Ultracold neutrons at the WWR-K: From the first experiments to a high-intensity UCN source

This article presents the development of ultracold neutron (UCN) research in Kazakhstan and outlines a concept for a new high-intensity UCN source at the WWR-K research reactor of the Institute of Nuclear Physics (INP, Almaty). A brief overview of the emergence of UCN physics and the formation of the INP scientific school is given in the context of early work at WWR-type research reactors equipped with thermal columns, where the first UCN sources were realized. The results of experiments performed at the WWR-K reactor are summarized, including configurations of UCN production and transport systems, key measurements, and limitations of the existing infrastructure. Based on an analysis of the neutronic characteristics of the WWR-K thermal column, a concept for a modernized UCN source is developed. The proposed approach includes the installation of a dedicated cryogenic module in the thermal column, optimization of the neutron spectrum and spatial distribution, and efficient extraction of UCNs to experimental stations. It is shown that the combination of reactor parameters, thermal column design, and proposed engineering solutions provides favorable conditions for the creation of an internationally competitive high-intensity UCN source and for the implementation of a long-term program of fundamental and applied research in Kazakhstan.