Development of UCN sources at PNPI

This article reviews the development of various sources for ultracold neutrons (UCNs) at Petersburg Nuclear Physics Institute (PNPI). For 45 years, PNPI has proposed and manufactured cryogenic devices neutron conversion to low energies. Based on beryllium, hydrogen deuterium, they can be operated in intense radiation fields near core a nuclear reactor. A more recently launched UCN source utilizes superfluid helium (He-II) as medium. Initially designed PNPI’s old WWR-M reactor, project been reshaped equip institute’s PIK reactor with modern this type. The projected density closed chamber is 2.2 × 103 cm−3, which, calculations transport show, will provide 200 cm−3 chambers EDM spectrometer connected by guide. Experiments full-scale model have demonstrated that heat load 60 W removed from He-II converter temperature 1.37 K. fact confirms practical possibility implement low-temperature converters under “in-pile” conditions large inflows. review concludes presentation options based European Spallation Source.