Cryogenic magnetic shielding for SCUBA-2

摘要

SCUBA-2 is a new wide-field submillimeter continuum instrument being commissioned on the James ClerkMaxwell Telescope on Mauna Kea in Hawaii. SCUBA-2 uses large-scale arrays of superconducting bolometerswith SQUID- (superconducting quantum interference device) based multiplexing and amplification. The sensitiv-ity of the devices that compose the detector arrays to magnetic fields is such that magnetic shielding, consistingof superconducting and high-permeability materials, was fitted to the detector enclosure at 1 K to reduce themagnetic field strength at the focal plane. This paper describes the design and construction of the cryogenicshielding, and presents verification measurements. The shielding performance was found to meet the instrumentrequirements, and compared well to the modelled results.