Method and apparatus for balancing the magnetic field detecting loops of a cryogenic gradiometer using trimming coils and superconducting disks

DETAILED DESCRIPTION In the present invention a gradiometer is balanced by inserting a trimming element, which is comprised of two relatively small balancing loops of opposite, flux cancelling, winding sense, in series with but physically external to one of the gradiometer loops.
A superconducting disk of the proper characteristics is placed within one of the balancing loops of the trimming element to compensate for measured imbalance of the gradiometer loops.
Additional balancing may be achieved by adding an additional superconducting disk in the vicinity of but external to one of the balancing loops and in a plane that is orthogonal to the plane of the balancing loops.
Further balancing may be achieved by inserting a second trimming element in one of the gradiometer loops but in a direction that is orthogonal to that of the first trimming element.