Speaker
Description
New high-brilliance ultracold neutron source at the IBR-2 pulsed reactor is currently being developed at the FLNP JINR. Work on the project of a new type of UCN source requires conducting a series of methodical experiments with very cold neutrons, which are currently not feasible at JINR. Therefore, at the first stage of work on the project, it is planned to create a prototype VCN channel. It is assumed that one of the main components of this VCN facility will be a monochromator, which makes it possible to produce a monochromatic neutron beam with velocities of $v = 20 \pm 1$ m/s.
In this work, an optical Bragg monochromator for very cold neutrons is considered. The monochromator consists of two multilayered NiMo-Ti mirrors arranged to preserve the initial beam direction. The necessary requirements for such a monochromator were analyzed and compared with a mechanical velocity selector. It has been shown that the Bragg monochromator allows for higher transmissivity with a better monochromatization. Moreover, as an extension to the monochromator, neutron interference filter with sharp transmissivity line was also considered. This filter allows to maintain even better monochromatization with a neutron velocity range of $v = 20.2 \pm 0.1$ m/s.
