
                      ahydrogen-rich moderator is required to effectively slow
                      neutrons to the VCN energy range withinthe limited volume
                      that aligns with the HBS footprint. Methane, a
                      well-established and highly efficientneutron moderator is a
                      promising candidate to serve as a VCN moderator since it
                      possessesa desirable low-lying rotor mode at ~ 1 meV. Liquid
                      parahydrogen (l-pH₂) is a known efficient coldneutron
                      moderator since it is able to convert thermal neutrons to
                      cold neutrons via a single interaction.Various geometrical
                      configurations combining methane and l-pH₂ have been
                      considered toharness the complementary properties of both
                      materials in potential designs of a VCN moderatorfor the
                      HBS. Monte Carlo simulations using the PHITS particle
                      transport code were conducted toevaluate the performance of
                      these configurations when fed by the HBS tantalum source.
                      This studypresents a comparative analysis of the results
                      obtained for various moderator geometries consideredwhen
                      compared with a pure, low dimensional l-pH₂ cold
                      source.References[1] J.M Carpenter and B.J. Micklich, ANL
                      (05/42) (2005).[2] V. Santoro et al, (2023). Nuclear Science
                      and Engineering, 198 31–63 (2023)[3] Baggemann J. et al.
                      (2023). Technical Design Report HBS Volume 2 –Target
                      Stations and Moderators.Grafische Medien, Forschungszentrum
                      Jülich GmbH. ISBN 978-3-95806-710-3.},
      month         = {Feb},
      date          = {2025-02-24},
      organization  = {11th International Meeting of the
                       Union for Compact Accelerator-driven
                       Neutron Sources, Pinnacle Hotel at the
                       Pier, North Vancouver (Canada), 24 Feb
                       2025 - 28 Feb 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)6},
      url          = {https://juser.fz-juelich.de/record/1040554},
}