A magnetically shielded room

A magnetically shielded room (passive / DC shielding) for conducting paleomagnetic and rock-magnetic experiments in an ultra-low magnetic field environment will be installed within the Solid Earth Geophysics (SEG-BK102) Laboratory, Department of Geosciences and Geography, University of Helsinki, located in the Physicum building. The shielded room will contain a horizontal 2G cryogenic magnetometer (SRM) with its associated electronics, one large-volume thermal demagnetizer (oven), a Molspin magnetometer, a non-magnetic working desk, and necessary shelving for SRM electronics and storage. The shielded space therefore requires a relatively large internal area (4x3.3 m = 13.2 m²) with adequate ventilation. The effective laboratory space available is approximately 23.8 m² (5.4 × 4.4 m). The laboratory has a structural floor-to-ceiling height of ~3.75 m, with overhead ducting at this level defining the maximum allowable installation height 3 meters. Therefore, the walls, floor, and ceiling of the shielded room must be designed to be as thin as technically feasible while still achieving the required shielding performance. Because several instruments will be installed inside the room, the magnetometers cannot be positioned at the geometric center of the shielded volume, and thus the shielding performance must remain effective throughout the usable interior space, including near the perimeter, with a low spatial magnetic field gradient across the working area.