Skip to Main Content
Your organization might have access to this article on the publisher's site. To check, click on this link:http://dx.doi.org/+10.1063/1.332422
We present a technique for orienting a superconductive magnetic gradiometer, formed by two coplanar pickup loops, to suppress gradient fluctuations originating from nearby magnetic objects. We developed the technique to quiet fluctuations coming from the steel structure of an oceanographic research tower that impressed gradients of about 200 nT/m at the gradiometer. Facing the loops nearly edgewise to the tower quiets noise to the level of inherent instrument noise, ∼0.1 (pT/m)/(Hz)1/2, at frequencies from 1 to 25 Hz. It also quiets noise nearly to inherent instrument noise at frequencies from 0.1 to 10 mHz. Comparison of the empirical result with the quieting expected from a formulation of gradiometer response shows that gradient fluctuations coming from a nearby magnetic object appear to a gradiometer to come from fluctuations in location and moment of a magnetic dipole near the magnetic centroid of the object, whatever the magnetic structure of the object.