UK SBS PR16197 Magnetic Shield for Vertical Cryostat

The Science and Technology Facilities Council (STFC), through its Daresbury Laboratory, invites tenders for the supply of a passive magnetic shielding for a liquid helium test cryostat for SRF cavities. A magnetic shield is required to attenuate stray magnetic field to less than 1 micro-T in the region surrounding Superconducting - RF (SRF) cavities in a large vertical cryostat. SRF cavities mounted on an especially designed insert will be tested at a temperature of 2 K with superfluid liquid helium. Stray magnetic field surrounding the cryostat varies between 60 micro-T to 100 micro-T. The shield will surround the entire cryostat from outside except the top opening. Considering the large dimensions, it is foreseen that the shield will consist of a number of parts assembled together on site to form a single shield. The cryostat will be located inside a square shaped concrete pit of 2200 mm x 2200 mm.