Ultracold neutron facility

Instrument layout

The high intensity of UCN/VCN at the experimental site stems from a combination of several design features that result in the strongest flux of UCN/VCN worldwide: A beam of very cold neutrons is extracted from ILL's vertical cold source by an optimized neutron guide system that dips into the liquid deuterium. UCN are produced "externally" by a Doppler shift device, the so called Steyerl neutron turbine.

In this way the high reflection and absorption losses associated with the windows that would be necessary in the case of direct UCN extraction are greatly reduced; furthermore, part of the beam can be used for experiments where VCN are required.

The neutrons are transported to five experimental platforms, where scientic users can connect their own experiment:

  • The platform PF2/VCN is dedicated to experiments using very cold neutrons.
  • The platforms PF2/MAM, PF2/UCN, and PF2/EDM can be used for experiments with ultracold neutrons. They are running in time-shared mode, making advantage of the fact that during the time of storage of UCN in one experiment, another experiment can be fed.
  • The platform PF2/TEST is operating at a lower flux. It is used for test experiments.