Magnetic shielding in a low-temperature torsion pendulum experiment

Abstract

A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 10(-4) G while simultaneously the moment of the magnet can be reduced by a factor of 7 x 10(4).