A superconducting magnet arrangement including: an outer vacuum container (OVC) housing magnet coils; a cryogen vessel thermally linked to the magnet coils; a cold head sock accommodating a cold head, with a thermal contact provided between the cold head and the magnet coils; tubes linking the interior of the cryogen vessel with the interior of the cold head sock; and a thermosiphon circuit defined by the cryogen vessel, the tubes, and the cold head sock. Pre-cooling and removal of ice build-up may be performed using the thermosiphon circuit.