Neutron Guide System of the Ultracold Neutron Source for the PIK Nuclear Reactor

The optimization of the neutron guide system of a new ultracold neutron source based on superfluid helium for fundamental interaction physics research at the PIK reactor is considered. In the current configuration, it is planned to achieve a UCN density of 950 cm–3 in the closed converter chamber. After the upgrade, replacing the steel heat exchanger with a copper one can increase the UCN density in the closed converter chamber to 3400 cm–3. Monte Carlo simulations for the new source to calculate the UCN densities in the closed converter chamber and at the splitter outlet for future users planning experiments at this source are performed. In the simulations, the entire geometry and components of the neutron guide system are taken into account. The results show a steady-state density in the 10-L trap at the splitter outlet of 340 cm–3 after the heat exchanger upgrade.