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| Home > Publications database > TOWARDS THE DEVELOPMENT OF A COMPACT VERY COLD NEUTRON SOURCE FOR THE HIGH BRILLIANCE NEUTRON SOURCE |
| Poster (Invited) | FZJ-2024-05627 |
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2024
Abstract: Very cold neutron (VCN) sources present an exciting opportunity for scientists to access unprecedented length and time scales, and achieve improved sensitivity in neutron experiments [1]. VCNs are defined over a wide spectral range, from 1 meV (9 Å) down to a few hundred neV (> several 100 Å). Wavelengths of up to several tens of Å are of particular interest to many research communities. Recently, thermal scattering kernels were developed for candidate VCN moderator and reflector materials under the HighNESS project [2]. These advances present an opportunity for the conceptual design of VCN sources at newly emerging high-current compact accelerator-driven neutron sources (Hi-CANS). The High Brilliance neutron Source (HBS) is a Hi-CANS project which hosts a linear accelerator delivering a pulsed proton beam of energy, 70 MeV, and peak current, 100 mA, to a novel high-power tantalum target and compact target-moderator-reflector (TMR) [3]. A low-dimensional parahydrogen cold moderator has already been designed for the HBS and tested at the JULIC Neutron Platform. Starting from this concept, a Monte Carlo study is underway to develop a target moderator reflector (TMR) to realise a very cold neutron source for the HBS. The low dimensional parahydrogen moderator will serve as an efficient cold neutron converter, and within it, an appropriate secondary moderator is implemented to shift the neutron spectrum generated by the parahydrogen to lower energies, or equivalently longer wavelengths. As methane is known to generate a colder neutron spectrum than parahydrogen, it is currently being investigated to shift the cold spectrum of parahydrogen to lower energies. Figure 1 a.) shows a geometry with parahydrogen only and that with methane embedded in parahydrogen. Figure 1 b.) clearly shows that methane shifts the spectrum to lower energies. Results from a full optimization of this moderator-reflector geometry conducted in PHITS shall be presented. [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] T. Brückel, T. Gutberlet (Eds.), Conceptual Design Report Jülich High Brilliance Neutron Source, ISBN 978-3-95806-501-7 (Forschungszentrum Jülich, 2020).
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