Replacement for a Helium liquefier

The "Sektion Kälteanlagen" currently operates a helium liquefier, a Sulzer plant built in 1977. It cools heavy hydrogen gas for the large-scale research facility UCN (Ultra Cold Neutrons). The neutron source UCN produces neutrons that have an extremely low velocity, so-called ultra-cold neutrons. A 30 litre container filled with 5kg of heavy hydrogen (deuterium) forms the heart of this facility. To solidify the hydrogen gas, the gas has to be cooled down to a temperature below minus 255 The Sulzer liquefier of 1977 has become outdated and no longer meets today's requirements, neither in terms of performance nor energy efficiency. For details, see requirement specification PSI-DD93-001